This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.

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Electron-Ion Collider: The next QCD frontier: Understanding the glue that binds us all

Particle colliders for high energy physics have been in the forefront of scientific discoveries for more than half a century. The accelerator technology of the collider has progressed immensely, while the beam energy, luminosity, facility size and the cost have grown by several orders of magnitude. The method of colliding beams has not fully exhausted its potential but its pace of progress has greatly slowed down. In this paper we very briefly review the method and the history of colliders, discuss in detail the developments over the past two decades and the directions of the R and D toward near future colliders which are currently being explored. Finally, we make an attempt to look beyond the current horizon and outline the changes in the paradigm required for the next breakthroughs.

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High-energy particle colliders: past 20 years, next 20 years, and beyond

Particle colliders for high energy physics have been in the forefront of scientific discoveries for more than half a century The accelerator technology of the collider has progressed immensely, while the beam energy, luminosity, facility size and the cost have grown by several orders of magnitude The method of colliding beams has not fully exhausted its potential but its pace of progress has greatly slowed down In this paper we very briefly review the method and the history of colliders, discuss in detail the developments over the past two decades and the directions of the R&D toward near future colliders which are currently being explored Finally, we make an attempt to look beyond the current horizon and outline the changes in the paradigm required for the next breakthroughs

High energy particle colliders: past 20 years, next 20 years and beyond

Abstract.This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.

/pdf/electron-ion-collider-the-next-qcd-frontier-2ur3ujx2lg.pdf

Electron Ion Collider: The next QCD frontier

Since the initial development of charged particle colliders in the middle of the 20th century, these advanced scientific instruments have been at the forefront of scientific discoveries in high energy physics over the past 60 years. Collider accelerator technology and beam physics have progressed immensely and modern facilities now operate at energies and luminosities many orders of magnitude greater than the pioneering colliders of the early 1960s. In addition, the field of colliders remains extremely dynamic and continues to develop many innovative approaches. Indeed, several novel concepts are currently being considered for designing and constructing even more powerful future colliders. In this paper, we first review the colliding beam method and the history of colliders, and then present, in detail, the major achievements of operational machines and the key features of near-term collider projects that are currently under development. We conclude with an analysis of numerous proposals and studies for far-future colliders. The evaluation of their respective potentials reveals tantalizing prospects for further significant breakthroughs in the collider field.

Modern and Future Colliders

We report on an experimental demonstration of electron cooling of high-energy antiprotons circulating in a storage ring. In our experiments, electron cooling, a well-established method at low energies (< 500 MeV/nucleon), was carried out in a new region of beam parameters, requiring a multi-MeV dc electron beam and an unusual beam transport line. In this letter we present the results of the longitudinal cooling force measurements and compare them with theoretical predictions.

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Experimental demonstration of relativistic electron cooling.

The 8.9‐GeV/c Recycler antiproton storage ring is equipped with both stochastic and electron cooling systems. These cooling systems are designed to assist accumulation of antiprotons for the Tevatron collider operations. In this paper we report on an experimental demonstration of electron cooling of high‐energy antiprotons. At the time of writing this report, the Recycler electron cooling system is routinely used in collider operations. It has helped to set recent peak luminosity records.

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Antiproton Cooling in the Fermilab Recycler Ring

The High Intensity Neutrino Source (HINS) R&D program requires super conducting single spoke resonators operating at 325 MHz (SSR1) [1]. After coupler installation, these cavities are tested at the HINS-SRF facility at Fermilab. The LLRF requirements for these tests include support for continuous wave and pulsed mode operations, with the ability to track the resonance frequency of the tested cavity. Real-time measurement of the cavity loaded Q and Q0 are implemented using gradient decay techniques, allowing for Q0 versus Eacc plots. A real time cavity simulator was also developed to test the LLRF system and verify its functionality. LLRF SYSTEM OVERVIEW The LLRF system is depicted in Fig. 1. The 325 MHz RF reference is provided by a signal generator (Aeroflex IFR 2023A), for tunability. The master oscillator and local oscillator chassis distributes the 325 MHz reference signal and generates the 338 MHz LO. The LO is obtained by mixing the 325 MHz RF signal with a 13 MHz intermediate frequency (IF), internally generated by dividing the 325 MHz reference by 25. This allows the LO to track the RF signal when it is tuned to match the cavity resonance frequency.

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LLRF Design for the HINS-SRF Test Facility at Fermilab

Electron cooling of 8 GeV antiprotons at Fermilab's Recycler storage ring is now routinely used in the collider operation. It requires a 0.1-0.5 A, 4.3 MeV dc electron beam and is designed to increase the longitudinal phase-space density of the circulating antiproton beam. This paper briefly describes the characteristics of the electron beam that were achieved to successfully cool antiprotons. Then, results from various cooling force measurements along with comparison to a nonmagnetized model are presented. Finally, operational aspects of the implementation of electron cooling at the Recycler are discussed, such as adjustments to the cooling rate and the influence of the electron beam on the antiproton beam lifetime.

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Electron cooling of 8 GeV antiprotons at Fermilab's Recycler: Results and operational implications *

The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler’s electron beam and details of operation.

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V. Tupikov

Papers

Experimental demonstration of relativistic electron cooling.

Antiproton Cooling in the Fermilab Recycler Ring

LLRF Design for the HINS-SRF Test Facility at Fermilab

Electron cooling of 8 GeV antiprotons at Fermilab's Recycler: Results and operational implications *

Attainment of a High‐Quality Electron Beam for Fermilab’s 4.3 MeV Cooler