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Dark Matter Search with SuperCDMSResults, Status and Future

Wolfgang RauQueens UniversityW. Rau - CAP 20142IntroductionSuperCDMS technologyImplementation for SuperCDMS SoudanResults from SuperCDMS SoudanStatus and plansfor SuperCDMS SNOLABSuperCDMS CollaborationCalifornia Institute of Technology CNRS/LPN Fermi National Accelerator LaboratoryMassachusetts Institute of Technology PNNL Queens UniversitySanta Clara University SLAC/KIPAC Southern Methodist UniversityStanford University Syracuse University Texas A&M Universidad Atnoma de MadridUniversity of British Columbia University of California, BerkeleyUniversity of Colorado Denver University of Evansville University of FloridaUniversity of Minnesota University of South Dakota

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Phonon energy [keV]Ionization energy [keV eeq]Nuclear recoilsfrom neutronsElectron recoilsfrom s and sThermal couplingThermalbathPhonon sensor Target++++----++++-------+++enPhonon signal (single crystal): measures energy depositionIonization signal (semiconductor): quenched for nuclear recoils (lower signal efficiency)Combination:efficient rejection of electron recoil backgroundPhonon signalCharge signalElectron recoil (ER)Nuclear recoil (NR)SuperCDMS Technology4W. Rau - CAP 2014+- -In Vacuum-+- In MatterElectron gains kinetic energy(E = q V 1 eV for 1 V potential)Deposited energy in crystal lattice:Neganov-Luke phonons

V, # chargesLuke phonons mix charge and phonon signal reduced discriminationApply high voltage large final phonon signal, measures charge!!ER much more amplified than NR gain in threshold; dilute background from ERNeganov-Luke Phonons5W. Rau - CAP 2014Background dilution with Luke EffectElectron Recoil SpectrumEnergyNumber of CountsNuclear Recoil Spectrum6W. Rau - CAP 2014

Basic configuration+2 V0 V-2 V0 V

Electric field calculationImplementation SuperCDMS SoudanGermanium single crystals (620 g modules)Thermal readout: superconducting phase transition sensor (TES); Tc = 50 100 mKCharge readout: Al electrode; interleaved with phonon sensorsLow bias voltage (4 V) in regular operationOne detector: ~70 V for some timeCDMSlite configuration0 V-69 V7W. Rau - CAP 2014Implementation (Soudan)Stack detectors (3) to mount (tower)5 towers deployed in cryostat (~9 kg Ge)Shielded with PE (for neutrons), Pb (gammas) and muon veto (cosmic radiation)Located at Soudan Underground Lab (Minnesota) to shield from cosmic radiation

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Surface eventsDetector Performance9W. Rau - CAP 2014

Past Analysis Approaches

Classic CDMS approach: minimize expected BG (