Notable Recent Publications

For the full CDMS publication list, please see CDMS publications

  • Collaboration, C. et al., "Dark Matter Search Results Using the Silicon Detectors of CDMS II", arXiv:1304.4279, submitted to Phys. Rev. Lett. (2013).
We report results of a search for Weakly Interacting Massive Particles (WIMPs) with the silicon (Si) detectors of the CDMS II experiment. A blind analysis of data from eight Si detectors, with a total raw exposure of 140.2 kg-days, revealed three WIMP-candidate events with a final surface-event background estimate of 0.41 (-0.08 +0.20)(stat.) (-0.24 +0.28) (syst.). Other known backgrounds from neutrons and 206Pb are limited to < 0.13 and < 0.08 events at the 90% confidence level, respectively. These data place a 90% upper confidence limit on the WIMP-nucleon cross section of 2.4E-41 cm2 at a WIMP mass of 10 GeV/c2. Simulations indicate a 5.4% probability that a statistical fluctuation of the known backgrounds would produce three or more events in the signal region. A profile likelihood ratio test that includes the measured recoil energies of the three events gives a 0.19% probability for the known-background-only hypothesis when tested against the alternative WIMP+background hypothesis. The highest likelihood was found for a WIMP mass of 8.6 GeV/c2 and WIMP-nucleon cross section of 1.9E-41 cm2.
  • Collaboration, C. et al., "Silicon Detector Results fron the First Five-Tower Run of CDMS II", arXiv:1304.3706, submitted to Phys. Rev. Lett. (2013).
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. 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; this limit improves to 8.3x10-42 cm2 in combination with previous Si data from this installation. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs.
  • Collaboration, C. et al., "Search for annual modulation in low-energy CDMS-II data", arXiv:1203.1309 (2012).
We report limits on annual modulation of the low-energy event rate from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Such a modulation could be produced by interactions from Weakly Interacting Massive Particles (WIMPs) with masses ~10 GeV/c2. We find no evidence for annual modulation in the event rate of veto-anticoincident single-detector interactions consistent with nuclear recoils, and constrain the magnitude of any modulation to <0.06 event [keVnr kg day]-1 in the 5-11.9 keVnr energy range at the 99% confidence level. These results disfavor an explanation for the reported modulation in the 1.2-3.2 keVee energy range in CoGeNT in terms of nuclear recoils resulting from elastic scattering of WIMPs at >98% confidence. For events consistent with electron recoils, no significant modulation is observed for either single- or multiple-detector interactions in the 3.0-7.4 keVee range.
  • Ahmed, Z. et al., "Combined limis on WIMPs from the CDMS and EDELWEISS experiments", Phys. Rev. D 84 011102 PDF (2011).
The CDMS and EDELWEISS collaborations have combined the results of their direct searches for dark matter using cryogenic germanium detectors. The total data set represents 614 kg·days equivalent exposure. A straightforward method of combination was chosen for its simplicity before data were exchanged between experiments. The results are interpreted in terms of limits on spin-independent weakly interacting, massive particle (WIMP)-nucleon cross section. For a WIMP mass of 90 GeV/c2, where this analysis is most sensitive, a cross section of 3.3x10-44 cm2 is excluded at 90%C.L. At higher WIMP masses, the combination improves the individual limits, by a factor 1.6 above 700 GeV/c2. Alternative methods of combining the data provide stronger constraints for some ranges of WIMP masses and weaker constraints for others.
  • Ahmed, Z. et al., "Search for inelastic dark matter with the CDMS II experiment", Phys. Rev. D 83 112002 PDF (2011).
The CDMS and EDELWEISS collaborations have combined the results of their direct searches for dark matter using cryogenic germanium detectors. The total data set represents 614 kg·days equivalent exposure. A straightforward method of combination was chosen for its simplicity before data were exchanged between experiments. The results are interpreted in terms of limits on spin-independent weakly interacting, massive particle (WIMP)-nucleon cross section. For a WIMP mass of 90 GeV/c2, where this analysis is most sensitive, a cross section of 3.3x10-44 cm2 is excluded at 90%C.L. At higher WIMP masses, the combination improves the individual limits, by a factor 1.6 above 700 GeV/c2. Alternative methods of combining the data provide stronger constraints for some ranges of WIMP masses and weaker constraints for others.
  • Bauer, D.A. et al., "The CDMS II Data Acquisition System", Nuclear Instruments and Methods in Physics Research Section A623 127133 PDF (2011).
The Data Acquisition System for the CDMS II dark matter experiment was designed and built when the experiment moved to its new underground installation at the Soudan Lab. The combination of remote operation and increased data load necessitated a completely new design. Elements of the original LabView system remained as stand-alone diagnostic programs, but the main data processing moved to a VME-based system with custom electronics for signal conditioning, trigger formation and buffering. The data rate was increased 100-fold and the automated cryogenic system was linked to the data acquisition. A modular server framework with associated user interfaces was implemented in Java to allow control and monitoring of the entire experiment remotely.
  • Ahmed, Z. et al., "Results from a Low-Energy Analysis of the CDMS II Germanium Data", Phys. Rev. Lett 106 131302 PDF (2011).
We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below -10 GeV/c2. This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c2 and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.