Triggers and scalers

When studying efficiencies of rare signal triggers, we want to save considerable computational resources by pre-selecting events according to some basic trigger criteria, avoiding the costly propagation and reconstruction of uninteresting events.
One recent example: the study of J/Psi and Upsilon trigger based on calorimeter hits.
A new feature has been implemented that includes:
- A template for the event selection logic
- Augmented event header structure which carries the running scaler for rejected events, allowing the user to correctly calculate the normalization factors.
- The “g2t” interface with reconstruction for transparent access to such data in root files.
How to do that:
- Write the “AGUDIGI” subroutine called automatically by GEANT at the hits digitization stage
- Use any of the methods available to check for the trigger condition such as number of hits in a particular detector subsystem
- Set the IEOTRI flag (standard GEANT) according to the event selection criteria. Rejected events will then be completely ignored and won’t be present in the output stream.

When studying efficiencies of rare signal triggers, we want to save considerable computational resources by pre-selecting events according to some basic trigger criteria, avoiding the costly propagation and reconstruction of uninteresting events.