A new ELE-timing discriminator for high counting rate experiments

A new type of timing discriminator was designed and tested for an experiment at the National Laboratory for High Energy Physics (KEK). Since the required time resolution is better than 1 ns for signals from a plastic scintillation counter, the method of time pick-off is chosen for the extrapolation of leading edge timing (ELET). This digital method, as opposed to the conventional analog method, was developed to obtain a high repetition rate capability. The extrapolation circuits are fabricated on ECL (emitter coupled logic) semicustom ICs so that the discriminator can handle fast signals. The performance of the discriminator was tested by comparing it with a dual threshold (DT) discriminator and a leading edge timing discriminator. The time walk was measured and found to be less than ±400 ps for pulse heights from 50 mV to 2 V when the threshold voltage was set to 30 mV. It was found that the discriminator had better performance than the DT discriminator. The module was found to be best suited for an experiment performed at a high event-rate with a high background rate condition