Some Thoughts On a Possible Future Electron-Ion Collider T. Hallman Electron-Ion Collider User Group Meeting July 30, 2018 Catholic University of America

A strong community emphasis on the need for a machine capable of illuminating the dynamical basis of hadron structure in terms of the fundamental quark and gluon fields exploring has been a persistent message for almost two decades

Discussion of an EIC in the 2002 Long Range Plan The Electron-Ion Collider (EIC). The EIC is a new accelerator concept that has been proposed to extend our understanding of the structure of matter in terms of its quark and gluon constituents. Two classes of machine design for the EIC have been considered: a ring-ring option where both electron and ion beams circulate in storage rings, and a ring-linac option where a linear electron beam is incident on a stored ion beam. These first two initiatives, in particular, require ongoing R&D. For the field to be ready to implement the RHIC upgrade later in the decade, essential accelerator and detector R&D should be given very high priority in the short term. Likewise, there is a strong consensus among nuclear scientists to pursue R&D over the next three years to address a number of EIC design issues. In parallel, the scientific case for the EIC will be significantly refined. 2002

Discussion of the EIC in the 2007 Long Range Plan “Gluons and their interactions are critical to QCD. But their properties and dynamics in matter remain largely unexplored. Recent theoretical breakthroughs and experimental results suggest that both nucleons and nuclei, when viewed at high energies, appear as dense systems of gluons, creating fields whose intensity may be the strongest allowed in nature. The emerging science of this universal gluonic matter drives the development of a next-generation facility, the high-luminosity Electron-Ion Collider (EIC). The EIC’s ability to collide high-energy electron beams with high-energy ion beams will provide 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 gluons in the proton.” While significant progress has been made in developing concepts for an EIC, many open questions remain. Realization of an EIC will require advancements in accelerator science and technology, and detector research and development. The nuclear science community has recognized the importance of this future facility and makes the following recommendation.” “We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron-Ion Collider. The EIC would explore the new QCD frontier of strong color fields in nuclei and precisely image the gluons in the proton.”

2009 Report on Physics with a High Energy, High luminosity EIC Physics at a High Energy Electron Ion Collider (09-43W) October 19 - 23, 2009 Exploring and understanding fully the role of gluons and sea quarks in the structure of the nucleon and atomic nuclei is a major frontier of nuclear and particle physics. Although there has been much progress thanks to data from HERA, a new dedicated facility will be essential for answering some of the most central questions. This facility is the Electron Ion Collider (EIC).…The present workshop primarily addresses the science at such a "stage-I" EIC…

2010 Report on Gluons and the Quark Sea Executive summary Understanding the fundamental structure of matter in the physical universe is one of the central goals of scientific research. Strongly bound atomic nuclei predominantly constitute the matter from which humans and the observable physical world around us are formed. In the closing decades of the twentieth century, physicists developed a beautiful theory, Quantum Chromodynamics (QCD), which explains all strongly interacting matter in terms of point-like quarks interacting by the exchange of gauge bosons, known as gluons…. However, more than thirty years after QCD was first proposed as the fundamental theory of the strong force...the understanding of how QCD works in detail remains an outstanding problem in physics. Very little is known about the dynamical basis of hadron structure in terms of the fundamental quark and gluon fields of the theory. How do these fundamental degrees of freedom dynamically generate the mass, spin, motion, and spatial distribution of color charges inside hadrons with varying momentum resolution and energy scales? Deep Inelastic Scattering (DIS) experiments at the HERA collider revealed clearly that at high momentum resolution and energy scales, the proton is a complex, many-body system of gluons and sea quarks, a picture very different from a more familiar view of the proton as a few point-like partons… each carrying a large fraction of its momentum. This picture, which is confirmed at hadron colliders, raises more questions than it answers about the dynamical structure of matter. For instance, how is the spin-1/2 of the proton distributed in this many-body system of sea quarks and gluons? In the early universe, how did the many-body plasma of quarks and gluons cool into hadrons with several simple structural properties? Recreating key features of this quark-hadron transition in heavy ion collisions has been a major activity in nuclear physics, with several surprising findings including the realization that this matter flows with very little resistance as a nearly perfect fluid. A deep understanding ultimately requires detailed knowledge of the quark-gluon structure of hadrons and nuclei. 2010 INT Workshop & Report

Early Effort for Guiding EIC R&D Collaboration

2012 Report: The next QCD Frontier, an Electron-Ion Collider Proton (and nuclei) and black holes are the only fully relativistic (high enough energy density to excite the vacuum) stable bound systems in the universe. Protons can be studied in the laboratory. Protons are fundamental to the visible universe (including us) and their properties are dominated by emergent phenomena of the self-coupling strong force that generates high density gluon fields: The mass of the proton (and the visible universe) The spin of the proton The dynamics of quarks and gluons in nucleons and nuclei The formation of hadrons from quarks and gluons The study of the high density gluon field that is at the center of it all requires a high energy, high luminosity, polarized Electron Ion Collider 9-1-15 version

An EIC Was Also Identified by NSAC as “Absolutely Central” to the Future of NP The 2013 NSAC Subcommittee on Future Facilities identified an Electron- Ion Collider as absolutely central to the nuclear science program of the next decade.

The EIC in the 2015 Long Range Plan Recommendations: The progress achieved under the guidance of the 2007 Long Range Plan has reinforced U.S. world leadership in nuclear science. The highest priority in this 2015 Plan is to capitalize on the investments made. The observation of neutrinoless double beta decay in nuclei would…have profound implications.. We recommend the timely development and deployment of a U.S.-led ton-scale neutrinoless double beta decay experiment. Gluons…generate nearly all of the visible mass in the universe. Despite their importance, fundamental questions remain…. These can only be answered with a powerful new electron ion collider (EIC). We recommend a high-energy high-luminosity polarized EIC as the highest priority for new facility construction following the completion of FRIB. We recommend increasing investment in small-scale and mid- scale projects and initiatives that enable forefront research at universities and laboratories. NP is working to implement these recommendations

2015 Long Range Plan for Nuclear Science RECOMMENDATION III Gluons, the carriers of the strong force, bind the quarks together inside nucleons and nuclei and generate nearly all of the visible mass in the universe. Despite their importance, fundamental questions remain about the role of gluons in nucleons and nuclei. These questions can only be answered with a powerful new electron ion collider (EIC), providing unprecedented precision and versatility. The realization of this instrument is enabled by recent advances in accelerator technology. We recommend a high-energy high-luminosity polarized EIC as the highest priority for new facility construction following the completion of FRIB.

EIC Relevance to DOE Nuclear Physics’ Mission Quantum Chromodynamics (QCD) seeks to develop a complete understanding of how quarks and gluons assemble themselves into protons and neutrons, how nuclear forces arise, and what forms of bulk strongly interacting matter can exist in nature… Nuclear Structure and Nuclear Astrophysics seeks to understand how protons and neutrons combine to form atomic nuclei, including some now being observed for the first time, and how these nuclei have arisen during the 13.8 billion years since the birth of the cosmos. Fundamental Symmetries of neutrons and nuclei seeks to develop a better understanding of fundamental interactions by studying the properties of neutrons and targeted, single focus experiments using nuclei to study whether the neutrino is its own anti-particle.

Ongoing EIC Concept Stewardship Strategy In response to the community’s persistent strong emphasis on the need for the capabilities of an electron-ion collider and the significant effort already made on pre-conceptual R&D, NP has been implementing the following strategic plan in discussion and coordination with EIC stakeholders. It has pursued/continues to pursue: An independent science assessment of a US-based EIC by the National Academy of Sciences A major NP Community EIC Accelerator R&D Panel Review A mechanism for increased accelerator R&D funding

NAS Study of the EIC Science Case THE NATIONAL ACADEMIES OF SCIENCES, ENGINEERING, AND MEDICINE Division on Engineering and Physical Science Board on Physics and Astronomy U.S.-Based Electron Ion Collider Science Assessment Summary The National Academies of Sciences, Engineering, and Medicine (“National Academies”) will form a committee to carry out a thorough, independent assessment of the scientific justification for a U.S. domestic electron ion collider facility. In preparing its report, the committee will address the role that such a facility would play in the future of nuclear science, considering the field broadly, but placing emphasis on its potential scientific impact on quantum chromodynamics. The need for such an accelerator will be addressed in the context of international efforts in this area. “U.S.-Based Electron Ion Collider Science Assessment” is now complete.

Goals for The NAS EIC Study As Embodied in the SOT

Findings from the 2018 NAS Assessment

Findings from the 2018 NAS Assessment

Findings from the 2018 NAS Assessment

Findings from the 2018 NAS Assessment

Spreading the Word NAS Briefings so far: DOE NP OMB House S&T Committee DOE S4/SC1 Webinar

FY 2019 President’s Request for DOE NP: The Big Picture FY19 President’s DOE NP Request Summary ($ in 000s) FY17 Enacted FY18 Enacted FY19 President’s Request FY18 vs. FY17 FY19 vs. FY18 Research 182,664 199,750 178,540 +17,086 -21,210 User Facility Operations 293,727 324,250 292,138 +30,523 -32,112 Other Operations 21,826 24,200 25,275 +2,374 +1,075 Projects 103,000 112,400 83,700 +9,400 -28,700 Other 20,783 23,400 20,347 +2,617 -3,053 TOTAL NP 622,000 684,000 600,000 +62,000 -84,000 “Other Operations”: Isotope Production Facilities & Infrastructure, 88 Inch Cyclotron “Other”: SBIR FY19 House Mark for DOE NP: $690M FY19 Senate Mark for DOE NP: $710M

Facility for Rare Isotope Beams is More Than 86% Complete Construction Carried Our Under a Co-Operative Agreement with Michigan State University PYs FY 2017 FY 2018 FY 2019 FY 2020 FY 2021 DOE Total MSU TOTAL FUNDING PROFILE 318,000 100,000 97,200 75,000 40,000 5,300 635,500 94,500 730,000

Facility for Rare Isotope Beams is  86% Complete FRIB will increase the number of isotopes with known properties from ~2,000 observed over the last century to ~5,000 and will provide world-leading capabilities for research on: Nuclear Structure The limits of existence for nuclei Nuclei that have neutron skins Synthesis of super heavy elements Nuclear Astrophysics The origin of the heavy elements and explosive nucleo-synthesis Composition of neutron star crusts Fundamental Symmetries Tests of fundamental symmetries, Atomic EDMs, Weak Charge This research will provide the basis for a predictive model of nuclei and how they interact. The FY 2019 Request supports: The ongoing fabrication, assembly, installation, and testing of cryomodules and experimental systems that will be housed in the newly constructed tunnel. The continued commissioning of the linear accelerator (linac) system. The continuation of modest pre-operations funding in advance of full scale operations.

Going Forward What next: Inside the DOE: Discussion of the NAS report and what it implies of the DOE NP Mission Depending on that outcome, similar discussion with OMB Discussion with key stakeholders on process for making important decisions If/when all that goes well, steps towards getting the EIC into a Congressional budget In parallel, exploring international interest in Collaboration

It is Good to Push, But Hazardous to Make Projections

Outlook The nuclear science community has articulated a persistent strong emphasis, for almost two decades, on the need for and electron ion collider to discover the dynamical basis of hadron structure via the fundamental quark and gluon fields Significant effort has been invested in documenting the science case for an EIC over that period Significant effort has been invested in pre-conceptual accelerator R&D to make progress in areas key to the feasibility of a future machine The 2015 Long Range Plan identified the construction of a high luminosity, polarized electron-ion collider as the highest priority for new construction following the completion of FRIB ( currently planned for FY2021) Realization of an EIC will also be a focus within SC generally for advancements in accelerator science and technology, and detector research and development. An independent NAS assessment has now confirmed the merit and “urgency” of the science an EIC could enable and the unique role for such a facility in the United States

Support for Isotope Research/Mission Readiness is Enabling the Saving of Lives Ga-68 PET/CT scans of a different patient with metastatic prostate cancer. Image A shows pre-therapeutic tumor spread. Image B was taken 2 months after the third cycle of treatment with the α-emitting isotope Ac-225 attached to a tumor seeking drug. Image C was taken 2 months after one additional treatment dose. Clemens Kratochwil et al. J Nucl Med 2016;57:1941-1944