Exclusion limits on the WIMP-nucleon cross section from the Cryogenic Dark Matter Search
American Physical Society
The Cryogenic Dark Matter Search (CDMS) employs low-temperature Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.9% efficiency, and surface events are rejected with >95% efficiency. The estimate of the background due to neutrons is based primarily on the observation of multiple-scatter events that should all be neutrons. Data selection is determined primarily by examining calibration data and vetoed events. Resulting efficiencies should be accurate to ∼10%. Results of CDMS data from 1998 and 1999 with a relaxed fiducial-volume cut (resulting in 15.8 kg days exposure on Ge) are consistent with an earlier analysis with a more restrictive fiducial-volume cut. Twenty-three WIMP candidate events are observed, but these events are consistent with a background from neutrons in all ways tested. Resulting limits on the spin-independent WIMP-nucleon elastic-scattering cross section exclude unexplored parameter space for WIMPs with masses between 10–70 GeV/c2. These limits border, but do not exclude, parameter space allowed by supersymmetry models and accelerator constraints. Results are compatible with some regions reported as allowed at 3σ by the annual-modulation measurement of the DAMA Collaboration. However, under the assumptions of standard WIMP interactions and a standard halo, the results are incompatible with the DAMA most likely value at >99.9% confidence level (C.L.), and are incompatible with the model-independent annual-modulation signal of DAMA at 99.99% C.L. in the asymptotic limit.
CDMS Collaboration, Abrams, D., Akerib, D. S., Armel-Funkhouser, M. S., Baudis, L., Bauer, D. A., Bolozdynya, A., Brink, P. L., Bunker, R., Cabrera, B., Caldwell, D. O., Castle, J. P., Chang, C. L., Clarke, R. M., Crisler, M. B., Dixon, R., Driscoll, D., Eichblatt, S., Gaitskell, R. J., … Young, B. A. (2002). Exclusion limits on the WIMP-nucleon cross section from the Cryogenic Dark Matter Search. Physical Review D, 66(12), 122003. https://doi.org/10.1103/PhysRevD.66.122003.