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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 ? and ? decays, and to search with high efficiency for the spatially-correlated decays of various radioisotope sequences. Using spatially-correlated ? decays, we measure a bulk radioactive contamination of 32Si in the CCDs of 140 ± 30 ?Bq/kg, and place an upper limit on bulk 210Pb of < 160 ?Bq/kg. Using similar analyses of spatially-correlated ? and ? decays, we set upper limits of < 11 ?Bq/kg (0.9 ppt) on 238U and < 7.3 ?Bq/kg (1.8 ppt) on 232Th in the bulk silicon. The ability of DAMIC CCDs to identify and reject spatially-coincident backgrounds, particularly from 32Si, has significant implications for the next generation of silicon-based dark matter experiments, where ?'s from 32Si decay will likely be a dominant background.
Fuente: Journal of instrumentation. Vol. 16 (2021). P06019
Publisher: Institute of Physics
Year of publication: 2021
No. of pages: 14
Publication type: Article
ISSN: 1748-0221
THE DAMIC COLLABORATION
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-PÉREZ, F.
GAÏOR, R.
GUARDINCERRI, Y.
HOSSBACH, T. W.
KILMINSTER, B.
LAWSON, I.
LEE, S. J.
LETESSIER-SELVON, A.
ROCIO VILAR CORTABITARTE
MARIA AMPARO LOPEZ VIRTO
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