Study of Thresholds in the Pb Glass in a Level 1 Trigger

Abstract

We have studied the efficiency and background reduction using energy deposited in the LGD in a Level 1 trigger. Using data samples triggered with and without the MAM, we investigated triggers which discriminate on single LGD cells and summing over four cells before discrimination. In both cases, most of the events in the MAMless run are rejected while at the same time retaining most of the events in the run with the MAM requirement. At 80% acceptance, our measurements indicate that the four-cell trigger rejects 99.4% of the MAMless events and the one-cell trigger rejects 99%, resulting in about twice the rate. At higher acceptance, rejection of both triggers is smaller but similar. We conclude that that a four-cell trigger offers little advantage over the one-cell trigger.