  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/c2. These data set an upper limit of 1.7x10-41 cm2 on the WIMP-nucleon
spin-independent cross section of a 10 GeV/c2 WIMP. These data exclude
parameter space for spin-independent WIMP-nucleon elastic scattering that is
relevant to recent searches for low-mass WIMPs.
