Recent progress on FFAGS for rapid acceleration

Muon acceleration is one of the more difficult stages to develop for a Neutrino Factory or Muon Collider. The large transverse and longitudinal admittances which must be designed into the system and the rapidity with which acceleration must take place because of muon decay preclude the use of conventional synchrotron design. The approach here employs fixed-field architectures for muon acceleration; specifically, a fixed-field alternating gradient or FFAG accelerator. This paper explores the FFAG option, in particular addressing an adjustment in the rf phase which, although characteristic of fixed-field machines, becomes problematic in the context of rapid acceleration