Status of the XMASS Experiment

The goal of the XMASS experiment is direct detection of dark matter using single-phase liquid xenon. The current-phase detector XMASS-I has the largest target mass (835 kg in total) and achieves the lowest energy threshold (300-eV-electron equivalent). The next phase detector XMASS-1.5 will have a total five tons of liquid xenon and is planned to start in 2015. This paper reports results of searches conducted with XMASS-I [low-mass weakly interacting massive particles (WIMPs), solar axions, annual modulation of event rate at low energy, and inelastic scattering of 129Xe nuclei by WIMPs] the current status of hardware modification of XMASS-I to reduce background, and progress in designing XMASS-1.5.