Sensitivity analysis towards trace-uranium detection with $\gamma$-$\gamma$ coincidence NAA

TL;DR

This paper introduces an improved neutron activation analysis method using gamma-gamma coincidence counting to detect trace uranium, demonstrating an eightfold sensitivity enhancement over traditional single gamma detection.

Contribution

The paper develops and validates a GEANT4-based model for gamma-gamma coincidence detection, showing significant sensitivity improvements in trace uranium detection.

Findings

Gamma-gamma coincidence counting enhances detection sensitivity by about 8 times.

The empirical method effectively evaluates sensitivity gains amidst background noise.

The extended GEANT4 model accurately predicts detection limits for the two-detector setup.

Abstract

We present an improved approach for detection of trace amounts of $^{238}$U by means of neutron activation analysis (NAA). The analysis enhancement is obtained by utilizing $\gamma$-$\gamma$ coincidence counting. An empirical method for evaluating the sensitivity gain in the presence of a large source-related background is presented. A comparison of detection limits is made between two counting schemes; namely, counting single gammas using one HPGe detector versus counting coincident gammas using two HPGe detectors placed face-to-face. A data-validated radiation transport model, created in GEANT4 for a single HPGe detector, is extended to handle the two-detector setup. In this counting scheme, a $^{238}$U-detection sensitivity enhancement of about a factor of 8 is predicted for a sample of Saint-Gobain G3 Sapphire when compared to the simpler singles counting approach.