Scovell, P.R., Meehan, E., Araújo, H.M. et al. (12 more authors) (2018) Low Background Gamma Spectroscopy at the Boulby Underground Laboratory. Astroparticle Physics, 97. pp. 160-173. ISSN 0927-6505
Abstract
The Boulby Underground Germanium Suite (BUGS) comprises three low background, high-purity germanium detectors operating in the Boulby Underground Laboratory, located 1.1 km underground in the north-east of England, UK. BUGS utilises three types of detector to facilitate a high-sensitivity, high-throughput radioassay 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 3.6 mBq/kg for 234Th and 6.6 mBq/kg 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 0.9 mBq/kg for 226Ra, 1.1 mBq/kg for 228 Ra, 0.3 mBq/kg for 224Ra, and 8.6 mBq/kg 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.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Elsevier. This is an author produced version of a paper subsequently published in Astroparticle Physics. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
Keywords: | Instrumentation and Detectors; Nuclear Experiment |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/K006444/1 SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/M003469/1 Science and Technology Facilities Council ST/N000277/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 04 Sep 2017 08:48 |
Last Modified: | 15 Nov 2018 01:39 |
Published Version: | https://doi.org/10.1016/j.astropartphys.2017.11.00... |
Status: | Published |
Publisher: | Elsevier |
Refereed: | Yes |
Identification Number: | 10.1016/j.astropartphys.2017.11.006 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:120711 |