Last update Nov 5th, 1997
The ADMLs (Amplifier Discriminator Multiplexer Logic) are ASU/Philips modules which process the analog signals from the E-Counters. The signals are first amplified by a factor of 50, and then discriminated. The maximum threshold on the discriminator level of the board is 30mV. Evidently, any noise from the baseline (the amplitude of which was measured to be .80 mV on november 5th by C. Cuevas, M. Dugger, and L.Y. Murphy) will trigger the unit.
As a result, a new approach was necessary in order to raise the maximum threshold to a level where the noise from the baseline would not trigger the unit continuously. The solution was found by forcing the effective ground of the unit to a level above which the noise would no longer trigger the discriminator. The DC level was provided by a simple variable DC power supply capable of supplying potentials from 0 to 25V. G. Kezerashvili and L. Murphy calibrated the units by supplying an analog signal of known amplitude to the ADMLs and varying the DC level until the output ECL signal vanished, or reappeared. Five input amplitudes (1-5mV input) were supplied which spanned the entire range of DC values. The results are shown on the plot below.
Due to time constraints during the august commissioning run, we were unable to perform plateaux measurements for a wide set of effective threshold settings. Our measurements were performed at an effective threshold of 4.2mV, or Vdc 20V.