GEANT4 simulation of the response of a liquid scintillation counter

Abstract

Liquid Scintillation Counting (LSC) is widely used as a very efficient technique for radioactivity quantification. LSC is a powerful tool applied as much in low level environmental radioactivity monitoring, as in radionuclide metrology for the activity standardization of electron capture, pure-beta, and alpha nuclides. In order to quantify the sample activity, the number of scintillation photons are counted by one or several PMTs. However, the scintillation count rate varies with the detection efficiency. As an alternative to traditional methods for the calculation of detection efficiency, a Monte Carlo approach based on GEANT4 toolkit is presented for the simulation of light emission inside a Quantulus 1220 liquid scintillation counter with two PMT photomultipliers tubes working in sum-coincidence mode. To this end, the GEANT4 simulation handles a variety of processes at optical wavelengths including refraction and reflection at medium boundaries, Rayleigh scattering and bulk absorption, and additional processes which produce optical photons such as Cherenkov effect, transition radiation and scintillation, and includes a description of optical properties associated with each material constituting the detection system. The objective is to simulate the propagation of optical photons from their creation in the liquid scintillation cocktail to the production of photoelectrons in the PMTs. In this paper, we report in detail the results of the proposed simulation (detection efficiency, and additionally wall effect and absorption probabilities of gamma-rays) for different radionuclides such as 14C, 3H, 54Mn and 90Y, and its validation through the comparison with the experimental measurements.

Study on rapid measurement of α and β activity in radioactive wastewater by liquid scintillation spectrometer

“…According to the literature research, the main factors affecting the liquid scintillation measurement include the formula of scintillation solution, the material of sample bottle, the quenching effect of PH value, the volume ratio of sample/ liquid scintillation, the standing time of sample and so on (Hurtado, 2017, S. et al, 2020, Gaca et al, 2017. Starting from the actual demand and according to the market research results, the commonly used commercial liquid scintillation cocktail and sample bottle materials are selected for experiments, and the influence effects of various factors are studied according to the basic idea of controlling variables.…”