Technical note: Quantifying uranium-series disequilibrium in natural samples for dosimetric dating – Part 1: gamma spectrometry

Dosimetric dating techniques rely on accurate and precise determination of environmental radioactivity. Gamma spectrometry is the method of choice for determining the activity of inline-formula²³⁸U, inline-formula²³²Th, and inline-formula⁴⁰K. With the aim to standardize gamma-spectrometric procedures for the purpose of determining accurate parent nuclide activities in natural samples, we outline the basics of gamma spectrometry and practical laboratory procedures here. This includes gamma radiation and instrumentation, sample preparation, finding the suitable measurement geometry and sample size for a given detector, and using the most suitable energy peaks in a gamma spectrum. The issue of correct efficiency calibration is highlighted. The procedures outlined are required for estimating contemporary parent nuclide activity. For estimating changing activities during burial specific data analyses are required, and these are also highlighted.