Results from a Search for Light-Mass Dark Matter with a p -Type Point Contact Germanium Detector
O. Tench, D. Reyna, P. De Lurgio, J. L. Orrell, N. S. Bowden, M. L. Miller, J. E. Fast, T. W. Hossbach, J. D. Kephart, D. C. Radford, M. G. Marino, N. Fields, J. F. Wilkerson, B. Cabrera-Palmer, T.D. Van Wechel, K. M. Yocum, C. E. Aalseth, Martin E. Keillor, J. I. Collar, C. Greenberg, S. Dazeley, J. Colaresi, H.S. Miley, P. S. Barbeau
Abstract
We report on several features in the energy spectrum from an ultralow-noise germanium detector operated deep underground. By implementing a new technique able to reject surface events, a number of cosmogenic peaks can be observed for the first time. We discuss an irreducible excess of bulklike events below 3 keV in ionization energy. These could be caused by unknown backgrounds, but also dark matter interactions consistent with DAMA/LIBRA. It is not yet possible to determine their origin. Improved constraints are placed on a cosmological origin for the DAMA/LIBRA effect.