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The LUX experiment (for Large Underground Xenon) just released its first results in the race to identify the particle nature of dark matter. Dark matter particles - more specifically WIMPs (Weakly Interacting Massive Particles) - are so weakly interacting that they normally pass through regular matter unimpeded. The aim of LUX - the latest among many direct detection experiments, is to intercept a few of these elusive particles and measure the tiny quanta of light that they create as they collide with the atoms inside a detector. Such a signal would ordinarily be swamped by the millions of cosmic ray particles that bombard the earth every second. To overcome this, LUX takes place under 1.5 km of rock in the Sanford Underground Research Facility in Lead, South Dakota. The detector itself consists of 370 kg of purified liquid xenon. When a WIMP drifts through the rock and hits a xenon nucleus in the detector, a flash of light and an electric current are measured by high-precision equipment, allowing even a small number of events to be recorded.

LUX has a low energy threshold, and thus it can directly test the low mass WIMP region, where hints from the DAMA, CoGeNT, CRESST-II, and CDMS-II silicon experiments are pointing to.

In their analysis of 85.3 live-days of LUX data taken in the period of April to August 2013, it is shown that the data is consistent with the background-only hypothesis. A 90% confidence limit is set on the spin-independent elastic WIMP-nucleon cross section, and the LUX results are in strong disagreement with signals from the experiments pointing to light WIMPs if the Standard Halo Model is assumed. LUX sets a minimum upper limit of 7.6 x 10^-46 cm^2 on the WIMP-nucleon cross section for a WIMP mass of 33 GeV/c^2. LUX will continue running during 2014 and 2015, and is expected to eventually conduct a blinded 300 live-day WIMP search and explore new regions in the plane of dark matter mass and cross section.

Link to the scientific paper: http://luxdarkmatter.org/papers/LUX_First_Results_2013.pdf

A popular science article in WIRED: http://www.wired.com/wiredscience/2013/10/lux-dark-matter/