A new possible way to explain the DAMA results

Abstract

At present there is an effort to reconcile the results of the DAMA experiment with those from other Dark Matter experiments such as CoGeNT, CRESST, CDMS, and all LXe experiments. The author suggests a new model describing the Dark Matter signal as the result of collisions of very light (1-to-few GeV/c 2 ) WIMPs with hydrogen, and compares it with currently accepted models of collisions with heavy nuclei (Na, Ge or Xe). The hydrogen target would come from H-contamination of NaI(Tl), Ge and CaWO 4 crystals. Initial tuning indicates that one can explain the modulation amplitude of DAMA and CoGeNT with this model, assuming a WIMPproton cross section between 10 −33 and 10 −32 cm 2 . This paper should be considered to be a new idea which will need substantial new experimental input from all involved experiments.

GeV WIMPs scattering off of OH impurities cannot explain the DAMA signal

“…Ref. [1] assumes that dark matter particles might only scatter off of Hydrogen, but not off of Na. This, if at all possible, would definitely make for highly peculiar particle properties.…”

“…In this study we explore whether OH impurities indeed lead to a self-consistent explanation of the DAMA signal, focussing on the broad very light WIMP (for definiteness, 1 − 8 GeV) window, and thus extending the mass range originally under consideration in Ref. [1]. We also study the effect of a variation in the assumptions about the WIMP velocity distribution in the Galaxy.…”

“…The key point made in Ref. [1] is that a contamination of OHmolecules is likely to be present in the NaI(Tl) crystals used by the DAMA collaboration. The precise level of such contamination is unknown, but, if at all at a reasonable level, it would be supposedly sufficient to allow a O(1) GeV WIMP to strike a Hydrogen nucleus only, which in turn would produce photons then captured by the PMTs in the DAMA detector.…”

“…Ref. [1] hypothesizes and utilizes a 1 ppm contamination level; In what follows we will assume this same value.…”

Molecular excitations: a new way to detect Dark Matter

“…Reference [1] used proton recoils from hydrogen atoms to provide a possible new explanation of the DAMA signal. The signal was created through the scintillation mechanism of the NaI(Tl) crystal.…”