A gamma spectrometry protocol for gold determination in big samples by neutron activation analysis, using a linac as a source of irradiation

TL;DR

This paper develops a gamma spectrometry protocol using a linear accelerator for neutron activation analysis to accurately determine gold in large mineral samples, offering a reliable alternative to reactor-based methods.

Contribution

It introduces a novel gamma spectrometry protocol for gold determination in large samples using a linac as a neutron source, validated through MCNP modeling and efficiency evaluations.

Findings

Achieved accurate gold quantification in large mineral samples.

Validated the method with MCNP simulations and efficiency assessments.

Demonstrated comparable accuracy to reactor-based NAA methods.

Abstract

This work presents a study on the fundamental aspects of a reliable gold determination in voluminous mineral samples by Neutron Activation Analysis, using a Linear Particle Accelerator as a source of irradiation and a single detector as a detection system. The report includes i) an evaluation of the detection efficiency of the system, particularly the evaluation of the geometric efficiency in samples with significant volumes (with approximate volumes from 20 to 30 cm3); ii) a few methods for the calculation of the gamma ray self attenuation in the sample; iii) some gold in-homogeneity tests in the sample; iv) several validation calculations obtained with the MCNP code - the complete system was modeled with this program. This group of results has produced a gamma-spectrometry protocol for this determination, in order to obtain accurately the gold concentration in mineral samples this study was required by a legal bureau to determine the gold abundance in a Patagonian small deposit. According to the high quality of the results obtained from the process of characterization of this method, it is concluded that this gold analysis would be obtained with an accuracy similar than the one provided by the usual NAA using a reactor, in small samples exactitude values around few %.