Measurement of radioactive contamination in the CCD's of the DAMIC experiment

14th International Conference on Topics in Astroparticle and Underground Physics

物理学;天文学

Aguilar-Arevalo, A.^1 ; Amidei, D.^2 ; Bertou, X.^3 ; Bole, D.^2 ; Butner, M.^4,10 ; Cancelo, G.^4 ; Castañeda Vásquez, A.^1 ; Chavarria, A.E.^5 ; De Mello Neto, J.R.T.^6 ; Dixon, S.^5 ; D'Olivo, J.C.^1 ; Estrada, J.^2 ; Fernandez Moroni, G.^4 ; Hernández Torres, K.P.^1 ; Izraelevitch, F.^4 ; Kavner, A.^2 ; Kilminster, B.^7 ; Lawson, I.^8 ; Liao, J.^7 ; López, M.^9 ; Molina, J.^9 ; Moreno-Granados, G.^1 ; Pena, J.^5 ; Privitera, P.^5 ; Sarkis, Y.^1 ; Scarpine, V.^4 ; Schwarz, T.^2 ; Sofo Haro, M.^3 ; Tiffenberg, J.^4 ; Torres Machado, D.^6 ; Trillaud, F.^1 ; Yol, X.^6 ; Zhou, J.^5

Universidad Nacional Autónoma de México, México D.F., Mexico^1

University of Michigan, Department of Physics, Ann Arbor

MI, United States^2

Centro Atómico Bariloche, Institute Balseiro, CNEA/CONICET, Argentina^3

Fermi National Accelerator Laboratory, Batavia

IL, United States^4

Kavli Institute for Cosmological Physics, Eurico Fermi Institute, University of Chicago, Chicago

IL, United States^5

Universidade Federal Do Rio de Janeiro, Instituto de Fisica, RJ, Rio de Janeiro, Brazil^6

Universität Zürich Physik Institut, Zurich, Switzerland^7

SNOLAB, Lively

ON, Canada^8

Facultad de Ingeniería, Universidad Nacional de Asunción, Paraguay

(10) Northern Illinois University, DeKalb

IL, United States^9

关键词: Correlated electrons;    Cosmogenic isotopes;    Dark matter particles;    Fully depleted;    Novel techniques;    Radioactive contamination;    Radon daughters;    Upper limits;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/718/4/042057/pdf
DOI  :  10.1088/1742-6596/718/4/042057

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

DAMIC (Dark Matter in CCDs) is an experiment searching for dark matter particles employing fully-depleted charge-coupled devices. Using the bulk silicon which composes the detector as target, we expect to observe coherent WIMP-nucleus elastic scattering. Although located in the SNOLAB laboratory, 2 km below the surface, the CCDs are not completely free of radioactive contamination, in particular coming from radon daughters or from the detector itself. We present novel techniques for the measurement of the radioactive contamination in the bulk silicon and on the surface of DAMIC CCDs. Limits on the Uranium and Thorium contamination as well as on the cosmogenic isotope32Si, intrinsically present on the detector, were performed. We have obtained upper limits on the238TJ (232Th) decay rate of 5 (15) kg-1d-1at 95% CL. Pairs of spatially correlated electron tracks expected from32Si-32P and210Pb-210Bi beta decays were also measured. We have found a decay rate of 80+l10-65 kg-1d-1for32Si and an upper limit of-35 kg-1d-1for210Pb, both at 95% CL.