  We summarize the current state of a concept for muon acceleration aimed at a
future Neutrino Factory. The main thrust of these studies was to reduce the
overall cost while maintaining performance by exploring the interplay between
the complexity of the cooling systems and the acceptance of the accelerator
complex. To ensure adequate survival for the short-lived muons, acceleration
must occur at high average gradient. The need for large transverse and
longitudinal acceptances drives the design of the acceleration system to an
initially low RF frequency, e.g., 325 MHz, which is then increased to 650 MHz
as the transverse size shrinks with increasing energy. High-gradient normal
conducting RF cavities at these frequencies require extremely high peak-power
RF sources. Hence superconducting RF (SRF) cavities are chosen. We consider two
cost effective schemes for accelerating muon beams for a stageable Neutrino
Factory: exploration of the so-called 'dual-use' linac concept, where the same
linac structure is used for acceleration of both H minus and muons and,
alternatively, an SRF-efficient design based on a multi-pass (4.5) 'dogbone'
RLA, extendable to multi-pass FFAG-like arcs.
