BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
eRHIC, a future high luminosity electron-ion collider at BNL, will add polarized electrons to the list of colliding species in RHIC. A 10-to-30 GeV electron energy recovery linac will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (3-to-5 mm gap) dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small-magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test results.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
After having provided collisions of polarized protons at a beam energy of 100 GeV since 2001, the Relativistic Heavy Ion Collider~(RHIC) at BNL reached its design energy of polarized proton collision at 250 GeV. With the help of the two full Siberian snakes in each ring as well as careful orbit correction and working point control, polarization was preserved during acceleration from injection to 250~GeV. During the course of the Physics data taking, the spin rotators on either side of the experiments of STAR and PHENIX were set up to provide collisions with longitudinal polarization at both experiments. Various techniques to increase luminosity like further beta star squeeze and RF system upgrades as well as gymnastics to shorten the bunch length at store were also explored during the run. This paper reports the performance of the run as well as the plan for future performance improvement in RHIC.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Medium Energy eRHIC (MeRHIC), the first stage design of eRHIC, includes a multi-pass ERL that provides 4GeV high quality electron beam to collide with the ion beam of RHIC. It delivers a minimum luminosity of 1032 cm-2s-1. Beam-beam effects present one of major factors limiting the luminosity of colliders. In this paper, both beam-beam effects on the electron beam and the proton beam in MeRHIC are investigated. The beam-beam interaction can induce a head-tail type instability of the proton beam referred to as the kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure that the beam quality is good enough for the energy recovery pass. The relation of proton beam stability, electron disruption and consequential luminosity are carried out after thorough discussion.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Beam-beam effects present one of major factors limiting the luminosity of colliders. In the linac-ring option of the eRHIC design, an electron beam accelerated in a superconducting energy recovery linac collides with a proton beam circulating in the RHIC ring. Some specific features of beam-beam interactions should be carefully evaluated for the linac-ring configuration. One of the most important effects on ion beam stability originates from a strongly focused electron beam because of the beam-beam force. This electron pinch effect makes the beam-beam parameter of the ion beam several times larger than the design value, and leads to the fast emittance growth of the ion beam. The electron pinch effect can be controlled by adjustments of electron lattice and the incident emittance. We present results of simulations optimizing ion beam quality in the presence of this pinch effect.
BNL, Upton, Long Island, New York
MIT, Middleton, Massachusetts
Funding: Work performed under US DOE contract DE-AC02-98CH1-886
Design of a medium energy electron-ion collider (MEeIC) is under development at Collider-Accelerator Department, BNL. The design envisions a construction of 4 GeV electron accelerator in a local area inside the RHIC tunnel. The electrons will be produced by a polarized electron source and accelerated in the energy recovery linac. Collisions of the electron beam with 100 GeV/u heavy ions or with 250 GeV polarized protons will be arranged in the existing IP2 interaction region of RHIC. The luminosity of electron-proton collisions at 1032 cm-2 s-1 level will be achieved with 40 mA CW electron current with presently available parameters of the proton beam. Efficient cooling of proton beam at the collision energy may bring the luminosity to 1033 cm-2 s-1 level. The important feature of the MEeIC is that it would serve as first stage of eRHIC, a future electron-ion collider at BNL with both higher luminosity and energy reach. The majority of the MEeIC accelerator components will be used for eRHIC.
IHEP Beijing, Beijing
China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. The beam extraction from the RCS will be realized by ten vertical kicker magnet and one Lambertson magnet. One prototype kicker magnet has been successfully designed and developed in Institute of High Energy Physics. In this paper, the physical and structural design of the prototype kicker magnet are presented, and issues of the magnet development, construction and test are discussed.
IHEP Beijing, Beijing
China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. Two sets of pulsed painting bump magnets, 4 magnets in each set , will be used in CSNS RCS to create a dynamic orbit bump for injection process. The design of these 8 bump magnets has been completed. One prototype bump magnet has been assembled and tested. In this paper, the magnetic field analysis, the eddy current and thermal consideration in the end plates of the prototype bump magnet are presented, and issues of the magnet development, construction and test are discussed.