Measurement of the bulk radioactive contamination of detector-grade silicon with DAMIC at SNOLAB. (21st June 2021)

• Record Type: Journal Article
• Authors: Aguilar-Arevalo, A.; Amidei, D.; Baxter, D.; Cancelo, G.; Cervantes Vergara, B.A.; Chavarria, A.E.; Darragh-Ford, E.; D'Olivo, J.C.; Estrada, J.; Favela-Perez, F.; Gaïor, R.; Guardincerri, Y.; Hossbach, T.W.; Kilminster, B.; Lawson, I.; Lee, S.J.; Letessier-Selvon, A.; Matalon, A.; Mitra, P.; Piers, A.; Privitera, P.; Ramanathan, K.; Da Rocha, J.; Sarkis, Y.; Settimo, M.; Smida, R.; Thomas, R.; Tiffenberg, J.; Traina, M.; Vilar, R.; Virto, A.L.;
• Other Names: collab.
• Is Part Of: Journal of instrumentation. Volume 16:Number 6(2021)
• Publication Date: 2021-06-21
• Subjects: Dark Matter detectors (WIMPs, axions, etc.) -- Particle identification methods -- Search for radioactive and fissile materials -- Solid state detectors; Scientific apparatus and instruments -- Periodicals; 502.84
• DOI: 10.1088/1748-0221/16/06/P06019
• Languages: English
• ISSNs: 1748-0221

Abstract

Abstract: We present measurements of bulk radiocontaminants in the high-resistivity silicon CCDs from the DAMIC experiment at SNOLAB. We utilize the exquisite spatial resolution of CCDs to discriminate between α and β decays, and to search with high efficiency for the spatially-correlated decays of various radioisotope sequences. Using spatially-correlated β decays, we measure a bulk radioactive contamination of 32 Si in the CCDs of 140 ± 30 μBq/kg, and place an upper limit on bulk 210 Pb of < 160 μBq/kg. Using similar analyses of spatially-correlated α and β decays, we set upper limits of < 11 μBq/kg (0.9 ppt) on 238 U and < 7.3 μBq/kg (1.8 ppt) on 232 Th in the bulk silicon. The ability of DAMIC CCDs to identify and reject spatially-coincident backgrounds, particularly from 32 Si, has significant implications for the next generation of silicon-based dark matter experiments, where β's from 32 Si decay will likely be a dominant background.