Ultra-Low Background Germanium Assay at the Boulby Underground Laboratory

TL;DR

This paper details the deployment of ultra-low background germanium detectors at Boulby Laboratory, achieving high sensitivity for material assay crucial for next-generation low-background physics experiments.

Contribution

It introduces specialized ultra-low background detectors with optimized shielding and radon reduction, enabling rapid, high-sensitivity material assay without complex shielding.

Findings

Sensitivity approaching 10 μBq/kg for key isotopes

Detectors installed and commissioned between 2017-2021

Potential for 100-day measurements to detect extremely low isotope levels

Abstract

As we move to an era where next generation low-background particle physics experiments begin to be designed and constructed, the ability to assay materials with high sensitivity and at speed with a variety of techniques will be key. This paper describes the Mirion Technologies (Canberra) specialty ultra-low background detectors installed and commissioned at the Boulby Underground Laboratory between 2017 and 2021. The low background levels of the detectors combine with low background shielding and a radon-reduced dry nitrogen purge system to give sensitivity approaching the best in the world without the need for intricate shielding solutions. For an optimised sample geometry, run for 100 days, it would be possible to reach close to 10 $\mu$Bq/kg ($10^{-12}$ g/g) for background isotopes of interest in neutrinoless double-beta decay.