Automated Digital Threshold Determination

A system for automatically measuring and displaying the thresholds of many channels of nanosecond-speed discriminators is described. It is used in high-energy physics experiments in which the results depend critically upon the stability of the discriminator thresholds. Measurements are made in the dead time between accelerator beam spills. The system includes a programable pulse generator, a 20-channel pulse distribution transformer, and a multichannel coincidence array which is sequentially addressed. Since the distribution transformer is constructed as a throughline, matched-impedance element, it remains permanently connected in the signal lines from the phototubes, and no cables whatever need be disturbed to allow threshold measurement.