Large Underground Xenon experiment

The Large Underground Xenon experiment (LUX) aims to directly detect weakly interacting massive particle (WIMP) dark matter interactions with ordinary matter on Earth. Despite the wealth of (gravitational) evidence supporting the existence of non-baryonic dark matter in the Universe, dark matter particles in our galaxy have never been directly detected in an experiment. LUX utilizes a 370 kg liquid xenon detection mass in a time-projection chamber (TPC) to identify individual particle interactions, searching for faint dark matter interactions with unprecedented sensitivity.

The LUX experiment, which cost approximately $10 million to build, is located 1,510 m (4,950 ft) underground at the Sanford Underground Laboratory (SURF, formerly the Deep Underground Science and Engineering Laboratory, or DUSEL) in the Homestake Mine (South Dakota) in Lead, South Dakota. The detector is located in the Davis campus, former site of the Nobel Prize-winning Homestake neutrino experiment led by Raymond Davis. It is operated underground to reduce the background noise signal caused by high-energy cosmic rays at the Earth's surface.

The detector is isolated from background particles by a surrounding water tank and the earth above. This shielding reduces cosmic rays and radiation interacting with the xenon.

Interactions in liquid xenon generate 175 nm ultraviolet photons and electrons. The photons are immediately detected by two arrays of 61 photomultiplier tubes at the top and bottom of the detector. These prompt photons are the S1 signal. Electrons generated by the particle interactions drift upwards towards the xenon gas by an electric field. The electrons are pulled in the gas at the surface by a stronger electric field, and produce electroluminescence photons detected as the S2 signal. The S1 and subsequent S2 signal constitute a particle interaction in the liquid xenon.

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