Simplified Efficiency Calibration Methods for Semiconductor Detectors used in Criticality Dosimetry

TL;DR

This paper proposes and verifies simplified methods for calibrating semiconductor HPGe detectors' efficiency using true coincidence summing effects, enabling accurate neutron dose estimation in criticality scenarios.

Contribution

It introduces new simplified calibration techniques for HPGe detectors based on true coincidence summing, suitable for criticality dosimetry applications.

Findings

Calibration accuracy is within 5-8% for the proposed methods.

Methods enable effective detector commissioning with a $^{60}$Co source.

Efficiency calibration for $^{60}$Co can be applied to $^{24}$Na gamma-ray lines.

Abstract

``Oversimplified'' and ``simplified'' methods based on true coincidence summing effect used in uncomplicated determination of the photo-peak efficiency of the semiconductor High Purity Germanium (HPGe) detector system are suggested and verified. The methods and calibrated $^{60}$Co radioactive source may be used to commission any HPGe detector to use during potential criticality event. The determined accuracy of the semiconductor HPGe detector system using this method is a few percent (for the detector system used in this study it was $\simeq$8\% for oversimplified and $\simeq$5\% for simplified methods accordingly) reasonable, expected, and good enough to use for estimation of neutron dose from irradiated human blood in a potential criticality event. Moreover, if one can experimentally deduce the photo-peak efficiency for $^{60}$Co 1333 keV $\gamma$-ray line using the suggested methods, then with a few percent accuracy this efficiency could be also used for 1369 keV $\gamma$-ray line in the decay of $^{24}$Na isotope.