Method and system for analyzing electrical pulses contained in a pulse train signal representative of the interaction of x-ray bursts with a nuclear detector configured for subsurface disposal. The pulse train signal is sampled to form a digitized signal. The total energy deposited at the detector during an x-ray burst is determined from the digitized signal, and a count rate of x-ray pulses from the burst is determined. A subsurface parameter is determined using the total energy deposit.