An empirical correction for dead-time and pulse pile-up losses in gamma-ray spectrometry

The method of fixed dead-time per event was used to correct for pulse losses due to random summing in the amplifier and dead-time of the multichannel analyser (MCA) when a sample containing a mixture of short- and long-lived radioisotopes is assayed. The monostable was used as an on-and-off switch of the input linear gate of the ADC thereby keeping it closed for 50 μs each time a pulse was detected. This time was found adequate for the conversion of all pulse heights encountered in this work.

The correction curve, which will be discussed below, was then used in the analysis of some NBS reference standards irradiated in the experimental reactor having a thermal flux of 2.2×10¹² n/cm²s. This method was found credible for analysis of samples with activities as high as 5×10⁴ cps.