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arXiv · 1405.4215

Phonon-Based Position Determination in SuperCDMS iZIP Detectors

A. J. Anderson
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Abstract

SuperCDMS is currently operating a 10-kg array of cryogenic germanium detectors in the Soudan underground laboratory to search for weakly interacting massive particles, a leading dark matter candidate. These detectors, known as iZIPs, measure ionization and athermal phonons from particle interactions with sensors on both sides of a Ge crystal. The ionization signal can be used to efficiently tag events at high radius and near the top and bottoms surfaces, where diminished charge collection can cause events to mimic WIMP-induced nuclear recoils. Using calibration data taken with a 210Pb source underground at Soudan, we demonstrate rejection of surface events of (4.5 +/- 0.9) x 10^-4 with 46% acceptance of nuclear recoils using the phonon signal only. We also show with 133Ba calibration data underground that the phonon channels can efficiently identify events near the sidewall. This phonon-based approach can also be extended to lower energies than the ionization-based position reconstruction.

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A. J. Anderson. 2014-05-16. Phonon-Based Position Determination in SuperCDMS iZIP Detectors. https://doi.org/10.1007/s10909-013-1015-2

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