ForewordThe study of the fundamental structure of nuclear matter is a central thrust of physics research in the United States. As indicated in Frontiers of Nuclear Science, the 2007 Nuclear Science Advisory Committee long range plan, consideration of a future Electron-Ion Collider (EIC) is a priority and will likely be a significant focus of discussion at the next long range plan. We are therefore pleased to have supported the ten week program in fall 2010 at the Institute of Nuclear Theory which examined at length the science case for the EIC. This program was a major effort; it attracted the maximum allowable attendance over ten weeks.This report summarizes the current understanding of the physics and articulates important open questions that can be addressed by an EIC. It converges towards a set of "golden" experiments that illustrate both the science reach and the technical demands on such a facility, and thereby establishes a firm ground from which to launch the next phase in preparation for the upcoming long range plan discussions. We thank all the participants in this productive program. In particular, we would like to acknowledge the leadership and dedication of the five co-organizers of the program who are also the co-editors of this report.David Kaplan, Director, National Institute for Nuclear Theory Hugh Montgomery, Director, Thomas Jefferson National Accelerator Facility Steven Vigdor, Associate Lab Director, Brookhaven National Laboratory iii Preface This volume is based on a ten-week program on "Gluons and the quark sea at high energies", which took place at the Institute for Nuclear Theory (INT) in Seattle from September 13 to November 19, 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. Guiding questions were• What are the crucial science issues?• How do they fit within the overall goals for nuclear physics?• Why can't they be addressed adequately at existing facilities?• Will they still be interesting in the 2020's, when a suitable facility might be realized?The program started with a five-day workshop on "Perturbative and Non-Perturbative Aspects of QCD at Collider Energies", which was followed by eight weeks of regular program and a concluding four-day workshop on "The Science Case for an EIC".More than 120 theorists and experimentalists took part in the program over ten weeks. It was only possible to smoothly accommodate such a large number of participants because of the extraordinary efforts of the INT staff, to whom we extend our warm thanks and appreciation. We thank the INT Director, David Kaplan, for his strong support of the program and for covering a significant portion of the costs for printing this volume. We gratefully acknowledge additional financial support provided by BNL and JLab.The program w...

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Two electron lenses (e-lenses) have been in operation during the 2015 RHIC physics run as part of a head-on beam-beam compensation scheme. While the RHIC lattice was chosen to reduce the beam-beaminduced resonance-driving terms, the electron lenses reduced the beam-beam-induced tune spread. This has been demonstrated for the first time. The beam-beam compensation scheme allows for higher beam-beam parameters and therefore higher intensities and luminosity. In this paper, we detail the design considerations and verification of the electron beam parameters of the RHIC e-lenses. Longitudinal and transverse alignments with ion beams and the transverse beam transfer function measurement with head-on electronproton beam are presented.

CW photoinjectors operating at high accelerating gradients promise to revolutionize many areas of science and applications. They can establish the basis for a new generation of monochromatic Xray free electron lasers, high brightness hadron beams, or a new generation of microchip production.In this letter we report on the record-performing superconducting RF electron gun with CsK2Sb photocathode. The gun is generating high charge electron bunches (up to 10 nC/bunch) and low transverse emittances, while operating for months with a single photocathode. This achievement opens a new era in generating high-power beams with a very high average brightness.

The expansion of the Brookhaven accelerator facilities, and the ongoing efforts to raise the AGS beam intensity, have been a driving force for the addition of new kickers and the upgrading of older ones to meet this challenge. All kicker power supply systems are running above their design specifications to provide wider operating ranges. The newly upgraded Booster fast extraction kicker power supply was commissioned in September 1997. Its compact high voltage modulator structure offers a pulse length almost three times longer than the preceding package within the confines of the same physical space. The AGS A5 injection kicker and the AGS G10 extraction kickers are also discussed. In order to expedite design, assembly, and commissioning, and to facilitate interchangeability, standardized modules have been adopted where possible. This paper gives an overview of the AGS and Booster fast injection and extraction kicker systems including their parameters, structure and status.

High-bunch-charge photoemission electron-sources operating in a continuous wave (CW) mode are required for many advanced applications of particle accelerators, such as electron coolers for hadron beams, electronion colliders, and free-electron lasers (FELs). Superconducting RF (SRF) has several advantages over other electron-gun technologies in CW mode as it offers higher acceleration rate and potentially can generate higher bunch charges and average beam currents. A 112 MHz SRF electron photoinjector (gun) was developed at Brookhaven National Laboratory (BNL) to produce high-brightness and high-bunch-charge bunches for the Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment. The gun utilizes a quarter-wave resonator (QWR) geometry for assuring beam dynamics, and uses high quantum efficiency (QE) multi-alkali photocathodes for generating electrons.