The ERL high-energy cooler for RHIC

Electron cooling [1] entered a new era with the July 2005 cooling of the Tevatron recycler ring [2] at Fermilab, using γ=9.5. Considering that the cooling rate decreases as faster than γ² and the electron energy forces higher electron currents, new acceleration techniques, high-energy electron cooling presents special challenges to the accelerator scientists and engineers. For example, electron cooling of RHIC at collisions requires electron beam energy up to about 54 MeV at an average current of between 50 to 100 mA and a particularly bright electron beam. The accelerator chosen to generate this electron beam is a superconducting Energy Recovery Linac (ERL) with a superconducting RF gun with a laser-photocathode.