Development of the measurement for radium using germanium detector with molecular recognition resin

TL;DR

This paper presents a new chemical extraction method using molecular recognition resin to measure radium with high-purity germanium detectors, improving detection efficiency for low-concentration samples in large-volume measurements.

Contribution

A novel chemical extraction technique with molecular recognition resin enhances radium detection efficiency in HPGe measurements by concentrating samples and reducing self-screening effects.

Findings

Radium can be extracted with 81% recovery rate.

The method allows closer sample placement to the detector.

Detection efficiency is improved by reducing self-screening.

Abstract

High-purity germanium (HPGe) detectors are widely used for the measurement of the low concentrated radioactivities. For the Super-Kamiokande-Gadolinium project, the concentration of radium in Gd$_2$(SO$_4$)$_3{\cdot}$8H$_2$O is determined by using HPGe detectors. The amount of the sample is generally limited by the size of the sample space of a HPGe detector. This leads the limitation of the detector efficiency. A new method of chemical extraction using the molecular recognition resin was developed to minimize this problem. Using the developed method, radium could be extracted from Gd$_2$(SO$_4$)$_3{\cdot}$8H$_2$O and concentrated to smaller amount of the resin at a recovery rate of 81$\pm$4\%, which was estimated by using barium as a recovery monitor. This made it possible to set the sample closer to an HPGe crystal and reduce self screening effect, resulting in increasing the detection efficiency of an HPGe detector. The developed method is reported on this letter.