Dark matter detector on track
Scientists at Edinburgh have helped create the most sensitive dark matter detector in the world, new results show.
Researchers have taken part in the first run of an underground detector known as Large Underground Xenon (LUX), situated a mile underground in a mine in South Dakota, US.
The detector is searching for Weakly Interacting Massive Particles (WIMPs) – tiny, sub-atomic particles that indicate the existence of dark matter. Dark matter and dark energy are thought to account for about 95% of the Universe, but remain unseen. Initial results demonstrate that the LUX detector is working well, which fuels hope of detection of dark matter in the near future.
These first results, which reveal data from a run of more than 85 days, also rule out some existing theories of what comprises dark matter.
“Understanding dark matter may well be the key to unlocking a much deeper understanding of the universe, and it is very fitting that Edinburgh should be part of the team making this progress now." Dr Alex Murphy, School of Physics & Astronomy, University of Edinburgh
Dark matter has so far been observed only by its gravitational effects on galaxies and clusters of galaxies, despite being the predominant form of matter in the Universe. According to physics theory, WIMPs are the most likely particles to explain the dark matter. WIMPS are difficult to spot because they collide with normal matter only rarely, and their faint signals are drowned out by cosmic radiation from space.
The LUX detector
LUX has been designed to be the world's premier instrument in this area of physics and astronomy. It is housed deep underground where few cosmic ray particles can penetrate, and is held in a tank of purified water which further protects from background radiation given off by surrounding rock.
The tank contains cooled liquid xenon, whose atoms, if struck by a WIMP, will recoil and give off light and a small electric charge. These electrons are drawn upward by an electrical field and interact with a thin layer of xenon gas at the top of the tank, releasing more photons. Light detectors in the top and bottom of the tank can spot any light emitted and measure the energy of the interaction, giving valuable information on the behaviour of the WIMP.
The LUX collaboration includes 17 research universities and national laboratories in the United States and Europe. Taking part from the United Kingdom are the University of Edinburgh, Imperial College London and University College London.