Trigger Possibilities

In the RICH local LVL-1 trigger, one trigger segment has 20 PMT's. Thus, the signals from 20 PMT's are summed in the RICH FEE to generate one trigger signal. The method to generate the trigger signal should be described below. There are two steps. First, 4 signals from PMT's are summed in the Int-R chip on the AMU/ADC board. Next, outputs of 5 Int-R chips are summed on the bus of the back plane of the RICH FEE. There are 5 AMU/ADC boards in the half of the RICH FEE crate and these 5 board share the bus line for the trigger signal. The signal currents from each boards are summed using a wired-or method.

If the signal of the Aerogel Cerenkov counter will be used for the LVL-1 trigger, this summation method should be changed. The number of PMT's in a trigger segment is the important number to develop the trigger scheme.