Universal calibration of a scintillation spectrometer with a NaI(Tl) detector when measuring 137Cs activity in counting samples of arbitrary density and volume

Abstract

The article proposes an empirical method for constructing a universal calibration for a scintillation gamma spectrometer, which allows determining the activity and specific activity of ¹³⁷Cs with an accuracy of no more than 15% in counting samples of arbitrary density and volume in cylindrical containers with a volume of 250 ml and 500 ml. To construct calibration ratios, measurements of ¹³⁷Cs sample media prepared on the basis of materials of different densities (quartz sand, plastic granules and sawdust) were performed. The calibration was carried out by preparing samples from the listed materials with a volume of 50 to 250 ml in increments of 50 ml for a 250 ml container and 100-500 ml in increments of 100 ml for a 500 ml container. Along with taking into account the volume of the counting sample, its weighing was also carried out. The result of the measurements performed for each material was the ratio of the activity of the counting sample to the counting intensity in the ¹³⁷Cs window, depending on the volume. The universal calibration factor is obtained by taking into account the counting rate from the mass and volume of the sample for the corresponding measuring vessel.