Description
With excellent energy resolution and ultra-low backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter models. Sterile neutrinos at the keV mass scale have been proposed as a dark matter candidate, and in this work we search for their signature via the transition magnetic moment of a sterile-to-active conversion in the vicinity of an atom. This scattering process can be enhanced when the 4-momentum transfer to the target atom approaches the $q^2$ = 0 limit, and the virtual exchange photon interacts coherently with the atom, producing ionization. The interaction cross section is enhanced by orders of magnitude when the energy transfer to the ionization electron is half the sterile neutrino mass, producing a peak-like signature in the energy spectrum. We search for this effect, and report results from additional beyond-Standard Model physics searches, using the 1–100 keV range of a 38 kg-year exposure taken by the Majorana Demonstrator between May 2016 and November 2019.
This material is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.
| Collaboration | Majorana Demonstrator |
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