Search for WIMP-$^{129}$Xe inelastic scattering with particle
  identification in XMASS-I
  A search for Weakly Interacting Massive Particles (WIMPs) was conducted with
the single-phase liquid-xenon detector XMASS through inelastic scattering in
which $^{129}$Xe nuclei were excited, using an exposure ($\rm 327\; kg \times
800.0 \; days$) 48 times larger than that of our previous study. The inelastic
excitation sensitivity was improved by detailed evaluation of background, event
classification based on scintillation timing that distinguished $\gamma$-rays
and $\beta$-rays, and simultaneous fitting of the energy spectra of
$\gamma$-like and $\beta$-like samples. No evidence of a WIMP signal was found.
Thus, we set the upper limits of the inelastic channel cross section at 90\%
confidence level, for example, $4.1\times 10^{-39} \;{\rm cm^2}$ for a $200\;
{\rm GeV}/c^2$ WIMP. This result provides the most stringent limits on the SD
WIMP-neutron interaction and is better by a factor of 7.7 at $200\;{\rm
GeV}/c^2$ than the existing experimental limit.
