* Astronomy

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C-4 Dark Matter Experiment

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RE: CoGeNT

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Title: Implications of CoGeNT's New Results For Dark Matter
Authors: Dan Hooper, Chris Kelso

The CoGeNT collaboration has recently presented the results of their first 15 months of data, including the measurement of the spectrum of nuclear recoil candidate events, and the time variation of those events. These results appear consistent with the signal anticipated from a relatively light dark matter particle scattering elastically with nuclei. In this paper, we independently analyse the data set collected by CoGeNT and explore the implications of these results for dark matter. We find that the observed spectrum and rate is consistent with originating from dark matter particles with a mass in the range of 4.5-12 GeV and an elastic scattering cross section with nucleons of approximately ~10^-40 cm². We confirm the conclusion of the CoGeNT collaboration that the data also includes a somewhat statistically significant (2.7 sigma) indication of annual modulation, with a phase, period, and amplitude consistent with that predicted for dark matter. CoGeNT's phase is also consistent with the annual modulation reported by the DAMA/LIBRA collaboration. We also discuss the null results reported by CDMS and XENON100, and comment on the prospects for other experiments to detect a dark matter particle with the properties implied by CoGeNT.

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Second experiment hints at seasonal dark matter signal

For years, one lonely team has been insisting that it sees a seasonal variation in dark matter signals now another group is reporting similar findings

Things just got a little less lonely for researchers who have been insisting for years not only that their experiment has found dark matter, but also that the dark matter signal varies with the seasons. Now a second experiment, called CoGeNT, is reporting similar findings, though both results are in conflict with two other teams' observations.
No one knows what dark matter is - astronomers merely detect its gravitational pull on normal matter, which it seems to outweigh by a factor of five to one. But many researchers believe it is made of theoretical particles called WIMPs, which interact only weakly with normal matter.
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Title: Results from a Search for Light-Mass Dark Matter with a P-type Point Contact Germanium Detector
Authors: C.E. Aalseth, P.S. Barbeau, N.S. Bowden, B. Cabrera-Palmer, J. Colaresi, J.I. Collar, S. Dazeley, P. de Lurgio, G. Drake, J.E. Fast, N. Fields, C.H. Greenberg, T.W. Hossbach, M.E. Keillor, J.D. Kephart, M.G. Marino, H.S. Miley, M.L. Miller, J.L. Orrell, D.C. Radford, D. Reyna, R.G.H. Robertson, R.L. Talaga, O. Tench, T.D. Van Wechel, J.F. Wilkerson, K.M. Yocum (CoGeNT collaboration)
(Version v2)

We report on several features present in the energy spectrum from an ultra low-noise germanium detector operated at 2,100 m.w.e. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss several possible causes for an irreducible excess of bulk-like events below 3 keVee, including a dark matter candidate common to the DAMA/LIBRA annual modulation effect, the hint of a signal in CDMS, and phenomenological predictions. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.

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