May 19 – 23, 2019
Europe/Madrid timezone

Measurements of radioactive backgrounds in high-resistivity silicon CCDs of the DAMIC-100 experiment

Not scheduled
20m

Speaker

Mr Ariel Matalon (Kavli Institute for Cosmological Physics at the University of Chicago; Laboratoire de Physique Nucléaire et de Hautes Energies, Paris)

Description

The DAMIC (Dark Matter in CCDs) experiment employs the bulk silicon of scientific-grade charge coupled devices (CCDs) to detect Dark Matter particles. DAMIC-100, a 41 g detector, is operating in the SNOLAB laboratory, located 2 km below the surface within the Vale Creighton Mine near Sudbury, Ontario, Canada. We present a powerful technique to distinguish and reject background events. Utilizing the exquisite spatial resolution of CCDs, discriminating between $\alpha$ and $\beta$ particles, we identify spatially-correlated decay sequences over long periods. We report measurements of the radioactive contamination of $^{210}$Pb and $^{32}$Si in DAMIC-100 CCDs, and place limits on $^{238}$U and $^{232}$Th contamination. DAMIC's capability to measure contamination has significant implications for the next generation of silicon-based dark matter experiments. For example, $^{32}$Si could become a dominant and irreducible background for future programs. We show that $^{32}$Si levels may vary significantly in high-purity silicon, and indicate feasible methods to screen materials for fabrication of future detectors in order to push experimental sensitivity to unprecedented levels.

Primary author

Mr Ariel Matalon (Kavli Institute for Cosmological Physics at the University of Chicago; Laboratoire de Physique Nucléaire et de Hautes Energies, Paris)

Co-author

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