XMASS is a multipurpose

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

experiment in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

that monitors a large tank of

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

for flashes of light that might be caused by hypothetical

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

particles. In addition to searching for dark matter, XMASS is also studying neutrinoless double beta decay and solar neutrinos. Its results have not confirmed the annual variation seen in some earlier experiments.

History

Construction started in April 2007. The detector was completed in September 2010. Commissioning run was conducted between October 2010 and June 2012. Scientific data taking begun in November 2013. The detector is sometimes called XMASS-I, as it is planned to be superseded by an upgrade called XMASS-1.5 (a 5 ton detector) and eventually XMASS-II (24 ton detector). The XMASS-I experiment shut down and ceased data taking 20 February 2019. Results were published in 2021.

Detector

The detector is located 1000m underground in the

Kamioka Observatory The is a neutrino and gravitational waves laboratory located underground in the Mozumi mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan. A set of groundbreaking neutrino experiment ...

in Japan. It contains about 800 kg of liquid xenon.About XMASS : Detector
/ref>

References

External links

Direct Dark Matter Search by Annual Modulation [Results from XMASS] Sept 2015
Dark matter Experiments for dark matter search Research in Japan {{physics-stub