The effects of chopper jitter on the time-dependent intensity transmitted by multiple-slot multiple disk chopper systems

The author presents Monte Carlo calculations of the time dependence of the intensity transmitted by single- and multiple-slot multiple disk chopper assemblies, taking into account the effects of chopper jitter. In the case of multiple-slot systems, where each of at least two choppers and a mask is fitted with two or more slots, a switching function is employed to suppress contaminated pulses, i.e., pulses in which neutrons can pass through slots that would never line up in the absence of jitter. Such pulses, if accepted, would degrade the time resolution of the system. His results for the time-integrated intensity are in good agreement with previously reported semi-analytic calculations. The need to reject contaminated pulses in multiple-slot systems is emphasized. 5 refs., 6 figs., 2 tabs