Digital timing walk correction and its application to a time-dependent fast neutron energy spectrum measurement

Abstract

Timing walk is the pulse height dependent shift in the mean time at which a discriminator triggers. If there is any such walk, when a pulse height spectrum is sampled over short time intervals, as is the case in time-dependent fast neutron spectroscopy, severe distortions to the pulse height spectrum can occur. Results are given of measurements of walk and consequent pulse height spectrum distortions. A procedure which uses an on-line computer to compensate for walk is described and its effectiveness evaluated. A study is made of distortions of time-dependent spectra, resulting from noise which broadens time resolution at low pulse amplitudes. The reduction of timing walk to ±35 ps is illustrated for a time-dependent neutron energy spectrum measurement.