Abstract

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 isotope 32 Si, intrinsically present on the detector, were performed. We have obtained upper limits on the 238 TJ (232 Th) decay rate of 5 (15) kg_1 d_1 at 95% CL. Pairs of spatially correlated electron tracks expected from 32 Si-32 P and 210 Pb-210 Bi beta decays were also measured. We have found a decay rate of 80+l10 -65 kg_1 d_1 for 32 Si and an upper limit of - 35 kg-1 d-1 for 210 Pb, both at 95% CL.

Details

Title
Measurement of radioactive contamination in the CCD’s of the DAMIC experiment
Author
Aguilar-Arevalo, A 1 ; Amidei, D 2 ; Bertou, X 3 ; Bole, D 2 ; Butner, M 4 ; Cancelo, G 5 ; A Castañeda Vásquez 1 ; Chavarria, A E 6 ; J R T de Mello Neto 7 ; Dixon, S 6 ; J C D’Olivo 1 ; Estrada, J 2 ; G Fernandez Moroni 5 ; Hernández Torres, K P 1 ; Izraelevitch, F 5 ; Kavner, A 2 ; Kilminster, B 8 ; Lawson, I 9 ; Liao, J 8 ; López, M 10 ; Molina, J 10 ; Moreno-Granados, G 1 ; Pena, J 6 ; Privitera, P 6 ; Sarkis, Y 1 ; Scarpine, V 5 ; Schwarz, T 2 ; M Sofo Haro 3 ; Tiffenberg, J 5 ; D Torres Machado 7 ; Trillaud, F 1 ; Yol, X 7 ; Zhou, J 6 

1  Universidad Nacional Autónoma de México, México D.F., México 
2  University of Michigan, Department of Physics, Ann Arbor, MI, U.S.A. 
3  Centro Atómico Bariloche - Institute Balseiro, CNEA/CONICET, Argentina 
4  Fermi National Accelerator Laboratory, Batavia, IL, U.S.A.; Northern Illinois University, DeKalb, IL, U.S.A. 
5  Fermi National Accelerator Laboratory, Batavia, IL, U.S.A. 
6  Kavli Institute for Cosmological Physics and The Eurico Fermi Institute, The University of Chicago, Chicago, IL, U.S.A. 
7  Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ, Brazil 
8  Universität Zürich Physik Institut, Zurich, Switzerland 
9  SNOLAB, Lively, ON, Canada 
10  Facultad de Ingeniería - Universidad Nacional de Asunción, Paraguay 
Publication year
2016
Publication date
May 2016
Publisher
IOP Publishing
ISSN
17426588
e-ISSN
17426596
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1088/1742-6596/718/4/042057
ProQuest document ID
2575125538
Copyright
© 2016. This work is published under http://creativecommons.org/licenses/by/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.