Optimization of an underwater in-situ LaBr3:Ce spectrometer with energy self-calibration and efficiency calibration

摘要

An underwater in situ gamma ray spectrometer based on LaBr3 was developed andoptimized to monitor marine radioactivity. The intrinsic background mainly fromLa138 and Ac227 of LaBr3 was well determined by low background measurement andpulse shape discrimination method. A method of self-calibration using threeinternal contaminant peaks was proposed to eliminate the peak shift during longterm monitoring. With experiments under different temperatures, the method wasproved to be helpful for maintaining long term stability. To monitor the marineradioactivity, the spectrometer efficiency was calculated via water tankexperiment as well as Monte Carlo simulation.