Trigger Group Software Summary (July 1996)

There has been great progress on the necessary infrastructure during Spring 1996. Most current needs are in actual trigger studies! (Data set requests are covered in a later section.)

Current efforts focus on completing the conceptual design of the Level 1 hardware trigger. We need to have an implementation model of the design by end of October, 1996, for the trigger workshop. During 1996, Software filters (Level 3) are studied to validate the trigger architecture and aid design of the online farm.

L1 contains Drift Chamber and Calorimeter triggers.

Code functions:

• digitization, to make up for the fact that TRG schedule has historically been ahead of both DCH and EMC,
• trigger algorithms, which is feature extraction, pattern recognition and reconstruction all in one,
• analysis code to tabulate efficiencies, rates and event time jitter,
• event display code for debugging and quality control.

In the current structure (SRT + GEANT 3.21), trigger packages are equivalent to the digitization stage of the 5 detector subsystems.

Input data:
Level 1 input data are GEANT hits from the DCHA and EMCA systems. Both DC and EM triggers use GHits from dbio bbsim.xdr files. The DC trigger also has an ascii interface for standalone use. Geometry is communicated via ascii files.
Level 3 input data are outputs from Level 1, GHits and SVT digis. In principle, Level 3 needs the data of all subsystems at the digi level, including IFR and DRC.
Thus trigger is a consumer of geometry and hits.

Output data:
Currently only data saved to disk is HBOOK histogram and ntuple files.
Digi data will be written at some point in the future after the DAQ interface has been defined.

Trigger code is written to explore new ideas and algorithms - the current code is neither standard nor long-lived. To meet the schedule demands with existing low level of manpower, Level 1 trigger digitization and algorithm code is written in Fortran 77 (with extensions, of course) and analysis and event display code consists of PAW kumacs. The Framework interface and Level 3 code is written in C++ and Fortran 77.

Fast Simulation