[en] We present new measurements on a Cryogenic Dark Matter Search (CDMS) detector with electron, neutron, and gamma sources. The measurements have been performed to investigate the dead layer of one of the CDMS Z-dependent Ionization Phonon germanium detectors. The dead layer has been studied at both charge electrodes and at different electric field intensities. We also present a method to remove the dependence of athermal phonon measurements on event position

[en] A new method to study the origin of the dead-layer in ionization-phonon detectors was developed wherein the ionization is measured via a 25 micron gap between the collection electrodes and germanium absorber. Phonon signals are measured with small tungsten thermometers (Tc∼90 mK) varnished to the Ge substrates. The Ge samples were studied using collimated ²⁴¹Am sources. With this geometry, different contributions to the 'dead-layer' effect can be studied independently: Carrier back diffusion, trapping on surface states, Schottky barrier lowering, etc.

[en] The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si detectors to seek weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei. Simultaneous measurements of both ionization and phonon energy provide discrimination against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.99% efficiency. Electromagnetic events very near the detector surface can mimic nuclear recoils because of reduced charge collection, but these surface events are rejected with >96% efficiency by using additional information from the phonon pulse shape. Efficient use of active and passive shielding, combined with the 2090 m.w.e. overburden at the experimental site in the Soudan mine, makes the background from neutrons negligible for this first exposure. All cuts are determined in a blind manner from in situ calibrations with external radioactive sources without any prior knowledge of the event distribution in the signal region. Resulting efficiencies are known to ∼10%. A single event with a recoil of 64 keV passes all of the cuts and is consistent with the expected misidentification rate of surface electron recoils. Under the assumptions for a standard dark matter halo, these data exclude previously unexplored parameter space for both spin-independent and spin-dependent WIMP-nucleon elastic scattering. The resulting limit on the spin-independent WIMP-nucleon elastic-scattering cross section has a minimum of 4x10^-43 cm² at a WIMP mass of 60 GeVc^-2. The minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering cross section is 2x10^-37 cm² at a WIMP mass of 50 GeVc^-2

[en] The Cryogenic Dark Matter Search (CDMS) is an experiment to detect weakly interacting massive particles (WIMPs), which may constitute the universe's dark matter, based on their interactions with Ge and Si nuclei. We report the results of an analysis of data from the first two runs of CDMS at the Soudan Underground Laboratory in terms of spin-dependent WIMP-nucleon interactions on ⁷³Ge and ²⁹Si. These data exclude new regions of WIMP parameter space, including regions relevant to spin-dependent interpretations of the annual modulation signal reported by the DAMA/NaI experiment

[en] We report the first results from a search for weakly interacting massive particles (WIMPs) in the Cryogenic Dark Matter Search experiment at the Soudan Underground Laboratory. Four Ge and two Si detectors were operated for 52.6 live days, providing 19.4 kg d of Ge net exposure after cuts for recoil energies between 10 and 100 keV. A blind analysis was performed using only calibration data to define the energy threshold and selection criteria for nuclear-recoil candidates. Using the standard dark-matter halo and nuclear-physics WIMP model, these data set the world's lowest exclusion limits on the coherent WIMP-nucleon scalar cross section for all WIMP masses above 15 GeV/c², ruling out a significant range of neutralino supersymmetric models. The minimum of this limit curve at the 90% C.L. is 4x10^-43 cm² at a WIMP mass of 60 GeV/c²

[en] The Cryogenic Dark Matter Search experiment (CDMS) is using Phonon+Ionization detectors to search for Dark Matter in the form of Weakly Interactive Massive Particles (WIMPs). We report on new results from the operation of CDMS five 'towers' at Soudan underground laboratory. With new and more massive detectors, SuperCDMS project has been started since March 2009. We report on the current status of SuperCDMS and its perspective.

[en] We present results on quasidiffusion studies in large, 3 inch diameter, 1 inch thick [100] high purity germanium crystals, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare data obtained in two different detector types, with different phonon sensor area coverage, with results from a Monte Carlo. The Monte Carlo includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels.