Application of a low-background gamma-ray spectrometer to the determination of 90Sr

A method for quantitative determination of 90Sr with a germanium γ-ray spectrometer is presented. The bremsstrahlung energy spectrum produced by high-energy beta particles from the 90Sr source encapsulated in a given absorbing material is measured. The idea was tested on various types of low-background germanium γ-ray spectrometers. The optimisation of absorber thickness for aluminium, iron, copper, cadmium, tantalum and lead is presented. The lowest achieved detection limit for a 10% efficiency HPGe detector was 0.38 Bq/sample which allows this method to be applied to some environmental studies.