Large Underground Xenon experiment

The detector was a time-projection chamber (TPC), using the time between S1 and S2 signals to find the interaction depth since electrons move at constant velocity in liquid xenon (around 1–2 km/s, depending on the electric field).

The x-y coordinate of the event was inferred from electroluminescence photons at the top array by statistical methods (Monte Carlo and maximum likelihood estimation) to a resolution under 1 cm.

[5] WIMPs would be expected to interact exclusively with the liquid xenon nuclei, resulting in nuclear recoils that would appear very similar to neutron collisions.

The assembled detector was transported underground from the surface laboratory in a two-day operation in the summer of 2012 and began data taking April 2013, presenting initial results Fall 2013.

In an 85 live-day run with 118 kg fiducial volume, LUX obtained 160 events passing the data analysis selection criteria, all consistent with electron recoil backgrounds.

This was the most sensitive dark matter direct detection result in the world, and ruled out low-mass WIMP signal hints such as from CoGeNT and CDMS-II.

[10] In the final run from October 2014 to May 2016, at four times its original design sensitivity with 368 kg of liquid xenon, LUX saw no signs of dark matter candidate—WIMPs.

[7] According to Ethan Siegel, the results from LUX and XENON1T have provided evidence against the supersymmetric "WIMP Miracle" strong enough to motivate theorists towards alternate models of dark matter.

The Large Underground Xenon experiment installed 1,480 m (4,850 ft) underground inside the water tank shield.
The Large Underground Xenon experiment installed 1,480 m (4,850 ft) underground inside a 260 m 3 (70,000 US gal) water tank shield. The experiment was a 370 kg liquid xenon time projection chamber that aimed to detect the faint interactions between WIMP dark matter and ordinary matter.
A particle interaction in the LUX detector
Particle interactions inside the LUX detector produced photons and electrons. The photons ( ), moving at the speed of light, were quickly detected by the photomultiplier tubes. This photon signal was called S1. An electric field in the liquid xenon drifted the electrons towards the liquid surface. A much higher electric field above the liquid surface pulled the electrons out of the liquid and into the gas, where they procued electroluminescence photons (in the same way that neon sign produces light). The electroluminescence photons were detected by the photomultiplier tubes as the S2 signal. A single particle interaction in the liquid xenon could be identified by the pair of an S1 and an S2 signal.
Schematic of the Large Underground Xenon detector
Schematic of the Large Underground Xenon (LUX) detector. The detector consisted of an inner cryostat filled with 370 kg of liquid xenon (300 kg in the inner region, called the "active volume") cooled to −100 °C. 122 photomultiplier tubes detected light generated inside the detector. The LUX detector had an outer cryostat that provided vacuum insulation. An 8-meter-diameter by 6-meter-high water tank shielded the detector from external radiation, such as gamma rays and neutrons .