# Measurement of reactor thermal neutron fluence of NTD-Ge by activation High-Purity Ge itself

## TL;DR

This study demonstrates a novel method to measure reactor thermal neutron fluence in neutron transmutation doped germanium using the germanium's own X-ray emissions, avoiding traditional flux monitors.

## Contribution

First experimental demonstration of using NTD-Ge's emitted X-rays to directly measure thermal neutron fluence in reactor irradiation.

## Key findings

- X-ray detection accurately measures neutron fluence
- MMD and SDD detectors yield consistent results
- Method enhances radiological safety and measurement precision

## Abstract

In neutron transmutation doped germanium, the thermal neutron fluence of reactor irradiation is as high as 10$^{18}$~n$\cdot$cm$^{-2}$. For radiological safety reasons, general Co or Au neutron flux monitors cannot be easily used. We have experimentally demonstrated the feasibility of measuring the X-rays emitted by the NTD-Ge itself to determine the absolute thermal neutron fluence for the first time. A Micro-Megas Detector (MMD) and a Silicon Drift Detector (SDD) are set up to detect the tagging KX-rays with 9.2 keV and 10.3 keV cascading from the decays of $^{71}$Ge. Combined the detection efficiencies calculated by GEANT4, neutron fluence results given with proper accuracy by MMD and SDD are in a good agreement with each other.