  Orbital period in a ring accelerator and time of flight in a linear
accelerator depend on the amplitude of betatron oscillations. The variation is
negligible in ordinary particle accelerators with relatively small beam
emittance. In an accelerator for large emittance beams like muons and unstable
nuclei, however, this effect cannot be ignored. We measured orbital period in a
linear non-scaling fixed field alternating gradient (FFAG) accelerator, which
is a candidate for muon acceleration, and compared with the theoretical
prediction. The good agreement between them gives important ground for the
design of particle accelerators for a new generation of particle and nuclear
physics experiments.
