XMASS experiment aims to detect the cold dark matter directly using liquid Xenon (at about -100℃). Dark matter is unknown matter which is 5~6 times quantity of ordinary visible matter in the universe (see more). Dark matter plays an important role to form the present structure of the universe. If the direct detection of the dark matter is achieved, it can be a great help to solve the mysteries of the universe and also to discover new particles.
Now, the XMASS detector using ~1ton liquid Xenon is being constructed in the Kamioka mine. The new hall for XMASS was completed in August 2008. The construction of ~800 ton water tank to reduce radioactive backgrounds from the outside started in autumn 2008. The XMASS detector is installed in this tank. The observation will be started from spring 2011.
The sensitivity of XMASS detector is 50 times better than the other dark matter search experiments. The possibility of the direct detection and discovery of dark matter is highly expected. In future, we will plan to extend to a 20ton multi-purpose detector.