Orsay data: selecting different strips in detector 4

require a good event in strip 3 of detector 4: here are the coincident events in det 1:

same for strip 7 of det 4:

same for strip 11 of det 4:

same for strip 15 of det 4:


As the strip number in det 4 increases, more events come in lower strip numbers in det 1. (This is eyeballing it, because I can't remember how to take the area of a 2d spectrum in Midas.)