Scientists Describe Detector Goals for Electron-Ion Collider (EIC)

International community of EIC scientists publishes "yellow report" laying out physics case, detector requirements, and evolving detector concepts for future nuclear physics facility

March 16, 2021

The EIC Yellow Report is published in three volumes: an executive summary, a detailed description of the physics, and a discussion of detector concepts. Cover art by Yulia Furletova and Shannon West for the EIC User Group.

UPTON, NY—What do you need to study the fine details of the building blocks of matter? A new kind of particle accelerator called an Electron-Ion Collider (EIC)—planned to be built in the United States over the next decade—and a state-of-the-art detector to capture the action when electrons and ions collide. As part of the plan to build the EIC, an international team of more than 400 scientists representing 151 research institutions around the world prepared a detailed report of the detector components they believe are needed to meet the scientific goals of this new facility.

The report, titled “Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report,” was posted online on March 8, 2021.

“The enormous effort that led to this document aimed to provide the basis for further development of concepts for experimental equipment best suited for the science needs,” said Thomas Ullrich, a nuclear physicist involved in compiling the report and representative of the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory in the international EIC User Group (EICUG). “It is timely, as the formation of EIC collaborations is beginning. This is a big step toward the realization of a general-purpose detector that will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter.”

The EIC is in the early stage of development with the DOE Office of Science’s Nuclear Physics Program. It is slated to be built at Brookhaven Lab in partnership with physicists from DOE’s Thomas Jefferson National Accelerator Facility (Jefferson Lab) and scientists throughout the worldwide nuclear physics research community, with funding from the Office of Science and other national and international partners.

Jefferson Lab EICUG representative Rolf Ent said, “The Yellow Report represents a year-long superb effort of the EIC community. This community spans the world, with crucial contributions coming from many scientists in many countries, underscoring that we all work together as one community toward shared science goals.”

The EIC will be a powerful new facility for nuclear physics research that will collide high-energy electron beams with high-energy proton and ion beams (nuclei of atoms that have been stripped of their electrons). The collisions will give scientists access to the dynamic internal structure of protons, neutrons, and nuclei in a regime where their structure is dominated by gluons. Studying gluons—the force-carrier particles that hold together the internal building blocks of protons and neutrons (known as quarks)—will help scientists understand how quarks and gluons build up the mass and structure of the visible matter in our universe. In addition, because the EIC’s beams will be polarized—meaning the “spin” of the colliding particles can be aligned and controlled in desired ways—scientists will be able to explore how quarks and gluons contribute to the spin of fundamental particles.

“We may know more about some distant stars and galaxies than we do about the inner-workings of the building blocks of the matter right around us,” said Olga Evdokimov of the University of Illinois, Chicago, who is one of the EIC Physics Working Group conveners and chair of the EICUG Institutional Board. “The developments of the Yellow Report bring us one step closer to realizing a unique facility in the world for exploring how the tiny, nearly massless quarks and massless gluons hidden within protons and neutrons give mass to these much heavier particles that make up all visible matter in the Universe.”

“In addition, the technological innovations in detector design and computing streaming from this project will undoubtedly benefit other sciences and have a broad impact on society through workforce development across the science, technology, engineering, and mathematics (STEM) fields,” she said.

The EIC Yellow Report lays out the facility’s scientific goals in great detail, describes the specific detector requirements needed to address those goals, and presents the evolving detector concepts being explored to realize the EIC’s experimental program.

The report is the culmination of a series of studies commissioned and organized by the EIC User Group. But it is not intended to be a final plan. Rather, the EICUG sees the report as the basis for further development of concepts for experimental equipment best suited for the EIC’s science needs.

“In the long, one-year effort towards the completion of the Yellow Report, we have formed an international collaborative community. Now it is time to strengthen the collaboration,” said Silvia Dalla Torre, an EICUG Steering Committee member from Italy’s National Institute for Nuclear Physics. “We look forward to the next exciting phase, namely the common effort of design and construction of one or possibly two detectors that will make possible accessing the physics goals of the EIC.”

Brookhaven National Laboratory and Thomas Jefferson National Accelerator Facility are supported by the U.S. Department of Energy’s Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://www.energy.gov/science/.

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