Thaindian News

Washington, Feb 12 (ANI): A 9-year search from a unique observatory in an old iron mine 2,000 feet underground has yielded possible detections of the elusive dark matter, but physicists say they might only be background noise.

What came to be known as “dark matter” - dark because it neither reflects nor absorbs light in any form, visible or other - is now estimated to comprise as much as 23 percent of the universe.

But, despite abundant evidence for its influence, no one has ever observed dark matter directly.

There are several possibilities for the composition of this mysterious, omnipresent matter.

Particle physics theory points toward weakly interacting massive particles, or WIMPs, as one of the most likely candidates.

WIMPs are “weakly interacting” because, although their masses are thought to be comparable to the masses of standard atomic nuclei, they have little or no effect on ordinary matter.

Among other things, that makes them extremely difficult to detect.

However, scientists believe WIMPs should occasionally “kick” or bounce off standard atomic nuclei, leaving behind a small amount of energy that should be possible to detect.

The search yielded two possible detections of weakly interacting massive particles, or WIMPs.

But, physicists, who include two University of Florida researchers, say that there is about a one in four chance that the detections were merely background noise - meaning that a worldwide hunt involving at least two dozen different observatories and hundreds of scientists will continue.

“With one or two events, it’s tough. The numbers are too small,” said Tarek Saab, a UF assistant professor and one of dozens of physicists participating in the Cryogenic Dark Matter Search II, or CDMS II, experiment based in the Soudan mine in Northern Minnesota.

The CDMS II observatory is located a half-mile underground beneath rock that blocks most particles, such as those accompanying cosmic rays.

At the observatory’s heart are 30 hockey-puck-sized germanium and silicon detectors cryogenically frozen to negative 459.58 Fahrenheit, just shy of absolute zero.

The 15 institutions participating in CDMS II gathered data from 2003 to 2009.

Observers recorded the two possible WIMP events in 2007, one on Aug. 8 and the second on Oct. 27 last year.

Scientists had estimated that five detections would be sufficient to confirm WIMPs — meaning that the two fell short, according to the CDMS.

But while the two detections may not be conclusive, they do help to set more stringent values on the WIMPs’ interaction with subatomic particles. (ANI)