CeBr ₃ gamma-ray logging probe qualification for uranium mining applications

The development and optimization of gamma-ray spectrometry tools are crucial for ORANO Mining and geophysical exploration. This study presents a comprehensive study on the ALT QL40-SGR-2G spectrometric probe, equipped with a cerium bromide (CeBr3) detector, aimed at its detailed characterization and the validation of its numerical model through various experimental setups and MCNP (Monte Carlo N-Particle) simulations. The study described energy calibration, resolution and detection efficiency measurements at a 15 cm distance, crystal length characterization, probe rotation effects on performance, counting loss estimation, and response profile determination in a sand silo setup. These experiments aimed to validate the MCNP model of the probe and understand factors affecting its performance. Utilizing standard gamma sources, energy resolution and detection efficiency of the probe were evaluated, revealing a close match between experimental data and MCNP calculations, with a 2.4% average discrepancy across the energy spectrum. This validation highlights the reliability of the numerical model and the robustness of the probe in diverse measurement scenarios. Further investigations on the effective length of crystal confirmed the manufacturer’s specifications, while tests on the probe’s rotational impact showed minimal effect on spectral response (< 4%). The use of the 2 sources method allowed for accurate dead time estimation, which is crucial for correcting counting losses in high-radiation environments. In addition, this study involved the spatial response of the probe using a 137 Cs source within a sand silo. This experiment demonstrated the potential of this probe in simulating complex geological formations and validated the MCNP model accuracy in predicting spatial response, which is crucial for borehole modelling. The successful correlation between experimental findings and MCNP simulations enhances confidence in using the QL40-SGR-2G probe for accurate gamma-ray detection and analysis in varied settings.