Timing Discriminator Uses Leading - Edge Extrapolation "

A discriminator circuit uses dual current sources charging a capacitor to produce an output timing edge a fixed time after the starting corner of the input pulse, nearly independent of risetime and threshold setting. Performance with artificial and real pulses in the microsecond range is described. Background Obtaining a good timing information from slow-rising pulses is an old problem in pulse spectroscopy, and one of renewed interest in connection with high-energy calorimeters. In this type of detector the output pulse may have a long risetime for many reasons; for instance, 1. It may be derived from many proportional chamber wires ganged together, with varying drift times to the sense wires for any given particle trajectory. 2. The preamplifier is often deliberately designed to integrate the incoming charge. 3. Additional high-frequency rolloff may be used to stabilize the preamplifier, to reduce high-frequency noise, or to provide a pulse shape more suitable for sampling. "Work supported in part by NSF Grant PHY 79-20821 and in part by the Department of Energy, contract DE-AC03-76SF00515. "%urrently on leave of absence from Northeastern University, Boston, Massachusetts. (Submitted to Nuclear Instruments & Methods)