Patent ID: RE45226

Claim:
A borehole instrument comprising a neutron generator axially spaced from a gamma ray detector assembly, said assembly comprising: a LaBr3 scintillation crystal; and a digital spectrometer cooperating with said LaBr3 scintillation crystal and configured to measure pulses from said scintillation crystal, digitally filter said pulses from said scintillation crystal, digitally inspect the filtered pulses to detect pile-up pulses, periodically forming an estimate of an average ratio of said measured pulses per non-pile-up pulse, and reject said pile-up pulses by combining said measured pulses with said ratio; wherein; said neutron generator emits a plurality of bursts of neutrons the duration of each burst of said plurality of bursts being about 30 microseconds and said plurality of bursts being emitted at a repetition rate of about 5 KHz; and said detector assembly is operated during said bursts.