PaperlayerView exact revision on arXiv

Source-linked AI summary

Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report

R. Abdul Khalek, A. Accardi, J. Adam, D. Adamiak, W. Akers, M. Albaladejo, A. Al-bataineh, M. G. Alexeev, F. Ameli, P. Antonioli, N. Armesto, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, M. Asai, E. C. Aschenauer, S. Aune, H. Avagyan, C. Ayerbe Gayoso, B. Azmoun, A. Bacchetta, M. D. Baker, F. Barbosa, L. Barion, K. N. Barish, P. C. Barry, M. Battaglieri, A. Bazilevsky, N. K. Behera, F. Benmokhtar, V. V. Berdnikov, J. C. Bernauer, V. Bertone, S. Bhattacharya, C. Bissolotti, D. Boer, M. Boglione, M. Bondì, P. Boora, I. Borsa, F. Bossù, G. Bozzi, J. D. Brandenburg, N. Brei, A. Bressan, W. K. Brooks, S. Bufalino, M. H. S. Bukhari, V. Burkert, N. H. Buttimore, A. Camsonne, A. Celentano, F. G. Celiberto, W. Chang, C. Chatterjee, K. Chen, T. Chetry, T. Chiarusi, Y. -T. Chien, M. Chiosso, X. Chu, E. Chudakov, G. Cicala, E. Cisbani, I. C. Cloet, C. Cocuzza, P. L. Cole, D. Colella, J. L. Collins, M. Constantinou, M. Contalbrigo, G. Contin, R. Corliss, W. Cosyn, A. Courtoy, J. Crafts, R. Cruz-Torres, R. C. Cuevas, U. D'Alesio, S. Dalla Torre, D. Das, S. S. Dasgupta, C. Da Silva, W. Deconinck, M. Defurne, W. DeGraw, K. Dehmelt, A. Del Dotto, F. Delcarro, A. Deshpande, W. Detmold, R. De Vita, M. Diefenthaler, C. Dilks, D. U. Dixit, S. Dulat, A. Dumitru, R. Dupré, J. M. Durham, M. G. Echevarria, L. El Fassi, D. Elia, R. Ent, R. Esha, J. J. Ethier, O. Evdokimov, K. O. Eyser, C. Fanelli, R. Fatemi, S. Fazio, C. Fernandez-Ramirez, M. Finger, M. Finger, D. Fitzgerald, C. Flore, T. Frederico, I. Friščić, S. Fucini, S. Furletov, Y. Furletova, C. Gal, L. Gamberg, H. Gao, P. Garg, D. Gaskell, K. Gates, M. B. Gay Ducati, M. Gericke, G. Gil da Silveira, F. -X. Girod, D. I. Glazier, K. Gnanvo, V. P. Goncalves, L. Gonella, J. O. Gonzalez Hernandez, Y. Goto, F. Grancagnolo, L. C. Greiner, W. Guryn, V. Guzey, Y. Hatta, M. Hattawy, F. Hauenstein, X. He, T. K. Hemmick, O. Hen, G. Heyes, D. W. Higinbotham, A. N. Hiller Blin, T. J. Hobbs, M. Hohlmann, T. Horn, T. -J. Hou, J. Huang, Q. Huang, G. M. Huber, C. E. Hyde, G. Iakovidis, Y. Ilieva, B. V. Jacak, P. M. Jacobs, M. Jadhav, Z. Janoska, A. Jentsch, T. Jezo, X. Jing, P. G. Jones, K. Joo, S. Joosten, V. Kafka, N. Kalantarians, G. Kalicy, D. Kang, Z. B. Kang, K. Kauder, S. J. D. Kay, C. E. Keppel, J. Kim, A. Kiselev, M. Klasen, S. Klein, H. T. Klest, O. Korchak, A. Kostina, P. Kotko, Y. V. Kovchegov, M. Krelina, S. Kuleshov, S. Kumano, K. S. Kumar, R. Kumar, L. Kumar, K. Kumerički, A. Kusina, K. Kutak, Y. S. Lai, K. Lalwani, T. Lappi, J. Lauret, M. Lavinsky, D. Lawrence, D. Lednicky, C. Lee, K. Lee, S. H. Lee, S. Levorato, H. Li, S. Li, W. Li, X. Li, X. Li, W. B. Li, T. Ligonzo, H. Liu, M. X. Liu, X. Liu, S. Liuti, N. Liyanage, C. Lorcé, Z. Lu, G. Lucero, N. S. Lukow, E. Lunghi, R. Majka, Y. Makris, I. Mandjavidze, S. Mantry, H. Mäntysaari, F. Marhauser, P. Markowitz, L. Marsicano, A. Mastroserio, V. Mathieu, Y. Mehtar-Tani, W. Melnitchouk, L. Mendez, A. Metz, Z. -E. Meziani, C. Mezrag, M. Mihovilovič, R. Milner, M. Mirazita, H. Mkrtchyan, A. Mkrtchyan, V. Mochalov, V. Moiseev, M. M. Mondal, A. Morreale, D. Morrison, L. Motyka, H. Moutarde, C. Muñoz Camacho, F. Murgia, M. J. Murray, P. Musico, P. Nadel-Turonski, P. M. Nadolsky, J. Nam, P. R. Newman, D. Neyret, D. Nguyen, E. R. Nocera, F. Noferini, F. Noto, A. S. Nunes, V. A. Okorokov, F. Olness, J. D. Osborn, B. S. Page, S. Park, A. Parker, K. Paschke, B. Pasquini, H. Paukkunen, S. Paul, C. Pecar, I. L. Pegg, C. Pellegrino, C. Peng, L. Pentchev, R. Perrino, F. Petriello, R. Petti, A. Pilloni, C. Pinkenburg, B. Pire, C. Pisano, D. Pitonyak, A. A. Poblaguev, T. Polakovic, M. Posik, M. Potekhin, R. Preghenella, S. Preins, A. Prokudin, P. Pujahari, M. L. Purschke, J. R. Pybus, M. Radici, R. Rajput-Ghoshal, P. E. Reimer, M. Rinaldi, F. Ringer, C. D. Roberts, S. Rodini, J. Rojo, D. Romanov, P. Rossi, E. Santopinto, M. Sarsour, R. Sassot, N. Sato, B. Schenke, W. B. Schmidke, I. Schmidt, A. Schmidt, B. Schmookler, G. Schnell, P. Schweitzer, J. Schwiening, I. Scimemi, S. Scopetta, J. Segovia, R. Seidl, S. Sekula, K. Semenov-Tian-Shanskiy, D. Y. Shao, N. Sherrill, E. Sichtermann, M. Siddikov, A. Signori, B. K. Singh, S. Širca, K. Slifer, W. Slominski, D. Sokhan, W. E. Sondheim, Y. Song, O. Soto, H. Spiesberger, A. M. Stasto, P. Stepanov, G. Sterman, J. R. Stevens, I. W. Stewart, I. Strakovsky, M. Strikman, M. Sturm, M. L. Stutzman, M. Sullivan, B. Surrow, P. Svihra, S. Syritsyn, A. Szczepaniak, P. Sznajder, H. Szumila-Vance, L. Szymanowski, A. S. Tadepalli, J. D. Tapia Takaki, G. F. Tassielli, J. Terry, F. Tessarotto, K. Tezgin, L. Tomasek, F. Torales Acosta, P. Tribedy, A. Tricoli, Triloki, S. Tripathi, R. L. Trotta, O. D. Tsai, Z. Tu, C. Tuvè, T. Ullrich, M. Ungaro, G. M. Urciuoli, A. Valentini, P. Vancura, M. Vandenbroucke, C. Van Hulse, G. Varner, R. Venugopalan, I. Vitev, A. Vladimirov, G. Volpe, A. Vossen, E. Voutier, J. Wagner, S. Wallon, H. Wang, Q. Wang, X. Wang, S. Y. Wei, C. Weiss, T. Wenaus, H. Wennlöf, N. Wickramaarachchi, A. Wikramanayake, D. Winney, C. P. Wong, C. Woody, L. Xia, B. W. Xiao, J. Xie, H. Xing, Q. H. Xu, J. Zhang, S. Zhang, Z. Zhang, Z. W. Zhao, Y. X. Zhao, L. Zheng, Y. Zhou, P. Zurita

arXiv:2103.05419v3physics.ins-dethep-exhep-phnucl-exnucl-th

TL;DR

EIC physics measurements call for detector requirements matched to a wide range of topics. The Yellow Report summarizes those topics and requirements and develops detector concepts. It recommends two general-purpose detectors to support independent cross-checking of important results.

  • Problem

    The report addresses how to match detector acceptance and performance to the EIC’s wide range of physics measurements.

    Source: §2.1 · p. 24

  • Method

    The report selects crucial EIC physics topics and summarizes the machine parameters and detector requirements needed to address them.

    Source: §2.1 · p. 24

  • Results

    The Yellow Report recommends two general-purpose detectors, whose independent cross-checks can build confidence in important results.

    Source: §12.6 · p. 668

  • Takeaways & Limitations

    Electromagnetic-calorimetry requirements can be met or nearly met with developed technologies; PbWO4 is the practical compact choice for η < −2, while several options exist elsewhere.

    Source: Discussion · p. 517

    It remains unclear whether current front-end ASIC capabilities cover the final detector requirements, making suitable electronics development a high-risk, high-priority area.

    Source: §14.6 · p. 716

Abstract

from arXiv · show

This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions. This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter

Author List

The author list documents an extensive collaboration, linking contributors to numbered institutional affiliations and marking editorial and working-group roles.

Author List

  • The roster runs from R. Abdul Khalek to P. Zurita, with contributors listed across multiple entries.The final author entry is followed by the numbered institutional affiliations.Source: Author List · pp. 5–6
  • The numbered affiliations include universities, national laboratories, and research institutes in multiple countries.The listed locations span institutions in the Americas, Europe, Asia, and the Middle East.Source: Author List · pp. 6–9
  • Symbols in the author list identify editors, working-group conveners, sub-working-group conveners, and the technical editor.The legend assigns $, *, +, and # to these roles, respectively.Source: Author List · p. 9

10 Detector Challenges & Performance Requirements

Section 10 organizes detector challenges and performance requirements around beam conditions, detector and interaction-region design, event rates, backgrounds, systematic uncertainties, and physics requirements.

10.1 Beam Energies, Polarization, Versatility, Luminosities

  • The section addresses beam energies, polarization, versatility, and luminosities.Source: §10 · p. 15

10.2 Integrated Detector and Interaction Region

  • It considers the integrated detector and interaction region.Source: §10 · p. 15

10.3 Rate and Multiplicities

10.4 Backgrounds

10.5 Systematic Uncertainties

10.6 Physics Requirements

11 Detector Aspects … The Electron-Ion Collider

The Yellow Report documents the EIC’s science case and emerging detector concepts, supporting development of equipment suited to the program. The supplied material describes the collider’s capabilities and lists detector topics, but provides no detailed detector-performance findings.

11 Detector Aspects

  • Chapter 11 covers detector magnets, tracking, electromagnetic and hadron calorimetry, particle identification, and far-forward and far-backward detectors.Source: §11 · p. 15
  • Chapter 11 also lists detector challenges and technologies, polarimetry, readout electronics and data acquisition, software and data preservation, and artificial intelligence.Source: §11 · p. 15
  • The report’s detector-concept contents include silicon-vertex tracking, tracking, particle identification, calorimetry, auxiliary detectors, and electronics.Source: §11 · p. 16

The Electron-Ion Collider

  • The EIC will collide high-energy electrons with proton or ion beams, including polarized beams, to study nucleon and nuclear structure.The report describes the facility as a high-intensity electron-ion collider with access to polarized electron and light-ion beams.Source: The Electron-Ion Collider · pp. 21–22
  • The design includes ion beams from deuterons to heavy nuclei, variable e+p center-of-mass energies of 20−100 GeV with an upgrade to 140 GeV, and the possibility of multiple interaction regions.Source: The Electron-Ion Collider · p. 21
  • The Yellow Report initiative advances community physics studies and detector concepts, providing a basis for equipment development that considers complementary detectors.The report describes its studies as preparation for EIC realization and future Technical Design Reports.Source: The Electron-Ion Collider · p. 23
  • The Yellow Report work was organized by the EIC User Group through a sustained 2020 effort involving four meetings and remote interactions during the pandemic.The effort was overseen by eight conveners and 41 sub-conveners.Source: The Electron-Ion Collider · p. 23

Physics Measurements and Requirements … Nonperturbative charm

This section outlines the EIC’s broad physics program, spanning nucleon structure, spin and mass, nuclear QCD, hadronization, and parton distributions, including studies of flavor and nonperturbative charm. It summarizes the machine and detector requirements, concepts, and capabilities needed to support these measurements.

2.1 Introduction

  • The EIC addresses how nucleon mass and spin emerge, how partons are distributed in momentum and position, and how quarks and gluons behave in nuclear matter.The motivating questions also include gluon density and possible saturation in nuclei.Source: §2.1 · pp. 24–25

2.2 Origin of Nucleon Spin

  • Measurements below x ≲ 0.005 would constrain quark and gluon helicity distributions and reduce uncertainties in the nucleon spin decomposition and parton angular momenta.The EIC’s polarized DIS program requires a broad x and Q2 range; detector needs include precise scattered-electron energy measurement and electron/hadron separation.Source: §2.2 · p. 27

2.3 Origin of Nucleon Mass

  • Near-threshold exclusive quarkonium production can probe the QCD trace anomaly’s role in nucleon mass, while pion and kaon form factors and structure functions probe hadron-mass generation.The quarkonium cross-section measurement requires high luminosity, low-Q2 electron-energy precision, and forward recoil-proton detection to measure t-dependence; comparing pion and kaon form factors across Q2 is informative because of their different quark-mass contributions.Source: §2.3 · p. 28

2.4 Multi-Dimensional Imaging of the Nucleon

  • With polarized beams and broad x and Q2 coverage, the EIC can map quark- and gluon-flavor TMDs and study their QCD evolution across transverse-momentum scales.SIDIS identifies hadrons in coincidence with scattered electrons; π/K/p separation at 3 σ is required up to 50 GeV/c forward, 10 GeV/c central, and 7 GeV/c backward, with neutron-rich D or 3He beams needed to disentangle flavor dependence.Source: §2.4 · p. 29, §2.5 · p. 30

2.5 Imaging the Transverse Spatial Distributions of Partons

  • Exclusive DVCS and meson production can determine GPDs and probe transverse parton distributions, proton angular momentum, the energy-momentum tensor, and internal pressure and shear forces.For protons, measurements over 0.04 ≲ t < 1.5 GeV2 are anticipated to map parton distributions down to 0.1 fm; low cross-sections require high luminosity and forward-proton acceptance.Source: §2.5 · pp. 30–31

2.6 Physics with High-Energy Nuclear Beams at the EIC

  • At low x, inclusive and semi-inclusive EIC measurements can explore nuclear sea-quark and gluon structure and test for saturation in large nuclei.Proposed signatures include suppression of away-side dihadron correlations with increasing nuclear size and coherent diffraction, predicted to exceed 20% of the e+A cross-section; studies require high energies, heavy nuclei, forward instrumentation, and detector hermeticity.Source: §2.6 · p. 31, §2.7 · p. 32

2.7 Nuclear Modifications of Parton Distribution Functions

  • EIC measurements from photoproduction to high Q2 can constrain nuclear PDFs across a broad continuous range and improve understanding of nuclear modifications.F2 and FL constrain nuclear PDFs, with FL requiring multiple center-of-mass energies; charm production via photon-gluon fusion supplies an independent high-x gluon constraint, and charm measurements require impact-parameter resolution σxy ∼20/pT ⊗5 µm.Source: §2.7 · pp. 32–33

2.8 Passage of Color Charge Through Cold QCD Matter

  • Jets and heavy-flavor production across nuclei of different sizes can probe parton energy loss, transverse-momentum broadening, hadronization, and nuclear-matter transport.Comparisons of e+p and e+A collisions, matched beam energies, and a broad nuclear-size range support systematic studies; jet measurements require high center-of-mass energy, tracking, and calorimetry.Source: §2.8 · pp. 34–35

2.9 Connections to Other Fields

  • EIC precision data can constrain parton distributions and BSM couplings, test the running of the weak mixing angle, and support new-particle searches and astroparticle studies.Hadronic-interaction models, nuclear parton distributions, and neutrino scattering are among the connections described.Source: §2.9 · p. 35
  • High-energy diffractive scattering can probe short-range nuclear forces through target-region nucleon correlations, while nuclear structure informs tomography and spectator-tagged reactions.The passage connects short-range nucleon-nucleon correlations to high-momentum tails of nuclear wave functions and notes signs of universal behavior across nuclei.Source: §2.10 · p. 36

2.10 Summary of Machine Design Parameters

  • The machine design depends on luminosity, variable center-of-mass energy, polarized lepton and light-ion beams, and ion beams from deuterons to heavy nuclei; two interaction regions are desired.Heavy ions provide access to high gluon densities, while light ions support studies of gluon-saturation A-dependence and short-range correlations.Source: §2.10 · pp. 36–37

Detector Concepts

  • Detector concepts combine region-specific technologies to meet differing requirements, with complementary detector options considered for the two interaction regions.The detector effort emphasizes integrated forward and backward systems and multiple hermetic functions for measuring and identifying final-state particles.Source: §2.11 · p. 37, Detector Concepts · p. 41, §3.1 · p. 42

2.11 Summary of Detector Requirements

  • The detector must provide 4π hermetic coverage, primary acceptance over −4 < η < 4, and precise reconstruction of final-state particles across the EIC kinematic range.Auxiliary detectors extend coverage for low-Q2 electrons and far-forward protons and neutrons; requirements also include central and backward momentum resolution, heavy-flavor impact-parameter resolution, and particle identification.Source: §2.11 · p. 39

3.1 Tracking and Vertexing Detector Systems

  • Two baseline tracking concepts are an all-silicon system and a hybrid silicon-vertex-detector-plus-TPC system, with alternative forward and backward endcap options.The concepts draw on semiconductor and gaseous technologies; silicon systems target high tracking and vertexing resolution with low material budgets.Source: §3.1 · pp. 42–43

3.2 Particle Identification Detector Systems

  • Particle identification must separate electrons, pions, kaons, and protons; proposed systems combine Cherenkov detectors and time-of-flight, with region-specific options including dRICH, DIRC, and mRICH.The required separation is better than 3σ for pion/kaon/proton in all rapidity regions; low-momentum timing and GEM transition-radiation detectors are also considered.Source: §3.2 · p. 43, §3.3 · p. 44

3.3 Calorimeter Detector Systems

  • Calorimetry combines electromagnetic and hadronic systems, while auxiliary detectors measure luminosity, tag forward particles, and determine beam polarization.Short-radiation-length materials are favored for ECAL; HCAL designs include sampling calorimeters, and specialized far-forward and far-backward devices support particle tagging and luminosity determination.Source: §3.3 · pp. 44–45, §3.4 · p. 45

3.5 Two Complementary Detectors

  • Complementary detector designs and interaction regions can maximize acceptance, resolution, precision, and kinematic reach while providing technology redundancy.The report argues that differing detector fields and subdetector choices can optimize overall physics output and complement acceptance and systematic effects.Source: §3.5 · p. 46

3.5. TWO COMPLEMENTARY DETECTORS

  • Two detectors with different systematics also enable independent cross-checks, helping establish confidence in important results and discoveries.The report says complementary detectors and interaction regions are planned from the start.Source: §3.5 · p. 46

Opportunities for Detector Technology and Computing

CHAPTER 4. OPPORTUNITIES FOR DETECTOR TECHNOLOGY AND COMPUTING31

  • Further R&D could improve detector capabilities and support future upgrades, including lower-material tracking, particle identification, calorimetry, streaming-readout electronics, and Zero-Degree Calorimeters.The report identifies opportunities for a complementary second detector and cost-effective upgrades as EIC science evolves.Source: CHAPTER 4. OPPORTUNITIES FOR DETECTOR… · pp. 49–50

CHAPTER 4. OPPORTUNITIES FOR DETECTOR TECHNOLOGY AND COMPUTING33

  • An integrated streaming-readout and analysis model could converge online and offline analysis, support continuous calibration and data-quality control, and apply AI to analysis and detector-design optimization.The proposed approach combines modern electronics, computing, statistical methods, and AI; examples include rare-event filtering, jet and quark-flavor tagging, and analysis of sparse Wigner-distribution data.Source: CHAPTER 4. OPPORTUNITIES FOR DETECTOR… · pp. 50–51

Introduction to Volume II

  • The Yellow Report effort organized physics studies and detector R&D to quantify planned measurements, derive detector requirements, and prepare concepts for future technical design reports.The initiative was open to broad community participation and intended to guide further EIC studies and detector development.Source: Introduction to Volume II · pp. 56–57

The EIC Physics Case

  • EIC science questions include how nucleon mass and spin arise and what emergent properties characterize dense gluon systems.The report frames these questions within a broader effort to study hadron structure using high-energy, high-luminosity electromagnetic probes and polarized beams.Source: Introduction to Volume II · p. 55, The EIC Physics Case · p. 58

1. Global properties and parton structure of hadrons

  • About 25% of nucleon spin is carried by quark and antiquark spins [32], while ∆Σ and especially ∆G remain highly uncertain.The EIC’s study of nucleon spin and mass includes resolving the partonic contributions to these hadron properties.Source: §1 · pp. 59–60
  • Polarized DIS at the EIC will extend precise access to helicity distributions down to x ~ 10^-4, while quarkonium production near threshold can deepen understanding of nucleon mass.The bulk of nucleon mass is attributed to quark and gluon kinetic and potential energies; valence-quark masses sum to about 1% of the nucleon mass.Source: §1 · p. 60

2. Multi-dimensional imaging of nucleons, nuclei and mesons

  • Semi-inclusive and exclusive EIC measurements will provide information on the multidimensional quark and gluon structure of nucleons, nuclei, and light mesons.Generalized parton distributions accessed in hard exclusive processes such as DVCS and meson production can inform studies of parton orbital angular momentum and internal pressure and shear forces.Source: §2 · pp. 60, 62

Imaging in momentum space — transverse momentum dependent parton dis-

  • TMDs provide complementary three-dimensional momentum-space images of hadrons and can be studied at the EIC through semi-inclusive DIS and other final states.The Sivers and Collins effects are highlighted as important SIDIS observables; TMD measurements are also possible with di-hadrons, jets, and in processes such as Drell–Yan.Source: Imaging in momentum space — transverse… · pp. 62–63, Figure 6.3 · p. 62

3. The nucleus: a laboratory for QCD

  • The EIC aims to obtain clear evidence for nonlinear QCD dynamics at Q_s > 1 GeV and characterize gluon density across energy and nuclear thickness.Existing DIS data establish nuclear modifications, including shadowing at x < 0.1, antishadowing at 0.1 < x < 0.3, and the EMC effect at 0.3 < x < 0.7; EIC measurements are expected to improve nPDF determination and probe cold-matter energy loss, including through jets.Source: §3 · pp. 64–66

4. Understanding hadronization

  • EIC measurements will advance studies of fragmentation and hadron formation, including in nuclear matter, using identified hadrons, jets, and jet substructure.The program includes light-meson and polarized-Λ fragmentation, di-hadron fragmentation functions, and heavy-flavor-tagged jet substructure; reconstructed leading jets can probe energetic-parton energy loss in nuclei.Source: §4 · p. 67

7.1 Global Properties and Parton Structure of Hadrons

  • The EIC program also targets parton distributions, meson structure, multi-parton correlations, and inclusive diffraction as parts of its broader study of hadron structure.Pion and kaon structure can be explored through selected final states in electron-proton scattering; polarized DIS accesses the twist-3 structure function gT related to quark-gluon-quark correlations, and EIC diffraction offers kinematic complementarity to HERA.Source: §7.1 · pp. 70–71
  • Event-shape measurements at the EIC are presented as a prospect for determining αs through observables that can be computed reliably in perturbative QCD.Source: §7.1 · p. 71

Inclusive neutral-current and charged-current DIS

  • EIC pseudodata could discriminate strange-sea hypotheses at up to 3σ at low x and low Q2, 2σ in a narrow high-x, high-Q2 region, and only marginally at moderate x.The complementary PDFSense analysis indicates modest sensitivity of EIC electron data to Rs. At 100 fb−1, projected NC uncertainties are currently expected to be systematics-limited; halving them would yield average discrimination above 5σ across the acceptance for central versus non-central PDF replicas.Source: Inclusive neutral-current and… · pp. 72–73, Figure 7.2 · p. 73, Figure 7.3 · p. 74
  • EIC data with systematic uncertainties as large as 2% could significantly constrain unpolarized PDFs, reducing valence uncertainties by up to 80% and sea uncertainties by up to 50%.The projected valence impact could provide new insight into d/u, while the sea-sector changes are concentrated at small x. The report also notes that these constraints could improve information used in HL-LHC studies.Source: Inclusive neutral-current and… · p. 75, Figure 7.4 · p. 75

Positron beam

  • Positron NC and CC data could add unique flavor-current information, further constrain d-type PDFs and d/u, and probe strange–antistrange symmetry breaking and charge-symmetry violation.The report also identifies e+d scattering as a way to improve understanding of nuclear effects in a region free of 1/Q2 power-correction contamination.Source: Positron beam · pp. 75–76, Figure 7.5 · p. 76

Parity-violating DIS

  • Parity-violating DIS is projected to strongly constrain x(s + ¯s), particularly at low x, though smaller observable uncertainties do not guarantee smaller uncertainties for every PDF flavor at every x.The projections include proton and deuteron beams at several energies, with integrated luminosities of 100 fb−1 and 10 fb−1, respectively.Source: Parity-violating DIS · p. 76

Tagged DIS

  • Tagged DIS with spectator-proton tagging and on-shell extrapolation can provide an effective free-neutron cross section and improve PDF determination, particularly d/u at large x.Collider tagging extends reach to higher Q2, reduces power corrections, and offers cleaner spectator detection, including neutron tagging. Combined inclusive deuteron and tagged-neutron data could probe nuclear binding, Fermi motion, off-shell structure, the d/(p + n) ratio, and the EMC effect.Source: Tagged DIS · pp. 76–78

Sea quark PDFs via SIDIS measurements

  • SIDIS with charged pions and kaons is projected to substantially constrain poorly known strange PDFs, especially at lower x, while effects on up, down, anti-up, and anti-down PDFs are moderate.The study uses simulated pion and kaon data and evaluates their impact simultaneously on PDFs and fragmentation functions; it also projects improved determination of the strange-to-light sea-quark ratio at lower x.Source: Sea quark PDFs via SIDIS measurements · p. 78

Nonperturbative charm

  • Precision charm-structure-function measurements at x ≳0.3 and ⟨Q2⟩∼20 GeV2 could help resolve proton nonperturbative charm and constrain twist-4 gluon correlators.Charm tagging may further help disentangle this contribution; EIC constraints would complement those from the LHC.Source: Nonperturbative charm · p. 79

Charm jets … Twist-3 PDF gq

This section surveys projected EIC measurements of quark, gluon, neutron-spin, and orbital-angular-momentum structure, including probes of small-x evolution and flavor-dependent spin contributions. It also covers pion and kaon structure, PDFs and form factors, and studies of hadron-mass generation and twist-3 structure, with meson-structure comparisons to continuum Schwinger methods and lattice QCD.

Charm jets

  • Charm-jet yields in charged-current DIS strongly distinguish suppressed from enhanced nucleon strangeness, making them sensitive to the strange PDF and SU(3) breaking.The comparison uses Rs = 0.325 and Rs = 0.863; hypothetical measurements near x ∼0.35 are also discussed as a way to distinguish nonperturbative-charm scenarios.Source: Charm jets · p. 80, Figure 7.10 · p. 81, Figure 7.9

7.1.2 Spin structure of the proton and neutron

  • Projected EIC spin-asymmetry data significantly reduce gluon-helicity uncertainty, while truncated-moment gains depend on low-x extrapolation and SU(3) assumptions.With SU(3), the gluon truncated-moment uncertainty improves by 80–90% and the quark-singlet uncertainty by about 80%; without SU(3), the gluon reduction is about 60%, with no clear quark-singlet reduction from proton data alone.Source: §7.1.2 · pp. 81, 83, Figure 7.12 · p. 82

Helicity and small-x dipole formalism

  • EIC data are expected to sharply narrow small-x g1 predictions from KPS helicity evolution, though the extrapolation uncertainty differs between pQCD formalisms.The KPS calculation fits existing DIS data for x < 0.1 and extrapolates to lower x; EIC data are expected to shrink its uncertainty band substantially [91].Source: Helicity and small-x dipole formalism · pp. 83–84

Neutron spin structure from inclusive and tagged DIS with polarized 3He and 2H

  • Combining proton and neutron data advances flavor separation and neutron-spin extraction; tagged deuteron DIS with on-shell extrapolation can remove nuclear modifications and final-state interactions.Across scenarios, deuteron or 3He data reduce gluon truncated-moment uncertainty by about 60–90% and quark-singlet uncertainty by about 20–90%; without SU(3), the quark-singlet impact is unclear, and proton data alone constrain the gluon moment similarly.Source: Neutron spin structure from inclusive… · pp. 84, 85, 87, Figure 7.15 · p. 85

Orbital angular momentum contribution to nucleon spin

  • Projected EIC data can rule out at least one extreme orbital-angular-momentum scenario, while exclusive measurements can extract quark-flavor and total gluon OAM contributions.DVCS on proton and neutron and hard exclusive meson production provide complementary access to GPDs; multiple processes are needed for flavor separation.Source: Orbital angular momentum contribution… · pp. 88–89

Parity-violating DIS

  • Parity-violating DIS offers an axial-charge-dependent constraint on helicity moments, while SIDIS substantially improves sea-quark helicity uncertainties and can test for strange polarization above x = 0.5 × 10−5.The parity-violating DIS impact on the quark singlet is about 30% at low xmin using JAM17 axial charges [90], but is diminished with hyperon-decay values under SU(3); its statistical uncertainties are large.Source: Parity-violating DIS · pp. 89–90, Figure 7.19 · p. 90
  • Dijet ALL can tag photon-gluon fusion and cross-check inclusive g1, while projected charm ALL data assess gluon polarization using D0 → Kπ measurements.The dijet study found viable reconstruction and access to struck-gluon momentum fraction; its expected precision could improve polarized PDFs, though inclusive g1 is likely more constraining. Charm projections use 10 fb−1 for measurement uncertainties and 100 fb−1 for the leading-order impact study.Source: Parity-violating DIS · pp. 91–92, Figure 7.21 · p. 93

Introduction

  • Pion and kaon structure studies address open questions about gluon content, mass mechanisms, and quark behavior, requiring luminosity well above 10^33 cm−2 sec−1 and broad tagged-nucleon xL coverage.The stated xL reach is up to ∼1 for e+p and at least ∼0.5 for e+D; π− and π0 channels are also important for constraining reaction mechanisms and theory backgrounds.Source: Introduction · p. 93, Sullivan process · p. 94

Sullivan process

  • At low −t, meson-pole dominance in the Sullivan process can provide access to pion and kaon structure, while elastic scattering probes meson form factors and DIS probes mesonic parton content.The cited calculation places the low −t limits at −t < 0.6 GeV2 for pions and 0.9 GeV2 for kaons; data across −t are needed to test the extraction conditions.Source: Sullivan process · pp. 94–95

Theoretical backgrounds in extracting the data

  • Meson-structure extraction is model-dependent and requires accounting for non-pion-pole contributions, resonances, absorptive effects, and pion-flux uncertainty.Corrections are minimized at the lowest −t with fine −t binning; under assumed 50% correction and 20% flux uncertainties, the overall theoretical systematic uncertainty could approach 25%.Source: Theoretical backgrounds in extracting… · pp. 95–96

Kinematics of interest to address specific theory questions

  • Pion and kaon measurements typically require center-of-mass energies of ∼10–100 GeV, balancing broad x and Q2 reach against identification of the remnant neutron or hyperon.Similar-energy e+p and e+D measurements help validate the reaction mechanism; lower energies favor large-x access, while higher energies extend Q2 reach.Source: Kinematics of interest to address… · p. 96

Meson structure function projections

  • With 100 fb−1, pion-structure projections cover mid-to-high x across four Q2 bins, with uncertainties rising rapidly as x →1; accessible small −t offers an order-of-magnitude statistical gain over HERA.The projected x coverage is described as unprecedented and potentially enabling detailed pion–kaon structure comparisons; the −t reach includes the low −t region relevant to pion structure.Source: Meson structure function projections · pp. 97–98, Figure 7.23 · p. 97

Impact on global QCD analysis

  • EIC data are projected to reduce pion sea-quark and gluon PDF uncertainties by factors of ∼5–10 and valence uncertainties by ∼5; first-moment quark and gluon uncertainties fall by ∼10.The study assumes √s = 73.5 GeV, 100 fb−1, and 1.2% systematic uncertainty; omitted pion-flux model uncertainties of 10–20% could reduce the projected PDF impact by several-fold.Source: Impact on global QCD analysis · pp. 98–99, Figure 7.24 · p. 98

Complementarity with other facilities

  • The EIC’s larger energy range is expected to extend pion and kaon structure knowledge in x and Q2 and clarify their gluon contributions relative to protons.The report identifies access to a versatile center-of-mass energy range of ∼29–141 GeV as a distinctive role of the EIC.Source: Complementarity with other facilities · p. 99
  • Figure 7.25 juxtaposes CSM, lattice-QCD, and data comparisons for the pion valence-quark distribution and the kaon-to-pion valence-quark ratio.Source: Figure 7.25 · p. 100

Synergy with theory efforts

  • The CSM pion valence-quark PDF agrees with the predicted large-x behavior and matches the pointwise form from a resummed analysis; lattice results are in fair agreement with CSM.CSM also predicts pion glue and sea PDFs and all kaon PDFs; the kaon valence distributions show qualitative similarities to pion PDFs, while uK/uπ predictions are compared with K−/π− event-distribution data.Source: Synergy with theory efforts · p. 100

7.1.4 Origin of the hadron mass

  • Near-threshold J/ψ or Υ production can probe the gluon contribution to the proton mass trace anomaly, while also providing information on the gluonic D-term.The EIC Υ photoproduction projection is compared with GlueX J/ψ results and JLab SoLID projections; low-energy running and forward-region detection pose technical challenges.Source: §7.1.4 · pp. 102–103, Figure 7.26 · p. 103
  • Comparing charged-pion and charged-kaon form factors across a wide Q^2 range can inform hadron-mass generation, since the Higgs mechanism contributes more to the K+ mass than to the π+ mass.Planned simulation work extends pion-form-factor measurements to K+, contingent on JLab-12 exclusive K+ electroproduction beyond the resonance region confirming feasibility.Source: §7.1.4 · pp. 103–104

Introduction

  • Twist-3 SIDIS extraction is challenging, but semi-inclusive jets and dihadron production offer complementary access, while global studies can constrain twist-3 functions and twist-2 TMDs.Proposed EIC examples include ALT in inclusive DIS, sensitive to gT(x), and longitudinal beam-spin asymmetries in SIDIS, which access e(x).Source: Introduction · pp. 104–105

Twist-3 PDF gq

  • EIC pseudodata are projected to provide new insights into gT, multiparton correlations, and interactions between the struck quark and surrounding partons.The projection uses proton, deuteron, and helium targets at 100 fb−1, with 1.6% point-by-point uncorrelated systematic uncertainties; its baseline uses world data and assumes DGLAP evolution for Q^2 dependence.Source: Figure 7.27 · p. 106, Twist-3 PDF gq · p. 106

Inclusive diffraction … Introduction

The section examines how EIC measurements can probe QCD through diffraction and DIS event-shape observables. It introduces 1-jettiness as a probe of the strong coupling and hadronization, with potential applications to nuclear PDFs and medium effects, and notes its current-hemisphere measurement requirement.

Inclusive diffraction

  • At 7 mrad acceptance and 275 GeV proton energy, the EIC reaches −t of at least 2 GeV2, beyond HERA’s range, expanding leading-proton coverage in t and xL.Figure 7.30 compares the accessible t and xL ranges across EIC proton-energy scenarios and angular acceptances.Source: Inclusive diffraction · p. 109, Figure 7.30 · p. 109
  • The EIC can probe ξ > 0.1, where Reggeon exchange begins to dominate, and its longitudinal diffractive structure-function contribution is non-negligible where HERA’s was extremely small.High luminosity and variable center-of-mass energies offer opportunities for precise measurements of the longitudinal diffractive structure function.Source: Inclusive diffraction · pp. 110–111
  • EIC pseudodata projections significantly reduce quark DPDF uncertainty relative to HERA, particularly at large z.The projection assumes 5% systematic error and 2 fb−1 integrated luminosity; statistical errors are negligible in the study.Source: Inclusive diffraction · p. 112, Figure 7.33 · p. 113

Diffractive dijets

  • EIC dijet predictions extend only to 8 GeV in average jet transverse momentum, versus 15 GeV at HERA, have K ≈2, and differ substantially across DPDF sets, especially at large zobs_IP.The predictions also cover coherent diffractive dijet photoproduction on nuclei.Source: Diffractive dijets · p. 114, Figure 7.34 · p. 115

Large-|t| diffractive production of vector mesons

  • EIC luminosity enables tests of BFKL-predicted cross-section dependence up to four rapidity units; η = 3.5 acceptance suffices, while η = 4.5 provides a longer lever arm.Rapidity-gap production of ρ mesons may also be promising, potentially over a broader |t| range than J/ψ production.Source: Large-|t| diffractive production of… · p. 116

Introduction

  • Event shapes summarize final-state hadron momentum distributions and probe QCD; DIS 1-jettiness groups particles into beam and jet regions and approaches zero for collimated jets.The section notes that measuring 1-jettiness requires particles in both beam and current hemispheres.Source: Introduction · pp. 116–118
  • By contrast, Eq. (7.14) requires measuring particles only in the current hemisphere.Source: Introduction · p. 118
  • 1-jettiness can probe the strong coupling αs and hadronization, and may also probe nuclear PDFs and medium effects [298] [299].Refs. [298] [299] explored its use for nuclear PDFs and medium effects.Source: Introduction · p. 118

Theoretical precision … Helicity TMDs and PDFs at small x

This section surveys how EIC measurements and theoretical developments can probe hadron and nuclear structure, including through DIS event shapes, form factors, exclusive reactions, TMDs, and nuclear targets. It covers observables and projections for imaging partons, studying spin and gluon structure, and investigating low-x saturation, alongside the detector capabilities and theoretical limitations shaping these studies.

Theoretical precision

  • N3LL+O(αs) 1-jettiness predictions show order-by-order convergence, with theoretical uncertainties generally improving at larger Q and smaller x.The transition from resummed to fixed-order predictions depends on x; the studies do not yet include resummation of logs of x at very small x.Source: Theoretical precision · pp. 121–122
  • A single 1-jettiness distribution could determine αs(MZ) at the few-percent level, while fitting αs and Ω1 together and sampling broad x-Q ranges can help address their degeneracy.The predictions’ perturbative uncertainties could be further reduced by higher fixed-order calculations of nonsingular contributions at large τ1.Source: Theoretical precision · p. 123

7.2 Multi-dimensional Imaging of Nucleons, Nuclei, and Mesons

  • TMDs describe hadron structure in momentum space, while partonic Wigner functions also encode impact-parameter dependence and can probe gluon structure through diffractive exclusive dijet production.Wigner functions additionally provide access to spin-orbit correlations, including parton orbital angular momentum.Source: §7.2 · p. 123, 106 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 124

106 7.2. MULTI-DIMENSIONAL IMAGING OF NUCLEONS, NUCLEI, AND MESONS

  • Light polarized nuclei can enable neutron studies and investigations of nuclear structure, including the EMC effect in position space and tensor-polarized deuteron observables.Nuclear corrections complicate neutron extraction, while the spin-1 deuteron offers opportunities through tensor polarization.Source: 106 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 124

Nucleon form factors

  • The EIC could measure unpolarized elastic ep cross sections up to Q2 ≈40 GeV2, but collider kinematics yield ε ∼1 and preclude a Rosenbluth separation.At large Q2, the cross section is dominated by GM, allowing extraction of the magnetic form factor; both scattered particles must be detected to suppress backgrounds.Source: Nucleon form factors · p. 125, Figure 7.38 · p. 125

108 7.2. MULTI-DIMENSIONAL IMAGING OF NUCLEONS, NUCLEI, AND MESONS

  • Elastic ed cross sections are measurable up to Q2 ≈5 GeV2 and tensor-polarized asymmetries up to Q2 ≈2.5 GeV2; scattered deuterons and far-forward detection are needed to suppress backgrounds.If the beam cannot provide the m = 0 state, negative tensor polarization along the beam can be obtained using polarization perpendicular to it, which gives equivalent cross sections in the simulation.Source: 108 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 126, Figure 7.40 · p. 127

Meson form factors

  • Because suitable π+ targets or beams are unavailable, spacelike Fπ studies use exclusive pion electroproduction; Rosenbluth L/T separation is impractical at the EIC because low-ε data cannot be acquired.At sufficiently small −t, scattering from the proton’s virtual π+ cloud dominates the longitudinal photon cross section; the passage proposes an alternate model-based technique to access σL.Source: Meson form factors · pp. 126–127

110 7.2. MULTI-DIMENSIONAL IMAGING OF NUCLEONS, NUCLEI, AND MESONS

7.2.2 Imaging of quarks and gluons in impact-parameter space

  • GPDs connect PDFs and form factors to correlations between parton longitudinal momentum and transverse position, but their x dependence enters observables through nontrivial convolutions.DVCS is the cleanest probe at high Q2 and low |t|; its CFFs are convolutions of GPDs, with the leading-order imaginary part probing x = ±ξ [395].Source: §7.2.2 · p. 130, Phenomenology of GPDs · p. 131

Phenomenology of GPDs

  • TCS complements DVCS through amplitude analyticity and provides more direct access to the dominant CFF’s real part, while DVMP channels probe gluon, flavor, parity-odd, or chiral-odd GPDs.Confronting TCS and DVCS is an EIC goal for testing factorization and GPD universality [399] [400]; heavy, light vector, and light pseudoscalar mesons provide the stated complementary sensitivities [7].Source: 114 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 132

114 7.2. MULTI-DIMENSIONAL IMAGING OF NUCLEONS, NUCLEI, AND MESONS

  • EIC pseudodata significantly improve constraints on gluon H, while transverse target-spin asymmetry AUT enables accurate extraction of sea-quark E, now almost unconstrained [23].The study used global fits to DVCS measurements and found that precise AUT measurements are needed for the sea-quark E extraction.Source: Figure 7.44 · p. 133, 114 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 133

116 7.2. MULTI-DIMENSIONAL IMAGING OF NUCLEONS, NUCLEI, AND MESONS

  • Additional proposed processes access GPDs through diffractive production and photon-pair or photon-meson photoproduction, with polarization separating chiral-even from transversity contributions.Photon-pion production also accesses gluon GPDs, while charged-current ρ- and π-meson cross-section comparisons offer another method despite suppressed rates [411].Source: 116 7.2. MULTI-DIMENSIONAL IMAGING OF… · pp. 134–135

Impact parameter distributions

Form factors of the energy momentum tensor

Transition distribution amplitudes

  • Leading-twist nucleon-to-meson TDAs involve three-parton exchange and comprise eight independent amplitudes classified by exchanged-quark light-cone helicity, enabling studies of correlated-quark helicity and transverse location.Their transverse structure can quantify diquark clustering, and EIC measurements can contribute to their exploration.Source: Transition distribution amplitudes · p. 139

7.2.3 Imaging of quarks and gluons in momentum space

  • TMD-factorization applicability is nontrivial: bins with relatively high zh and PT, and relatively large x and Q2, are especially important for its description.Recent analyses commonly adopt δ = PT/(zQ) < 0.25 at high Q; other bins may support collinear-factorization descriptions.Source: §7.2.3 · p. 141, Figure 7.50 · p. 142

Unpolarized TMDs and TMD evolution

Quark Sivers and Collins measurements

Gluon TMD measurements

  • The EIC can uniquely test gluon-TMD non-universality through Weizsäcker–Williams gluon TMDs in DIS, whose T-odd distributions are predicted to change sign relative to corresponding color-singlet hadronic-collision measurements.Experimentally, little is known about gluon TMDs beyond the unpolarized distribution at very small x; open-charm production is an ideal but statistically challenging probe.Source: Gluon TMD measurements · p. 147
  • Dijet measurements at the EIC can probe the gluon Sivers asymmetry down to 5% of the positivity bound, but require hermetic coverage and good tracking and momentum and angular resolution.Detector-response effects become significant only at large x in the projection, where statistics are limited.Source: 130 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 149

Chiral-odd distribution functions via di-hadron measurements

  • Di-hadron correlations couple PDFs to di-hadron fragmentation functions and provide access to transversity through H∢1 and to the Boer–Mulders function through the TMD DiFF H̄∢1.The section also notes transverse-polarization-sensitive fragmentation functions in the collinear framework.Source: Chiral-odd distribution functions via… · p. 149

Di-hadron transversity

  • Factor 2 average precision improvement is projected for transversity; polarized 3He data reduce down-quark uncertainty width by almost an order of magnitude at x < 0.01.For the isovector tensor charge, the extraction changes from gT = 0.53(25) to 0.63(9) with EIC proton data and 0.54(2) with proton+3He data. Projections use 10 × 100 GeV beams, 10 fb−1, and a conservative 0.1 ≤ y ≤ 0.85 cut; 3% relative and 3% polarization-scale uncertainties are included.Source: 132 7.2. MULTI-DIMENSIONAL IMAGING OF… · pp. 150–151, Figure 7.56 · p. 151

Di-hadron TMDs

  • Di-hadron measurements complement single-hadron and hadrons-in-jets methods for tensor charges, while their averaged acceptance effects and reduced higher-twist contributions may lower systematics.Di-hadron correlations also offer a route to the sparsely measured chiral-odd Boer–Mulders function, with the fragmentation function measured either in correlations or jets.Source: 134 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 152

Jet-based TMD studies: electron-jet Sivers, hadron-in-jet Collins, and TMD evolution with substructure

  • Jets separate current from target fragmentation and can probe TMD PDFs independently of fragmentation functions; hadron-in-jet and groomed or winner-take-all observables extend access to Collins effects and TMD evolution.The approaches use Breit-frame jets or lab-frame electron–jet imbalance; flavor sensitivity can be added through jet charge, identified leading hadrons, or neutrino–jet correlations.Source: Jet-based TMD studies: electron-jet… · pp. 152–153

Event shapes

  • DIS TEEC offers a precision TMD probe: its back-to-back cross section factorizes into hard, beam, jet, and soft functions, while a Breit-frame EEC definition is insensitive to lab-frame pseudorapidity cuts.The TEEC prediction reaches N3LL matched to NLO; its beam function combined with part of the soft function is the conventional TMD PDF, and the jet function is the second moment of the TMD fragmentation-function matching coefficient.Source: Event shapes · p. 153, 136 7.2. MULTI-DIMENSIONAL IMAGING OF… · pp. 154–155

Opportunities with heavy quarks

  • Charm-pair production probes gluon TMDs through azimuthal anisotropies, and simulations find the pair-momentum correlation survives hadronization, although the Sivers signal can be reduced by up to 30%.Fast detector simulations with track smearing and secondary-vertex selections were used for projected AUT uncertainties in Q2 and xB bins.Source: Opportunities with heavy quarks · p. 155, Figure 7.60 · p. 156

7.2.4 Wigner functions

  • Exclusive dijet azimuthal modulations can access the small-x gluon Wigner distribution in the correlation limit, though higher-order corrections and soft-gluon resummation may affect the signal.The distribution encodes correlations unavailable from TMDs and GPDs separately, and Wigner distributions offer access to canonical and kinetic orbital angular momentum complementary to GPD-based studies.Source: §7.2.4 · pp. 156–157, 140 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 158

Exclusive π0 production and GTMDs

  • At top EIC energy, exclusive π0 production is predicted to be dominated by gluon GTMD Fo12, whose forward limit is the gluon Sivers function and is equivalent to the QCD odderon at small x.GTMD/Wigner studies remain early-stage; exclusive pion-nucleon double Drell–Yan is the identified quark-GTMD process, but its cross section is small.Source: 140 7.2. MULTI-DIMENSIONAL IMAGING OF… · p. 158

Coherent DVCS on light nuclei

  • Coherent DVCS on light nuclei could support nuclear tomography, tests for non-nucleonic degrees of freedom, studies of nuclear energy-momentum structure and gluon GPDs, and access to free-neutron information.The first separation of coherent and incoherent DVCS channels off 4He opens new measurements; deuteron is a candidate for neutron extraction, with small expected nuclear effects in the coherent setting.Source: Coherent DVCS on light nuclei · pp. 158–159
  • In coherent DVCS, polarized 3He CFFs appear neutron-dominated with negligible final-state interactions, while spin-0 4He requires only one leading-twist chiral-even GPD and one CFF.A 4He impulse-approximation model reproduced beam-spin-asymmetry and CFF data, and the collider setup facilitates detection of the intact recoiling nucleus.Source: 142 7.2. MULTI-DIMENSIONAL IMAGING OF… · pp. 160–161

Tensor polarized deuteron

Medium modification of azimuthal modulations in SIDIS

  • Medium-modified beam-spin asymmetries are sensitive to the relative transverse-momentum widths of nucleon TMDs, while their overall magnitude is governed by transport parameter qhat or broadening Δ2F.The g⊥ TMD contributes to the beam SSA; jet measurements could study medium-modified TMDs without unknown fragmentation functions, although jet formation and parent-parton correlations must be understood.Source: Medium modification of azimuthal… · p. 163

Collective effects

  • Small-x DIS at the EIC can test competing explanations of collective long-range correlations in small systems: final-state phenomena and initial-state effects.Source: Collective effects · p. 164

Special opportunities with jets and heavy quarks

  • Jet angularity can image three-dimensional nucleon and nuclear structure and hadronization, while jet charge can distinguish quark from antiquark jets and constrain nuclear up/down PDFs.Jet-substructure flavor tagging also enables studies of initial- and final-state nuclear modifications for different hard-scattered partons.Source: Special opportunities with jets and… · pp. 164–165

Inclusive cross sections at small x

  • At HERA, inclusive DIS data with x < 0.01 and Q2 < 450 GeV2 collapsed onto one curve in τ, a scaling derived from nonlinear BK evolution.The EIC’s low-x e+A inclusive cross section is expected to inform nuclear shadowing and saturation; small-x evolution combines soft-gluon emission with nonlinear recombination.Source: §7.3.1 · pp. 165–166, Inclusive cross sections at small x · p. 166

Accessing low-x gluons via di-jets or di-hadrons

  • A significant suppression of the away-side dihadron peak is projected in e+A relative to e+p, with negligible detector-smearing impact at 10 fb^-1/A.The back-to-back correlation probes the Weizsäcker-Williams gluon distribution; its broadening and possible disappearance provide a signature of saturation.Source: Accessing low-x gluons via di-jets or… · pp. 168–169, Figure 7.63 · p. 168

Recent Progress in Probing Gluon Saturation with Jet Observables

  • Forward and moderate- or low-x jet measurements can probe new saturation-sensitive TMDs and the interplay of Sudakov effects with nonlinear gluon saturation, including through small-x Improved TMD factorization.Source: Recent Progress in Probing Gluon… · p. 169
  • Dihadron/dijet azimuthal correlations in diffractive e+A probe nuclear gluon transverse-momentum distributions and correlations, enabling saturation tests and studies of nonlinear spatial multigluon evolution [759] [7].The report identifies precise measurements of these correlations at an EIC as a way to determine whether saturation has been reached and study its evolution.Source: Recent Progress in Probing Gluon… · pp. 169–170
  • At small x, semi-inclusive photon+dijet production probes gluon-saturation many-body dynamics through dipole and quadrupole Wilson-line correlators, while photon+jet/hadron offers complementary sensitivity to the saturation scale [760] [761].The leading-order calculation agrees with prior LO dijet results in the soft-photon limit [537].Source: Recent Progress in Probing Gluon… · p. 170
  • NLO e+A photon+dijet cross-sections encompass inclusive photon, photon+jet, dijet, single-jet, and fully inclusive production, and combine with next-to-leading-log JIMWLK evolution for dipole and quadrupole correlators [762] [763] [722] [723].Extracting EIC-kinematics predictions for the semi-inclusive channels is described as crucial for cleanly characterizing gluon saturation.Source: Recent Progress in Probing Gluon… · p. 170

Helicity TMDs and PDFs at small x

  • Small-x helicity evolution equations resum αs log^2(1/x) in polarization-dependent evolution and αs log(1/x) in unpolarized evolution, reducing to BER equations for g1 in the ladder approximation [92, 93, 764, 765].Initial conditions analogous to the McLerran–Venugopalan model for an unpolarized large nucleus have also been constructed [766].Source: Helicity TMDs and PDFs at small x · p. 170

Inclusive diffraction with nuclei … Detector Requirements

This section surveys EIC studies of nuclear structure, diffraction, hadronization, exclusive processes, and electroweak physics, including their connections to other areas of high-energy physics. It relates these measurements to the theory work and detector acceptance, identification, and reconstruction capabilities needed to carry them out.

Inclusive diffraction with nuclei

  • Nuclear diffraction offers a sharp saturation test: dipole-model predictions show enhancement, whereas leading-twist shadowing predicts suppression of diffractive structure functions and parton distributions.The contrast reflects different treatments of multiple scattering and gap survival probability; inclusive diffraction in e+A has never been measured, and forward detectors are assumed to distinguish coherent events.Source: Inclusive diffraction with nuclei · pp. 170, 172, Figure 7.64 · p. 171

7.3.3 Nuclear PDFs

  • EIC inclusive DIS pseudodata are expected to nearly double existing nPDF kinematic coverage, with few-percent systematic uncertainties and negligible statistical uncertainties except at the largest x.The improved coverage is expected to significantly reduce nPDF uncertainties in the low-x region, where data are scarce or absent.Source: §7.3.3 · p. 175, Figure 7.66 · p. 175, Figure 7.67 · p. 176

nPDFs via inclusive DIS

  • Including EIC DIS pseudodata significantly reduces nPDF uncertainties in the low-x region, where existing data are scarce or absent.The comparison covers three modern nPDF sets for gold; the high-x, low-Q2 region is covered by fixed-target experiments and will be further explored at CLAS.Source: nPDFs via inclusive DIS · p. 176, Figure 7.68 · p. 177

Probing nuclear gluons with heavy flavor production

  • Heavy-flavor pairs produced through photon–gluon fusion can directly constrain nuclear gluon densities, and particle identification significantly increases charm reconstruction.The measurements can also study heavy-quark mass schemes and constrain intrinsic heavy-flavor components in nPDFs.Source: Probing nuclear gluons with heavy… · pp. 177–178

Investigating the A dependence of nPDFs

  • The EIC can scan kinematic space for individual nuclei, enabling robust extraction of nPDF A dependence and a combined proton, deuteron, and nuclear PDF analysis.This would avoid some biases and assumptions in current PDF determinations.Source: Investigating the A dependence of nPDFs · p. 179

Parton showers and energy loss in cold nuclear matter

  • Cold-nuclear-matter transport-coefficient estimates vary sevenfold, from 0.02 to 0.14 GeV2/fm; EIC measurements can address this spread.Because medium-induced energy loss becomes negligible at very high parton energy in the nuclear rest frame, studies should focus forward and minimize the rapidity gap between jet and nucleus.Source: Parton showers and energy loss in cold… · p. 179

Formation of hadrons in matter

  • At the EIC, light pions and kaons are unlikely to hadronize within τf < 10 fm, making heavy mesons such as D and B the best opportunity to study hadron absorption.The larger collision energy and detector coverage relative to nucleon/nucleus rapidity boost formation times.Source: Formation of hadrons in matter · p. 180

Jet production and modification in e+A collisions

  • 10–20% suppression from final-state effects is predicted for jets at pT ∼5 GeV; the ratio of jet modifications at different radii eliminates initial-state effects.Smaller radii show stronger suppression from broader medium-induced showers, with the nuclear effect further enhanced at lower center-of-mass energy.Source: Jet production and modification in e+A… · pp. 181–182, Figure 7.71 · p. 181

7.3.5 Collective effects

  • EIC small-x DIS can test collective effects because virtual-photon size and lifetime vary with x and Q2, while higher luminosity enables samples of rare high-multiplicity events.The incoming photon’s low-virtuality wave function can contain many active partons after rare QCD fluctuations; the resulting studies may help unravel the origin of collectivity.Source: §7.3.5 · pp. 183–184

Flavor-tagged jets and the jet charge

Light and heavy-flavor tagged jet angularities

Jets as precision probes in electron-nucleus collisions with electron-jet correlations and jet substructure measurements

  • Electron-jet momentum balance, azimuthal correlations, and substructure in tag-and-probe DIS can provide orthogonal constraints on parton transport in nuclei and its kinematic dependence.The proposed approach uses scattered-electron measurements to calibrate jets and includes comparisons of standard and winner-take-all reconstruction.Source: Jets as precision probes in… · pp. 186–187

Energy flow and quantum number correlations in jets

  • In exploratory Pythia studies, opposite-sign leading and subleading particle-pair cross sections dominate, especially for kaon and proton-antiproton pairs.The kinematic-phase-space dependence is still being studied; correlations between jets and forward particles are proposed as a probe of target-fragmentation hadronization and global color neutralization.Source: Energy flow and quantum number… · p. 187

Diffractive J/psi production in electron-deuteron scattering at the EIC and its implication to short-range correlations

  • EIC far-forward detector simulations indicate that spectator tagging in incoherent diffractive J/ψ production can access high-momentum deuteron configurations, with acceptance and resolution varying by spectator type and momentum.Neutron acceptance is almost 100% up to 600 MeV and about 80% near 1 GeV; proton tagging has better high-momentum acceptance and less low-momentum bin migration.Source: Diffractive J/psi production in… · p. 190, Figure 7.75 · p. 191
  • A 10% difference in proton size is projected to produce a 3σ difference in the gluon source distribution, subject to signal strength and statistical precision.The estimate assumes statistical precision similar to the H1 result; rigorous theoretical calculations are needed for a quantitative prediction.Source: Diffractive J/psi production in… · p. 190

Studying short-range correlations with an EIC

  • The EIC’s recoil-nucleon capability and higher reachable Q2 support SRC tagging, with simulated recoil-spectator acceptance spanning a large momentum range and nearly complete for neutrons at the highest energy setting.The design aims to measure the struck nucleon or target-remnant jet, SRC partner, final-state-interaction spectators, and nuclear remnant.Source: Studying short-range correlations with… · pp. 191–192

7.3.8 Structure of light nuclei

  • Polarized light-ion beams and forward spectator detection can probe spin structure and select active nucleons, breakup channels, and initial-state nucleon distances.The EIC can study the Q2 dependence of the EMC effect and the still-unknown magnitude of the spin-dependent contribution; reaction mechanisms must be controlled to distinguish medium modifications from final-state interactions, especially for spectators with momenta of a few hundred MeV.Source: §7.3.8 · pp. 193–194

Studying nucleon structure in A=3 nuclei using double spectators tagging

  • Double-spectator tagging in 3He can constrain the initial neutron to near rest, enabling effective free-neutron measurements with minimal model dependence.Tagging two neutrons in 3H instead tests reaction mechanisms and 3He neutron extractions, while higher spectator momenta probe medium modifications and final-state interactions. For spin-dependent SIDIS, the cited generalized-eikonal calculations find final-state interactions theoretically under control.Source: Studying nucleon structure in A=3… · pp. 194–196

Coherent scattering off the lightest nuclei

  • Light nuclei allow separate tests of gluon shadowing involving two versus three nucleons, complementing heavy-nucleus measurements where the average number involved is around two at Q2 ∼ few GeV2 and x = 10^-3.Their well-known wave functions support reliable impulse-approximation calculations; combining 3He and 4He measurements can separate double and triple rescattering contributions.Source: Coherent scattering off the lightest… · p. 197
  • At x = 10^-3, the shift in the coherent-production minimum should be measurable with acceptance to −t ≲ 0.5 GeV2, enabling studies of rescattering in light nuclei.For 4He, the single-scattering term vanishes near −t ≈ 0.3 GeV2; combining 3He and 4He measurements can separate double and triple rescattering amplitudes with little model dependence.Source: Coherent scattering off the lightest… · p. 197, Figure 7.81 · p. 198

7.3.9 Coherent and incoherent photoproduction on heavy targets

  • At low Q2, the scaled coherent photoproduction ratio is predicted to fall to 0.6 for ρ, while J/ψ exhibits little shadowing; the ratio approaches one at high Q2.This motivates measurements of light mesons over Q2 extending down to zero.Source: §7.3.9 · pp. 198–199, Figure 7.82 · p. 199

Photoproduction and partonic structure

  • Projected EIC rates include 40–50 billion ρ0 events per 10 fb−1/A and about 100 million J/ψ events/year.About 5 million J/ψ electroproduction events with Q2 > 1 GeV2 are expected per 10 fb−1/A, enabling multidimensional studies of nuclear shape and fluctuations in narrow x and Q2 bins.Source: Photoproduction and partonic structure · pp. 200–201

Good-Walker and coherent photoproduction

  • Coherent production probes the average target wave function, whereas incoherent production probes fluctuations; at small t, coherent production has an A2 enhancement while coherence is maintained.Without multiple interactions, the coherent cross-section scales as A4/3; the incoherent component is the difference between total and coherent cross-sections.Source: Good-Walker and coherent photoproduction · p. 201, Incoherent photoproduction · p. 203

Coherent photoproduction

  • Coherent photoproduction can image transverse gluonic structure, while incoherent production is sensitive to event-by-event nuclear configuration and partonic-density fluctuations.Extracting the impact-parameter profile is limited by finite pT coverage, coherent–incoherent separation, detector resolution, and photon pT; the pT and t geometries also differ for heavier mesons such as Υ.Source: Coherent photoproduction · pp. 201–203, Incoherent photoproduction · p. 203

Separating coherent and incoherent production

  • At the third diffractive minimum, incoherent production is about 400 times larger than coherent production, requiring accurately known rejection better than 400:1.Vetoing neutrons, protons, and photons above 50 MeV yields only 100:1 rejection in BeAGLE simulations; at |t| < 0.01 GeV2, coherent production can instead be up to 100 times larger than incoherent production. HERA data support large event-by-event proton fluctuations [406] [865], while LHC UPC studies suggest these increase the incoherent cross-section by about a factor of 2 for heavy targets [406] [898].Source: Incoherent photoproduction · p. 203, Separating coherent and incoherent… · p. 204

7.4 Understanding Hadronization

  • The EIC may advance hadronization studies by testing production mechanisms beyond fragmentation and enabling searches for rare QCD processes and exotic heavy-quark states.The report highlights threshold production, string-breaking, and coalescence or recombination, as well as possible hard C-odd three-gluon exchange and detailed studies of exotic states enabled by high luminosity.Source: §7.4 · p. 205

Light meson fragmentation functions and flavor sensitivity

  • EIC pseudo-data improve light-meson fragmentation-function determinations, especially for unfavored pion and favored kaon fragmentation.The unfavored-kaon result warrants caution because of its more rigid assumed functional form; EIC data are also projected to enable the first measurements of spin-averaged and spin-dependent fragmentation functions in jets, providing direct access to transverse-momentum-dependent fragmentation functions.Source: Light meson fragmentation functions… · p. 206, Figure 7.84 · p. 206

Fragmentation into polarized Λ hyperons

  • High-precision EIC Λ and anti-Λ spin-transfer measurements can constrain polarized fragmentation functions and strange-quark distributions.The polarized fragmentation function remains poorly constrained; the EIC will provide a high-statistics sample of Λ hyperons in the current fragmentation region and projected longitudinal spin-transfer measurements at 18×275 GeV.Source: Fragmentation into polarized Λ hyperons · pp. 207–208, Figure 7.85 · p. 207

Partial wave decomposition of polarized and unpolarized di-hadron FFs including TMDs

  • Di-hadron partial-wave extraction requires decay-angle coverage because unknown contributions can interfere with asymmetries and dominate systematic effects.The spin-averaged cross-section contains 12 leading-twist terms through l=2; projections indicate reasonable precision for all partial waves at 10 fb−1 and 5×41 GeV, with larger low-x uncertainties from the smaller depolarization factor D(y).Source: Partial wave decomposition of… · pp. 209–210, Figure 7.87 · p. 210

Leading jets

  • Leading-jet measurements in the Breit frame can determine the energy-loss distribution and average energy loss, ⟨zloss⟩, in electron-proton and electron-nucleus collisions.The measurements provide a way to study energetic quark and gluon interactions with cold nuclear matter and connect with corresponding proton-nucleus and nucleus-nucleus measurements.Source: Leading jets · pp. 210–211

Jet substructure

  • Jet substructure at the EIC can probe fragmentation and radiation patterns, while angularities support studies of perturbative predictions and nonperturbative hadronization effects.The program also includes single hadrons in jets, heavy-quark meson tagging, and soft-drop declustering to suppress or enhance nonperturbative effects.Source: Jet substructure · pp. 211–212, Figure 7.89 · p. 212

Collinear nuclear fragmentation functions for light hadrons; In medium evolution for light and heavy flavor mesons

  • EIC SIDIS pseudo-data are projected to retain about 10% of nuclear-fragmentation-function replicas, while the z ≤ 0.2 modification remains unconstrained by existing data.The EIC can broaden nFF characterization and flavor separation; higher energies produce similar reweighting results. Higher energies also enable open-heavy-meson studies in electron-proton and electron-nucleus collisions, with e+Au-to-e+p cross-section ratios normalized to inclusive jets to reduce nuclear-PDF effects.Source: Figure 7.90 · p. 213, Collinear nuclear fragmentation… · p. 213, In medium evolution for light and… · p. 214

In medium evolution for light and heavy flavor mesons

  • For D and B mesons, nuclear modification is suppressed at large z but enhanced below z = 0.65 and z = 0.8, respectively, most strongly at forward rapidities.The passage argues that eA dependence on z is more suitable for cold-nuclear-matter tomography than laboratory-frame hadron transverse-momentum modification alone; lower center-of-mass energies enhance nuclear effects.Source: In medium evolution for light and… · p. 215

Heavy meson reconstruction and physics projections

Heavy flavor-tagged jet substructure at the EIC

  • Jet shapes, fragmentation functions, and grooming can probe medium-modified fragmentation and hadronization, while heavy-quark mass effects can be studied in jet splitting functions.Comparisons of e+p and e+A substructure can test hadronization models such as parton recombination, including for mesons and baryons in jets.Source: Heavy flavor-tagged jet substructure… · p. 217

7.4.3 Particle production for identified hadron species

  • Identified-hadron measurements can probe hadronization through flavor-sensitive baryon-to-meson ratios and semi-inclusive hadrons in or outside jets.Broad kinematic and energy coverage, studies across ion species, and light, strange, and heavy quark samples can constrain competing hadronization contributions and their density dependence.Source: §7.4.3 · pp. 218–219

Precision quarkonium physics at the EIC

  • Quarkonium production models differ in how heavy-quark pairs form bound states, and the production theory remains unsettled; EIC multidifferential measurements can help establish a global picture.DIS kinematics can distinguish channels: resolved production dominates at y ≲ 0.3, direct production at intermediate and large y, and diffractive production near y ≃ 1.Source: §7.4.4 · pp. 219–220, Precision quarkonium physics at the EIC · p. 220

Production of quarkonia and exotics in e+A collisions

  • In e+A collisions, quarkonium interactions with nuclear matter can suppress production, while greater disruption of weakly bound states can test quarkonium and exotic-hadron structure.The section describes NRQCD extensions incorporating Glauber/Coulomb interactions and notes that EIC backgrounds may permit studies of higher charmonium states and comparisons of molecular and compact exotic-state models.Source: Production of quarkonia and exotics in… · pp. 221–222, Figure 7.96 · p. 222

7.4.5 New particle production mechanisms

  • The section considers alternative exclusive-production mechanisms, including Odderon exchange and backward production involving baryon trajectories; charge-asymmetry observables could reveal small Odderon contributions.Large-|t| exclusive pseudoscalar production is a possible hard-Odderon channel, while two-pion production could yield measurable asymmetries if the Odderon-to-Pomeron coupling is not unexpectedly small.Source: §7.4.5 · p. 223, Odderon exchange · pp. 223–225

Exclusive backward (u-channel) production

u-Channel exclusive meson electroproduction

  • EIC acceptance and forward tagging enable simultaneous near-forward and near-backward meson electroproduction; low-Q2 W mapping and Q2-dependent u slopes test the Regge-to-TDA transition.The objectives include probing the transition from a soft, hadronic-scale interaction to the hard QCD regime and from non-perturbative to perturbative QCD.Source: u-Channel exclusive meson… · p. 227

Three-gluon exchange and near-threshold production

  • Near-threshold quarkonium production is sensitive to the quarkonium-nucleon potential [1063]; unlike JLab, the EIC can reach ψ′ and Υ, study electroproduction, and requires hadron-going acceptance for threshold studies.GlueX measured a near-threshold J/ψ cross-section above the two-gluon expectation but consistent with two- plus three-gluon exchange; it found no narrow J/ψp peaks and set limits eliminating some, not all, pentaquark models.Source: Three-gluon exchange and… · pp. 227–228

7.4.6 Spectroscopy

  • Predicted XYZ photoproduction cross sections of ~1–10 nb [1079] could yield statistics comparable to similar measurements; exotica favor forward acceptance, while lower EIC energies may centralize production.Fixed-spin exchange describes the near-threshold region and Regge exchange the higher-energy region; photon-Reggeon fusion accesses a wider range of quantum numbers than photon-Pomeron fusion.Source: §7.4.6 · pp. 228–229, Figure 7.100 · p. 229

7.4.7 Target fragmentation

  • EIC measurements can make target fragmentation systematic by tracking its xF dependence, spin transfer, and quark-versus-gluon fracture functions, with continuous xF coverage from ~1 to ~0.1.The proposed measurements address multiparton structure and fragmentation dynamics; continuous coverage without gaps between central and forward detectors is an important requirement.Source: §7.4.7 · pp. 230–231

7.5 Connections with Other Fields

  • EIC precision and polarized beams can probe BSM couplings and new particles, while measurements can inform neutrino, astroparticle, hadronic-collision, and nuclear-structure research.The cross-field links include nuclear effects relevant to neutrino experiments, hadronic-interaction models for cosmic-ray air showers, and inputs to heavy-ion collision studies.Source: §7.5 · p. 232

Introduction

  • High luminosity, polarized beams, diverse nuclear targets, and broad kinematic coverage enable EIC searches beyond conventional nuclear-physics boundaries, including charged-current flavor separation and neutral-current γ−Z observables.The section frames these capabilities as a basis for exploring BSM physics and comparing the EIC’s expected reach with other experimental efforts.Source: Introduction · p. 233

Weak neutral-current measurements

  • EIC measurements can access C2q and C3q combinations and test the running of sin2 θW; polarized positron beams enable charge-conjugation asymmetries, while precision weak-angle tests can probe light new physics.The EIC offers complementary C2q measurements on proton and deuteron over a higher Q2 range, can improve C3q measurements, and can test sin2 θW in the previously unexplored 10–70 GeV scale region.Source: Weak neutral-current measurements · pp. 234–236

Weak neutral-current measurements / Charged current chiral structure

  • For Q=10–70 GeV, a dark Z with mZd≈10–30 GeV could shift the running weak mixing angle within projected EIC sensitivity; polarized charged-current data could modestly improve HERA limits on WR mass.The EIC charged-current measurements would complement LHC limits, which probe a time-like charged boson and can be affected by different chiral and flavor structures.Source: Weak neutral-current measurements · pp. 236–237, Charged current chiral structure · p. 239

Charged lepton flavor violation

  • With 250 fb−1, the EIC could improve the CLFV bound on z by one to two orders of magnitude, depending on the leptoquark state considered.A polarized positron beam and combinations of lepton-beam charge and polarization, kinematic range, and proton or deuteron targets can help distinguish leptoquark states and CLFV mechanisms.Source: Charged lepton flavor violation · pp. 237–238, Figure 7.103 · p. 238

Heavy-photon and neutral-lepton searches

  • EIC heavy-photon searches reach above the Z0 threshold and are competitive with the CMS dimuon result, while preliminary HNL studies indicate sensitivity beyond existing limits around 5 GeV.Radiative dark-photon production could test electronic and muon couplings, and HNL searches focus on production with a displaced vertex.Source: Heavy-photon and neutral-lepton searches · pp. 239–240

General BSM searches

  • Polarized EIC/LHC fits probe SMEFT Wilson-coefficient combinations inaccessible to LHC measurements alone, while 100 fb−1 inclusive DIS could tighten quark-sector Lorentz/CPT bounds by two orders of magnitude over HERA.Polarized positrons could constrain further SMEFT flat directions; Lorentz- and CPT-violating effects could appear as sidereal-time cross-section variations.Source: General BSM searches · pp. 240–241

7.5.2 Neutrino physics / Cross sections and kinematical regions / Electroweak measurements and the NuTeV anomaly

Studies of (anti)neutrino-nucleus interactions / Measurements of the strangeness content of the nucleon

  • Neutrino and antineutrino measurements on nuclei can probe nuclear modifications and weak-current structure; charm production can determine s(x), s̄(x), and their asymmetry, while neutral-current elastic scattering probes strange axial form factors and Δs.The charm-decay channels could yield statistics more than an order of magnitude above the largest existing samples; combining neutrino measurements with EIC data can improve determination of the nucleon’s strange content.Source: Studies of (anti)neutrino-nucleus… · pp. 243–244, Measurements of the strangeness… · p. 244

Isospin physics and sum rules

  • Neutrino and antineutrino interactions on hydrogen can determine the free-neutron structure functions and d/u up to x near 1; proton and nuclear data can test isospin symmetry and constrain the Adler and GLS sum rules.The Q2 dependence of the GLS sum rule can be used to extract αs, and EIC small-x data can reduce uncertainties on both sum rules.Source: Isospin physics and sum rules · p. 245

Electroweak measurements and the NuTeV anomaly

  • EIC parity-violating asymmetries can measure corrections to the Paschos–Wolfenstein relation, including PDF isospin breaking and nuclear effects, providing an independent check of the NuTeV anomaly [1096].The passages also call for combined electron and neutrino or antineutrino electroweak measurements because neutrinos directly access both the weak-mixing angle and the Z0 coupling to (anti)neutrinos.Source: Electroweak measurements and the NuTeV… · pp. 245–246

Possible GPD measurements in neutrino scattering

Cosmic ray air showers

  • Auger Xmax analyses find mixed composition at 10^19.5 eV, with ⟨ln(A)⟩≈1.3 under QGSJET-II-04 and about 0.5 higher under EPOS-LHC [1208]; muon content is 40–50% above lighter-composition expectations.EIC measurements, especially of forward hadronic particle production, could help tune the models; low-x parton distributions and oxygen or nitrogen targets could also be valuable.Source: Cosmic ray air showers · p. 248

Astrophysical neutrinos

  • EIC data can constrain low-x nuclear PDFs and charm production for prompt atmospheric neutrinos, and nuclear quark distributions for astrophysical-neutrino cross sections and inelasticity.At 10^20 eV, cited estimates give DIS cross-section uncertainties of roughly 15% [1161] and 50% [1219]; a newer NNLO calculation is about 10% below earlier calculations and states uncertainties under 10%, except above 10^19 eV [85]. EIC proton-gluon measurements could also reduce uncertainties in astrophysical-source neutrino fluxes and spectra.Source: Astrophysical neutrinos · pp. 249–250

Low-x gluons and factorization in eA (ep) vs pA and AA

  • At low x, the WW and dipole gluon distributions are process-dependent building blocks; back-to-back DIS dijets directly probe WW, while many processes probe dipole distributions.The passages describe p+A collisions as complementary to EIC saturation studies and note that A+A hadronic final states require more complicated factorization because of color entanglement [1231] [1232] [1234] [1235].Source: Low-x gluons and factorization in eA… · p. 251, Table 7.2 · p. 251

Implications of PDF determinations for proton-proton collisions

Implications of PDF determinations for proton-nucleus collisions

  • EIC measurements of nuclear PDFs can sharpen p+A predictions and reduce room to tune small-x distributions, strengthening searches for non-linear evolution at the LHC.The passages identify forward D-meson and direct-photon production, inclusive W and Z production, and J/ψ production in ultra-peripheral Pb-Pb collisions as relevant observables.Source: Implications of PDF determinations for… · pp. 253–254

Initial conditions for hydrodynamics in A+Acollisions

  • EIC exclusive and diffractive measurements can constrain spatial distributions and fluctuations of quarks and gluons in protons and nuclei, informing heavy-ion hydrodynamic initial conditions.EIC measurements of initial-state correlations can help distinguish them from hydrodynamic flow and constrain understanding of pre-equilibrium thermalization [749] [1245].Source: Initial conditions for hydrodynamics… · pp. 254–255

7.5.5 The EIC and nuclear structure physics

  • Exclusive quarkonium production with deuteron breakup can probe color-singlet and color-octet short-range correlations, with simulations indicating access to configurations with internal momenta up to 1 GeV.The two mechanisms differ according to whether the exchanged gluons attach to the same nucleon or to different nucleons; isolating final-state interactions remains a challenge.Source: §7.5.5 · p. 257, Figure 7.109 · p. 257
  • Diffractive measurements and spectator tagging can probe nuclear fragments, free-neutron structure, short-range forces, and medium modifications, but require accurate nuclear input and control of final-state interactions.The collider’s far-forward detectors and high luminosity support fragment measurements; coherent and incoherent breakup channels also present detection and veto challenges.Source: §7.5.5 · pp. 257–259
  • Tensor-polarized deuteron observables constrain its D-wave and probe nuclear interactions, while spin-1 beams also enable measurements of linearly polarized gluons unavailable for nucleons.Nuclear-structure corrections are a dominant uncertainty for inclusive DIS neutron structure at high x, and are essential for interpreting medium modifications and non-nucleonic components.Source: §7.5.5 · p. 258

7.5.6 Exotic Nuclei at the EIC

  • EIC collisions can produce rare isotopes far from stability, and relativistic boost extends in-flight survival to nuclei with half-lives above about 1 ns; photon spectroscopy can reveal their level structure.BeAGLE simulations suggest abundant medium-mass fission fragments from uranium and heavier exotic nuclei from lead evaporation; coincidence photon detection benefits spectroscopy but is not a critical requirement.Source: §7.5.6 · pp. 259–260, Figure 7.110 · p. 261
  • Isotope identification requires forward measurements of magnetic rigidity and an independent charge measurement, while rare-isotope studies favor strong forward acceptance without sacrificing maximum-energy ion luminosity.A compact Cherenkov detector behind the Roman-pot tracker is proposed as a way to measure charge.Source: §7.5.6 · pp. 260–261

7.5.7 Interface to High-Energy Physics efforts

  • EIC tomography will constrain parton distributions and their flavor composition, with precise TMD measurements reducing theoretical uncertainty in LHC W-boson-mass determinations.The program includes transverse-momentum-dependent, generalized, and collinear distributions, and supports tests of QCD relations and comparisons with advanced QCD and lattice predictions.Source: §7.5.7 · p. 263
  • Semi-inclusive DIS and jets can test perturbative and nonperturbative QCD mechanisms, while EIC heavy-flavor measurements can constrain intrinsic charm and inform forward-neutrino studies at the LHC.The EIC’s energy range, resolution, and particle identification support studies of hadronization, jet structure, and heavy-quark production.Source: §7.5.7 · pp. 263–264
  • Polarized beams, high luminosity, and varied energies enable electroweak precision tests and searches for new physics, including weak mixing-angle measurements and complementary constraints on leptoquarks and SMEFT operators.The EIC can measure parity-violating observables and probe weak couplings at Q = 10–70 GeV; combined LHC and projected EIC data can strengthen constraints.Source: §7.5.7 · pp. 264–265
  • Theory efforts for the EIC include higher-order QCD corrections and resummation, non-perturbative models, lattice QCD synergy, precise QED radiative corrections, and machine learning for proton tomography.Non-perturbative approaches can guide experiments and provide observables; lattice calculations can help interpret EIC data, while radiative corrections are essential for precision extraction.Source: §7.5.7 · p. 266, §7.6 · p. 266

7.6.1 Lattice QCD

  • Lattice QCD provides independent checks on αs determinations and has yielded a 30% improved-precision average relative to 2016, while its zero-density QCD equation of state locates the cross-over temperature to 1% accuracy.The lattice average is more precise than non-lattice determinations [1304, 355]; finite-density calculations remain limited by the sign problem, with Taylor expansion and analytic continuation yielding lower bounds on the critical-point location.Source: §7.6.1 · pp. 267–268
  • Lattice QCD provides a rigorous non-perturbative framework, and newer approaches connect lattice-calculable matrix elements to x-dependent PDFs, GPDs, and TMDs.Small- and large-x regions cannot currently be accessed reliably through lattice calculations, but combining lattice and experimental data can constrain a wider kinematic range.Source: §7.6.1 · pp. 267, 268, 270
  • Lattice data reduce JAM global-analysis uncertainties by a factor of 3–4 for transversity PDFs and 3–6 for helicity PDFs, depending on x region.The transversity result uses lattice tensor-charge constraints; the helicity comparison combines lattice and experimental data. Figure 7.111 shows these comparisons.Source: §7.6.1 · p. 269, Figure 7.111 · p. 269
  • Lattice studies of light nuclei are developing predictions for spin- and flavor-dependent EMC-like effects, while nuclear double-helicity-flip distributions probe exotic gluons and lattice inputs can improve weak-mixing-angle determinations.Moments of the deuteron double-helicity-flip distribution have been accessed in initial studies [1335]; rudimentary lattice calculations of flavor-symmetry-violating quark distributions could improve extraction of θW.Source: §7.6.1 · p. 270

7.6.2 Radiative corrections

  • Radiative corrections can reach a couple of tens of a percent and are especially large at small x and large y, with strong sensitivity to experimental conditions and their treatment.Recently available second-order QED corrections are comparatively small, but reliable uncertainty estimates require accurate calculations.Source: §7.6.2 · pp. 272–273
  • Radiative corrections should be treated both as an uncertainty to manage and as a physics opportunity, with detected-photon measurements and positron beams enabling additional studies.The positron-to-electron scattering ratio directly accesses the term beyond leading single-photon exchange [1360], while detected photons can reveal target structure through processes such as deeply-virtual Compton scattering.Source: §7.6.2 · pp. 274–275

Detector Requirements

  • EIC detector requirements include precise luminosity monitoring, polarimetry, and scattered-electron reconstruction, while exclusive and diffractive reactions require hermeticity and precision far-forward detectors.Central-region tracking and magnet design are linked to momentum resolution; SIDIS and jet or heavy-quark studies also require broad hadron identification, full azimuthal coverage, and excellent vertexing.Source: Detector Requirements · pp. 276–277
  • Central requirements begin with near-hermetic coverage over ±4 in pseudorapidity, later considered more realistically ±3.5 with reduced performance up to 4, plus low-material tracking, electron identification, vertex resolution, and hadron PID.The stated targets include material below 5% of X/XD, momentum resolution under 5%, pion suppression of 10−4, primary-vertex resolution near 20 micrometers, and 3σ pion, kaon, and proton identification to about 7 and 50 GeV/c at mid-to-forward rapidities, respectively.Source: Detector Requirements · p. 277

8.1 Inclusive Measurements

  • Inclusive reactions include neutral-current photon or Z exchange and charged-current W exchange, impose no flavor or final-particle constraints, and probe parton distributions, nonlinear QCD, higher twists, and symmetry violation.Source: §8.1 · pp. 278–279

8.1.1 Reconstruction of kinematic variables

  • NC kinematics can be reconstructed from the scattered electron, hadronic recoil, or a mixture; CC relies on Jacquet-Blondel recoil reconstruction, typically favored at small y because electron-method x and y resolutions worsen there.Source: §8.1.1 · pp. 279–280

8.1.2 Kinematic phase space

  • Scattered electrons typically occupy −3.5 < η < 1, while hadronic recoil is concentrated forward; CC events also have a higher-momentum tail into mid-forward rapidity, motivating forward electromagnetic and hadronic calorimeter coverage.For scattered electrons, average momentum rises with √s and Q2 and peaks at mid-to-forward rapidities; CC photons have distributions similar to the hadrons.Source: §8.1.2 · pp. 281, 283, Figure 8.5 · p. 281, Figure 8.7 · p. 282

8.1.3 Electron acceptance and particle identification

  • For most inclusive channels, Q2 > 1 GeV2 and W2 > 4 GeV2 cuts exclude nearly all phase space at η < −3.5; low-Q2 saturation, color-glass-condensate, and photoproduction studies may need far-backward detectors.Source: §8.1.3 · pp. 283–284
  • The 1% pion-contamination goal for ALL is unmet at the highest beam energy, while AePV requires contamination below 1 × 10−3 π−/e−; estimated suppression falls from 104 to 102 toward midrapidity.The ALL goal is also unmet for η > −1 (−2) at 5 (10) GeV electron beams; only the far-backward region at the two lowest beam energies meets the AePV target. Software pion-ID algorithms may improve suppression by factors of 2-4, but realistic-material studies are needed.Source: §8.1.3 · pp. 287–288

8.1.4 Resolution and bin migration effects in electron reconstruction.

  • With y > 0.01 and y < 0.95 cuts, proposed resolutions yield purity and stability above 30% in all tested bins, while mitigating low-y x bias and avoiding degraded forward-scattering energy resolution.The low-y resolutions in ∆x/x and ∆y/y diverge, and applying y > 0.01 mitigates the high-x events reconstructed at very low x; the study concludes the detector resolutions suffice with that cut.Source: §8.1.4 · pp. 289–290, Figure 8.19 · p. 292

8.1.5 Acceptance, resolution, and bin migration effects in Jacquet-Blondel reconstruction

  • Despite approximately 30% of final-state particles falling outside −3.5 < η < 3.5, reconstructed x, y and Q2 change minimally, with negligible difference between nominal and expanded acceptance.Expanded acceptance is −4.0 < η < 4.0.Source: §8.1.5 · p. 293, Figure 8.21 · p. 293, Figure 8.20 · p. 293
  • For forward hadronic-calorimeter resolutions of 40% ⊕5%, 45% ⊕6% and 50% ⊕10%, Jacquet–Blondel purity and stability are worse than for electron reconstruction, but differences are small.The results suggest that bin migration effects are not driven by differences among these hadronic-calorimeter resolutions.Source: §8.1.5 · p. 293, Figure 8.22 · p. 294

8.1.6 Generator verification

  • At HERA, DJANGOH agrees better with data at lower Q2, while both DJANGOH and PYTHIA6 agree well at higher Q2.Modern LO, NLO and NNLO PDF fits were also compared with HERA data and served as the baseline for validating EIC-energy simulations.Source: Figure 8.23 · p. 295, Figure 8.24 · p. 296, §8.1.6 · p. 297
  • Within 10% over most of the kinematic phase space, the simulations agree with fit results, with cteq61 better at low x, low Q2 and cteq6ll better at higher x, higher Q2.For DJANGOH, the passage specifies cteq61; the PDF-set comparison concerns PYTHIA6.Source: §8.1.6 · p. 297
  • At Q2 = 110, 130, 200 and 400 GeV2, reconstructed differential charged-current cross sections agree excellently with NLO xFitter theory curves.The 10 f b−1 of charged-current pseudo-data was simulated with DJANGOH.Source: §8.1.6 · p. 297

Systematic uncertainties for the inclusive pseudo-data … Scintillating fibers embedded in absorber

The studies define EIC measurement and detector requirements by examining how systematic uncertainties, acceptance, resolution, particle identification, reconstruction, and backgrounds affect inclusive, SIDIS, jet, exclusive, diffractive, and structure measurements. They also assess reference detector concepts and tracking and calorimeter technologies, describing performance trade-offs and areas for further refinement or R&D.

Systematic uncertainties for the inclusive pseudo-data

  • The inclusive pseudo-data use optimistic and conservative uncertainty scenarios, with NC, CC, and asymmetry systematics assigned separately.For unpolarized NC electron-proton data, uncorrelated uncertainties are 1.5% (2.3%) and normalization uncertainties 2.5% (4.3%) in the optimistic (conservative) scenarios; CC uses 2% uncorrelated and 2.3/5.8% normalization uncertainties. The parity-violating asymmetry estimate of 1% is considered optimistic for most EIC kinematics, especially η > −2.Source: Systematic uncertainties for the… · pp. 300–301

8.1.7 Summary of the inclusive detector requirements

  • The EIC Handbook detector coverage and capabilities meet nearly all inclusive-channel requirements, but limited e−/π− discrimination at η > −2 is expected to make APV and ALL systematically limited there.Source: §8.1.7 · p. 301

8.2.1 General SIDIS kinematics and requirements

  • SIDIS requires scattered-lepton and hadron detection with Q2 > 1 GeV2, 0.01 < y < 0.95, W2 > 10 GeV2, and homogeneous coverage from at least −3 < η < 3, preferably ±3.5.Good momentum resolution is needed for both particles, especially the scattered lepton, whose momentum determines the boost used to reconstruct hadron transverse momenta and azimuthal angles.Source: §8.2.1 · p. 302

8.2.2 Hadron PID impact on 4D TMD measurements

  • The proposed pion PID ranges cover most SIDIS kinematics, but the barrel limit significantly reduces intermediate-x, high-Q2, higher-z acceptance important for TMD evolution studies.Three-σ π/K separation is needed; the stated momentum reach is 7 GeV/c backward, preferably 8–10 GeV/c centrally, and up to 50 GeV/c forward.Source: §8.2.2 · pp. 304–305

8.2.3 Using the hadronic final state to reconstruct SIDIS variables

  • Hadronic reconstruction methods improve SIDIS-variable resolution: double-angle reconstruction improves DIS variables at high x and moderate Q2 and improves z resolution at low y, while hadronic methods outperform electron-only reconstruction for Breit-frame jets at low y and low pTjet.Extending hadron-side coverage to η = 4.0 expands reconstruction into the highest-x, low-y region.Source: §8.2.3 · pp. 306–307

8.2.4 Requirements for di-hadron measurements

  • For di-hadron partial-wave analysis, tracks down to pT > 100 MeV/c are required, and three-σ π/K separation keeps all pair-sample purities above 95%.With two-σ separation, ππ purity remains above 95%, but πK falls below 70% and KK is about 75%.Source: §8.2.4 · p. 309

8.2.5 Requirements for Λ measurements

  • Λ reconstruction requires decay pions with pT > 100 MeV/c; photon reconstruction down to 200 MeV centrally and 400 MeV forward supports distinguishing Λ feed-down from Σ0.A pT > 300 MeV restriction would leave less than 5% of Λs even at the highest energies.Source: §8.2.5 · pp. 309–310

8.2.6 Spectroscopy requirements for forward electron identification

  • Forward acceptance limits high-beam-energy XYZ photoproduction because many decay tracks have η > 3.5, while stricter e/π separation reduces background relative to the Zc(3900)+ signal.The low-beam-energy option offers higher acceptance and the high-beam-energy option higher luminosity, making them complementary.Source: §8.2.6 · p. 311
  • Forward J/ψ identification requires electron-pion separation greater than 3σ; 3σ separation yields roughly 90% purity for further resonance and decay-angular studies.Tracking and hadron identification beyond η > 3.5 are preferable because of the boost of the produced states.Source: §8.2.6 · p. 312

8.2.7 Summary of SIDIS-related Detector requirements

  • SIDIS detector priorities are broad momentum-range particle identification, low minimum momentum or energy reconstruction, and forward tracking and calorimetry to η < 4 for hadronic DIS kinematics.Source: §8.2.7 · p. 312

8.3.1 Simulation and detector modeling

  • Jet and heavy-flavor studies used PYTHIA6 or PYTHIA8 with fast-smearing frameworks for jets and more complete detector geometries for many heavy-flavor analyses.The PYTHIA8 jet comparisons with ZEUS data and theory showed excellent agreement in the relevant kinematic regions.Source: §8.3.1 · pp. 314–315

Momentum resolution

  • 3 T and 1.5 T track-momentum resolutions produce practically no change in jet energy scale or resolution; the studied resolutions are sufficient for jet measurements.JES is several percent and JER is below 10% for jet energies above roughly 20 GeV; both should be amenable to unfolding corrections.Source: Figure 8.43 · p. 319, Momentum resolution · pp. 319–320
  • Lower track-pT thresholds modestly improve jet-angularity scale and resolution and raise D* soft-pion acceptance from 60% to 90% at midrapidity and from 20% to 70% at |η| = 3.The compared D* acceptances correspond to thresholds of roughly 200 MeV/c and 100 MeV/c, respectively; lower thresholds also benefit substructure measurements and heavy-hadron reconstruction.Source: Momentum resolution · pp. 320–321, Figure 8.44 · p. 321

Vertex resolution

  • Requested transverse-DCA resolutions were derived from open-charm and bottom feasibility studies and support precision measurements of the nuclear modification factor R_eA.The studies span a wide pseudorapidity range and aim to distinguish models of parton energy loss and hadronization.Source: Vertex resolution · p. 322
  • 100 µm DCA resolutions caused a 60% loss in charm-jet efficiency, while 10 µm resolutions increased charm yield by 30% at the same light-jet contamination [86].The tagging procedure was optimized at 20 µm; the study did not establish that the requested resolutions were inadequate.Source: Vertex resolution · p. 323

8.3.4 Particle identification

  • Charged-hadron identification supports flavor-dependent hadron-in-jet fragmentation and Collins measurements, jet grooming and substructure, and reduced combinatorial background in heavy-flavor tagging.Source: §8.3.4 · p. 324
  • Restricted PID momentum reach removes much of the identified-hadron jT coverage, makes z > 0.5 inaccessible, and severely limits high-z Collins measurements, especially for 1.0 < η < 2.5.Requested reach is particularly ambitious in the barrel; for light and heavy ions, lost barrel phase space cannot be recovered by changing detector region or center-of-mass energy.Source: §8.3.4 · pp. 326–327, Figure 8.49 · p. 327, Figure 8.51 · p. 329
  • With barrel PID limited to 5 GeV, useful rasy data below z = 0.4 will be difficult to extract, with increased statistical uncertainty.The comparison shown is for identified proton-proton, kaon-kaon, and pion-pion pairs at 18 GeV electrons on 275 GeV protons and Q2 > 65 GeV2.Source: §8.3.4 · pp. 328, 330, Figure 8.52 · p. 330

8.3.5 Calorimetry

  • Calorimeters measure neutral jet energy unavailable to tracking, including roughly 25% electromagnetic and 10% neutral-hadron energy; neutral-hadron isolation can also affect jet reconstruction.At the most forward rapidities, calorimeter energy resolution may be competitive with or better than tracker resolution for charged hadrons.Source: §8.3.5 · p. 330, Hadron calorimetry · pp. 332, 334

Electromagnetic calorimetry

  • Changing from standard to ideal ECal resolution produces little change in JER, indicating that other contributions, including hadron-calorimeter energy fluctuations, dominate the jet-resolution budget.The ECal assessment also identifies hit thresholds, cluster separation, and position resolution as performance considerations; position resolution was not studied in detail.Source: Electromagnetic calorimetry · pp. 331–332, Figure 8.53 · p. 331

Hadron calorimetry

  • A neutral-hadron veto can reduce barrel-HCal-induced jet energy bias and improve resolution, but depends on isolating showers and matching them to charged-particle tracks.The requested HCal coverage is −3.5 < η < 3.5; forward resolution is 50%/√E ⊕ 10%, with the 10% constant term retained despite leakage challenges beyond η > 3.Source: Hadron calorimetry · pp. 332, 334, Figure 8.57 · p. 335

Coverage continuity

  • Calorimeter gaps distort jets more for wider gaps and smaller jet radii, with electromagnetic gaps having a larger effect than hadron-calorimeter gaps; the group requests gaps be kept as small as possible.The assessment compared gaps of 0.1 and 0.3 units of pseudorapidity centered at η = 1.Source: Coverage continuity · p. 336, Figure 8.58 · p. 336

8.3.6 Systematic uncertainties and unfolding: 1-jettiness

  • 1-jettiness detector residuals are significantly non-Gaussian, with RMS of 18% for tracks and 36% for particle flow; the shift from particle flow to tracks exceeds variations from detector performance.The track-level distribution shifts lower because of lower jet pT and fewer terms in the observable’s numerator.Source: §8.3.6 · p. 337
  • For 30 < Q < 40 GeV, unfolded flow-level τa distributions have 2–4% statistical and systematic uncertainties across the full range, with systematic uncertainty around 4% for 0.1 < τa < 0.7.Raw and unfolded statistical uncertainties in that interval are each within 2%; calorimeter performance is the largest systematic contribution, and uncertainty correlations were not assessed.Source: Figure 8.60 · p. 339, §8.3.6 · pp. 339–340

8.3.7 Summary

  • The Jets and Heavy Quarks requirements find either 3 T or 1.5 T tracking adequate, prefer lower minimum-track-pT thresholds at 1.5 T, request 3σ π/K/P separation, and deem standard ECal resolution adequate with a 100 MeV-or-better threshold.Neutral-hadron isolation may also be important for jet energy scale and resolution.Source: §8.3.7 · pp. 340–341

8.4.1 Deeply virtual Compton scattering and exclusive production of π0 in e+p

  • For DVCS at 18 GeV × 275 GeV, assumed |η| < 3.5 acceptance loses 14% of events at electron acceptance and 17% at electron-plus-photon acceptance; extending backward coverage to η < −3.7 nearly recovers the DVCS loss.At 5 GeV × 41 GeV, the loss is about 1%; at the highest energy, the scattered-electron distribution peaks near η ∼ −3.6.Source: §8.4.1 · pp. 342–343, Figure 8.62 · p. 344
  • With |η| < 3.5 and no photon-energy or π0-photon-separation cuts, exclusive π0 production may yield significantly relative to DVCS at high xB, motivating ECAL studies of acceptance, thresholds, and granularity.The π0 background arises when a decay photon escapes detection, falls below threshold, or its shower cannot be distinguished from the other photon’s.Source: §8.4.1 · pp. 341, 343, 345, Figure 8.64 · p. 345

8.4.2 Neutron target

  • Spectator tagging in deuteron DVCS can identify neutron GPD measurements with a spectator proton; the cited studies expect nearly 100% spectator-proton acceptance and precise t distributions over a wide range with suitable forward detectors.Combining t-reconstruction methods can also help assess systematic uncertainties from beam momentum spread and angular divergence.Source: §8.4.2 · p. 346

8.4.3 Deeply virtual Compton scattering off helium

  • For coherent DVCS off helium, the study focuses on helium because t acceptance is expected to be the main limitation and is most challenging for helium.Other tagged DVCS or DVMP studies would also require the detector needs identified for tagged DIS and DVMP on the proton.Source: §8.4.3 · p. 346

The Orsay-Perugia Event Generator (TOPEG)

  • Accounting for far-forward helium acceptance reduces the generated coherent-DVCS cross section by around 95% or more; the pre-acceptance total cross section is 4–11 µb across the considered scenarios.The cross section grows with beam energy in this study because it is dominated by the strongly t-dependent 4He form factor.Source: The Orsay-Perugia Event Generator… · p. 347

Central detector

  • At the highest energy setting, the central-detector photon acceptance loses up to 20% of coherent helium-DVCS events, particularly low-xB events; the |η| = 3.5 boundary is therefore critical.The affected region is dominated by the Bethe–Heitler contribution and has little importance for CFF extraction, but the loss may affect low-xB physics reach.Source: Central detector · p. 347, Figure 8.66 · p. 348

Overall performance

  • Quark-density profiles remain extractable at Roman Pot thresholds of pT = 0.1, 0.2, and 0.3 GeV, but the errors correlate strongly with the threshold.The profiles were extracted from TOPEG pseudo-data at 10 fb−1 using a leading-order fit; optimizing the threshold is important for exploiting nuclear DVCS data.Source: Overall performance · pp. 348–349, Figure 8.67 · p. 349

8.4.4 Timelike Compton scattering

  • The Bethe-Heitler contribution exceeds the TCS cross section by about two orders of magnitude, while BH–TCS interference is expected to boost the TCS signal by 10–15%.Central acceptance of |η| < 3.5 loses only the highest-momentum leptons; extended far-forward acceptance to η < 4.5 catches most pairs at the highest energy, and t resolution is worse when reconstructed from photons than from beam and recoil protons at the lowest energy.Source: §8.4.4 · pp. 350–351

8.4.5 Exclusive vector meson production in e+p

  • The e+p vector-meson studies simulated J/ψ and Υ photoproduction and dilepton backgrounds, then applied EIC-smear detector effects across nominal beam configurations.The reported results focus on the lowest and highest energy configurations as an envelope for the others.Source: §8.4.5 · pp. 352–353

Detector requirements

  • Photoproduction at higher energies depends on the low-Q2 tagger, while expanding its acceptance would improve event counts, especially for near-threshold Υ production.Muon PID is important to control backward-region dilepton backgrounds; the muon channel also doubles available statistics, which is valuable where threshold bins may have single-digit counts.Source: Detector requirements · pp. 354, 355, 356, 359

Kinematic coverage

  • At 100 fb−1, the study projects precise Q2-dependence measurements for J/ψ and enough statistics to study Υ in several Q2 + M2 bins.Υ DVMP probes gluonic structure at a larger scale than J/ψ; near-threshold Υ photoproduction remains challenging and would benefit from expanded backward or low-Q2 tagger acceptance.Source: Kinematic coverage · pp. 359–360, Figure 8.81 · p. 360

8.4.6 Exclusive vector meson production in e+A

  • For coherent e+A vector-meson production, the study focuses on central-detector reconstruction of t, with transverse-momentum resolution and multiple scattering setting the precision.The smallest |t| in coherent heavy-nucleus events makes these measurements especially demanding; central reconstruction also supports light-ion and incoherent studies and cross-checks of far-forward spectrometers.Source: §8.4.6 · pp. 361–362

Event generation and decay channels

  • The e+A simulations show that barrel acceptance of −1 < η < 1 yields sufficient statistics for electroproduction decay daughters, concentrated near midrapidity for J/ψ, η ∼−1 for φ, and η ∼−2 for ρ.The study used Sartre samples for ρ, φ, and J/ψ at maximum energy in photoproduction and 1 < Q2 < 10 GeV2; φ → K+K− requires low-pT tracking, while ρ → π+π− is feasible at low Q2 but also needs a low tracking threshold.Source: Event generation and decay channels · pp. 362–363, Kinematic coverage · p. 363, Figure 8.83 · p. 363

Kinematic coverage

  • Vector-meson decay particles span the tracking threshold to 2–3 GeV in pT, making multiple scattering dominant; photoproduction electrons can fall below η = −5 and require a low-Q2 tagger.Decay products peak near η ∼−1.5 for J/ψ, η ∼−3 for φ, and η ∼−4 for ρ in photoproduction; simulations use a 300 MeV lower pT cut unless noted otherwise.Source: Kinematic coverage · p. 364

Beam effects

  • Method A gives small-to-negligible beam-induced t-resolution effects except at very small t, with J/ψ, φ, and ρ resolutions worsening in the lowest t bins.For J/ψ, σt is 10% at t < 0.01 GeV2, 1.8% at t = 0.10 GeV2, and 1.6% at t = 0.16 GeV2; φ and ρ have σt/t of 6.3% at t < 0.01 GeV2 and 0.45% and 0.3%, respectively, at t > 0.10 GeV2.Source: Beam effects · pp. 365–366

Impact of momentum resolution

  • A 0.5 GeV multiple-scattering term is required to reconstruct the impact-parameter profile; measurement-precision effects are small, while handbook resolutions wash out diffractive structure.The passage identifies this as the nominal requirement: a factor-2 improvement over the handbook detector for the barrel and factor-4 for the scattered electron. Resolving the first three minima is crucial.Source: Impact of momentum resolution · pp. 366, 367, 370, Figure 8.86 · p. 369

Separating coherent and incoherent processes

  • Incoherent-background suppression can vary by a factor of four around nominal before significant source-profile distortions, but the studied veto cuts alone do not achieve the required suppression.Adding detection of nuclear γ-decay photons in the ZDC and B0 could improve veto efficiency, but that rejection factor remains unquantified.Source: Separating coherent and incoherent… · pp. 371–372

8.4.7 u-channel exclusive electroproduction of π0

  • For u-channel exclusive π0 production, the recoiled proton is near |η| ∼4.1 and may require dedicated tagging or missing-mass reconstruction if the Hadron End Cap cannot reach that acceptance.At the stated kinematics, the scattered electron has |η| < 1.5 and momentum ∼5.4 GeV, while the π0 momentum is ∼50 GeV; lower proton energy can send its decay photons outside ZDC acceptance.Source: §8.4.7 · p. 373

8.4.8 Exclusive meson production by charged currents

  • Charged-current exclusive meson production is suppressed relative to photoproduction but within EIC reach; nuclear cross sections are expected to scale as ∼Z4, with model-dependent corrections of ∼2.Other exclusive charged-current channels, including strangeness or charm, are expected to have cross sections of the same order; challenges include exclusivity and quasi-real photoproduction backgrounds.Source: §8.4.8 · pp. 374–375

Kinematics reconstruction

  • In charged-current e+p→νe π−p events, the neutrino and trigger electron are absent, so measuring the charged pion and recoil proton enables kinematic reconstruction.Pions are produced mostly backward with momenta ≲20 GeV, while recoil protons scatter predominantly forward with momenta ≲10 GeV.Source: Kinematics reconstruction · pp. 375–376
  • Recoil-proton momentum is tightly constrained when pion momentum is fixed, and process kinematics can be reconstructed using only the pion and recoil-proton momenta.The dominant DVMP region lies at the intersection of 0 < Q2 ≲ 100 GeV2 and |t| ≲ 1 GeV2 in the physical region 0 < xB < 1.Source: Kinematics reconstruction · pp. 376–377, Figure 8.95 · p. 377

Photoproduction backgrounds

  • Charged-current exclusive processes are measurable at EIC kinematics, but huge photoproduction backgrounds make their rejection crucial; nuclear targets cannot be used for CCDVMP studies.Missing-mass and missing-energy cutoffs target additional-hadron and quasi-elastic backgrounds; the strict missing-mass cutoff requires relative momentum precision of ≲10^-5, though a relaxed cutoff may help.Source: Photoproduction backgrounds · pp. 378–379

8.4.9 Diffractive dijets

  • Diffractive-event identification by rapidity gaps depends strongly on detector rapidity coverage; larger η coverage improves purity, while the method provides higher statistics than forward spectrometry.The study assumes an inclusive-DIS-to-diffractive ratio of 7:1 and compares η coverage ranges of (−3, 3) and (−4, 4).Source: §8.4.9 · pp. 380–381, Figure 8.98 · p. 380

8.4.10 Summary

  • Exclusive-process studies identify backward and forward acceptance, muon detection, and central tracking resolution as important detector limitations.At η = −3.5, acceptance losses include 14%/17% for DVCS and 11%/12% for π0 production; extending to η > −3.7 can recover losses. A lower pT reach of 200 MeV is critical, muon detection can double statistics, and tracking resolution helps suppress charged-current photoproduction backgrounds.Source: §8.4.10 · pp. 381–382

8.5.1 Requirements for exclusive vector meson production

  • Exclusive vector-meson reconstruction requires broad pseudorapidity acceptance, momentum resolution, low-pT tracking, and limited detector thickness.Bremsstrahlung lowers reconstructed e+e− pair mass while raising pT, affecting dσ/dt; momentum resolution sets the width of the pair-mass cut.Source: §8.5.1 · pp. 383, 385

Pseudorapidity acceptance

  • Losing acceptance at y > −4 raises the minimum accessible x by a factor of e per unit of lost rapidity; losing near-threshold coverage also limits nuclear-correlation and exotic studies.Soft φ-decay kaons challenge reconstruction: the modeled all-silicon tracker has an acceptance drop near y = 0, and the resulting Q2 = 0 hole precludes φ measurements around x = 1/(2γ), or x = 0.005 for ions.Source: Pseudorapidity acceptance · pp. 385, 387

Momentum resolution

  • A 0.5% momentum resolution for tracks near 5 GeV is required to separate Υ(2S) and Υ(3S); simulated separation is adequate at 1.5 T and almost complete at 3.0 T.The stated Υ(2S)–Υ(3S) mass difference is 334 MeV, and a 100 MeV mass resolution gives a bit over 3σ separation.Source: Momentum resolution · pp. 387–388, Figure 8.102 · p. 388

Separating coherent and incoherent interactions

  • Separating coherent from incoherent production at moderate or large |t| requires rejection above 400:1 and forward detection of nuclear breakup products.Neutrons and protons require ZDC and forward-spectrometer acceptance to transverse momenta of several times the Fermi momentum; photon detectors may need sensitivity below 1 MeV in the nuclear rest frame. Lead’s 2.6 MeV excited state produces lab-frame photons of hundreds of MeV, but backward photons may be undetectable.Source: Separating coherent and incoherent… · p. 389
  • Gold’s long-lived 77 keV excitation and additional low-lying states make the separation of coherent and incoherent production unlikely to be achievable.Some deexcitation photons may be emitted after the nucleus leaves the interaction region; lead may make separation easier, but achievable rejection and its physics impact require further study.Source: Separating coherent and incoherent… · p. 389

8.5.2 Meson structure

  • Lower beam energies extend high-xπ coverage to lower Q2 and improve access to kaon structure through leading Λ detection.The high-xπ Q2 range is approximately 200–1000 GeV2 at 18 GeV on 275 GeV, 30–1000 GeV2 at 10 GeV on 135 GeV, and 5–1000 GeV2 at 5 GeV on 41 GeV.Source: §8.5.2 · p. 390
  • A 60×60 cm2 ZDC can provide close to 100% neutron detection efficiency for the Sullivan-process channel.At lower beam energies, total ZDC acceptance drives the size requirement; at higher energies, spatial resolution is important for measuring pT or t.Source: §8.5.2 · pp. 390–391
  • For Λ → n + π0, neutron and photon detection needs the ZDC and/or B0 electromagnetic calorimetry, with larger-angle photons at lower energies requiring B0 coverage.For Λ → p + π−, charged-particle tracking uses far-forward components including B0, off-momentum trackers, and Roman Pots; the B0 beam-pipe aperture affects pion efficiency and azimuthal coverage.Source: §8.5.2 · pp. 391, 392, 394, 397

Accelerator and instrumentation requirements

  • Λ tagging requires full azimuthal coverage in B0 and off-momentum tracking, while high-energy decays create reconstruction challenges.At higher energies, beam-pipe and FFQ dead regions impede pion detection; unknown decay vertices make momentum or angle correlations difficult, so mass reconstruction uses a Zvtx < 3–5 m event selection, with a Zvtx < 4 m cut applied for the reported efficiency study.Source: §8.5.2 · pp. 394–397, Accelerator and instrumentation… · p. 399

8.5.3 Deuteron DIS with spectator tagging: Free neutron structure and nuclear modifications

  • Spectator tagging in deuteron DIS identifies the active nucleon, removes dilution, and enables free-neutron extraction and studies of nuclear modifications.Proton pole extrapolation selects large-size pn configurations with absent nuclear interactions, while spectator momenta around 200–600 MeV/c select small-size configurations for tagged-EMC studies; the simulated pole-extrapolation procedure was verified against the model’s free-nucleon structure functions.Source: §8.5.3 · pp. 400–402

8.5.4 Diffractive J/Ψ production on the deuteron with spectator tagging

  • Diffractive J/Ψ production on the deuteron to probe short-range correlations requires tagging the spectator nucleon, with baseline acceptance and resolution studied using full Geant4 simulations.The spectators travel into the EIC far-forward region.Source: §8.5.4 · p. 402
  • Diffractive J/Ψ production on deuterium is measurable with good precision up to 800 MeV in internal nucleon momentum, requiring 30–500 fb−1.Momentum-transfer distributions in nucleon-momentum bins can provide gluon density distributions for studying gluon dynamics and short-range nuclear correlations.Source: §8.5.4 · pp. 402–403

8.5.5 Double tagging in the far forward region

  • Far-forward detection of spectator protons from 3He or neutrons from 3H would enable double spectator tagging in A=3 nuclei.This opens ways to extract nucleon information and study reaction-mechanism effects.Source: §8.5.5 · pp. 404–405

8.5.6 Short-range correlations and EMC effect studies

  • Simulations find that a significant fraction of highly correlated nucleons from short-range pairs in light nuclei can be detected in the far-forward region.Detection is especially promising at the highest center-of-mass energies; the representative proton-proton and neutron-neutron pair cases are described as extreme examples.Source: §8.5.6 · p. 405

8.5.7 Inclusive diffraction

  • Roman pots and B0 detectors provide broad diffractive-DIS proton acceptance, nearly reaching |t| = 1 GeV2 at proton energies of 275 and 100 GeV.The Roman-pot angular coverage spans the region of interest in ξ and much of t at high energy; the B0 detectors extend coverage to larger scattering angles. A lower scattering-angle limit and an acceptance gap remain constraints, with the gap shifting toward smaller |t| at lower √s.Source: §8.5.7 · pp. 408, 410

8.5.8 Summary of far forward region physics requirements

  • Far-forward requirements include B0 sensors with 50 × 50 µm pixels and Roman-pot sensors of 20 × 10 cm2 placed 10 σ from the beam halo.The off-momentum tracker is specified with a 10 cm inner radius and a 10 × 30 cm2 sensor; the zero-degree calorimeter is assumed to be at least 60 × 60 cm2 with electromagnetic and hadronic calorimetry.Source: §8.5.8 · p. 410

8.6 Summary of Requirements

  • A central-detector pseudorapidity coverage of −4 < η < 4 is crucial for flagship exclusive and diffractive measurements, including rapidity-gap selection.The report recommends pursuing greater high-η coverage to reduce the gap between central and far-forward detectors; increased forward coverage also supports hadronic-state reconstruction at high x and low y.Source: §8.6 · p. 411

8.6. SUMMARY OF REQUIREMENTS

  • The detector requirements also call for strong momentum resolution, low tracking thresholds, vertexing, particle identification, and electromagnetic and hadronic calorimetry.Examples include 100 MeV minimum pT for soft pions, 135 MeV for soft kaons, and 3σ π/K/p separation up to 50 GeV/c forward, 10 GeV/c centrally, and 7 GeV/c backward.Source: §8.6 · p. 412

Introduction to Volume III

  • Volume III surveys detector technologies and their performance against EIC requirements, considers instrumenting both planned interaction regions, and assesses detector integration and ongoing R&D.It builds on the physics studies and detector requirements developed in Volumes II, Chapters 7 and 8.Source: Introduction to Volume III · p. 417
  • Community members proposed novel detector ideas and options during the one-year effort that produced the Yellow Report.Source: Introduction to Volume III · p. 417

9.1 General EIC Detector Considerations

  • Reconstructing the full x–Q2 plane requires coverage at |η|>2; no technology ranking is established, and the EIC user group favors two complementary detector and interaction regions.The report says different detector approaches can contribute to complementary features and acceptances, technology redundancy, and cross-calibration.Source: §9.1 · pp. 418–419

9.2 Reference EIC Detector

  • The reference central detector spans −4<η<4, with full coverage for |η|<3.5, and targets 20 µm vertex resolution, 2% momentum resolution, and 3σ π/K separation to 50 GeV/c.Electron/hadron purity requirements are 10^-4 in the backward and barrel regions.Source: §9.2 · pp. 421–423

10.1 Beam Energies, Polarization, Versatility, Luminosities

  • EIC science depends on luminosity, center-of-mass energy, beam polarization, and ion species; two interaction regions are desired for complementary acceptance, technology redundancy, and cross-calibration.The report identifies complementary detector and interaction-region choices as a route to optimizing precision and kinematic range.Source: §10.1 · p. 425

10.2 Integrated Detector and Interaction Region

  • Nearby quadrupoles that support luminosity obstruct shallow-angle acceptance, especially for initial-state-ion particles, prompting detector integration across ±40 m beyond the main detector.Changes in this integrated region can affect beam dynamics, accelerator performance, magnet engineering, and detection acceptance, particle identification, and resolution.Source: §10.2 · pp. 428–429
  • Ancillary systems must determine beam polarization with order 1% systematic understanding and measure the electron-ion collision frequency to better than ∼1%.Beam dynamics can affect long-time averaging methods used for these measurements.Source: §10.2 · p. 429

10.2. INTEGRATED DETECTOR AND INTERACTION REGION

  • Near-complete acceptance requires a central detector plus integrated far-forward and far-backward regions to detect ion-beam fragments, intact diffractive particles, and shallow-angle scattered electrons.The far-forward region extends about 30 m downstream of the ion beam; the far-backward region supports luminosity monitoring and low-Q2 coverage, including photoproduction studies.Source: §10.2 · pp. 430–431

10.3 Rate and Multiplicities

  • Around 100 Gbps of collision-induced zero-suppressed streaming data is estimated at top instantaneous luminosity, the minimum raw rate to record all central-detector minimum-bias collisions without online reduction.The estimate combines the EIC PYTHIA6 tune with full detector GEANT simulation; backgrounds and excessive detector noise are not included.Source: §10.3 · p. 432, Figure 10.6 · p. 433

10.4.1 Ionization radiation dose and neutron flux from the EIC collisions

  • At top luminosity, e+p collisions produce about 2.5 kRad/year maximum ionizing dose in backward-arm crystal calorimeters and above 10^10 neutrons/cm2/year near the beam line.The vertex tracker and forward-backward calorimeters are among the regions with relatively high neutron flux.Source: §10.4.1 · p. 434

Synchrotron radiation

  • Synchrotron radiation requires shielding and absorbers, beam-pipe cooling, and mitigation of vacuum degradation; its background in the luminosity monitor and low-Q2 tagger also needs attention.A GEANT4-based hit-rate assessment integrating SynRad with detector response was being prepared, with results pending updates to the beam chamber and optics.Source: Synchrotron radiation · pp. 434–435

Beam-gas interactions

  • Beam-gas simulations estimate an annual dose of 6 · 10^10 n/cm2 (1 MeV equivalent) in the silicon vertex tracker, over three orders of magnitude below the suggested 10^14 n/cm2 tolerance.The modeled neutron spectrum includes fully thermalized neutrons below 1 eV and an evaporation-neutron knee around 10 MeV; the detector can act as both neutron sink and source.Source: Beam-gas interactions · p. 440

Beam halo

  • Beam halos from elastic beam-gas or beam-beam collisions can create large-angle particles that generate additional detector background and threaten beam stability; collimator scraping and placement are under study.Source: Beam halo · p. 441

Summary and outlook

  • The silicon vertex tracker faces annual neutron fluence of O(10^11)n/cm2 and synchrotron hit rates of O(10^8) to O(10^12) pixels per second; other tracking and PID detectors also receive considerable synchrotron hits.Hadronic showers are estimated to produce O(10^10)n/cm2 near the first calorimeter interaction lengths by the beam pipe; optimization and refinement remain ongoing.Source: Summary and outlook · p. 443

10.5 Systematic Uncertainties

  • A total systematic uncertainty of about 2% is important to exploit EIC statistical precision, while low-x asymmetries near 10^-4 require relative luminosity measured to ∼10^-5.Luminosity and polarization measurements are coupled because the bremsstrahlung rate depends on both beam polarizations; absolute cross sections require δL/L ∼1%.Source: §10.5 · p. 445

10.5. SYSTEMATIC UNCERTAINTIES

  • Radiative-correction systematics may dominate EIC measurements, so the report calls for dedicated generator development and experimental validation, particularly for e+A theory.A dedicated detector/beam configuration could target kinematics where corrections are large; radiative effects are an important uncertainty [1365].Source: §10.5 · pp. 446–447
  • Inclusive structure-function points are projected to have ≈3% total uncertainty, while exclusive-reaction −t-dependent point-to-point uncertainty is estimated at 1.0–1.2%.The inclusive estimate comprises ≈1.5% uncorrelated and ≈2.5% normalization uncertainties; the exclusive estimate is based on Jefferson Lab experience and alignment expectations.Source: §10.5 · pp. 447–448, Table 10.5 · p. 448
  • Electron beam polarization is targeted at 1% systematic uncertainty or better, while hadron polarization scale uncertainty has reached below 1.5%, with a 1% EIC goal.Laser polarization knowledge and detector response drive the electron uncertainty; hadron measurements must also monitor store-to-store differences, polarization decay, bunch profiles, and possible bunch-spacing backgrounds.Source: §10.5 · pp. 448–449

10.6 Physics Requirements

  • The EIC detector is required to be hermetic with low-mass tracking, cover −4 < η < 4, and handle data rates up to ∼500 kHz, with auxiliary forward and backward detectors.Requirements were developed from physics studies and compiled for central and beamline detectors; the main coverage includes electrons, photons, hadrons, and jets.Source: §10.6 · p. 450

11.1 Magnet

  • A 0.5 T field supports charged-particle detection below ∼0.1 GeV/c, while 3 T can improve momentum resolution by about a factor of two over 1.5 T.The report considers a new solenoid and reuse of the BABAR/sPHENIX magnet, whose field is up to 1.5 T; low-pT acceptance and momentum resolution are key field-strength tradeoffs.Source: §11.1 · pp. 453–454

11.2.1 Introduction

  • The detector concepts combine physics-working-group requirements with tracking technologies and design constraints, and identify targeted R&D areas to reduce deployment risk.The resulting concepts assess technology, services, mechanical support, and other components against what can reasonably be deployed on the EIC schedule.Source: §11.2.1 · pp. 454–455

11.2.2 Main requirements and acceptance coverage

  • Tracking requirements specify momentum resolution, material budget, pT cutoff, and pointing resolution across pseudorapidity ranges, forming the basis for detector designs.Source: Table 11.2 · p. 455, §11.2.2 · p. 455

11.2.3 Silicon Detector Technologies for EIC

  • MAPS are identified as the best current fit for the silicon vertex and tracking detector, while higher granularity and lower material budget can recover pointing resolution with the larger beam pipe.The cited configuration uses 10 × 10 µm2 pixels, 0.05% X/X0 vertex layers, 0.55% tracking layers, and 0.24% disks; integration time below 2 µs is required at 500 kHz.Source: §11.2.3 · pp. 456–457, Figure 11.1 · p. 456
  • A TJ 180 nm modified CMOS process has been positively evaluated for EIC MAPS development, while joint EIC SVT sensor development with ALICE ITS3 has begun to share development costs and leverage compatible specifications and timescales.Existing DMAPS prototypes meet HL-LHC requirements, but their suitability for EIC SVT use remains to be demonstrated; the 65 nm path offers improved granularity and power consumption, with higher NRE costs and complexity than older nodes.Source: §11.2.3 · p. 458

65 nm MAPS SVT detector

  • ITS3 65 nm MAPS specifications satisfy and exceed EIC SVT requirements, with higher granularity, lower power, shorter integration time, and lower fake-hit rate; its 10 µm pitch is key to vertex-layer design.The ITS3 concept combines low-power design, thinned large-area stitched sensors bent around the beam pipe, and minimized active-area support and cooling to target a 0.05% X0 material budget; EIC implementation is being developed by the EIC Silicon Consortium.Source: Table 11.4 · p. 459, §65 · pp. 459–460

11.2.4 Gaseous Detector Technologies

  • The EIC is considering gaseous detector technologies for central-region tracking, with comparative studies assessing where each technology is best suited in the detector.The comparison is presented in Figure 11.4.Source: §11.2.4 · p. 461, Figure 11.4 · p. 461

Time Projection Chambers (TPC)

  • A TPC can provide the EIC central detector’s required momentum resolution and dE/dx particle identification; a prototype test beam verified the sPHENIX position-resolution goal of σrφ ≲300 µm with 40 track points.The sPHENIX requirement corresponds to ∆p/p ≈1.2% for 4–10 GeV/c electrons and positrons; a gate-less readout uses quadruple-GEM amplification, while an MM2G alternative has demonstrated low ion backflow with energy resolution better than 12%.Source: Time Projection Chambers (TPC) · pp. 461–464, Figure 11.6 · p. 462

Micro Pattern Gaseous Detectors (MPGDs)

  • A proposed EIC drift chamber with an extended forward/backward configuration could exceed 99.5% solid-angle coverage and improve cluster-counting PID resolution to better than 3.0% forward-electron and less than 2.4% forward-hadron directions.For the baseline cylindrical concept, calculations give σdN/dx/dN/dx = 3.6%, and cluster counting is projected to separate pions from kaons by more than 4 sigma up to 100 GeV/c except near 1 GeV/c; the alternate configuration increases average samples, at the cost of increasing barrel material from 1.5% X0 to approximately 4% X0.Source: Micro Pattern Gaseous Detectors (MPGDs) · pp. 464, 468, 469, 470

Small-strip Thin Gap Chambers (sTGCs)

  • sTGCs offer approximately 100 µm space-point resolution, about 0.5% X0 material per layer, and robustness up to 100 kHz/cm2, making them candidates for large-area forward tracking beyond the central tracking and PID detectors.The proposed location is in the hadron-going direction at z ≈300 cm, beyond the RICH detector.Source: Small-strip Thin Gap Chambers (sTGCs) · p. 471
  • sTGC planes may provide a cost-effective option for large-area trackers in the electron-going direction, where multiple scattering makes precise space-point resolution less important.Source: Small-strip Thin Gap Chambers (sTGCs) · p. 472

11.2.5 Detector concepts and performance studies

  • The all-silicon and hybrid concepts offer different strengths: a compact tracker with excellent tracking, versus a gaseous detector that adds dE/dx PID while maintaining EIC-required tracking.The alternatives are intended to help select a detector meeting overall requirements and may inform complementary configurations at a second interaction point.Source: §11.2.5 · p. 472

Baseline All-Silicon Tracking Option (Barrel & End Caps)

  • The all-silicon MAPS concept offers similar or better momentum and angular performance than the BeAST hybrid TPC-silicon concept, identical vertexing performance, and a more compact radius.Its radius is 43.23 cm versus 80.0 cm, freeing 36.77 cm for other uses such as PID.Source: Baseline All-Silicon Tracking Option… · pp. 475, 477

Alternative Forward and Backward Tracking Options

  • Auxiliary stations improve momentum resolution most in the backward region at higher momentum and at higher pseudorapidity; forward GEM detectors give enhancement comparable to silicon disks.The stations have greater impact at |η| ≳2.5, so smaller stations can complement the all-silicon tracker.Source: Alternative Forward and Backward… · p. 477
  • Replacing the final FST plane with GEM leaves momentum and DCAT resolutions materially unchanged; the added gas RICH worsens momentum resolution by about 1% at η >2.5.With a 3 T (1.4 T) magnet, momentum resolutions are <10% (18%) at η <1 and <4% (8%) at η >1; DCAT resolutions are <50 µm at η <2 and <110 µm at η >2.Source: Alternative Forward and Backward… · p. 480, Figure 11.26 · p. 481, Figure 11.27 · p. 481

Hybrid Tracking Option (Si-Vertex + Gaseous Detector Trackers)

  • The hybrid layout meets pointing-resolution requirements in all regions; momentum requirements are unmet especially at 1.5 T, while 3.0 T meets them except at |η| ≥2.5.Minimum reconstructable pT was assessed using the cutoff where 90% of tracks were reconstructed; pion and kaon results were similar.Source: Hybrid Tracking Option (Si-Vertex +… · pp. 484–485

Barrel: Silicon Vertex + Cylindrical MPGDs

  • At 3 T, hybrid TPC and barrel MPGD trackers exceed PWG requirements; their momentum resolutions are similar overall, with BMT better at 3 < p < 12 GeV/c and TPC better at very low and higher momenta.The comparison studied configurations with two middle layers and three or four outer layers; at 1.5 T the results echo those for the hybrid TPC, while the 3 T results exceed requirements.Source: Barrel: Silicon Vertex + Cylindrical… · p. 487, Figure 11.31 · p. 488

Hadron & Electron End Cap: MPGDs

  • Adding outer forward GEMs significantly improves momentum resolution across 1–60 GeV/c, reaching a factor of two at small scattering angles within their 5°–35° acceptance.Below θ = 15° (η > 2), the TPC hit count drops rapidly and vertex tracking falls to one hit below θ = 18°; adding outer GEMs doubles GEM hits in that region.Source: Hadron & Electron End Cap: MPGDs · p. 489, Figure 11.32 · p. 489, Figure 11.33 · p. 490

Fast tracking Layers & Additional PID detectors

  • Two cylindrical µRWELL layers around the DIRC improve track angular resolution and are projected to help achieve the required 3σ π/K separation at 6 GeV.The study used π− particles in a 1.5 T field at scattering angles of 43°, 66°, and 89° over 1–7 GeV.Source: Fast tracking Layers & Additional PID… · p. 493

High space point resolution tracking layer for TPC field distortions correc-

  • µRWELL layers are proposed to calibrate TPC-track scale distortions and provide bunch-crossing timing, with timing resolution better than 9 ns.The proposed calibration configuration places one layer inside the TPC inner field cage and one outside.Source: High space point resolution tracking… · p. 493
  • A GEM-TRD/T module achieves an e/π rejection factor around 9 at 90% electron-identification efficiency with a roughly 15 cm radiator, and can reconstruct 3D track segments.In the hadron end cap, these track segments could improve dRICH angular resolution and correct for multiple scattering before the EMCAL.Source: High space point resolution tracking… · pp. 495–496
  • Optimized zigzag anodes maintain position resolution below 65 µm at a pitch as large as 3.3 mm, while straight-strip resolution degrades at larger pitch.Zigzags provide a Gaussian raw residual distribution without pad-response-function correction; their charge sharing can be tuned through pitch, periodicity, and stretch.Source: High space point resolution tracking… · pp. 496–497, Figure 11.40 · p. 497, Figure 11.41 · p. 497

Comparison: requirements versus performance

  • Both baseline tracking concepts stay below the 5% X0 material-budget limit; transverse pointing resolution meets requirements at 1.5 T and 3 T, while momentum resolution better matches them at 3 T in the central pseudorapidity region.The comparison considers all-silicon and hybrid systems against physics-simulation requirements.Source: Comparison: requirements versus… · p. 498
  • The hybrid tracker meets transverse-pointing requirements at both fields, but at 1.5 T its relative momentum resolution falls below requirements and low-momentum track reconstruction needs improvement.Performance-versus-requirement comparisons are tabulated for all-silicon and hybrid concepts at 1.5 T and 3 T; the supplied text does not state the all-silicon outcomes.Source: Comparison: requirements versus… · p. 498, Table 11.22 · p. 498, Table 11.23 · p. 499

11.2.6 Material Budget Considerations

  • Power-supply and return cabling dominate tracking-service mass, while sensor-power reduction, aluminum conductors, serial powering, DC-DC conversion, multiplexed readout, and cooling options require optimization or R&D.ITS3-like sensors are expected to halve power dissipation to 20 mW/cm2; lower voltage still leaves substantial conductor needs, and aluminum takes more space because its conductivity is 65% of copper.Source: §11.2.6 · p. 500

11.3 Electromagnetic Calorimetry

  • The ECAL must measure scattered-electron energy, distinguish electrons from pions and charged hadrons, detect photon energies and positions, and resolve high-energy π0 decays.Tracking measures the electron’s momentum, while ECAL energy measurement is especially important at small scattering angles where tracker momentum resolution is insufficient.Source: §11.3 · p. 501

11.3.1 Requirements and Overview

  • ECAL design favors best energy resolution at η < −2, two-photon resolution at η > 2, and coverage of about −4 < η < 4, within finite detector space.The report also specifies timing sufficient to separate bunches about 10 ns apart and moderate radiation hardness up to 3 krad/year electromagnetic and 10^10 n/cm2 hadronic.Source: §11.3.1 · pp. 501–504

11.3.2 ECAL: Requirements, Options and Features

  • ECAL performance depends on energy and position resolution, photon separation, shower containment, signal size, response uniformity, and readout threshold; shorter depth can worsen high-energy resolution through leakage.For E < 20 GeV, the stated thickness thresholds are >22 X0 at β=2.5%, >20 X0 at β=7%, and >18 X0 at β=12%.Source: §11.3.2 · pp. 504–505

Homogeneous Calorimeters

  • PbWO4 is the selected mature scintillating-crystal candidate, typically providing β ≈2.5% while balancing resolution, compactness, radiation hardness, signal length, cost, and availability.Scintillating glass is under development as a potentially cheaper, more available alternative with comparable resolution but lower density; lead glass offers medium resolution of β ≈6%.Source: Homogeneous Calorimeters · p. 506

Sampling Calorimeters

  • Sampling calorimeters use absorber-scintillator combinations, including Pb/ScFi or W/ScFi fibers and shashlyk plate stacks, with resolution depending on materials and geometry.Reported stochastic-term ranges are β = 6–15% for fiber designs and β = 5–15% for shashlyk; tungsten offers high density and a short calorimeter length.Source: Sampling Calorimeters · p. 507

ECAL technologies considered for EIC

  • The ECAL technology comparison orders promising options by radiation length and relates active thickness to resolution and module length, reserving 15 cm for photosensors, electronics, services, and support.A shorter active area would increase the constant term α.Source: Table 11.27 · p. 508
  • The listed ECAL technologies approach initial energy-resolution requirements, with PbWO4 crystals nearly meeting them for −4 < η < −2; choices for other regions depend on spectrometer constraints.All described technologies are considered radiation hard at the levels expected at EIC.Source: ECAL technologies considered for EIC · pp. 508–509

Impact of the material in front of ECAL

  • In front of ECAL, electron identification cuts can lose 5–30% of electrons, with 10–20% losses expected in some areas at p < 10 GeV even after partial photon recovery.The loss arises because electrons radiate and photons convert before ECAL; predicting radiated-photon positions can recover part of the energy.Source: Impact of the material in front of ECAL · p. 509, Figure 11.45 · p. 509

Impact of the Cell Size and the Projective Geometry

  • A cell size near the material’s Molière radius balances coordinate resolution and readout-channel count; fine segmentation and projective geometry also aid π0/γ discrimination and coordinate resolution.For dense material with X0 ≈ 10 mm and 25 mm cells, non-projective incidence at 45° adds about 7 mm to coordinate resolution; π0/γ momentum reach scales roughly as ZECAL/d.Source: Impact of the Cell Size and the… · pp. 509–511

Electron/pion separation

  • Across 4–20 GeV, sampling and lead-glass calorimeters provide pion rejection factors of 100–1,000, while PbWO4 may reach 3–5 times higher; rejection above 1,000 at moderate energies remains unconfirmed.The largest reported sampling-calorimeter rejection was 2,000 at 100 GeV and 90% electron efficiency; DIS electron purity exceeds 95% above 4 GeV in all studied areas, while the high-resolution area extends above 90% purity to 2 GeV.Source: Electron/pion separation · p. 512, Table 11.29 · p. 513

Lowest detectable energy

  • The minimum detectable energy is about 20 MeV for PbWO4 with low-noise sensors and electronics, versus an expected 50–100 MeV for sampling detectors.The PbWO4 threshold comes with 30–50% energy resolution.Source: Lowest detectable energy · p. 514

Readout Considerations

  • SiPMs are the current photosensor choice, but noise, radiation sensitivity, dynamic range, and nonlinearity may limit high-resolution calorimeters; about 1M pixels per crystal may be needed.The readout is expected to use ASICs and at least 12-bit fADCs; a 14-bit fADC is needed for the 0.02–20 GeV range and 2% energy resolution at η < −2.Source: Readout Considerations · pp. 514–516, Discussion · p. 517

Discussion

  • PbWO4 appears to be the only practical near-requirement option for η < −2; elsewhere, ECAL choices depend strongly on available geometry and space.The η > 1 region favors fine segmentation and high-A materials for resolving π0 decay photons; projective geometry improves coordinate resolution and e/π separation, but endcap geometry remains undecided.Source: Discussion · p. 517

PbWO4 crystals

  • PbWO4 is fast, compact, radiation hard, and sufficiently luminous for good energy resolution; PWO-II improved light output, while radiation hardness requires particular attention below 0°C.The improved PWO-II relative light output is 0.6 at room temperature and 2.5 at −25°C, compared with 0.3 and 0.8 for CMS PWO, respectively.Source: PbWO4 crystals · p. 518
  • More than 1,000 PWO crystals had been produced for PANDA and NPS by August 2020, with none rejected.SICCAS and CRYTUR both have mass-production capability; earlier full-size SICCAS crystals had typical failure rates of 20–30%, while CRYTUR began mass-producing PWO-II in 2018.Source: PbWO4 crystals · pp. 519–520

Scintillating glass

  • SciGlass production reached samples up to ∼10X0 and a first 40 cm block, with measured energy resolution comparable to PWO at 4–5 GeV for comparable radiation lengths.Tests found no damage up to 1000 Gy electromagnetic or 10^15 n/cm2 hadron irradiation; uniformity and macro-defect issues in DSB:Ce glass remain to be resolved before scale-up.Source: Scintillating glass · pp. 520–522

Lead glass

  • Lead glass typically has a 1.5–3.1 cm radiation length and 2.6–3.7 cm Molière radius, and a 20-radiation-length calorimeter requires 30–50 cm depth.Radiation damage can recover over 1–3 months, be cured in situ with UV, or be treated by heating; measured energy resolution depends on optical quality, light yield, detection efficiency, and electronic noise.Source: Lead glass · pp. 523–524

Scintillating fibers embedded in absorber

  • The sPHENIX tungsten/scintillating-fiber calorimeter uses more than 6,000 absorber blocks and SiPM readout, while future EIC designs could reduce response nonuniformities by shortening light guides.The compact design has a total radial length of 26 cm; block and light-guide boundaries cause response nonuniformities that can be corrected using calorimeter position information and/or tracking.Source: Scintillating fibers embedded in… · pp. 524–525

Shashlyk … Far-Backward Electron Detection and Requirements

The section surveys EIC detector concepts and requirements across calorimetry, particle identification, and far-forward and far-backward instrumentation, including luminosity measurement. It describes performance considerations and design constraints such as resolution, acceptance, magnetic fields, radiation, backgrounds, and accelerator integration.

Shashlyk

  • β≈0.027(pd/fsamp −0.74) and β≈0.049(pd/fsamp −0.92) describe two shashlyk groups; GEANT4 matches the lower curve at moderate layer thickness.The reason for the two groups is unclear. For the EIC space constraint, a W/Sc structure of 0.75/1.5 mm is estimated to provide a stochastic term of 6.3% GeV^0.5.Source: Figure 11.54 · p. 526, Shashlyk · pp. 526–528

11.4.1 General consideration for Hadron Calorimeters

  • About 90% of jet energy is measured precisely by the tracker and ECAL in the EIC energy-flow approach, while calorimetry accounts for neutral hadrons.In three approximately compensated calorimeters, hadronic resolution is dominated by sampling fluctuations; compensation is of little value for most central EIC hadrons below 10 GeV, where ZEUS data showed e/h decreasing by 30%.Source: §11.4.1 · pp. 529–531

11.4.2 Central detector consideration

  • Approximately 5 λint of calorimeter depth is sufficient in most central regions, while the forward hadron endcap requires about 6–7 λint for shower containment.Steel absorbers generate fewer neutrons than lower-Z alternatives, which is preferable when using SiPM readout.Source: §11.4.2 · p. 532

11.4.3 HCAL Energy resolution

  • For η > 2.5, the forward hadron endcap targets better than ≈40%/√E resolution with ≈5% constant term, favoring a dense fiber calorimeter that can serve as ECAL and HCAL.Steel can provide mechanical support for the ECAL and eliminate dead material between calorimeter sections; limited space also motivates integrating the tail catcher into the HCAL.Source: §11.4.3 · pp. 532–533

11.4.4 eRD1 EIC R&D and STAR forward developments

  • ≈30% better hadronic energy resolution was measured for an earlier compensated prototype than for the non-compensated version.The non-compensated STAR FCS prototype, with Pb/Sc shashlyk and Fe/Sc sections, achieved a resolution close to 60%/√E + 6% after accounting for transverse leakage; the compensated W/ScFi EM section was designed for ≈12%/√E.Source: §11.4.4 · p. 534

11.4.5 Alternative methods for high resolution HCAL

  • No meaningful correlation between the fast shower component and total energy was observed in the steel-absorber test, so event-by-event EM-fraction correction by dual readout appears unpromising.Dual readout compares scintillation and Cherenkov signals to estimate the EM shower fraction, which is relevant because EM fluctuations complicate hadronic calorimetry.Source: §11.4.5 · p. 535
  • The technically conservative hadron-calorimeter parameters appear achievable with existing technologies, while higher-resolution calorimetry requires further R&D.The report cites eRD1 and the STAR Forward upgrade as demonstrations; higher resolution may require a high-density fiber calorimeter with SiPM readout or another suitable technology.Source: §11.4.5 · p. 535

11.4.6 TOPSiDE Calorimetry

  • TOPSiDE uses ultra-fast silicon tracking for π-K-p time-of-flight identification, reducing the need for dedicated central-detector PID and minimizing material and subsystem count.Its calorimetry can use varied technologies; the concept describes monolithic-sensor SiW electromagnetic calorimetry, an inner backward-endcap PbWO4 crystal calorimeter, and granular hadron options including scintillator pads or RPCs.Source: §11.4.6 · p. 536

11.5 Particle Identification

  • PID combines momentum with velocity information, obtained through TOF or velocity-dependent detector interactions; electromagnetic-calorimeter bremsstrahlung supports electron identification.The listed interactions include specific ionization and Cherenkov radiation; the report also identifies transition radiation as an electron-identification option at EIC.Source: §11.5 · p. 537

11.5.1 Physics Requirements

  • Simulations across EIC physics processes and center-of-mass energies inform a detector-performance requirements matrix specified as a function of η.The PID-relevant subset is presented in Table 11.38.Source: §11.5.1 · pp. 537–538, Table 11.38 · p. 539

11.5.2 PID via Energy Loss

  • The sPHENIX test-beam dE/dx results were comparable to STAR despite fewer samples and a shorter detector, while cluster counting could extend π-K separation but needs further short-length R&D.The report attributes the comparable test-beam performance to a gas with fewer secondary electrons per primary ionization event, mitigating the Landau tail; the cluster-counting performance is simulated.Source: §11.5.2 · p. 540

11.5.3 Cherenkov

  • Cherenkov PID trades higher-momentum reach at lower refractive index against higher thresholds and reduced photon yield, so radiator index must be tuned across EIC regions.Track-direction errors smear the apparent Cherenkov angle, with higher photon statistics mitigating the effect; chromaticity, emission-point error, pixelation, magnetic field, and tracking also limit resolution.Source: §11.5.3 · pp. 541–543

Hadron Blind Detector (HBD)

  • The HBD uses unfocused Cherenkov light in threshold mode, making it suitable for electron identification rather than general PID; a simulated HBD++ could nearly double pion rejection but remains unproven.The PHENIX implementation used CF4 and a CsI photocathode, but its ionization signal from charged particles limited electron-pion separation.Source: Hadron Blind Detector (HBD) · p. 543

CsI RICH

  • The CsI RICH’s low refractive index gives pion and kaon radiation thresholds of 4.17 and 14.75 GeV/c, requiring additional lower-momentum PID; its CF4 prototype showed π-K separation at 32 GeV/c.Measured performance extrapolated to 3-σ at 60 GeV/c, and simulations indicate the device is unaffected by track-pointing errors of roughly 2 mrad or less because chromaticity dominates.Source: CsI RICH · pp. 544–545
  • CsI photocathodes lose quantum efficiency under high-luminosity ion bombardment and require limited gain; HND offers similar UV quantum efficiency with greater chemical and mechanical robustness.HND-coated THGEM avalanche performance is unchanged after an appropriate heating protocol, but preservation of quantum efficiency is still under study and the protocol is being optimized.Source: CsI RICH · pp. 546–547

Dual RICH (dRICH)

  • The dRICH provides uninterrupted PID across the momentum range, eID to roughly 20 GeV/c, and π-K separation meeting the requirements; it is identified as the best-known approach for the hadron arm’s highest momenta.Its aerogel and C2F6 sections avoid low- and intermediate-momentum performance holes. The aerogel resolution is chromaticity-limited, while gas-section emission aberrations dominate; calculations indicate Ar at 3 atm would insignificantly affect performance, though low material budget remains an engineering challenge.Source: Dual RICH (dRICH) · pp. 548–551, Figure 11.73 · p. 550

Modular RICH (mRICH)

  • The mRICH simulation gives e-π rejection to roughly 2 GeV/c and π-K separation to roughly 6–7 GeV/c, with tracking tolerance of roughly 1 mrad.Its resolution is chromaticity-limited; a precision-timing readout could also provide a TOF tag to improve PID.Source: Modular RICH (mRICH) · pp. 551–552, Figure 11.75 · p. 552

Detection of Internally Reflected Cherenkov (DIRC)

11.5.4 Time Of Flight (TOF)

  • LAPPD provides roughly 5 ps σ timing resolution, but its photoelectron-avalanche signal is magnetic-field-sensitive, limiting current implementations to endcaps.Layered silicon timing can provide precise time measurements and space points for 4D tracking; its performance estimate assumes small common timing errors and no endcap HCAL to maximize flight path.Source: §11.5.4 · p. 557

11.5.5 Transition Radiation Detection

  • At EIC momenta, transition radiation detection is effectively an electron-identification method because heavier particles produce too few TR photons for effective measurement.TRD applications commonly measure particle trajectory and transition-radiation signal simultaneously.Source: §11.5.5 · p. 558

11.5.6 Photon Detection Technology Options

  • Photon sensors for EIC must detect single photoelectrons while retaining efficiency and gain in the spectrometer magnetic field, a criterion that excludes many traditional devices.Several suitable technologies exist or are under development and have been studied for EIC applicability.Source: §11.5.6 · p. 558
  • MCP-PMTs retain sufficient gain for RICH or DIRC use up to at least 1 T; at 10° they do so up to 1.2 T, but gain loss depends strongly on field angle.At 20°, gain falls to about 1% of its zero-field reference at 1.5 T, compared with 2.2 T at 0°. A 1 T photon-detection region appears plausible with a 3 T central field, but requires careful design.Source: §11.5.6 · p. 559, Figure 11.83 · p. 560
  • LAPPD signal loss is critical for Cherenkov readout, while SiPMs appear promising for calorimeter readout but still require demonstration as radiation-tolerant single-photon detectors for RICH.For SiPMs, low-temperature operation and high-temperature annealing can help maintain or restore performance; the cited development goal is operation up to 10^11 n-equivalent per cm2.Source: §11.5.6 · pp. 559–560

11.5.7 Configuration for EIC

  • Threshold-device eID is defined up to the pion radiation threshold, while imaging-device PID begins at the kaon radiation threshold.These criteria are used to compare detector options alongside the Cherenkov thresholds of the radiators considered.Source: §11.5.7 · p. 561

Forward Region

  • Forward-region PID requires gas-based Cherenkov detection for high momenta, with aerogel or another technology to cover the resulting low-momentum gap.The dRICH incorporates aerogel; the gRICH requires an aerogel-based mRICH or high-resolution TOF to cover the full dynamic range.Source: Forward Region · p. 562

Barrel

  • Limited barrel space makes DIRC and TOF leading options, but DIRC alone may not provide the needed eID or cover kaons below its 0.47 GeV/c radiation threshold.A complementary technology may be needed: dE/dx with a low-velocity tag from TOF, or, in non-hybrid tracking, cluster counting or a RICH option that still requires SiPM radiation-viability studies.Source: Barrel · p. 563

Backward Arm

  • Backward PID options range from a space-intensive dRICH that would exceed end-cap requirements to compact combinations such as mRICH with LAPPD timing or TRD.HBD-style technology matches the ideal 4 GeV/c eID need, but its proposed pion-rejection approaches were unproven; TRD, with a roughly 1 GeV threshold, can complement mRICH.Source: Backward Arm · pp. 563–564

11.6.1 Introduction

  • Diffractive measurements require robust far-forward hadron and photon detection at η > 4.5 and far-rear electron detection at η < −4.5, supported by multiple detector concepts.The far-forward layout must accommodate hadron-beam magnets while allowing scattered particles to pass, making full-acceptance coverage an engineering challenge.Source: §11.6.1 · p. 565, General Layout of Far-Forward IR Region · pp. 565–566

11.6.2 Roman Pots

Summary of the Current Design Constraints

  • 500 µm × 500 µm pixels balance smearing and R&D needs for Roman Pots, with about 100k channels per plane and ∼35 ps timing required.The simulations assumed one sensor plane per station, while operation may use 2–5 planes per station for redundancy and background rejection.Source: Summary of the Current Design… · p. 570

Basic Design Considerations; Summary of the Off-Momentum Detector Considerations

  • Off-momentum detectors tag charged particles from nuclear breakup and Λ decay, covering 0.25 < xL < 0.6 for protons, with azimuthal acceptance degrading below xL = 0.4.They sit outside the beam pipe, avoiding the Roman Pots’ 10σ cut; reconstruction must account for significant nonlinear effects from quadrupole fields, and Λ decay requires opposite-side detectors and a method for displaced vertices.Source: Basic Design Considerations · pp. 570–571, Summary of the Off-Momentum Detector… · p. 571

Basic requirements for B0; Silicon Sensors for B0-tracker; Pre-shower or EMCAL in the B0 spectrometer; Summary of the Current Design Constraints

Basic requirements for the ZDC; Summary of the current design

  • The ZDC must distinguish coherent from breakup events and support spectator tagging and collision-geometry studies, requiring neutron and low-energy-photon efficiency, broad acceptance, and energy, pT, and position resolution.A ∼60 × 60 cm² acceptance is proposed; 1 cm neutron position resolution corresponds to 300 µrad angular resolution and pT ∼30 MeV/c for 100 GeV neutrons, with a sampling calorimeter of ∼10 interaction lengths longitudinally and ∼2 transversely.Source: Basic requirements for the ZDC · p. 574, Summary of the current design · pp. 577–578

EMCAL technologies for ZDC; HCAL technologies for ZDC; Soft photon detection

  • FoCal-style silicon-tungsten sampling offers energy and position measurements, while ZDC hadron calorimetry must combine neutron energy and position performance; nuclear-excitation photons motivate a full-absorption crystal calorimeter.FoCal’s simulated photon resolution is σE = 25%/√E ⊕ 2%; tests of PbWO4 and SciGlass report ∼2%/√E at ∼4 GeV. Neutron tagging calls for σE < 50%/√E and angular resolution of at least 3 mrad/√E.Source: EMCAL technologies for ZDC · pp. 575–576, HCAL technologies for ZDC · p. 576, Soft photon detection · p. 576

Scintillator Tracker Detector

  • A scintillating-fiber tracker paired with the ZDC could veto π− for Λ → n + π0 measurements and improve charged-particle reconstruction, with high-rate and radiation-tolerant operation but low photon yield.A proposed layout can achieve ≈300 µm spatial and ≈500–220 ps time resolution.Source: Scintillator Tracker Detector · pp. 576–577

Beam parameters and lattice; Beam Pipe, Vacuum, and Background

  • Far-forward detector design must be integrated early with the accelerator, balancing acceptance and impedance, beam-pipe material, assembly, and protection against machine and beam-gas backgrounds.Vacuum pumps and shower tails can raise B0 occupancy; synchrotron-radiation heating may worsen out-gassing and neutron flux, and annual B0 radiation-dose estimates still need further study.Source: Beam parameters and lattice · p. 578, Beam Pipe, Vacuum, and Background · pp. 578–580

Simulation Details; Deeply Virtual Compton Scattering (DVCS)

Deeply Virtual Compton Scattering (DVCS)

  • Roman Pots acceptance depends on aperture and beam optics: high-acceptance optics reduce luminosity by up to about a factor of 2, and require approximately 25 cm × 10 cm active sensors.The study identifies 500 µm × 500 µm pixels as a resolution, cost, and design compromise.Source: Deeply Virtual Compton Scattering (DVCS) · pp. 583–584

Spectator Tagging in e+D Interactions

  • In e+D spectator tagging, off-momentum detectors are needed for breakup protons; narrower spectator scattering-angle distributions improve acceptance, but neutron acceptance is limited to < 5 mrad.At smaller angles, the broader proton transverse-momentum spread in neutron-spectator events causes losses in the lattice before the off-momentum detectors.Source: Spectator Tagging in e+D Interactions · pp. 584–585

Spectator Proton and Neutron Tagging in e+3He and e+3H Collisions

  • Spectator-proton double-tagging efficiencies in e+3He are mostly above 85% (above 90% at higher energy), except for lower-energy SRC events above 75%; neutron double-tagging is also promising.Proton losses mainly occur in gaps between B0 or off-momentum detectors and Roman Pots, driven partly by beam-pipe thickness; neutron losses are greatest in SRC events when a neutron enters the 4.5 mrad aperture.Source: Spectator Proton and Neutron Tagging… · p. 586

Meson Structure and FF Λ Decay

  • For Λ decays at 5×41 GeV, protons are expected mainly in off-momentum detectors and partly in B0, while B0 alone detects pions; the beam-pipe aperture limits pion efficiency.Λ decay vertices spread tens of meters along the beamline, complicating decay-product and mass reconstruction; full azimuthal detector coverage and adequate off-momentum coverage are also needed.Source: Meson Structure and FF Λ Decay · pp. 587–589

11.6.8 Conclusions

  • Far-forward coverage requires Roman Pots, a high-resolution zero-degree calorimeter, a silicon spectrometer in the first dipole, and silicon planes after B1apf for charged particles with xL < 0.6.The interaction-region design and B0 geometry remain under development, so further detailed simulations are needed to validate future detector designs.Source: §11.6.8 · pp. 589–590

Luminosity Measurement and Bremsstrahlung Photons

  • Bremsstrahlung luminosity measurements could reach about 1% scale uncertainty, but EIC polarization-dependent cross sections couple luminosity precision to polarization precision, especially for relative luminosities.Luminosity normalizes cross sections, combines running periods, and supports asymmetry measurements; the relative-luminosity requirement depends on the physics asymmetries, which can be as low as 10^-4.Source: Luminosity Measurement and… · pp. 591–593

Bremsstrahlung Photon Detection Principles and Requirements

  • A pair spectrometer can count converted e+e− coincidences with a tunable low-energy cutoff and rate, while calorimeters and position detectors support triggering, energy measurement, and acceptance corrections.The implementation places the exit window at z = -20.75 m, the pair detectors at z = -36.5 m, and the direct photon detector at z = -37.8 m; radiation-hard calorimeters and synchrotron shielding are required.Source: Bremsstrahlung Photon Detection… · p. 595, Bremsstrahlung Photon Detector… · p. 596

Bremsstrahlung Photon Detector Implementation

  • The geometric acceptance model agrees reasonably with full Geant4 simulation, and the plotted luminosity-spectrometer acceptance includes ~8% photon-to-pair conversion probability.The acceptance is defined by coincidence detection of both pair electrons; the simulation uses 1M generated bremsstrahlung events and requires at least 1 GeV in both detectors.Source: Figure 11.114 · p. 597, Bremsstrahlung Photon Detector… · pp. 597–598
  • The acceptance model can optimize the spectrometer dipole field for coincidence rates, with a different magnetic field required for each electron beam energy.Source: Bremsstrahlung Photon Detector… · p. 598

Far-Backward Electron Processes and Measurements

  • Bremsstrahlung-electron tagging can calibrate photon-based luminosity acceptance and support low-Q^2 measurements, but the latter face high bremsstrahlung-electron rates.Calibration requires special low-bunch-current runs to isolate one bremsstrahlung electron/photon pair per crossing; low-Q^2 tagger acceptance extends to Q^2 < 10^-2 GeV^2, with rates addressable through design and central-detector correlations.Source: Far-Backward Electron Processes and… · p. 598

Far-Backward Electron Detection and Requirements

  • Far-backward taggers need thin chamber exit windows, finely segmented calorimeters, and position-sensitive detectors to measure electron energy and coordinates for reconstructing Q^2 and x_BJ.Multiple position-detector layers can reconstruct direction to overconstrain the kinematic reconstruction and may help reject background.Source: Far-Backward Electron Detection and… · pp. 598–599

Far-Backward Electron Detector Implementation … 3He Polarimetry at the EIC

The section examines far-backward electron detector coverage and performance against EIC physics needs, alongside electron and hadron polarimetry concepts and requirements. It addresses detector limitations, operational constraints, and strategies for measuring beam, proton, and 3He polarization, including a Compton approach for electron-beam polarization.

Far-Backward Electron Detector Implementation

11.8 Considered Technologies and Detector Challenges

  • Detector technologies and assessed subdetector performance are summarized in tables and an interactive matrix, while comparisons with EIC requirements expose performance tensions needing further study.The report calls for assessing the physics impact of non-ideal performance and exploring additional technological options.Source: §11.8 · pp. 601, 602, 604, Table 11.49 · p. 605, Table 11.50 · p. 606

11.8.1 Acceptance requirements for the central detector

  • The reference detector’s acceptance matches the overall physics program, with full central coverage for |η| < 3.5 and specialized very-forward detectors extending beyond η = 4.6.Calorimeters extend to |η| = 4 with reduced edge performance; B0-spectrometer, off-momentum detectors, Roman pots, and ZDC serve specific exclusive and diffractive measurements.Source: §11.8.1 · p. 607

11.8.2 Particle identification challenges in the barrel

  • Barrel PID performance does not meet current requirements for electron–pion separation or hadron identification; proposed improvements face demanding timing, space, and technology constraints.The stated pion suppression need is 10^-4, while foreseen calorimetry plateaus near 10^-2; hpDIRC and TPC dE/dx provide limited momentum coverage, and TOF at O(10 ps) or better is challenging.Source: §11.8.2 · pp. 607–608

11.8.3 Hadron calorimetry challenges

  • Forward HCal performance falls short of desired resolution for η > 3; high-resolution inserts require additional R&D, including possible high-density fiber calorimetry with SiPM readout.The desired insert resolution is better than 40%/√E with an approximately 5% constant term; alternatives include tail catchers, dual readout, and digital calorimeters, with space and design constraints.Source: §11.8.3 · pp. 608–609

11.9 Polarimetry

  • EIC beam polarimetry must be non-destructive, achieve systematic uncertainty of 1% or better, measure each bunch, and provide rapid quasi-online feedback.Rapid, precise polarization measurements matter because polarization uncertainty propagates into observable uncertainties and polarimetry also supports accelerator setup.Source: §11.9 · p. 609

11.9.1 Electron Polarimetry

  • Compton polarimetry can measure longitudinal and transverse electron polarization, with estimated single-bunch 1% statistical measurement times shorter than the bunch lifetime.The study focuses conservatively on transverse measurements at IP 12 and assumes one Compton-scattered event per crossing; the detector concept uses photon energy and position-sensitive electron detection.Source: §11.9.1 · pp. 609, 612, 613, 614, Table 11.52 · p. 613
  • Segmented strip detectors will measure photon position directly, avoiding the nonlinear energy-asymmetry calibration uncertainty encountered at HERA [1673].CVD diamond strips are a candidate because they are radiation hard and can resolve 10 ns bunch spacing; photon conversion uses about 1 radiation length of lead, while synchrotron radiation remains a background and calorimeter-linearity concern.Source: §11.9.1 · pp. 614–616
  • At 18 GeV, transverse polarization extraction requires 100 µm vertical segmentation for photons and 25 µm for electrons; detector sizes are at least 16×16 mm2 and 10 cm × 1 mm, respectively.At IP 6, the electron detector is estimated to need a similar 8 cm × 1 mm size; 5 GeV photon acceptance sets the photon detector size, while 18 GeV segmentation requirements follow from the narrower cone.Source: §11.9.1 · pp. 614–615, Figure 11.126 · p. 615
  • The preferred RCS option is a Compton polarimeter during flat-top operation; if that mode is impractical, a transfer-line Møller polarimeter is a fallback with reduced precision and greater beamline impact.Flat-top Compton measurements take a few minutes; at 10 nA, transfer-line Compton measurements may take many days, while a 30 µm Møller target gives a 10% measurement in 1.5 hours.Source: §11.9.1 · pp. 616–618

11.9.2 Hadron Polarimetry

  • RHIC achieved relative systematic uncertainty below 1.5% in its most recent polarized-proton run, providing a starting point for EIC hadron polarimetry.Both RHIC hadron polarimeters could in principle be used at the EIC, though higher proton beam currents create additional challenges.Source: §11.9.2 · p. 618, Proton Polarimetry at the EIC · p. 621

Proton Polarimetry at RHIC

  • At RHIC, Hjet provides an absolute polarization scale independent of analyzing power, while pC provides rapid periodic measurements of polarization decay and transverse profile.The diffuse Hjet target limits precision to 5–8% per fill and measures only average polarization; pC measurements reach a few percent statistical precision in under 30 seconds.Source: Proton Polarimetry at RHIC · p. 619

Proton Polarimetry at the EIC

  • At EIC beam currents, pC backgrounds from adjacent bunches cannot be separated by energy-TOF, and carbon ribbon targets may break after seconds; a high-Z-target UPC neutron polarimeter is proposed as an alternative.A Xe gas jet could provide the photons without the carbon-target heating limitation, and promptly arriving neutrons detected in a zero-degree calorimeter avoid adjacent-bunch overlap.Source: Proton Polarimetry at the EIC · pp. 621–622

3He Polarimetry at the EIC

  • For 3He, absolute polarimetry could use polarized 3He targets, while relative polarimetry could adapt the EIC proton pC polarimeter; the estimated 3He-C analyzing power is about 70% of pC with opposite sign.Elastic-event selection is essential; if polarized 3He targets are available only for special runs, calibration must use the same center-of-mass energy as operation and exclude 3He breakup.Source: 3He Polarimetry at the EIC · pp. 622–623

R&D Studies at RHIC · Readout electronics terms

RHIC running offers opportunities to test polarimetry developments before EIC construction, while the EIC readout and DAQ architecture must meet detector and physics needs because online data filtering can affect physics outcomes.

R&D Studies at RHIC

  • RHIC polarimeters are expected to support physics measurements during the anticipated 2022 and 2024 polarized-proton runs and be available for EIC polarimetry studies.Potential developments could also be tested during normal polarized-proton running.Source: R&D Studies at RHIC · p. 623
  • Proposed proton-run tests include adding detector layers to tag punch-through events, testing carbon-target replacements, and trying a neutron-based UPC polarimeter with a high-Z target and downstream zero-degree calorimeter.A Xe gas jet is given as an example of a high-Z target.Source: R&D Studies at RHIC · p. 623
  • Polarized 3He beams may enable polarimetry studies at RHIC, first at injection energy and later up to ∼58 GeV/nucleon, with tests possible using a 3He target in the absolute polarimeter.Any 3He beam can support breakup tagging and tests of the carbon energy-TOF relation; 3He+3He energy-TOF and energy-angle relations can be tested with a 3He target.Source: R&D Studies at RHIC · p. 623
  • Polarized 3He beams and targets could establish target and beam asymmetries for 3He+3He scattering, beam asymmetry for 3He+C scattering, and beam polarization with both beam and target polarized.These measurements are described using Eqs. 11.17 and 11.18.Source: R&D Studies at RHIC · p. 624

11.10.1 Introduction

  • EIC readout electronics process detector signals into digital representations, while DAQ collects, filters, and stores the data; both must meet physics-program and operating constraints.Because online filtering can irretrievably discard data, the system requires careful design, construction, and validation; the review also considers detector and data-flow assumptions, architecture validation, and front-end technology.Source: §11.10.1 · p. 624

11.10.2 Glossary

  • The section defines potentially ambiguous DAQ and readout terms as its reference vocabulary.Source: §11.10.2 · p. 625

Readout electronics terms

  • Front-end electronics amplify and shape detector signals, then typically digitize them and handle data treatment, buffering, and transfer downstream.Digitization may use ADC, QDC, or TDC converters, and some front-end chips integrate digitization and data treatment.Source: Readout electronics terms · p. 625

Data acquisition system terms … Examples of readout chips

The section outlines EIC detector readout approaches, including triggered and streaming architectures, readout chains, digitization, and detector-specific constraints. It also surveys readout ASIC examples across MPGD, TPC, and fast-timing applications, covering their channel counts, processing architectures, digitization strategies, timing, and data-rate capabilities.

Data acquisition system terms

  • Triggered readout uses a fixed-latency decision based on partial detector information, whereas streaming readout sends threshold-crossing channel data onward for further processing.The glossary also distinguishes buffered asynchronous readout, timestamped unfiltered data, zero/noise suppression, feature extraction, online physics analysis, and data selection.Source: Data acquisition system terms · pp. 626–627

11.10.3 Overview on DAQ Structure

  • Triggerless readout can use timestamped channel data for CPU-based reconstruction and sophisticated event selection, with potential gains in calibration, close-track reconstruction, and electromagnetic/hadron discrimination.For EIC calorimeters, the report identifies improved energy reconstruction, wider-kinematics gamma/π0 separation, and pion rejection as possible benefits.Source: §11.10.3 · p. 628
  • The report is developing an integrated streaming-readout DAQ for the EIC, with seamless processing intended to support near-real-time analysis, detector calibration, alignment, and data-quality monitoring.The proposed software workflow could connect DAQ with online and offline analysis and accommodate emerging technologies such as AI/ML.Source: §11.10.3 · pp. 628–629

11.10.4 Constraints and Environment

  • EIC readout requirements vary by detector: calorimeters need high-dynamic-range waveform processing, while gaseous trackers, TPCs, and photosensors impose distinct rate and timing demands.The report cites calorimeter signals spanning 20 MeV to 20 GeV and sampling up to 250 MHz; TPC readout may require a gate up to 20 µs, and psTOF timing requirements are around 10–20 ps.Source: §11.10.4 · pp. 629–630
  • Approximately 100 Gb/s of collision signal is estimated for the EIC sPHENIX-based detector model at L = 10^34 cm^-2s^-1.The estimate includes collision signal only and a conservative MAPS-noise estimate; the channel-count figure notes that three, possibly four, readout solutions are anticipated.Source: §11.10.4 · pp. 630–631, Figure 11.131 · p. 631, Figure 11.132 · p. 632

Introduction

  • A detector readout chain combines electronics for signal conditioning, digitization, data treatment, buffering, and transfer, with clock, slow-control, and power support systems.A trigger system may also be included to reduce the data flow through the chain.Source: Introduction · p. 632

Front-end electronics

  • Front-end electronics amplify and shape detector signals, balancing fast timing against noise and signal occupancy; MAPS integrate front-end processing and adjustable-threshold zero suppression.The section gives gaseous-detector chip examples and reports typical chip properties of 32–64 channels, 25 ns–1 µs peaking times, and 10–30 mW/channel; Table 11.53 summarizes example-chip characteristics without values in the supplied passage.Source: Front-end electronics · pp. 632–633, Examples of readout chips · p. 634

Digitization and data treatment

  • Continuous digitization supports waveform transfer but demands ADC performance and link bandwidth; alternatives include extracting specific values or storing analog signals for triggered conversion.Data treatment can reduce data flow through common-mode reduction, zero suppression, peak finding, or inter-detector correlation; the analog-memory approach is described as largely incompatible with the planned streaming-readout structure.Source: Digitization and data treatment · pp. 633–634

Examples of readout chips

  • VMM combines peak and time detection with a three-ADC “Domino Architecture” and buffered precision readout.Its peak path uses 6-bit low-delay and 10-bit precision ADCs, while the time path uses an 8-bit TDC ADC; the FIFO accommodates 4 MHz data in a 16 µs latency window, and peak digitization completes in 250 ns.Source: Examples of readout chips · pp. 634–635
  • VMM’s latest versions achieve sub-fC and sub-ns resolutions at 200 pF and 25 ns, respectively, and data flow on the order of 1 Gbit/s.The report says they can be used to read out MPGD detectors requiring timing precision of a few nanoseconds.Source: Examples of readout chips · p. 635
  • TIGER provides 64-channel gaseous-detector readout with separate time and energy measurement paths, while SAMPA integrates digitization and DSP for high-bandwidth applications.TIGER includes two 10-bit Wilkinson ADCs per channel and trigger-less readout; SAMPA’s 32 channels are read through eleven 320 MB/s e-links, with sampling at 10 MSPS.Source: Examples of readout chips · pp. 635–636
  • AFTER uses a 511-cell analog memory and requires an external ADC, while AGET multiplexes 64 input channels to an external ADC and supports configurable sampling and split-memory event capture.AGET’s 512-cell circular buffer can be split to store two events within a 2 ms window; its sampling rate is adjustable from 1 MHz to 100 MHz.Source: Examples of readout chips · pp. 636–637
  • DREAM shares most AGET characteristics but maintains performance with input capacitance up to 200 pF, with a slightly lower dynamic range.SAMPIC combines 5 GHz analog-memory sampling with a DLL-based TDC to achieve timing resolution of a few ps rms; ALCOR provides single-photon time binning down to 50 ps and is a prototype for fast SiPM readout.Source: Examples of readout chips · pp. 637–638

Support system … The RCDAQ Data Acquisition System

The report identifies gaps in available readout chips, surveys streaming and hybrid DAQ systems, and describes RCDAQ’s use across sPHENIX and EIC R&D groups.

11.10.6 Possible Readout Chip Evolution and Future Technological Constraints

  • The proposed readout solution combines a greater-than-64-channel mixed-signal ASIC, a 10-/12-bit SAR ADC sampling at least 25 MHz, a high-speed TDC, and an FPGA.The ADC targets INL <2.0% and latency <10.0 ns; on-board buffering and glue logic are preferred, while DSP and companding ADCs are optional possibilities.Source: §11.10.6 · p. 638
  • No single chip yet meets all prospective EIC experiment needs, motivating further ASIC development and collaboration with CEA, INFN Torino, and Brookhaven National Laboratory.Available chips require detailed evaluation, including radiation, thermal, and magnetic-field effects; some have shown satisfactory performance in radiation tests.Source: §11.10.6 · pp. 638, 640

11.10.7 Existing streaming readout DAQ Systems for particle physics experiments

  • The report surveys existing streaming DAQ systems, including LHCb and sPHENIX, and notes ALICE O2 and Compass [1693] as further examples.These systems provide examples of particle-physics experiments adopting streaming readout approaches.Source: §11.10.7 · p. 640

LHCb streaming readout DAQ

  • LHCb’s upgraded streaming DAQ is designed to acquire and select events at 30 MHz, with an event builder scaled for up to 40 Tb/s.The system transports front-end data over optical links at up to 4.5 Gb/s per link; HLT1 reduces the event rate to approximately 1 MHz and HLT2 to approximately 100 kHz for disk storage.Source: LHCb streaming readout DAQ · p. 640

sPHENIX Hybrid DAQ

  • sPHENIX combines triggered calorimeter readout with streaming tracker readout, using timestamped data, front-end FPGA aggregation, and a global timing system.The front-end includes ALPIDE pixel, PHFX strip, and GEM-TPC readout; approximately 1,000 multi-Gb/s fiber links provide approximately 10 Tb/s overall bandwidth.Source: sPHENIX Hybrid DAQ · pp. 640–641
  • sPHENIX uses approximately 50 FELIX readout cards in commodity Linux PCs; each card supports 48 bidirectional 10-Gb/s optical links and a 100-Gb/s PCIe Gen3 link.Its peak disk-rate design accommodates top-luminosity RHIC Au+Au collisions, whose charged-particle production rate is described as orders of magnitude above the EIC’s.Source: sPHENIX Hybrid DAQ · p. 641
  • sPHENIX streaming tracker data enable heavy-flavor measurements otherwise inaccessible, within a hybrid system that also reads triggered calorimeter subsystems.The FELIX system can throttle calorimeter data according to triggers or record a fraction or all tracker data without triggers; the streaming development was commended by the RHIC Program Advisory Committee.Source: sPHENIX Hybrid DAQ · pp. 640–641

The RCDAQ Data Acquisition System

  • RCDAQ supports triggered and streaming readout, diverse front-end and commercial electronics, and is used by EIC R&D groups and dozens of external groups.Its built-in ROOT-based online monitoring, comprehensive controls, and small footprint support its use across EIC and RHIC R&D and beyond.Source: The RCDAQ Data Acquisition System · pp. 641–642

The ERSAP system · Thomas Jefferson Laboratory efforts

The report describes ERSAP’s configurable streaming-readout software and a staged EIC DAQ strategy that begins with hybrid streaming and advances toward online reconstruction and filtering. JLab beam tests examine streaming DAQ performance with CLAS12 and Hall D detector prototypes.

The ERSAP system

  • ERSAP combines CODA and CLARA-derived components as microservices with defined inputs and outputs, supporting local or remote communication, scaling, multiple programming languages, and replaceable services.A prototype was successfully tested with beam at the CLAS12 Forward Tagger in summer 2020; its Data Lake buffers data and automatically fails over to disk when memory is exhausted.Source: The ERSAP system · p. 642

11.10.8 A Progressive Approach toward the EIC DAQ System

  • The EIC streaming readout’s eventual goal is to reconstruct all events online with particle four-vectors and PID assignments, store the information to disk, and later filter events by conditions.Filtering could tag events in an exclusive channel to speed offline analysis.Source: §11.10.8 · p. 642
  • Early EIC operation will use hybrid streaming and cross-detector zero suppression, with online reconstruction and filtering introduced gradually as detector conditions become better understood.Unexpected noise or backgrounds could exceed system capacity, especially during initial machine tuning, while the detector knowledge needed for high-quality calibration may not yet be available.Source: §11.10.8 · pp. 642–643
  • A possible EIC readout architecture uses subdetector-specific front-end boards, FPGA-based processing, optical-fiber data transport, and commercial power and cooling, with R&D spanning the readout chain.The proposed R&D includes front-end options, transport, synchronization, and back-end online processing.Source: §11.10.8 · pp. 643–644, Figure 11.134 · p. 644

11.10.9 Experimental Validation of the Approach

  • Validating triggerless DAQ requires testing detector-specific combinations of front-end electronics, networking, and CPU algorithms against traditional approaches; a dedicated validation program has begun.The program uses complementary experimental efforts to inform EIC detector design and construction.Source: §11.10.9 · p. 644

Thomas Jefferson Laboratory efforts

  • Preliminary CLAS12 Forward Tagger tests found measured π0 energy distributions and total yields agree well with Monte Carlo, alongside online hit monitoring and clustering-efficiency measurements at a 3.0 GeV threshold.The π0 benchmark used two photons measured in the Forward Tagger Calorimeter and a scattered electron identified using the calorimeter and Hodoscope; analysis was ongoing.Source: Thomas Jefferson Laboratory efforts · p. 645, Figure 11.135 · p. 645
  • A CLAS12 Forward Tagger pilot used ERSAP microservices to stream, aggregate, curate, and reconstruct data, aiming to optimize performance and resource use and estimate reconstruction scaling requirements.CODA VTP firmware fed stream-aggregator, hit-finder, noise-reduction, and event-building services before standard CLAS12 reconstruction services; preliminary results were reported at the 22nd IEEE Real Time Conference.Source: Thomas Jefferson Laboratory efforts · pp. 645–646
  • Hall D tests successfully exercised the Waveboard–TriDAS–JANA2 streaming chain with software L2 triggers, reading calorimeter channels at rates up to 1.5 kHz per channel.The tests used a nine-scintillator prototype and tagged 4.5 GeV electrons; offline analysis was ongoing.Source: Thomas Jefferson Laboratory efforts · p. 646, Figure 11.136 · p. 646

BNL efforts · The Case for Two Detectors · 640 12.3. MOTIVATION FOR TWO DETECTORS: TECHNOLOGY CONSIDERATIONS

The report outlines EIC streaming readout and software development—including computing, simulation, preservation, and AI-based optimization—and motivates two complementary general-purpose detectors to address the breadth of EIC physics while enabling cross-checks, mitigating technology risks, supporting cross-calibration, and meeting machine and interaction-region constraints.

BNL efforts

  • Streaming FELIX readout increased the test-beam event rate by allowing trigger data to overlap in transmission and be reassembled using embedded clock information.The test also logged TPC streaming data simultaneously with beamline instrumentation in triggered mode and tested a common timing system that can provide triggers to legacy electronics.Source: BNL efforts · p. 647, §11.11 · p. 648

11.11. SOFTWARE, DATA ANALYSIS AND DATA PRESERVATION

  • At 500,000 events per second, reconstructing DIS events at 5 HS06s each would require 200,000 cores or 1,500 nodes on today’s hardware.The estimate assumes machine-background filtering preserves reconstruction time at 5 HS06s; projected CPU gains and possible AI/ML software improvements provide margin for more complex events.Source: §11.11 · p. 648
  • The EIC Software Consortium and Software Working Group built simulation, storage, and documentation infrastructure, and planned detector simulations, event generators, a full simulation-reconstruction chain, and AI/ML reconstruction methods.Their work also includes benchmark production and validation of Monte Carlo results, with generator efforts spanning polarized e+p, e+D, 3He, and e+A measurements.Source: §11.11 · pp. 649, 651
  • The software evaluation considers DD4hep for detector description, GEANT4 for simulation, and ACTS [1715] [1716] for tracking, alongside other reconstruction and analysis tools.DD4hep combines detector geometry and related information from a single source; GEANT4 work included requested photo-nuclear and electro-nuclear improvements, while ACTS is framework-independent and designed for modern computing architectures.Source: §11.11 · pp. 649–650
  • Data and analysis preservation is needed from detector design onward so that software, data constructs, and performance studies remain documented, reproducible, and usable for later studies.The effort includes preserving simulation and reconstruction tools, analysis code, data products, workflows, and test-beam and reference-detector simulation data; experience will inform EICUG strategies.Source: §11.11 · p. 651, §11.12 · p. 652

11.12. ARTIFICIAL INTELLIGENCE FOR THE EIC DETECTOR

  • AI/ML could support EIC data quality control, anomaly detection, calibration, track initialization, particle identification, event filtering, and faster detector simulation.Generative simulation methods may increase speed substantially but usually reduce accuracy; for tracking, AI could improve initial parameters and reduce Kalman-filter iterations.Source: §11.12 · pp. 652–653
  • Automated optimization of the dRICH design showed statistically significant performance improvement over its baseline, while multi-objective methods can account for detector performance and cost.AI optimization can also examine multiple subdetectors together under mechanical and geometrical constraints, a high-dimensional design problem that had not yet been explored.Source: §11.12 · p. 654

The Case for Two Detectors

  • Because EIC physics spans diverse signatures and energies, and a single detector cannot be optimized for its full breadth, the report motivates complementary detectors.A second interaction point was already part of the EIC machine design, but the experiment around it remained undecided before the Yellow Report process.Source: The Case for Two Detectors · p. 655

12.1. BOUNDARY CONDITIONS AND IMPORTANT RELATIONS

  • Detector design must balance full-range performance and machine-compatible interaction regions against acceptance, beam-pipe, and luminosity constraints.A 25-mrad crossing angle limits acceptance to rapidity ∼4.2; synchrotron radiation constrains beam-pipe radius and aligns the solenoid with the electron beam. Detector length sets minimum L*, with luminosity proportional to 1/L*; crab cavities also constrain forward-detector placement along the beamline.Source: §12.1 · pp. 656–657

12.2 Dedicated Detector Designs versus General Purpose Detectors

  • The current assumption is to develop two general-purpose detectors with different physics and technology foci, rather than a standalone detector with a narrow physics focus.The report identifies no dedicated-detector proposal with broad enough scope or compelling enough capability to justify its cost, and notes that general-purpose detectors ideally operate for the machine's full lifetime.Source: §12.2 · p. 657

12.3.1 Cross Checking

  • Independent detectors operated by different teams can cross-check potentially groundbreaking EIC results, with different instrumentation reducing correlated misleading signals.This can avoid spending substantial resources pursuing erroneous signals that additional data within one experiment may not resolve.Source: §12.3.1 · p. 658

12.3.2 Technology Redundancy

  • Using different technologies for similar detector roles can mitigate component-failure risks, including risks from uncertain near-beam operating conditions.The passage notes that no detector design is guaranteed to succeed and that conditions close to the beam cannot be perfectly known before operation.Source: §12.3.2 · p. 658

12.3.3 Cross Calibration

  • Combining H1 and ZEUS inclusive DIS data unexpectedly improved combined systematic uncertainties through redundant kinematic reconstruction and complementary calorimetry.The combined measurement benefited from H1's electromagnetic calorimetry and ZEUS's hadronic calorimetry; Figure 12.1 compares input data with the final combination.Source: §12.3.3 · p. 659, Figure 12.1 · p. 659

642 12.3. MOTIVATION FOR TWO DETECTORS: TECHNOLOGY CONSIDERATIONS … GEM and MicroMegas

This section examines design trade-offs and operational constraints for two complementary EIC detectors, alongside R&D on tracking technologies and their integration. It outlines candidate approaches, performance results, and remaining needs for technology maturity and construction readiness.

12.4.1 Experimental Solenoid Design

  • A single solenoid must trade low-pT acceptance against high-momentum resolution, whereas two detectors could use different fields to specialize and cross-check.Doubling the field can improve momentum resolution by about a factor of 2; at η ∼3, 3 T enables ∼2-3% resolution for pions up to about 30 GeV/c, while 0.5 T can detect charged particles below ∼0.05 GeV/c.Source: §12.4.1 · pp. 662–663

12.4.2 Tracking versus Particle Identification

  • Central tracking and particle-identification needs favor different layouts: a TPC-based design supports broad PID, while a compact all-silicon tracker improves momentum measurement and vertexing at PID-performance cost.The proposed MAPS tracker has a 45 cm outer radius versus 80 cm for the TPC-based design, and saved space could support other PID solutions; comparing designs requires integrated subdetector simulations.Source: §12.4.2 · p. 664

12.4.3 Hermiticity and Acceptance Gaps

  • Acceptance gaps are unavoidable in one detector, but complementary beam-pipe and instrumentation designs could shift scattered-electron Q2 gaps and help the combined program achieve coverage.The report also identifies opportunities to vary Roman-pot and B0-like detector positions and to plan around cracks between subdetector modules.Source: §12.4.3 · p. 665, Figure 12.3 · p. 665

12.4.4 Optimization to different centre of mass energies

  • Different center-of-mass energy priorities could motivate complementary interaction regions and detector configurations, including changes to quadrupole placement, crossing angle, secondary focus, and beamline instrumentation.The two detectors could operate throughout the EIC lifetime with performance optimized at different √s while retaining cross-checks.Source: §12.4.4 · p. 666

12.5 Opportunities from Fixed Target Mode Operation

  • Fixed-target operation, potentially using a spatially separated gas target, could access high-x and other forward kinematic regions that are hard to reach in collider mode and enable comparisons with earlier fixed-target experiments.Either or both electron and proton/ion beams could be used; e+p and e+A add high-x reach, while p+p and p+A address novel kinematic regions.Source: §12.5 · p. 668

12.3.4 Technology Redundancy and Cross Calibration at EIC

  • Different technologies and detector configurations can build redundancy and cross-calibration into two detectors, enabling cross-checks while optimizing precision and kinematic reach.The report stresses that complementary subdetector choices require collaboration between the experiments and shared test-beam information and GEANT tools; detailed performance studies await full-detector simulations.Source: §12.3.4 · p. 661, §12.6 · pp. 668–669

13.2 Safety and Environmental Protection

  • Safety plans rely on RHIC hall safety systems and BNL regulations, add an accelerator-integrated fast beam dump, and use an instrumented beam pipe during commissioning to protect the detector.The dump is intended to prevent radiation damage during unstable beam conditions.Source: §13.2 · p. 673

13.3 Installation

  • Installation constraints favor a modular detector: fixed beamline elements and limited hall space require endcaps to separate from the central assembly, with major assembly and maintenance done in the assembly hall.The approximately 9 m detector cannot pass intact through the 823 cm door; the installation area lacks space for significant assembly or maintenance.Source: §13.3 · p. 673

13.4 Detector Alignment

  • Detector components should be surveyed to about 100 µm using laser trackers and redundant marks; track-based software alignment is expected to reach micron-level accuracy.The report notes that maintaining survey-mark visibility, particularly for inner tracker modules, will be a concern.Source: §13.4 · pp. 676–677

13.5 Access and Maintenance

  • Access ranges from brief electronics access to endcap roll-out for short maintenance; long shutdowns require moving the barrel out and dismantling beam-pipe and shielding sections for several weeks.A long shutdown keeps the readout electronics on the rear carriage for testing detector sub-components.Source: §13.5 · p. 678

Detector R&D Goals and Accomplishments

  • The EIC community calls for two complementary general-purpose detectors, and its R&D program has advanced technologies but further work is needed for construction readiness.The program supported sensor, tracking, calorimetry, particle-identification, and software efforts, with more than 280 participants from 75 institutions.Source: Detector R&D Goals and Accomplishments · pp. 681–682

14.1.1 Monolithic Active Pixel Sensors (MAPS)

  • CERN’s ongoing 65 nm ITS3 MAPS development is proposed as the most efficient route to an EIC sensor, targeting < 5 µm single-point resolution and 30-40 µm-thick sensors.The design would need adaptation for EIC barrel and disc layers, with associated powering, cooling, support structures, and alignment mechanics and procedures. The development is expected to take the full four years of ITS3 sensor development plus two additional years for an EIC sensor variant.Source: §14.1.1 · p. 683, §14.1 · p. 684

14.1.2 Silicon-Sensor Tracking Fallback

  • 180 nm MAPS, including ALPIDE or MALTA DMAPS, is the most promising fallback if the 65 nm ITS3-based route proves unsuitable; SOI and LGAD developments should also be monitored.The report calls fallback R&D urgent, while noting that parallel silicon development may be costly and could become the primary route if needed to meet the schedule.Source: §14.1.2 · pp. 684–685

14.1.3 Services Reduction – Multiplexing and Serial-Fiber Off Detector Output

  • Silicon-tracker service R&D seeks to reduce cable loads and material in detector acceptance through multiplexing and high-speed optical transmission, while managing the risk of single-point failures.Radiation-tolerant multiplexing and 5 GHz-and-above fiber components should be developed with detector technologies; the work could support a day-one detector and potentially move early analysis onto the detector.Source: §14.1.3 · p. 685, §14.1 · p. 686

14.1.4 Services Reduction - Serial Powering and/or DC-DC Converters for Powering of Detector Components

  • Serial powering with possible on-chip regulation and radiation-tolerant on-detector DC-DC converters could reduce silicon-detector power cabling and service material, but serial-chain failures and converter current scaling require architectural R&D.HV MAPS and LGAD prototypes are considered for outermost discs and the hadron endcap or B0 tracker, not the central barrel or innermost discs; MAPS meet low-mass, low-power, and spatial-resolution needs, while LGADs offer timing in the tens of picoseconds.Source: §14.1.2 · p. 685, §14.1.4 · p. 686

14.2.1 Low-Mass Forward/Backward GEM Detectors

  • For 10 GeV pions, simulated GEM momentum resolution was σp/p ≤1.5% at 1.2 < η < 1.7 and rose to about 3% at η = 3.1; a 40 GeV pion at η = 2.0 gave 4%.The 1.5% value is close to the backward requirement, while the 40 GeV result meets it. With a 5% X0 budget and 0.6% X0 per active foil-based Triple-GEM layer, up to eight layers could be installed.Source: §14.2.1 · p. 687

14.2.2 R&D Needs for Planar µRWELL Detectors

  • µRWELL offers a simpler, potentially lower-cost amplification-and-readout device for end-cap tracking, but its large-area performance, discharge behavior, aging, and operating gas require further validation.Its basic configuration is expected to reach 100 kHz/cm2, above expected EIC end-cap rates; beam tests on large-area prototypes are needed to validate rate capability and spatial resolution, while gas studies target stable gain near 5 × 10^5 with minimal discharges.Source: §14.2.2 · p. 688, Generic R&D: Performances and… · p. 689

EIC specific R&D: Low-mass & large µRWELL trackers

  • End-cap µRWELL R&D targets about 0.4% radiation length per tracking layer and low-mass, low-channel-count 2D readout coupled to the amplification layer.Proposed approaches include rigid-PCB-free construction with lightweight supports and flexible capacitive-sharing or zigzag readout; a 10×10 cm2 zigzag-strip prototype is under investigation.Source: EIC specific R&D: Low-mass & large… · p. 689

14.2.3 Large Cylindrical µRWELL Layer

  • A cylindrical µRWELL could provide central tracking for PID seeding, TPC calibration, and few-nanosecond bunch-crossing tagging, with current simulations showing material below 1% χ0 for |η| < 1.R&D must reduce material, integrate foils to minimize dead regions, develop lightweight supports and interfaces, and assess rate capability, dE/dx, tracking and timing resolution, discharge, and aging.Source: §14.2.3 · pp. 690–691

14.2.4 Large Micromegas Barrel Tracker

  • Yellow Report studies found that a barrel tracker using CLAS12-like Micromegas tiles meets EIC material-budget and tracking-resolution requirements, motivating R&D to reduce material further and simplify production and integration.The CLAS12 BMT active-area tile is about 0.3% of X0; proposed work includes thin stretched detectors, modular flat elements, lighter readout strips and meshes, and lighter connectors.Source: §14.2.4 · pp. 691–692

14.2.5 MPGD Readout for a Time Projection Chamber

  • The EIC TPC estimate indicates that ion backflow will be no less concerning than in sPHENIX, though the calculation omits background events and configurations beyond the baseline.A MicroMegas-plus-GEM amplification stage is proposed to combine low IBF with energy resolution: MicroMegas supplies main amplification and GEMs pre-amplification; passive gating is also under investigation because continuous readout precludes a traditional gating grid.Source: §14.2.5 · p. 693, Table 14.1 · p. 693, Hybrid and Gating · p. 693

Readout Electronics … SATURDAY, 21 NOVEMBER

This section surveys EIC detector technologies, R&D needs, readout systems, and methods for describing scattering kinematics and structure. It also records workshop agendas and discussions spanning detector requirements and design, physics studies, and collaboration planning.

Readout Electronics

  • TPC readout electronics and their infrastructure are the major material-budget contribution, especially in the forward/backward region; proposed alternatives include microscopic readouts or a single-sided readout plane.The microscopic options register either single electrons or single clusters, while single-sided readout would require feasibility studies; the report calls for these R&D topics to mature before a final TPC design.Source: Readout Electronics · p. 694

14.3.1 A Modular RICH (mRICH) for Particle Identification

  • mRICH is designed for kaon/pion separation from 3 to 10 GeV/c and electron/pion separation around 2 GeV/c; two rounds of prototyping and beam tests have been completed.The 2016 test results were published, 2018 data analysis is ongoing, and two additional tests were being prepared to quantify PID performance and test photosensors.Source: §14.3.1 · pp. 695–696

14.3.2 A Dual-Radiator Ring Imaging Cherenkov Detector (dRICH)

  • For the EIC physics program, dRICH is considered a day-1 detector in light of the experiment’s particle-identification (PID) requirements.Source: §14.3.2 · p. 698

14.3.3 High-Performance DIRC

  • hpDIRC targets π/K separation of 3σ or more up to at least 6 GeV/c, with test-beam-based performance estimates in excellent agreement with simulation and prototype data.Its radial thickness is less than 8 cm; matching the final detector layout, cost optimization, and full-system prototype validation remain critical R&D items, with TDR readiness expected by 2024/2025 if funding continues.Source: §14.3.3 · pp. 698–699

14.3.4 Photosensor: MCP-PMT and LAPPD

  • Argonne 6 × 6 cm2 MCP-PMT R&D demonstrated gain of 10^6–10^7, timing of ∼80 ps (RMS) and ∼20 ps (SPE), >1.5 T tolerance, and <1 mm position resolution; LAPPD still lacks fine pixels and magnetic-field tolerance.The commercial LAPPD has achieved almost all requirements except fine pixel size and magnetic-field tolerance; 3 × 3 mm2 pixels are the urgent development focus.Source: §14.3.4 · p. 700

14.3.5 R&D Needs for GEM-TRD/Tracker in the Forward Direction

  • Forward GEM-TRD/tracker development targets pion rejection of 10–100, while a large-pad readout aims to reduce channels yet retain spatial resolution and improve noise.The current approximately $50-per-channel triggered readout motivates development of streaming zero-suppressed electronics; SAMPA v5’s 80 ns peaking time is too slow for studying GEM-TRD performance.Source: §14.3.5 · pp. 701–702

14.3.6 Gaseous Single Photon Detectors Based on MPGD Technologies

  • MPGD gaseous photon-detector R&D pursues HND photoconverters to avoid CsI fragility, but this innovative path will mature more slowly than the other EIC-enabling action items.The other listed action items are expected to be completed within a couple of years; HND could be selected according to its maturity when detector design is finalized.Source: §14.3.6 · pp. 703–704

14.3.7 Fast Timing Silicon Sensor: LGADs

  • LGADs with internal gain of 10–30 and 35–50 µm active thickness can achieve about 30 ps timing, enabling compact multilayer TOF-PID and trajectory reconstruction.They are described as tolerant of magnetic fields up to B∼4 T and radiation up to ∼2 × 10^15 neq/cm2, compared with expected EIC levels of ∼10^11 neq/cm2.Source: §14.3.7 · p. 704
  • Three stacked 35µm LGAD layers achieve 14 ps, while the EIC target is 20 ps or better per layer.Thinner sensors can reduce jitter and Landau noise; trench-isolated and AC-coupled designs improve fill factor or position sensitivity, while finer tracker granularity requires new ASIC designs.Source: §14.3.7 · pp. 704–705

14.4. ELECTROMAGNETIC AND HADRONIC CALORIMETRY

  • W/Scint calorimetry offers compact showers and tunable energy resolution across rapidities of approximately −2 to 4, while the forward hadron endcap faces demanding resolution needs and severe space constraints.That forward region may require a high-density, approximately compensated fiber calorimeter serving as both ECAL and HCAL.Source: §14.4.1 · p. 706, §14.4.3 · pp. 708–709

14.4.1 Tungsten Scintillator Calorimetry

  • W/SciFi blocks have reached industrial-scale production, while W/Shashlik offers individual-fiber SiPM readout but poses tungsten-machining and projective-assembly challenges.Both options use SiPMs, which are vulnerable to radiation damage, particularly from neutrons.Source: §14.4.1 · pp. 706–707

14.4.2 SciGlass for Electromagnetic Calorimetry

  • Initial SciGlass tests suggest PbWO4-competitive energy resolution above 15X0, and samples showed no damage up to 1000 Gy or 10^15 n/cm².Current samples reach about 10 radiation lengths; scale-up to at least 15X0 and further beam tests remain critical.Source: §14.4.2 · p. 707, §14.4 · p. 708

14.4.3 Hadronic Calorimetry

  • Hadronic calorimetry needs are modest in the electron endcap and barrel but greater in the hadron endcap, where prototype tests support initial requirements subject to improvements.Forward development is constrained by low light yield and neutron damage to SiPMs; the report recommends full-scale forward prototypes with WScFi ECAL, Fe/Sc HCAL, a tail catcher, and preshower.Source: §14.4.3 · pp. 708–709

14.4.4 CSGlass for Hadronic Calorimetry

  • CSGlass is proposed for dual-readout hadron calorimetry, using Cherenkov and scintillation signals to improve resolution and potentially reduce costs relative to crystals.Key R&D needs include sufficient UV transparency, separable signals, optimized formulation, and test-beam characterization.Source: §14.4.4 · p. 710

14.5.1 Roman Pots and LGAD Technology

  • 500 × 500 µm² pixels, 30–40 ps timing, and approximately 50 µm inactive edges meet the stated Roman Pots specifications with AC-LGADs.Further characterization, robustness tests, larger-area prototypes, and especially readout-ASIC development remain necessary.Source: §14.5.1 · pp. 711–712

14.5.2 Zero Degree Calorimeter

  • The ZDC must detect neutrons and low-energy photons efficiently while providing good energy, transverse-momentum, and position resolution over large acceptance.Candidate approaches include segmented Si+W calorimetry and crystals, glass, or W/SciFi; simulations estimate FoCal photon resolution at 27%/√E ⊕ 1%, while tests of other materials report approximately 2%/√E at ∼4 GeV.Source: §14.5.2 · pp. 712–713
  • The Zero Degree Calorimeter needs a wide readout dynamic range to accommodate a single MIP through 30 spectator neutrons and distinguish neutron counts from 20 to 30.The anticipated sampling calorimeter also requires about 10 interaction lengths longitudinally and about 2 interaction lengths transversely to limit leakage and achieve good hadron energy resolution.Source: §14.5.2 · p. 714

14.5.3 Superconducting-Nanowire Particle Detectors

  • SNSPD R&D targets small, fast, efficient pixels that can operate in magnetic fields above 5 T and serve multiple far-forward EIC detector systems.The Argonne effort aims for timing resolution as low as ≲20 ps; further work includes ion-detection optimization, cryogenic readout ASICs, and cold-bore integration.Source: §14.5.3 · pp. 714–715

14.6.1 Streaming-Capable Front-End Electronics, Data Aggregation, and Timing Distribution

  • Streaming readout is the likely EIC paradigm because it scales, reduces trigger bias and online event-building bottlenecks, and enables minimally biased data recording.Front-end ASIC development is a high-risk, high-priority task: new designs can take six or more years, while modifications may take three or more years.Source: §14.6.1 · p. 715, §14.6 · p. 716

14.6.2 Readout Software Architecture, Orchestration and Online Analysis

  • Readout software must scale across channels and processing, support online analysis and monitoring, and remain resilient to front-end errors.A logical data-exchange protocol is a priority for enabling interoperable hardware and software development; error recovery and bandwidth management require predictable, reconstructable control algorithms.Source: §14.6.2 · pp. 716–717
  • Uncertain initial background and dark rates could overwhelm the readout, so early data reduction may protect calibration and machine-tuning data at some cost to physics reach.Research is needed to determine whether software-based reduction can provide the flexibility of a proposed early hardware reduction stage.Source: §14.6.2 · p. 717

14.7.1 High Precision Timing Distribution Over Large System

  • High-precision timing distribution must deliver stable, low-jitter clocks to subdetectors and support online calibration of phase drift.A proposed back-end FPGA phase-stabilization approach would be benchmarked by full-path transmission with the system clock embedded; completion may take about one year, depending on EIC requirements and HL-LHC progress.Source: §14.7.1 · p. 718

14.7.2 Usage of COTS Devices in a Radiation Environment

  • Radiation-environment FPGA R&D will guide device selection and firmware mitigation of SEUs and SEFIs, with radiation tests expected to take 1 to 1.5 years.Potential mitigations include triple modular redundancy, error-correcting data coding, and configuration-memory scrubbing; commercial power regulators also require qualification.Source: §14.7.2 · p. 718

14.7.3 Micro-electronics, Opto-Electronics and Powering

  • Electronics development will evaluate ASIC technologies and update viable designs for streaming, while qualifying radiation-hard optical links for high-speed data and considering radiation-tolerant power distribution.Existing CERN optical-link designs at 2.5, 5, and 10 Gbps are expected to be adequate, with possible revisions for EIC clock frequencies and line rates.Source: §14.7.3 · p. 719

A.3 Laboratory frame

  • At high energies and small xP, t is approximated as transverse, and xP can be obtained from t, Q2, and W2.The passage notes that the approximation applies when momentum transfer is approximately transverse.Source: §A.3 · p. 729
  • For exclusive and semi-inclusive production, X is identified through decay-product invariant mass; for inclusive diffraction, its mass is determined from total energy and momentum.The hadron method can construct inelasticity, including for exclusive photoproduction when the scattered electron is undetected; different methods may be combined for accuracy [271].Source: §A.3 · p. 729

A.4 Breit frame

  • In the Breit frame, produced particles generally have negative z momentum while beam remnants have positive z momentum, helping separate them.The frame has no energy transfer to the proton and is not the parton–photon center-of-mass frame.Source: §A.4 · p. 729, §A.5 · p. 730

A.5 Helicity studies

  • Helicity studies require azimuthal angles Φ and φ∗, while the decay particle’s polar angle θ∗ specifies the produced particle’s polarization state.Φ is between the production and electron-scattering planes; φ∗ is between the decay and production planes. The angles are defined with photon and nucleon momenta aligned along one axis.Source: §A.5 · p. 730, Figure A.2 · p. 730

THURSDAY, 19 MARCH

  • Thursday’s Detector WGs included Calorimetry, Far Forward and Ancillary Detectors/Polarimetry/Luminosity, and PID, with talks on luminosity-detector and low-Q2-tagger requirements and lepton and hadron polarimeters.Source: THURSDAY, 19 MARCH · p. 738
  • Thursday’s Physics WGs scheduled Diffraction and Tagging, Exclusive, and Jets/Heavy Flavor sessions, including spectator tagging, DVCS/GPD studies, and jets for 3D imaging.Source: THURSDAY, 19 MARCH · p. 739

FRIDAY, 20 MARCH

  • Friday’s Central Detector/Magnet WG covered photosensors in strong magnetic fields, forward gaseous RICH performance, low-pT track cutoffs, momentum resolution, and solenoid design.The agenda also listed BeAST solenoid-field calculations.Source: FRIDAY, 20 MARCH · p. 740
  • Friday’s Electronics/DAQ session covered eRD23 activities and EIC data rates and noise estimates for a streaming readout system.The session also included discussion periods.Source: FRIDAY, 20 MARCH · pp. 740–741
  • Friday’s Inclusive Physics WG agenda included nuclear shadowing in DIS for future electron-ion colliders.The schedule also listed a preliminary study of EIC impact on unpolarized PDFs and a wish-list session.Source: FRIDAY, 20 MARCH · p. 742
  • Friday physics sessions covered jets and heavy flavor, semi-inclusive measurements, diffraction and tagging, and exclusive reactions.The listed topics included jet spin asymmetries, TMD measurements, heavy-flavor modification, and meson structure.Source: FRIDAY, 20 MARCH · pp. 742–744
  • Friday detector sessions addressed central detector and magnet topics, streaming readout simulation, and detector requirements for inclusive reactions.The schedule also included detector requirements or input for heavy flavor, jets, and SIDIS, plus a joint detector-complementarity discussion.Source: FRIDAY, 20 MARCH · pp. 743, 745

SATURDAY, 21 MARCH

  • Saturday summaries covered inclusive, semi-inclusive, jets and heavy quarks, exclusive reactions, and diffractive reactions and tagging.The diffractive reactions and tagging summary was scheduled for 9:30.Source: SATURDAY, 21 MARCH · p. 746
  • Saturday detector summaries covered tracking, particle identification, calorimetry, and far-forward, interaction-region, polarimetry, and ancillary detectors.The schedule also listed working-group summaries on detector topics alongside those on physics reactions.Source: SATURDAY, 21 MARCH · p. 746
  • The SATURDAY, 21 MARCH agenda schedules a 10-minute DAQ/Electronics WG summary at 10:40, followed by software and international-engagement discussions.The discussions are each listed for one hour, beginning at 11:30.Source: SATURDAY, 21 MARCH · p. 746

2nd EIC Yellow Report Workshop at Pavia University

  • The Pavia workshop agenda includes EIC project-status and accelerator/IR-design sessions, EoI discussion, working-group overviews, DAQ-structure discussions, and a detector-material-budget session.The DAQ session includes an introduction to discussed structural solutions and final conclusions; the material-budget session is scheduled from 10:30 to 12:30.Source: 2nd EIC Yellow Report Workshop at… · pp. 747–748
  • Pavia sessions covered diffractive, tagging, and exclusive topics alongside inclusive, SIDIS, jets, and heavy-quark inputs, followed by software and working-group workflow discussions.The schedule also lists material-budget requirements and summaries from physics and detector working groups.Source: 2nd EIC Yellow Report Workshop at… · pp. 751–752

3rd EIC Yellow Report Workshop at CUA

WEDNESDAY, 19 SEPTEMBER

  • Wednesday’s agenda included EIC project status, electronics and computing updates, and detector-complementarity sessions on low-COM-energy luminosity optimization and a second interaction region.The schedule also included open-mic discussion and accelerator and interaction-region design Q&A.Source: WEDNESDAY, 19 SEPTEMBER · p. 754

THURSDAY, 19 SEPTEMBER

  • Thursday’s agenda paired a Yellow Report overview and physics-working-group requirements review with detailed discussions of the reference detector, material budget, integration, and background levels.The physics-group review asked what requirements were established and what still needed work.Source: THURSDAY, 19 SEPTEMBER · pp. 754–755
  • Thursday’s sessions covered detector configurations, integration, material budget, and background levels.The program also listed a detector cartoon and boundary conditions overview.Source: THURSDAY, 19 SEPTEMBER · p. 755

FRIDAY, 19 SEPTEMBER

  • Friday’s agenda addressed Yellow Report completion tasks, Overleaf setup, timeline, detector-testing opportunities, planned activities, and project next steps.It also included an EICUG Charter Survey and a proposal concerning IR2.Source: FRIDAY, 19 SEPTEMBER · pp. 755–756

THURSDAY, 19 NOVEMBER

  • Thursday’s sessions covered project and Yellow Report status, physics working-group requirements, CDR reference-detector and project status, and detector updates.The listed requirements topics included inclusive, semi-inclusive, jets and heavy quarks, and exclusive reactions.Source: THURSDAY, 19 NOVEMBER · p. 757

FRIDAY, 20 NOVEMBER

  • Friday’s Yellow Report content discussions covered tracking, calorimetry, particle identification, magnetic field and magnet bore, far-forward detectors, and readout and data acquisition.Software was also listed as a discussion topic.Source: FRIDAY, 20 NOVEMBER · p. 758
  • Further Friday sessions reviewed Yellow Report sections 7.1–7.4 and discussed lower-energy luminosity optimization and second-interaction-region design and workshop plans.The agenda also included discussion of Yellow Report content in relation to complementarity.Source: FRIDAY, 20 NOVEMBER · pp. 758–759

SATURDAY, 21 NOVEMBER

  • Saturday’s agenda focused on detector R&D needs, archiving and reproducibility, Yellow Report plans and timeline, expressions of interest, and a call for detector proposals.The program ended with an open discussion.Source: SATURDAY, 21 NOVEMBER · p. 759

Related papers

Loading 2103.05419v3…