Conceptual design of a 1.1-GeV 500-μa fast cycling proton synchrotron

A very high intensity proton synchrotron system which could be used for a pulsed spallation neutron source and low energy neutrino and meson physics facility is designed. The synchrotron would accelerate 200 MeV protons to 1.1 GeV with a repetition rate of 50 pulses per sec. The number of protons per pulse is 6.3 × 10¹³, resulting in an average proton current of 500 μA. In order to accomodate the high intensity considerable attention was directed toward minimizing beam loss, controlling space charge forces, and eliminating beam instabilities. Special features of the conceptual design include H^- charge exchange injection, a guide field flat-bottom of 1.5 msec to facilitate low-loss injection and capture, 15 msec acceleration period, and 3.5 msec for reset of the guide field. A separated function lattice consists of normal cells, dispersion suppressor cells, and matching cells. It provides sufficient straight section length to accommodate a fairly long rf system. A low impedance rf system (cathode-follower) is considered in order to overcome strong beam loading effects in the cavities. Rapid bunch shaping is employed at the end of acceleration to produce pulses of 200 nsec duration for possible neutrino experiments. The transverse acceptances used in the design are: ε_H = 500 π mm mr and ε_V = 300 π mm mr.