Experimental test of the "zero dead time" count-loss correction method on a digital gamma-ray spectrometer

A DSPEC^plus™ digital gamma-ray spectrometer is tested on its ability to compensate for count loss due to pulse pileup rejection and to assess the statistical uncertainty on the measured number of counts in the gamma-ray spectra. In the applied LEGe detector set-up, count loss is compensated correctly up to about 90% system dead time. This is done by the so-called "zero dead time" count loss correction method, involving the regular addition of virtual counts to the true counts according to a short-term ratio of real time to system live time. Besides performing add-n operations to the gamma-ray spectrum instead of add-1, the spectrometer also builds up a Σn²-spectrum. Experimental tests in this work confirm that the statistical counting uncertainty in small regions of interest in the gamma-ray spectrum is well predicted from the sum of counts in the corresponding region of interest in the Σn²-spectrum. A correction formula is suggested to extend the validity of this method to large parts of the spectrum.