BNL, Upton, Long Island, New York, USA
Muon Colliders offer many advantages over electron-positron colliders, but have significant technical challenges. One of these is the needed muon cooling in both transverse and longitudinal phase space. Ionization cooling, from energy loss in materials plus rf re-acceleration, lowers transverse emittances. Cooling of longitudinal emittance requires, in addition, emittance exchange in a lattice giving greater energy loss for higher emittance muons. In a 'Guggenheim', or similar lattices, this is achieved by dispersion plus wedge shaped absorbers. Simulations of such cooling are reported. Two challenges in cooling to the required emittances will be discussed: a) the needed high magnetic fields and required super-conductor current densities; and b) the needed vacuum rf operating in these magnetic fields.
