In its first three months of operation, the Large Underground Xenon (LUX) experiment has proven itself to be the most sensitive dark matter detector¹ in the world, scientists with the experiment announced today. "LUX is blazing the path to illuminating² the nature of dark matter," Rick Gaitskell, professor of physics at Brown University and co-spokesperson for LUX. The detector's location, more than a mile underground at the Sanford Underground Research Facility in South Dakota, offers a "supremely³ quiet" environment to detect the rare, weak interactions between dark matter particles and ordinary matter, Gaitskell said.

 

The first results from the experiment's initial 90-day run were announced today during a seminar（讨论会） at the Sanford Lab in Lead, S.D.

 

"What we've done in these first three months of operation is look at how well the detector is performing, and we're extremely pleased with what we're seeing," said Gaitskell, one of the founders⁴ of the LUX experiment. "This first run demonstrates a sensitivity that is better than any previous experiment looking to detect dark matter particles directly."

 

With LUX's initial run complete, the team will now make a few adjustments to fine-tune the device's sensitivity in anticipation⁵ of a new 300-day run to begin in 2014.

 

Dark matter is thought to account for as much as 85 percent of the matter in the universe. But because it rarely interacts with other forms of matter, it has yet to be detected directly. The leading candidates for dark matter particles are called weakly interacting massive particles -- WIMPS⁶.

 

Theory and experimental results suggest that WIMPs could take either a high-mass or low-mass form. In the search for high-mass WIMPs weighing 40 times the mass of a proton, LUX has twice the sensitivity of any other dark matter direct-detection experiment, according to these new results. LUX also has greatly enhanced sensitivity to low-mass WIMPs, and new results suggest that potential detections of low-mass WIMPS by other dark matter experiments were likely the result of background radiation, not dark matter.

 

"There have been a number of dark matter experiments over the last few years that have strongly supported the idea that they're seeing events in the lowest energy bins⁷ of their detectors⁸ that could be consistent with the discovery of dark matter," Gaitskell said. "With the LUX, we have worked very hard to calibrate⁹（校正，调整） the performance of the detector in these lowest energy bins, and we're not seeing any evidence of dark matter particles there."

 

In the upcoming 300-day run, the LUX researchers hope either to detect dark matter definitively¹⁰ or to rule out a vast swath of parameter¹¹（参数） space where it might be found.

 

"Every day that we run a detector like this we are probing new models of dark matter," Gaitskell said. "That is extremely important because we don't yet understand the universe well enough to know which of the models is actually the correct one. LUX is helping¹² to pin that down."

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