and from description I thought this was a right mix of trident data
and beam background. However, I found some difficulty interpreting
these files:
1. there is no distinction between "signal" (trident) and
background, if you select events produced at t=0 and having no
parents they are still not distinguishable completely (usually >3
particles/event);
2. even if you find a combination of 3 particles with close missing
mass it is >10^-2 GeV (varying), while I expected <10^-4 GeV^2
(fixed).