Staging acceleration and cooling in a Neutrino Factory

All schemes to produce intense sources of high-energy muons-Neutrino factories, beta beams, Colliders-require collection, RF capture, and transport of particle beams with unprecedented emittances, both longitudinally and transversely. These large initial emittances must be reduced or “cooled” both in size and in energy spread before the muons can be efficiently accelerated to multi-GeV energies. The acceleration stage becomes critical in formulating and optimizing muon beams; individual stages are strongly interlinked and not independent as is the case in most conventional acceleration systems. Most importantly, the degree of cooling, or cooling channel, depends on the choice of acceleration. In the current US baseline scenario, the cooling required for acceleration is about a factor of 10 in transverse emittance per plane. Longitudinal cooling is also required. In the proposed Japanese scenario, using an alternative acceleration scheme, no cooling is presumed. This work discusses two basic, but different approaches to a Neutrino Factory and how the optimal strategy depends on beam parameters and method of acceleration.