Event selection
- Paddle Timing
- Dt < 8 ns selects events with vertex |z| cm
- Still contains background events
- ZDC Timing
- Dt < 20 ns confirms selected events as collisions
- However, at ?s=56 AGeV, rejects ~10% of central collisions. < 1% at ?s=130 AGeV. Threshold effect.
- Paddle Multiplicity
- Requiring PP,PN to have a large ADC sum recoups central events lost to ZDC cut.
- Offline event trigger is 1 AND (2 OR 3)