  Dark matter which scatters off ordinary matter with a relatively large cross
section cannot be constrained by deep underground WIMP experiments, due to the
energy loss of DM along its path. However, for a sufficiently large cross
section, DM particles in the GeV mass range can be captured and thermalized
within Earth, resulting in the accumulation of a DM atmosphere whose number
density can be as large as $10^{14} \text{ cm}^{-3}$ at Earth's surface. (If
the DM-nucleon interaction is attractive and bound states can be formed, most
DM bind to nuclei and the density is much lower.)
  Neufeld and Brach-Neufeld performed experiments to constrain the DM-baryon
scattering cross section of DM atmosphere around Earth, by measuring the
evaporation rate of liquid nitrogen in a storage dewar within which various
materials are immersed. If the DM-nitrogen cross section is in an appropriate
range, room temperature DM would penetrate the dewar walls and scatter on the
cold nitrogen, increasing its evaporation rate beyond the observed level.
Limits on the cross section of DM with other materials than nitrogen are
obtained by adding known amounts of different materials; if the material is
heated by interactions with DM, that heats and evaporates the liquid nitrogen.
  Because Born approximation is in general invalid in much of the relevant
cross section regime, it is non-trivial to interpret such experimental results
as a limit on the DM-nucleon cross section. In this paper we derive the
constraints on DM-baryon scattering, with the interaction modeled as a Yukawa
potential sourced by the finite sized nucleus. Combining the dewar constraints
with BBN, we exclude for the first time a cross section above $10^{-26} \text{
cm}^{2}$ for DM mass 0.8-5.5 GeV, for any sign interaction. One DM model that
is constrained is sexaquark $(uuddss)$ DM with mass $m_X \sim 2$ GeV; it
remains viable.
