Ultra Sensitive Dark Matter Detector Unable to Detect Dark Matter
Posted on July 22, 2016
The world's most sensitive dark matter detector has completed its search and has been unable to locate the mysterious matter. The Large Underground Xenon (LUX) dark matter detector was designed to find dark matter, which scientists believe accounts for over four-fifths of the mass in the universe.
The LUX was designed to find weakly interacting massive particles (WIMPs). WIMPS are the leading theoretical candidate for a dark matter particle. The LUX operates beneath a mile of rock at the Sanford Underground Research Facility in the Black Hills of South Dakota.
Rick Gaitskell, professor of physics at Brown University and co-spokesperson for the LUX experiment, says in a statement, "LUX has delivered the world’s best search sensitivity since its first run in 2013. With this final result from the 2014 to 2016 search, the scientists of the LUX Collaboration have pushed the sensitivity of the instrument to a final performance level that is four times better than the original project goals. It would have been marvelous if the improved sensitivity had also delivered a clear dark matter signal. However, what we have observed is consistent with background alone."
The LUX detector uses a third-of-a-ton of cooled liquid xenon surrounded by powerful sensors. The sensors were designed to detect the tiny flash of light and electrical charge emitted if a WIMP collides with a xenon atom within the tank. The LUX is also kept inside a 72,000-gallon, high-purity water tank (pictured below). The deep underground location combined with the tank helps shield the detector from cosmic rays and other radiation that would interfere with a dark matter signal.
The experiment was run for 20 months. Nearly a half-million gigabytes of data was analyzed. The research is described on the LUX Dark Matter site. Physicists still believe in the WIMP model, which Gaitskell says "remains alive and viable." A future experiment, called LUX-ZEPLIN (LZ), wil have a 10-ton liquid xenon target.
Gaitskell also says, "We viewed this as a David and Goliath race between ourselves and the much larger Large Hadron Collider (LHC) at CERN in Geneva. LUX was racing over the last three years to get first evidence for a dark matter signal. We will now have to wait and see if the new run this year at the LHC will show evidence of dark matter particles, or if the discovery occurs in the next generation of larger direct detectors."