Ionization cooling

In accelerator physics, ionization cooling is a process for reducing the emittance of ('cooling') a charged particle beam by passing the particles through some material, reducing their momentum as they ionize atomic electrons in the material.Thus the normalised beam emittance is reduced. By re-accelerating the beam, for example in an RF cavity, the longitudinal momentum may be restored without replacing transverse momentum. Thus overall the angular spread and hence the geometric emittance in the beam will be reduced. In accelerator physics, ionization cooling is a process for reducing the emittance of ('cooling') a charged particle beam by passing the particles through some material, reducing their momentum as they ionize atomic electrons in the material.Thus the normalised beam emittance is reduced. By re-accelerating the beam, for example in an RF cavity, the longitudinal momentum may be restored without replacing transverse momentum. Thus overall the angular spread and hence the geometric emittance in the beam will be reduced. Ionization cooling can be spoiled by stochastic physical processes. Multiple Coulomb scattering in muons as well as nuclear scattering in protons and ions can reduce the cooling or even lead to net heating transverse to the direction of beam motion. In addition, energy straggling can cause heating parallel to the direction of beam motion. The primary use of ionization cooling is envisaged to be for cooling of muon beams. This is because ionization cooling is the only technique that works on the timescale of the muon lifetime. Ionization cooling channels have been designed for use in a neutrino factory and a muon collider. Muon ionization cooling is expected to be demonstrated for the first time by the proof of principle International Muon Ionization Cooling Experiment (MICE). Other PoP muon ionization cooling experiments have been devised.