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Realizing the Scientific Program with Polarized Ion Beams at EIC

Grigor Atoian, Nigel Buttimore, Giuseppe Ciullo, Ian Cloet, Marco Contalbrigo, Jaydeep Datta, Abhay Deshpande, Shubham Dutta, Oleg Eyser, Muhammad Farooq, Renee Fatemi, Ishara Fernando, Michael Finger, Wolfram Fischer, Dave Gaskell, Prakash Gautam, Ralf Gebel, Boxing Gou, Daoning Gu, Yoshitaka Hatta, Mohammad Hattawy, Volker Hejny, Kiel Hock, Georg Hoffstaetter, Haixin Huang, Christopher Ianzano, Jiangyong Jia, Andro Kacharava, Maggie Kerr, Wolfgang Korsch, Dario Lattuada, Andreas Lehrach, Minxiang Li, Xiaqing Li, Paolo Lenisa, Win Lin, James Maxwell, Aleksei Melnikov, Zein-Eddine Meziani, Richard G. Milner, William R. Milner, Iurii Mitrankov, Hamlet Mkrtchyan, Prajwal MohanMurthy, Christoph Montag, Sergei Nagaitsev, Charles-Joseph Naim, Alexander Nass, Dien Nguyen, Nikolai Nikolaev, Luciano Pappalardo, Chao Peng, Anna Piccoli, Andrei Poblaguev, Deepak Raparia, Frank Rathmann, Thomas Roser, Premkumar Saganti, Andrew Sandorfi, Medani Sangroula, Vincent Schoefer, Yousif Shabaan El-Feky, Rahul Shankar, Vera Shmakova, Evgeny Shulga, Jamal Slim, Dannie Steski, Bernd Surrow, Noah Wuerfel, Yaojie Zhai

TL;DR

The paper argues that realizing polarized ion beams at the EIC is essential to tackle fundamental questions about nucleon and nuclear spin within QCD, enabling 3D imaging of partons via GPDs and TMDs and exploring gluonic phenomena in nuclei. It presents a comprehensive R&D plan (EPIOS) spanning polarized ion sources, hadron polarimetry, spin manipulation, and advanced AI/ML techniques to optimize performance across a decade, with an estimated workforce of ~200 FTE-years. The proposed program includes diverse ion species (^2H, ^3He, ^6Li, ^7Li, and others), multiple absolute and fast polarimeters (HJET, pC, ^3He-ABS), novel spin tools (RF Wien filters, spin rotators, spin tune feedback), and integration with the RHIC infrastructure, while addressing challenges in photocathodes, beam dynamics, and detector compatibility. The work aims to deliver high-polarization beams with precise control and measurement, enabling groundbreaking measurements of the nucleon’s spin structure, its modification in nuclei, and the role of gluons, ultimately advancing our understanding of QCD and hadronic matter with broad scientific and technological impact.

Abstract

Polarized ion beams at the Electron Ion Collider are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, we summarize the science case and identify polarized $^2$H, $^3$He, $^6$Li and $^7$Li ion beams as critical technology that will enable experiments which address the most important science. Further, we discuss the required ion polarimetry and spin manipulation in EIC. The current EIC accelerator design is presented. We identify a significant R\&D effort involving both national laboratories and universities that is required over about a decade to realize the polarized ion beams and estimate (based on previous experience) that it will require about 20 FTE over 10 years (or a total of about 200 FTE-years) of personnel, including graduate students, postdoctoral researchers, technicians and engineers. Attracting, educating and training a new generation of physicists in experimental spin techniques will be essential for successful realization. AI/ML is seen as having significant potential for both acceleration of R\&D and amplification of discovery in optimal realization of this unique quantum technology on a cutting-edge collider. The R\&D effort is synergistic with research in atomic physics and fusion energy science.

Realizing the Scientific Program with Polarized Ion Beams at EIC

TL;DR

The paper argues that realizing polarized ion beams at the EIC is essential to tackle fundamental questions about nucleon and nuclear spin within QCD, enabling 3D imaging of partons via GPDs and TMDs and exploring gluonic phenomena in nuclei. It presents a comprehensive R&D plan (EPIOS) spanning polarized ion sources, hadron polarimetry, spin manipulation, and advanced AI/ML techniques to optimize performance across a decade, with an estimated workforce of ~200 FTE-years. The proposed program includes diverse ion species (^2H, ^3He, ^6Li, ^7Li, and others), multiple absolute and fast polarimeters (HJET, pC, ^3He-ABS), novel spin tools (RF Wien filters, spin rotators, spin tune feedback), and integration with the RHIC infrastructure, while addressing challenges in photocathodes, beam dynamics, and detector compatibility. The work aims to deliver high-polarization beams with precise control and measurement, enabling groundbreaking measurements of the nucleon’s spin structure, its modification in nuclei, and the role of gluons, ultimately advancing our understanding of QCD and hadronic matter with broad scientific and technological impact.

Abstract

Polarized ion beams at the Electron Ion Collider are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, we summarize the science case and identify polarized H, He, Li and Li ion beams as critical technology that will enable experiments which address the most important science. Further, we discuss the required ion polarimetry and spin manipulation in EIC. The current EIC accelerator design is presented. We identify a significant R\&D effort involving both national laboratories and universities that is required over about a decade to realize the polarized ion beams and estimate (based on previous experience) that it will require about 20 FTE over 10 years (or a total of about 200 FTE-years) of personnel, including graduate students, postdoctoral researchers, technicians and engineers. Attracting, educating and training a new generation of physicists in experimental spin techniques will be essential for successful realization. AI/ML is seen as having significant potential for both acceleration of R\&D and amplification of discovery in optimal realization of this unique quantum technology on a cutting-edge collider. The R\&D effort is synergistic with research in atomic physics and fusion energy science.

Paper Structure

This paper contains 62 sections, 17 equations, 24 figures, 7 tables.

Table of Contents

  1. Introduction
  2. Executive Summary
  3. Science Case for Polarized Ion Beams at EIC
  4. Quark and Gluon Structure of Nucleon Spin
  5. Longitudinal Structure
  6. Mapping the Full 3D Structure of Nucleon and Nuclei
  7. Is the Nucleon Spin Structure Modified in the Nucleus?
  8. Exotic Gluon States in the Nucleus
  9. The Electron-Ion Collider
  10. The Electron-Ion Collider
  11. Introduction
  12. Interaction Region
  13. From RHIC to EIC
  14. Hadron Storage Ring
  15. Electron Storage Ring
  16. ...and 47 more sections

Figures (24)

  • Figure 1: The gluon helicity distribution is determined from the $Q^2$ evolution of the $g_1^p$ structure function. The curves above are extracted from the DSSV and JAMlowx global analysis Adamiak:2021ppq and show the associated errors with (darker) and without (lighter) EIC data. The curves diverge for $x < 0.001$ due to the application of different theoretical evolution formalisms.
  • Figure 2: The impact of projected inclusive scattering data off polarized proton and $^3$He beams at the EIC on the relative uncertainties of the extracted up, down and quark singlet helicity distributions.
  • Figure 3: Schematic representation of Wigner distributions in the lightcone frame for each parton species $a$ and their relation to the daughter distributions, GPDs and TMDs, and how these further connect to the one dimensional parton distribution functions (PDFs) and form factors (FF) Dudek:2012vr.
  • Figure 4: Results for the EMC and polarized EMC effects in $^6$Li and $^7$Li, where the latter predictions are from Ref. Cloet:2006bq.
  • Figure 5: Example of leading DIS process sensitive to ${\Delta}(x,Q^2)$Shanahan.
  • ...and 19 more figures