Quantitative Measurement of ¹²⁵l with Nal (Tl) Scintillation Survey Meter

Abstract

This paper describes a NaI (Tl) scintillation survey meter which can quantify ¹²⁵I on a contaminated surface in situ. This survey meter has four inherent windows; (1) 20-45 keV the singles photopeak region, (2) 45-80 keV the sum photopeak region, (3) 20-80 keV the total photopeak region, and (4) 80 keV-. The activity was calculated based on the sum peak method. The calculated activity of a point source agreed with the standardized source activity within an uncertainty of about 10% both up to the distance of 3 cm from the detector surface along the axis of the detector and on the detector surface. The activity of a simulated plate source also agreed with the source activity within the same uncertainty.