Speaker
Description
An electron accelerator for cooling hadron beams in the Relativistic Heavy Ion Collider (RHIC) has been constructed at Brookhaven National Laboratory in the Collider-Accelerator Department and is in the early stages of beam commissioning. Electron cooling is planned to increase the luminosity of the RHIC for heavy-ion beam energies below 10 GeV/nucleon. Such energies are necessary to map the quantum chromodynamic (QCD) phase diagram of quark-gluon plasma, a key goal of the RHIC project. The QCD critical point is a distinct feature of the phase diagram, and the LEReC project is driven by the effort to determine this critical point and characterize its properties. However, the required event statistics are much higher than previously achieved in the RHIC, requiring significant luminosity improvement at energies below γ = 10.7. Application of electron cooling can substantially increase the average integrated luminosity by countering the effect of intrabeam scattering at the lowest hadron energies. The LEReC project is a novel approach to cooling being the first to attempt bunched-electron beam cooling of a relatively high-energy hadron beam. The electron accelerator has been designed to deliver a beam with a range of energies from 1.6 MeV up to 2.6 MeV and a range of beam current up to 50 mA with an average design beam current of 30 mA. Electrons are generated by a DC gun comprising a photo-sensitive cathode contained in a cavity held at a DC potential of 400 kV. The beam then travels through a series of RF cavities, and is directed into the cooling section of the RHIC where the electron beam co-propagates with the hadron beam first into a section of one of the RHIC rings and then, after a 180-degree turn, into a section of the other RHIC ring. After these cooling sections, the electron beam is finally directed into a beam dump where it is discarded. New electron beam is generated by the accelerator and continues the cooling process. This presentation will provide an overview of the LEReC project, briefly discussing the nature of electron cooling and its application at RHIC as well as the key features of the electron accelerator including the requirements for the electron beam; the DC gun, cathode, and laser systems; the various RF cavities including a superconducting cavity; beamline instrumentation; and the mechanism for cooling. The presentation will also discuss the latest results of commissioning along with the plans for future commissioning and operation.
