Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8132766 | Astroparticle Physics | 2018 | 14 Pages |
Abstract
The Boulby Underground Germanium Suite (BUGS) comprises three low-background, high-purity germanium detectors operating in the Boulby Underground Laboratory, located 1.1â¯km underground in the north-east of England, UK. BUGS utilises three types of detector to facilitate a high-sensitivity, high-throughput radio-assay programme to support the development of rare-event search experiments. A Broad Energy Germanium (BEGe) detector delivers sensitivity to low-energy gamma-rays such as those emitted by 210Pb and 234Th. A Small Anode Germanium (SAGe) well-type detector is employed for efficient screening of small samples. Finally, a standard p-type coaxial detector provides fast screening of standard samples. This paper presents the steps used to characterise the performance of these detectors for a variety of sample geometries, including the corrections applied to account for cascade summing effects. For low-density materials, BUGS is able to radio-assay to specific activities down to 3.6mBqkgâ1 for 234Th and 6.6mBqkgâ1 for 210Pb both of which have uncovered some significant equilibrium breaks in the 238U chain. In denser materials, where gamma-ray self-absorption increases, sensitivity is demonstrated to specific activities of 0.9mBqkgâ1 for 226Ra, 1.1mBqkgâ1 for 228Ra, 0.3mBqkgâ1 for 224Ra, and 8.6mBqkgâ1 for 40K with all upper limits at a 90% confidence level. These meet the requirements of most screening campaigns presently under way for rare-event search experiments, such as the LUX-ZEPLIN (LZ) dark matter experiment. We also highlight the ability of the BEGe detector to probe the X-ray fluorescence region which can be important to identify the presence of radioisotopes associated with neutron production; this is of particular relevance in experiments sensitive to nuclear recoils.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Astronomy and Astrophysics
Authors
P.R. Scovell, E. Meehan, H.M. Araújo, J. Dobson, C. Ghag, H. Kraus, V.A. Kudryavtsev, X-.R. Liu, P. Majewski, S.M. Paling, R.M. Preece, R. Saakyan, A. Tomás, C. Toth, L.M. Yeoman,