a massive experiment quietly operating since spring roughly a mile underground in the black hills of south dakota and involving liquid xenon the worlds biggest detector and about a hundred international scientists including texas a&m university physicists has proven itself the most sensitive dark matter detector in the world among other distinguishing factors the federally funded large underground xenon (lux) experiment features greatly enhanced sensitivity to low-mass wimps or weakly interacting massive particles that are believed to be the leading theoretical candidates for dark matter which accounts for nearly a quarter of the universe but so far has been observed only by its gravitational effects on galaxies and clusters of galaxies photomultiplier tubes capable of detecting as little as a single photon of light line the top and bottom of the lux dark matter detector they will record the position and intensity of collisions between dark matter particles and xenon nuclei (all photographs courtesy of matt kapust/sanford underground research facility) the lux dark matter detector suspended in its protective water tank the detector is a titanium cryostat that is a vacuum thermos that will keep xenon cool enough to remain a liquid at about minus 150 degrees fahrenheit lux scientists claim a sensitivity limit three times better than any previous dark matter experiment as well as a sensitivity more than 20 times better than previous experiments for low-mass wimps whose possible detection has been suggested by other experiments three such candidate low-mass wimp events recently reported in ultra-cold silicon detectors would have produced more than 1 600 events in luxs much larger detector or one every 80 minutes during the experiments recent run no such signals were seen brown university physicist rick gaitskell and yale university physicist dan mckinsey co-spokespersons for lux announced the collaborations first-run results at a seminar today (wednesday oct 30) at the sanford underground research facility (sanford lab) in lead sd texas a&ms robert c webb professor of physics and texas a&m spokesperson for lux as well as a member of the george p and cynthia woods mitchell institute for fundamental physics and astronomy will present a related talk at 11 am friday (nov 1) in room m102 within the mitchell institute on the texas a&m campus the lux experiment which officially began collecting data this spring relies on purified liquid xenon a third of a ton of it encased in a 6-foot-tall titanium tank immersed in a second tank of ultra-pure water and cooled to minus 150 degrees fahrenheit the xenon is intended to highlight any particles that may be present as they pass through state-of-the-art detector equipment assembled during the previous three years 4 850 feet below the earths surface in the sanford laboratory ensconced within the repurposed homestake gold mine and shielded from gamma rays neutrons background radiation and other possible data-altering environmental factors webb holder of the ed rachal chair in high-energy physics and a principal investigator for lux along with the late texas a&m physicist james white acknowledges the result is highly preliminary given that it comes a mere 80 days into a 365-day run for the current phase of the experiment set to continue through the next two years however he says it tentatively confirms the collaborations expectations of seeing little activity or evidence of signals of dark matter collisions based on the deep undisturbed conditions of the experiment and high performance level of what the group views as the most sensitive detector available given the depth of the experiment the size of the detector and the amount of running we plan to do we expected either to get confirmation of previous results or to be setting new limits on the abundance of dark matter webb said our focus was to detect background levels and to calibrate the detector and overall parameters of the experiment in this 80-day run weve seen background levels that are lower than anyone has ever seen anywhere at any time the result is the most sensitive one to date but this is part of a much longer search and our work is still very much in a state of flux lux is pushing the cross-section to its lowest levels of course there are still lots of questions are we looking for dark matter in the right places are there different varieties that could hide in places that we dont see only time will tell but were in the cat birds seat to discover dark matter if its there as we think it is and interacts with xenon as we think it does this is a celebration of the long-term investment thats maturing and were hoping to cash in on it in the near future the lux scientific collaboration which is supported by the national science foundation (nsf) and the us department of energy (doe) includes 17 research universities and national laboratories in the united states the united kingdom and portugal the sanford underground research facilitys mission is to enable safe and compelling underground research and to foster transformational science education for more information please visit the sanford lab website at http://sanfordlaborg does office of science is the single largest supporter of basic research in the physical sciences in the united states and is working to address some of the most pressing challenges of our time to read more about the lux experiment from current result and next steps to background and a complete list of collaborators please see the official press release for more on webb and his research visit dr robert webb # # # # # # # # # # about research at texas a&m university: as one of the worlds leading research institutions texas a&m is in the vanguard in making significant contributions to the storehouse of knowledge including that of science and technology research conducted at texas a&m represents annual expenditures of more than $776 million that research creates new knowledge that provides basic fundamental and applied contributions resulting in many cases in economic benefits to the state nation and world to learn more visit http://vprtamuedu -atm- contact: shana k hutchins (979) 862-1237 or shutchins@sciencetamuedu or dr robert c webb (979) 845-4012 or webb@physicstamuedu