Early CAL LE trigger observations

In the standard Treq trigger tests using the muon telescope trigger only (with a wide GEM window and no delay on muon telescope trigger),  we typically observe:

Some further examination from offline as a function of the energy in the CAL:

Observatiuons:

• The late time tail are from events with low energy just above threshold, as expected. The GEM window may not be wide enough to entirely contain the very late events, but for the purpose of real gamma ray events during flight operation this hopefully only means a slight efficiency loss for events very close to the trigger threshold which the analyses can easily avoid by raising the analysis threshold slightly.
• The early triggers are in part due to occasional high energy hits (all E>60 MeV hits are gathered into the last bin).
• There are still some early trigger events with rather low energy in the CAL which is somewhat puzzling. Correlations with possible sources are still under investigation.