An automated drift correction method for in situ NaI(Tl)-detectors used in extreme environments

• Published in: Applied radiation and isotopes 2022-03, Vol.181, p.110069-110069, Article 110069
• Main Authors: le Roux, R.R., Bezuidenhout, J.
• Format: Article
• Language: English
• Subjects: Drift correction; Gaussian; in situ; NaI(Tl); Temperature
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2021.110069

Gamma-ray detection systems are exposed to extreme environments during in situ measurements and the NaI(TI)-detectors in these systems are frequently subjected to significant temperature fluctuations. Several elements within these detectors are sensitive to temperature deviations, which ultimately causes a drift in gamma-ray spectra. This study aimed to determine the relationship between temperature deviation and spectrum drift and found a linear relationship over a wide range of energies. It was found that an increase in the detector temperature shifts the gamma-ray spectrum to lower channels, whereas a decrease in the detector temperature shifts the spectrum to higher channels. Using this information, a novel drift correction method based on the Gaussian distribution of the 1460 keV gamma-peak of 40K was developed. Dividing the peak into five regions of interest (ROI), a weighted gain correction factor is calculated based on the comparative skewness of the measured data and the sensitivity of the drift. The detector gain is then adjusted by the same factor to correct the drift in gamma-spectrum. This method was first tested in a simulated in situ environment, followed by in situ measurements along a beach. As expected, the gain adjustments followed the trend in detector temperature. The corrected counts in each of the five bins also presented good results and a close fit to the Gaussian distribution. •Investigating the relationship between temperature deviation in NaI(Tl) detectors and spectrum shift caused.•Designing a drift correction method due to temperature deviation for NaI(Tl) detectors used in extreme environments.•A novel drift correction method for NaI(Tl) detectors based on the Gaussian distribution of the 1460 keV gamma-peak of 40K.•The sensitivity of the drift correction was derived from the counts under the 1460 keV gamma-peak of 40K.•A weighted gain correction factor was derived from the sensitivity to correct for spectrum drift.