Electron cooling


Electron cooling is a method to shrink the emittance of a charged particle beam without removing particles from the beam. Since the number of particles remains unchanged and the space coordinates and their derivatives are reduced, this means that the phase space occupied by the stored particles is compressed. It is equivalent to reducing the temperature of the beam. See also stochastic cooling.
The method was invented by Gersh Budker at INP, Novosibirsk, in 1966 for the purpose of increasing luminosity of hadron colliders. It was first tested in 1974 with 68 MeV protons at NAP-M storage ring at INP.
It is used at both operating ion colliders: the Relativistic Heavy Ion Collider and in the Low Energy Ion Ring at CERN.
Basically, electron cooling works as follows: