A 25-kV 75-kHz kicker for measurement of muon lifetime

An international collaboration plans to measure the lifetime of the muon to a precision of 1 part per million . The "MuLan" experiment will take place at the Paul Scherrer Institut (PSI) in Northern Switzerland. The MuLan experiment requires a fast beam line kicker, which can turn the beam on and off, to invoke an artificial time structure on the continuous beam which has a 50.6-MHz time microstructure. The kicker needs to run with a standard "on-off time cycle" or in a "Muon on Request" mode. The MuLan kicker consists of two pairs of deflector plates mechanically in series, driven by four modulators. Each modulator consists of two stacks of MOSFETs operating in push-pull mode. The specifications for the kicker demand that the rise and fall times of the deflector plate voltage do not exceed 45 ns. There is a requirement for an adjustable output voltage from 0 V to ±12.5 kV per deflector plate, a minimum pulse duration of 200 ns, and adjustable repetition rate up to a maximum of 50 kHz, continuous. Short turn-on and turn-off delays are required for the "Muon on Request" mode; the measured propagation delay is 200 ns. The specifications also require that the polarity of the pulses on the plates be selectable, although not on a pulse-by-pulse basis. This paper describes the novel design of the kicker and presents both predictions and measurements.