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

TL;DR

This paper presents an optimized underwater LaBr3:Ce gamma spectrometer with self-calibration and efficiency calibration methods, enhancing long-term marine radioactivity monitoring accuracy.

Contribution

It introduces a novel self-calibration technique using internal peaks and combines experimental and simulation approaches for efficiency calibration.

Findings

Effective background discrimination achieved

Self-calibration maintains peak stability over time

Efficiency calibration validated by experiments and simulations

Abstract

An underwater in situ gamma ray spectrometer based on LaBr3 was developed and optimized to monitor marine radioactivity. The intrinsic background mainly from La138 and Ac227 of LaBr3 was well determined by low background measurement and pulse shape discrimination method. A method of self-calibration using three internal contaminant peaks was proposed to eliminate the peak shift during long term monitoring. With experiments under different temperatures, the method was proved to be helpful for maintaining long term stability. To monitor the marine radioactivity, the spectrometer efficiency was calculated via water tank experiment as well as Monte Carlo simulation.