Measurement of Naturally-Occurring Radioactive Materials (NORM) using a scintillator-based alpha detector

Morishita, Yuki   ; Tomioka, Akifumi; Fujisawa, Makoto; Izaki, Kenji 

It is important to differentiate between natural and artificial radioactive materials such as plutonium in nuclear facilities. In this study, a scintillator-based alpha-particle detector was developed using YAP:Ce scintillator and Multi-Anode PhotoMultiplier Tube. The detector was used to measure various naturally occurring radioactive materials (NORM) samples including radon progeny, lead plate, lantern mantle, and radium ceramic ball. The measurement results were compared with Monte Carlo simulation calculations and were found to be in agreement. The energy resolution of the detector is 8.6%FWHM. In the measurement results of radon progeny, peaks of Bi (6.1 MeV), Po (7.7 MeV), and Po (8.8 MeV) can be observed. The lead plate contains Po and emits 5.3 MeV alpha particle. The simulation with the same energy was able to reproduce the actual measurement. The results showed the energy and distribution of the alpha particles emitted by the NORM samples. The study successfully demonstrated the capability of the developed alpha-particle detector in identifying NORM.