Dark Matter Search Results from the CDMS II Experiment

Science  26 Mar 2010:
Vol. 327, Issue 5973, pp. 1619-1621
DOI: 10.1126/science.1186112

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News from the Dark Side?

Dark matter is thought to represent 85% of all matter in the universe and to have been responsible for the formation of structure in the early universe, but its nature is still a mystery. Ahmed et al. (p. 1619, published online 11 February; see the Perspective by Lang) describe the results from the completed Cryogenic Dark Matter Search (CDMS II) experiment, which searched for dark matter in the form of weakly interacting massive particles (WIMP). Two candidate signals were observed, whereas only one background event was expected. The probability of having two or more events from the background would have been 23%. The results of this analysis cannot be interpreted with confidence as evidence for WIMP interactions, but, at the same time, neither event can be ruled out as representing signal.


Astrophysical observations indicate that dark matter constitutes most of the mass in our universe, but its nature remains unknown. Over the past decade, the Cryogenic Dark Matter Search (CDMS II) experiment has provided world-leading sensitivity for the direct detection of weakly interacting massive particle (WIMP) dark matter. The final exposure of our low-temperature germanium particle detectors at the Soudan Underground Laboratory yielded two candidate events, with an expected background of 0.9 ± 0.2 events. This is not statistically significant evidence for a WIMP signal. The combined CDMS II data place the strongest constraints on the WIMP-nucleon spin-independent scattering cross section for a wide range of WIMP masses and exclude new parameter space in inelastic dark matter models.

  • All authors and their affiliations appear at the end of this paper.

  • The CDMS II Collaboration

  • Z. Ahmed,1 D. S. Akerib,2 S. Arrenberg,18 C. N. Bailey,2 D. Balakishiyeva,16 L. Baudis,18 D. A. Bauer,3 P. L. Brink,10 T. Bruch,18 R. Bunker,14 B. Cabrera,10 D. O. Caldwell,14 J. Cooley,9 P. Cushman,17 M. Daal,13 F. DeJongh,3 M. R. Dragowsky,2 L. Duong,17 S. Fallows,17 E. Figueroa-Feliciano,5 J. Filippini,1 M. Fritts,17 S. R. Golwala,1 D. R. Grant,2 J. Hall,3 R. Hennings-Yeomans,2 S. A. Hertel,5 D. Holmgren,3 L. Hsu,3 M. E. Huber,15 O. Kamaev,17 M. Kiveni,11 M. Kos,11 S. W. Leman,5 R. Mahapatra,12 V. Mandic,17 K. A. McCarthy,5 N. Mirabolfathi,13 D. Moore,1 H. Nelson,14 R. W. Ogburn,10 A. Phipps,13 M. Pyle,10 X. Qiu,17 E. Ramberg,3 W. Rau,6 A. Reisetter,17,7 T. Saab,16 B. Sadoulet,4,13 J. Sander,14 R. W. Schnee,11 D. N. Seitz,13 B. Serfass,13 K. M. Sundqvist,13 M. Tarka,18 P. Wikus,5 S. Yellin,10,14 J. Yoo,3 B. A. Young,8 J. Zhang17

  • 1 Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA. 2Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA. 3Fermi National Accelerator Laboratory, Batavia, IL 60510, USA. 4Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 5Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. 6Department of Physics, Queen’s University, Kingston, ON K7L 3N6, Canada. 7Department of Physics, St. Olaf College, Northfield, MN 55057, USA. 8Department of Physics, Santa Clara University, Santa Clara, CA 95053, USA. 9Department of Physics, Southern Methodist University, Dallas, TX 75275, USA. 10Department of Physics, Stanford University, Stanford, CA 94305, USA. 11Department of Physics, Syracuse University, Syracuse, NY 13244, USA. 12Department of Physics, Texas A&M University, College Station, TX 77843, USA. 13Department of Physics, University of California, Berkeley, CA 94720, USA. 14Department of Physics, University of California, Santa Barbara, CA 93106, USA. 15Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, CO 80217, USA. 16Department of Physics, University of Florida, Gainesville, FL 32611, USA. 17School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA. 18Physics Institute, University of Zürich, Winterthurerstrasse 190, CH-8057, Switzerland.

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