Surface Event Rejection Using Phonon Information in CDMS

Abstract

The published CDMS analyses have used the shape of the phonon signal rising edge to reject low-ionization-yield surface events which produce acoustic phonons more quickly than bulk events do. To achieve better WIMP sensitivity with future larger exposures, we are using a simplified model of phonon production and propagation to construct event position estimators that help us to find more efficient surface event rejection cuts. We describe this model and the resulting new cuts, and summarize the surface event leakage rates and the sensitivity figures of merit of the five surface event rejection methods developed in the second CDMS II Soudan run data analysis.