Searching for low-mass dark matter particles with a massive Ge bolometer
  operated above-ground
  The EDELWEISS collaboration has performed a search for dark matter particles
with masses below the GeV-scale with a 33.4-g germanium cryogenic detector
operated in a surface lab. The energy deposits were measured using a
neutron-transmutation-doped Ge thermal sensor with a 17.7~eV (RMS) baseline
heat energy resolution leading to a 60~eV analysis energy threshold. Despite a
moderate lead shielding and the high-background environment, the first sub-GeV
spin-independent dark matter limit based on a germanium target has been
achieved. The experiment provides the most stringent, nuclear recoil based,
above-ground limit on spin-independent interactions above 600~MeV/c$^{2}$. The
experiment also provides the most stringent limits on spin-dependent
interactions with protons and neutrons below 1.3~GeV/c$^{2}$. Furthermore, the
dark matter search results were studied in the context of Strongly Interacting
Massive Particles, taking into account Earth-shielding effects, for which new
regions of the available parameter space have been excluded. Finally, the dark
matter search has also been extended to interactions via the Migdal effect,
resulting for the first time in the exclusion of particles with masses between
45 and 150~MeV/c$^{2}$ with spin-independent cross sections ranging from
$10^{-29}$ to $10^{-26}$~cm$^2$.
