BNL, Upton, Long Island, New York, USA
Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them.
BNL, Upton, Long Island, New York, USA
An electron lens for head-on beam-beam compensation planned for RHIC requires precise overlap of the electron and proton beams which both can have down to 0.3 mm rms transverse radial widths along the 2m long interaction region. Here we describe a new diagnostic tool that is being considered to aid in the tuning and verification of this overlap. Some of ultra relativistic protons (100 or 250 GeV) colliding with low energy electrons (2 to 10 keV) will transfer sufficient transverse momentum to cause the electrons to spiral around the magnetic guiding field in a way that will make them detectable outside of the main solenoid. Time-of-flight of the halo electron signals will provide position-sensitive information along the overlap region. Scattering cross sections are calculated and counting rate estimates are presented as function of electron energy and detector position.
BNL, Upton, Long Island, New York, USA
PKU/IHIP, Beijing, People's Republic of China
Stony Brook University, Stony Brook, USA
BNL, Upton, Long Island, New York, USA
As a part of the proposed electron lens system for RHIC, two 6 T, 200 mm aperture, 2.5 meter long superconducting solenoids are being designed and built at BNL. Because of several demanding requirements this has become a unique and technologically advanced magnet. For example, the field lines on axis must be straight over the length of the solenoid within ±50 microns. Since this is beyond the normal construction techniques, a correction package becomes an integral part of the design for which a new design has been developed. In addition, a minimum of 0.3 T field is required along the electron beam trajectory in the space between magnets. To achieve this fringe field superconducting solenoidal coils have been added at the two ends of the main solenoid. The main solenoid itself is a challenging magnet because of the high Lorentz forces and stored energy associated with the large aperture and high fields. An innovative structure has been developed to deal with the large axial forces at the ends. This paper will summarize the magnetic design and optimization of the entire package consisting of the main solenoid, the fringe field solenoids, and the corrector system.
BNL, Upton, Long Island, New York, USA
We are designing two electron lenses (E-lens) to compensate for the large beam-beam tune spread from proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). They will be installed in RHIC IR10. First, the layout of these two E-lenses is introduced. Then the effects of e-lenses on proton beam are discussed. For example, the transverse fields of the e-lens bending solenoids and the fringe field of the main solenoids will shift the proton beam. For the effects of the e-lens on proton beam trajectory, we calculate the transverse kicks that the proton beam receives in the electron lens via Opera at first. Then, after incorporating the simplified E-lens lattice in the RHIC lattice, we obtain the closed orbit effect with the Simtrack Code.
BNL, Upton, Long Island, New York, USA
We designed two electron lenses to apply head-on beam-beam compensation for RHIC; they will be installed near IP10. The electron-beam transport system is an important subsystem of the entire electron-lens system. Electrons are transported from the electron gun to the main solenoid and further to the collector. The system must allow for changes of the electron beam size inside the superconducting magnet, and for changes of the electron position by 5 mm in the horizontal- and vertical-planes.
ANL, Argonne, USA
BNL, Upton, Long Island, New York, USA
An Electron Beam Ion Source (EBIS) being developed at the Argonne National Laboratory (ANL) will be used to charge breed rare isotopes from a 1 Ci 252Cf source, the Californium Rare Isotope Breeder Upgrade (CARIBU). Simulations have been performed using commercially available software, TriComp, to ensure the electron collector is properly designed to dissipate the electron beam power and provide adequate acceptance for the injected ion beam.
BNL, Upton, Long Island, New York, USA
PKU/IHIP, Beijing, People's Republic of China
Stony Brook University, Stony Brook, USA
The future electron-ion collider eRHIC requires a high average current (~50 mA), short bunch (~3 mm), low emittance (~20 μm) polarized electron source. The maximum average current of a polarized electron source so far is more than 1 mA, but much less than 50 mA, from a GaAs:Cs cathode [1]. One possible approach to overcome the average current limit and to achieve the required 50 mA beam for eRHIC, is to combine beamlets from multiple cathodes to one beam. In this paper, we present the feasibility studies of this technique.
BNL, Upton, Long Island, New York, USA
Two electron lenses for a head-on beam-beam compensation are being planned for RHIC; one for each circulating proton beam. The transverse profile of the electron beam will be Gaussian up to a maximum radius of re=3σ. Simulations and design of the electron gun with Gaussian radial emission current density profile and of the electron collector are presented. Ions of the residual gas generated in the interaction region by electron and proton beams will be removed by an axial gradient of the electric field towards the electron collector. A method of optical observation the transverse profile of the electron beam is described.
BNL, Upton, Long Island, New York, USA
FRIB, East Lansing, Michigan, USA
MIT, Middleton, Massachusetts, USA
We present the design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2 s-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling and the compact magnets for recirculating passes. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs and a potential of adding polarized positrons are also presented.
BNL, Upton, Long Island, New York, USA
IAP, Frankfurt am Main, Germany
The construction and initial commissioning phase of a new heavy ion preinjector was completed at Brookhaven in September, 2010, and the preinjector is now operational. This preinjector, using an EBIS source to produce high charge state heavy ions, provided helium and neon ion beams for use at the NASA Space Radiation Laboratory in the Fall of 2010, and gold and uranium beams are being commissioned during the 2011 run cycle for use in RHIC. The EBIS operates with an electron beam current of up to 10 A, to produce mA level currents in 10 to 40 μs beam pulses. The source is followed by an RFQ and IH linac to accelerate ions with q/m > 0.16 to an energy of 2 MeV/amu, for injection into the Booster synchrotron. The performance of the preinjector is presented, including initial operational experience for the NASA and RHIC programs.
BNL, Upton, Long Island, New York, USA
Two electron lenses are under construction for RHIC to partially compensate the head-on beam-beam effect in order to increase both the peak and average luminosity. The final design of the overall system is reported as well as the status of the component design, acquisition, and manufacturing.