beamcooling
Beamcooling refers to a set of techniques used to reduce the phase-space volume, or emittance, of a charged-particle beam. By lowering the spread in position and momentum of particles, beamcooling improves beam quality, increases luminosity in colliders, and enhances stability in storage rings. The term is sometimes written as beam cooling, though beamcooling is also commonly used. Emittance reduction can be achieved through several established methods, most notably stochastic cooling, electron cooling, and laser-based approaches. In stochastic cooling, pickup devices measure fluctuations in the beam and a broadband electronic system provides corrective kicks downstream, gradually damping transverse and longitudinal deviations. Electron cooling uses Coulomb interactions between a hot particle beam and a co-propagating cold electron beam; energy exchange reduces momentum spread and transverse motion, and it is especially effective at lower energies or with heavy ions. Laser cooling, demonstrated primarily in atomic and ion-trap systems, has been explored for beams through laser interactions or laser-assisted processes in storage rings; its application to high-energy hadron beams remains largely experimental.
Beamcooling is applied to increase luminosity and reduce beam losses in particle accelerators and storage rings,