Washington, Dec 15 (IANS): Scientists have employed a new set of calibration techniques upon the world' most sensitive dark matter detector that is hunting for dark matter - the unseen stuff believed to account for most of the matter in the universe.

The Large Underground Xenon (LUX) dark matter experiment, which operates nearly a mile underground at the Sanford Underground Research Facility (SURF) in the Black Hills of South Dakota, has already proven itself to be the most sensitive detector in the hunt for dark matter.

Now, a new set of calibration techniques employed by LUX scientists has dramatically improved the detector's sensitivity.

"We have looked for dark matter particles during the experiment's first three-month run, but are exploiting new calibration techniques better pinning down how they would appear to our detector,” explained Alastair Currie from Imperial College London.

"These calibrations have deepened our understanding of the response of xenon to dark matter and to backgrounds. This allows us to search, with improved confidence, for particles that we hadn't previously known would be visible to LUX,” he added.

Researchers with LUX are looking for weakly interacting massive particles (WIMPs) which are among the leading candidates for dark matter.

"We have improved the sensitivity of LUX by more than a factor of 20 for low-mass dark matter particles, significantly enhancing our ability to look for WIMPs," noted Rick Gaitskell, professor of physics at Brown University.

"It is vital that we continue to push the capabilities of our detector in the search for the elusive dark matter particles," Gaitskell added.

Scientists are confident that dark matter exists because the effects of its gravity can be seen in the rotation of galaxies and in the way light bends as it travels through the universe.

Because WIMPs are thought to interact with other matter only on very rare occasions, they have yet to be detected directly.

LUX consists of one-third tonne of liquid xenon surrounded with sensitive light detectors.

It is designed to identify the very rare occasions when a dark matter particle collides with a xenon atom inside the detector.

So far LUX hasn't detected a dark matter signal, but its exquisite sensitivity has allowed scientists to all but rule out vast mass ranges where dark matter particles might exist.

These new calibrations increase that sensitivity even further.

The new research is described in a paper submitted to Physical Review Letters.