Li-rod based muon ionization cooling channel

A muon ionization cooling channel based on lithium rods (Li-rod) has been under consideration since the middle of the 1980s. Features of muon beam motion in such a channel are discussed, namely, an influence of nonparaxiality of motion and transverse-longitudinal coupling. Most simulations of muon beam cooling were performed using the specially developed software LYRICS (lithium rod ionization cooling simulation); a comparison between its results and the predictions of a linear model serves both to examine the simulation code and to determine the contribution of nonparaxiality to the beam motion. For numerical examples, we used muons around 200 MeV total energy since such energy is close to optimal. The idea of the inclusion of a symplectic (nondissipative) emittance exchanger to the cooling channel, which allows one to cool in all degrees of freedom, is introduced. The appropriate beam parameters for emittance exchange procedure and their dependence on transverse emittance and beam longitudinal parameters are discussed.