Wednesday, April 17, 2013

1304.4279 (CDMS Collaboration et al.)

Dark Matter Search Results Using the Silicon Detectors of CDMS II    [PDF]

CDMS Collaboration, R. Agnese, Z. Ahmed, A. J. Anderson, S. Arrenberg, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, D. Brandt, P. L. Brink, T. Bruch, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, F. Dejongh, E. Do Couto E Silva, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, J. Filippini, J. Fox, M. Fritts, G. L. Godfrey, S. R. Golwala, J. Hall, R. H. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, P. Kim, M. Kiveni, K. Koch, M. Kos, S. W. Leman, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, P. Nadeau, R. H. Nelson, K. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, K. M. Sundqvist, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, J. Yoo, B. A. Young, J. Zhang
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 cm^2 at a WIMP mass of 10 GeV/c^2. 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/c^2 and WIMP-nucleon cross section of 1.9E-41 cm^2.
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