BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
RHIC operations with heavy ion beams at energies below 10 GeV/nucleon are motivated by a search for the QCD Critical Point. An electron cooler is proposed as a means to increase RHIC luminosity for collider operations at these low energies. The electron cooling system should be able to deliver an electron beam of adequate quality over a wide range of electron beam energies (0.9-5 MeV). It also should provide optimum 3-D cooling for both hadron beams in the collider. A method based on bunched electron beam, which is also a natural approach for high-energy electron cooling, is being developed. In this paper, we describe the requirements for this system, its design aspects, as well as the associated challenges.
BNL, Upton, Long Island, New York, USA
A future electron ion collider "QCD test facility" is designed in the present Relativistic Heavy Ion Collider (RHIC) tunnel. Electron acceleration and de-acceleration is preformed with energy recovery linac with multiple passes. We report on a combination of a multi-pass linac with the Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs. A single NS-FFAG arc allow electrons to pass through the same structure with an energy range between 1.425 and 10 GeV. The NS-FFAG is placed in the existing RHIC tunnel. The 200 MeV injector bring the polarized electrons to the 1.225 GeV GeV superconducting linac. After one pass through the linac 1.425 GeV electrons enter NS-FFAG arc and after 7 passes reach the energy of 10 GeV. After collisions the beam is brought back by the NS-FFAG and decelerated to the initial energy and directed to the dump.
BNL, Upton, Long Island, New York, USA
The proposed electron ion collider (eRHIC) at Brookhaven National Laboratory requires a polarized electron source with high average current, short bunch length, and small emittance. The-state-of-the-art single polarized electron photocathode is far from delivering the required 50mA current due to ion back-bombardment limiting the cathode’s lifetime and surface charge limit. In our funneling gun design, currently under construction, the electron bunches, generated from 20 photocathodes in a 220 kV DC gun, funnel to a single common beam axis. This article details our design of a high-average-current polarized electron gun’s optics, and presents our simulation of beam dynamics and combiner design. We also report the progress of funneling gun construction here.