Counting losses from pulsed optical-feedback preamplifiers used with semiconductor detectors

Problems encountered with semiconductor detectors that are coupled to pulsed optical-feedback preamplifiers have been investigated theoretically. The resetting of the preamplifier causes a deadtime followed by a second deadtime during which counting of pulses in the multichannel analyzer is inhibited. Counts are lost also by the resetting itself, if this is not prevented by special electronics. In order to account for pile-up and deadtime losses the pulse-generator method is frequently applied. It is shown that this method is inadequate for the problem and that the counting losses depend on the detector- and generator-pulse amplitudes. (author)