A VERSATILE DIELECTRON TRIGGER FOR NUCLEON-NUCLEON AND NUCLEUS-NUCLEUS COLLISIONS

A novel approach for a versatile first level dielectron trigger is pre sented. This trigger operates in the low multiplicity environment of n ucleon-nucleon reactions as well as in the high multiplicity situation of nucleus-nucleus collisions. For optimal trigger performance, time- of-flight conditions for the two fastest particles of the event are co mbined with event multiplicity requirements. The dielectron trigger ef ficiency is given. The event reduction factor of such a trigger approa ch is studied for a low, a medium and a high multiplicity environment. The impact parameter dependence of the event reduction is given. The timing properties of the trigger signal are described. The losses due to deadtime are specified. Finally, the first level trigger rate is re ported. (C) 1998 Elsevier Science B.V. All rights reserved.