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
Niowave, Inc., Lansing, Michigan, USA
A 5-cell SRF cavity operating at 704 MHz will be used for Coherent Electron Cooling Proof of Principle (CeC PoP) system under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up 22 MeV. Novel mechanical designs, including the super fluid heat exchanger, helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. Structural and modal analysis, using ANSYS were performed to confirm the cavity chamber and He vessel structural stability and to calculate the tuning sensitivity of the cavity. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for CeC PoP experiment.
BNL, Upton, Long Island, New York, USA
A Quarter-Wave Resonator (QWR) type SRF gun operating at 112 MHz will be used for Coherent Electron Cooling Proof of Principle (CeC PoP) system under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. This cavity is designed to generate a 2 MeV, high charge (several nC), low repetition rate (78 kHz) electron beam using a new fundamental power coupler (FPC) design approach. Structural and thermal analysis, using ANSYS were performed to confirm the FPC structural stability and to calculate the deflection due to heat load from RF power generation. This paper provides an overview of the design, structural and thermal analysis, test results, and FPC tuning drive system for the 112 MHz gun.
BNL, Upton, Long Island, New York, USA
SLAC, Menlo Park, California, USA
Wake fields due to the wall roughness of the vacuum chamber can catch up to the bunch causing energy spread and emittance growth. Several theoretical models were developed in the past which showed rather different importance of this effect. Some models suggest that wake field due to the wall roughness can be minimized if the vacuum chamber surface can be characterized by a large aspect ratio of the surface roughness (characteristic length to the height of surface bumps). To explore these effects several surfaces were measured * and direct numerical simulations were performed for such realistic surfaces. Here we discuss results of such direct simulations for real surface data and compare them with expectations based on analytic models.
* Surface measurements used in these studies were performed by P. Takacs from the Instrumentation Division of BNL.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Niowave, Inc., Lansing, Michigan, USA
Fermilab, Batavia, USA
SBU, Stony Brook, New York, USA
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Efforts to experimentally prove a concept of the coherent electron cooling are underway at BNL. A short 22-MeV linac will provide high charge, low repetition rate beam to cool a single ion bunch in RHIC. The linac will consist of a 112 MHz SRF gun, two 500 MHz normal conducting bunching cavities and a 704 MHz five-cell accelerating SRF cavity. The paper describes the SRF and RF systems, the linac layout, and discusses the project status, first test results and schedule.