Radiation Reaction in a Continuous Focusing Channel

We show that the radiation damping rate of the transverse action of a particle in astraight, continuous focusing system is independent of the particle energy, and that noquantum excitation is induced. This absolute damping effect leads to the existence of atransverse ground state which the particle inevitably decays to, and yields the minimumbeam emittance that one can ever attain, fl ffl min = ? h=2mc, limited only by the uncertaintyprinciple. Due to adiabatic invariance, the particle can ...