MUON COOLING VIA IONIZATION-ENERGY LOSS IN A CRYSTAL CHANNEL

A possible method for high energy muon cooling via ionization energy l oss in a focusing crystal channel is outlined here. We show that start ing with an initially 'cool' muon beam, e.g. coming from a 25 GeV phot o-production source, with the normalized emittance of epsilon(N) = 10( -5) mrad, one can decrease the transverse emittance to less than epsil on(N) = 10(-7) mrad by passing muons through total of 280 m of the cry stal absorber, For a practical implementation, we suggest a storage ri ng configuration, where sections of crystal absorber are alternated wi th a conventional high gradient re-acceleration (20 MeV/m) inserts, Th e necessary circular confinement (bending) would be provided by additi onal sections of bent crystals employing powerful steering features of bent silicon crystal demonstrated by recent experiments. Required coo ling length of 280 m constitutes only about 2 x 10(-3) of the muon lif etime in the laboratory frame (about 120 turns in our model 'cooling r ing'). Dominant heating process (due to multiple scattering on electro n gas inside a crystal channel) limits the minimum achievable emittanc e to about epsilon(N) = 10(-9), while the characteristic ionization co oling damping length is about 62.5 m. Feasibility of effective ionizat ion cooling rests on the ultra high fundamental crystal fields availab le in a solid state environment.