[smartscience]

I never thought I'd see the issue of pulse selection in spallation neutron sources referred to on HN, let alone linked to music theory. In practice, most systems that select a subset of these pulses will select 1 pulse in every 2^n pulses, so fancy patterns aren't needed. But I work at a facility where 1 in every 5 pulses are removed in order to supply another part of the site, and where the particular instrument I work with uses 1 in every 2 or 3 pulses. At the moment, the selection of 1 in 2-3 pulses is accomplished with a spinning disc ('chopper') with a hole in it, to let though the required fraction of pulses. But the spin speed of the disc must generally be constant once set, meaning sometimes it lets though one of the missing 1-in-5 pulses that were already diverted somewhere else. We would need a better switching method to let through arbitrary irregularly spaced patterns of neutrons. I think I worked out once that it could offer the most advantage when running in our 1-in-3 mode.