OxGamma: A MATLAB based application for the analysis of gamma-ray spectra

Abstract

Gamma-ray spectrometry is a well-established technique which enables to perform qualitative and quantitative analyses of gamma-ray emitting radionuclides. In trapped charge dating, portable spectrometers can be used to acquire spectra in the field, allowing for the assessment of radionuclide concentrations and hence the determination of dose rates at the exact location where samples are collected for dating. Accurate assessment of concentrations and dose rates demands proper energy, width, and efficiency calibration of the instrument by comparison against one or several radioactive standards. The ‘Oxford blocks’ which consist of four concrete cubes doped with known concentrations of potassium [K-block], thorium [Th-block], and uranium [U-block], as well as a background [BG-block], were constructed for this purpose and have become widely adopted by researchers for calibrating their instruments. For inexperienced users, the calibration of detectors and the analysis of field spectra for determining the concentration of radionuclides can be a challenging and laborious task that often involves multiple steps (e.g., downloading and converting data files, peak identification and selection, energy calibration, true full-peak area calculation, efficiency calculation, etc.). The processing of calibration spectra from the Oxford blocks is further complicated by the fact that the K-block contains only ∼72% concrete and the Th-block contains a small amount of uranium. These factors must be accounted for in order to obtain accurate radionuclide concentrations and dose rates.Here, we present a practical and user-friendly MATLAB based application (OxGamma), available as a free download for both Windows OS and macOS, intended to facilitate the calibration process of portable gamma-ray detectors and to provide a quick and efficient means for determining the concentration of radionuclides (K, U and Th) and dose rates. The software has been tested and checked against results obtained independently and provides output using both the windows and threshold approaches. Crucially, it does not require users to possess in-depth experience in programming or gamma-spectrometry.