Edinburgh University scientists help with upgrade of dark matter detector Published duration 14 December 2015

image copyright C H Faham image caption The Lux detector is a mile underground in a former mine in South Dakota, USA

A sophisticated instrument that helps scientists gain new insights into the make-up of the universe has been upgraded by Edinburgh scientists.

The instrument, known as the Large Underground Xenon, or Lux, detector, is a mile underground in a former mine in South Dakota, USA.

It searches for tiny particles which would improve scientists' understanding of dark matter.

Dark matter is the invisible material thought to make up 27% of the universe.

Dark matter has yet to be detected directly by scientists and has so far been observed only by its effects on gravity, which can be seen in the rotation of galaxies and the way light bends as it travels through space.

The upgrade increases the chances of the detector identifying sub-atomic particles called Wimps - weakly interacting massive particles - which scientists believe are the main component of dark matter.

A team of physicists, including scientists at Edinburgh University, have made Lux's ability to identify the lightest form of Wimps about 20 times more sensitive.

image copyright C H Faham image caption The instrument is known as the Large Underground Xenon or Lux detector

This has allowed them to study data collected during Lux's initial run in 2013 which previously had to be ignored.

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.

Professor Alex Murphy, of Edinburgh University's school of physics and astronomy, said: "Since Lux's first run, we have developed several new calibration techniques and methods of analysis. We are now able to look for tell-tale signs of Wimps in data we previously had to ignore, increasing our chances of detecting dark matter."

Lux is housed deep underground where few cosmic rays can penetrate, and consists of a tank of liquid xenon surrounded by sensitive light detectors.

It is designed to spot collisions between Wimps and xenon atoms inside the detector.

Following a collision, the xenon atom emits a tiny flash of light, which is spotted by Lux's light sensors.

The upgrade was supported by the US Department for Energy and the National Science Foundation.

The Lux scientific collaborative involves 19 institutions in Europe and the US.