BNL, Upton, Long Island, New York
The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented.
BNL, Upton, Long Island, New York
The two rings in the Relativistic Heavy Ion Collider (RHIC) require a total of 933 power supplies to supply current to highly inductive superconducting magnets. Failure statistics for the RHIC power supplies will be presented for the last three RHIC runs. The failures of the power supplies will be analyzed. The statistics associated with the power supply failures will be presented. Comparisons of the failure statistics for the last three RHIC runs will be shown. Improvements that have increased power supply availability will be discussed. Further improvements to increase the availability of the power supplies will also be discussed.
BNL, Upton, Long Island, New York
The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development at BNL. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations at resolutions ~1 nm (at frequencies above ~8 Hz) in a spare RHIC quadrupole coldmass under cryogenic conditions. Some preliminary results of these studies were presented at the Nanobeam 2005 workshop*. These results were limited in resolution due to a rather large motion of the laser head itself. As a first step towards improving the measurement quality, an actively stabilized isolation table was used to reduce the motion of the laser holder. The improved set-up will be described, and vibration spectra measured at cryogenic temperatures, both with and without helium flow, will be presented.
*A. Jain, et al., Nanobeam 2005, Kyoto, Japan, Oct.17-21, 2005; paper WG2d-05; available at http://wwwal.kuicr.kyoto-u.ac.jp/NanoBM .
BNL, Upton, Long Island, New York
In this paper we describe unique features of magnets for R&D ERL, which is under construction in Collider-Accelerator Department, BNL. The R&D ERL serves as a test-bed future BNL ERLs, such as electron-cooler-ERL for RHIC and 20 GeV ERL for future electron-hadron, eRHIC. We present selected designs of various dipole and quadrupole magnets, which are used in Z-bend merging systems and the returning loop, 3-D simulations of the fields in these magnets, particle tracking and analysis of magnet's influence on the beam parameters. We discuss an uncommon method of setting requirements on the quality of magnetic field and transferring them into measurable parameters as well as into manufacturing tolerances. We compare selected simulation with results magnetic measurements.
BNL, Upton, Long Island, New York
We present conceptual design of the NSLS-II injection system. The injection system consists of low-energy linac, booster and transport lines. We review the requirements on the injection system imposed by the storage ring design and means of meeting these requirements. We discuss main parameters and layout of the injection system components.
BNL, Upton, Long Island, New York
After the last successful RHIC Au-Au run in 2004 (Run-4), RHIC experiments now require significantly enhanced luminosity to study very rare events in heavy ion collisions. RHIC has demonstrated its capability to operate routinely above its design average luminosity per store of 2x1026 cm-2 s-1. In Run-4 we already achieved 2.5 times the design luminosity in RHIC. This luminosity was achieved with only 40% of bunches filled, and with β* = 1 m. However, the goal is to reach 4 times the design luminosity, 8x1026 cm-2 s-1, by reducing the beta* value and increasing the number of bunches to the accelerator maximum of 111. In addition, the average time in store should be increased by a factor of 1.1 to about 60% of calendar time. We present an overview of the changes that increased the instantaneous luminosity and luminosity lifetime, raised the reliability, and improved the operational efficiency of RHIC Au-Au operations during Run-7.
BNL, Upton, Long Island, New York
ITEP, Moscow
The Relativistic Heavy Ion Collider~(RHIC) as the first high energy polarized proton collider was designed to provide polarized proton collisions at a maximum beam energy of 250GeV. It has been providing collisions at a beam energy of 100GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100GeV are about a factor of two stronger than those below 100GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated to the record energy of 250GeV in RHIC with a polarization of 45\% measured at top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136GeV, the first strong intrinsic resonance above 100GeV. This paper presents the results and discusses the sensitivity of the polarization survival to orbit distortions.
BNL, Upton, Long Island, New York
AES, Princeton, New Jersey
CLASSE, Ithaca
Stony Brook University, StonyBrook
Jefferson Lab, Newport News, Virginia
In this paper we present status and plans for the 20-MeV R&D energy recovery linac, which is under construction at Collider Accelerator Department at BNL. The facility is based on high current (up to 0.5 A of average current) super-conducting 2.5 MeV RF gun, single-mode super-conducting 5-cell RF linac and about 20-m long return loop with very flexible lattice. The R&D ERL, which is planned for commissioning in 2008, aims to address many outstanding questions relevant for high current, high brightness energy-recovery linacs.
BNL, Upton, Long Island, New York
Tech-X, Boulder, Colorado
ORNL, Oak Ridge, Tennessee
AES, Princeton, New Jersey
Fermilab, Batavia, Illinois
Jefferson Lab, Newport News, Virginia
BINP SB RAS, Novosibirsk
JINR, Dubna, Moscow Region
The physics interest in a luminosity upgrade of RHIC requires the development of a cooling-frontier facility. Detailed cooling calculations have been made to determine the efficacy of electron cooling of the stored RHIC beams. This has been followed by beam dynamics simulations to establish the feasibility of creating the necessary electron beam. Electron cooling of RHIC at collisions requires electron beam energy up to about 54 MeV at an average current of between 50 to 100 mA and a particularly bright electron beam. The accelerator chosen to generate this electron beam is a superconducting Energy Recovery Linac (ERL) with a superconducting RF gun with a laser-photocathode. An intensive experimental R&D program engages the various elements of the accelerator: Photocathodes of novel design, superconducting RF electron gun of a particularly high current and low emittance, a very high-current ERL cavity and a demonstration ERL using these components.