Low-threshold WIMP search at SuperCDMS

The Super Cryogenic Dark Matter Search (SuperCDMS) experiment aims to detecting nuclear recoils from weakly-interacting massive particles (WIMPs) by measuring phonon and ionization energy in crystalline Ge. It has been operating at the Soudan Underground Laboratory in Minnesota (USA) since March 2012 with improved background rejection capabilities with respect to CDMS II. A low-threshold analysis of the SuperCDMS data has been performed, allowing to explore WIMP masses below 30 GeV/c2. This is the first analysis using the full background rejection capabilities of SuperCDMS. In particular both phonon and ionization signals are used for defining a fiducial volume excluding events near any of the surfaces of the detectors. In addition, the background discrimination includes multivariate techniques optimized for several WIMP masses. The results are competitive with other low-threshold WIMP searches, and probe new parameter space for WIMP-nucleon scattering for WIMP masses between 4 and 6 GeV/c2.