Silicon detector results from the first five-tower run of CDMS II

Abstract

We report results of a search for weakly interacting massive particles (WIMPs) with the Si detectors of the CDMS II experiment. This report describes a blind analysis of the first data taken with CDMS II’s full complement of detectors in 2006–2007; results from this exposure using the Ge detectors have already been presented. We observed no candidate WIMP-scattering events in an exposure of 55.9 kg-days before analysis cuts, with an expected background of ∼1.1 events. The exposure of this analysis is equivalent to 10.3 kg-days over a recoil energy range of 7–100 keV for an ideal Si detector and a WIMP mass of 10 GeV/c[superscript 2]. These data set an upper limit of 1.7×10[superscript -41] cm[superscript 2] on the WIMP-nucleon spin-independent cross section of a 10 GeV/c[superscript 2] WIMP. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs.