Detection of dark matter particles?

Last Updated: Saturday, December 19, 2009 - 12:50

London: Reports indicate that an experiment buried deep beneath the forests of Minnesota in the US has seen two events that could be the first direct detection of dark matter.

According to a report in Nature News, the project is called the Cryogenic Dark Matter Search II (CDMSII) experiment.

If the detection of dark matter is confirmed, it will mark the end of a decades-long search for the mysterious particles.

Observations by Swiss astronomer Fritz Zwicky in the 1930s gave the first hints of the existence of dark matter.

Since then, studies of the Universe`s structure, and of the way galaxies rotate, have confirmed that there must be an unseen form of matter shaping the cosmos.

This dark matter is believed to make up as much as 85 percent of all the material in the Universe, although its identity is unknown.

The two events, seen by CDMSII in 2007, are the signatures of the most likely form of dark matter, known as weakly interacting massive particles (WIMPs).

Each particle could be as massive as an entire atom, yet reveal itself only rarely by interacting with conventional matter.

The possible WIMPs were caught in the experiment`s crystals of germanium and silicon, which are chilled to nearly absolute zero (-273.15 degrees Celsius).

When a WIMP strikes one of the crystals, it should trigger vibrations that raise the temperature of the detector very slightly; it should also create a small charge on the crystal`s surface.

Comparing the size and timing of the two signals can help to determine whether or not they were caused by WIMPs.

CDMSII scientists are remaining tight-lipped about the results until they are peer-reviewed.

But, in a series of talks delivered over the next few days in the US and Europe, they are expected to announce that their WIMP candidates have a mass of 30-60 gigaelectronvolts - roughly 30-60 times that of a single proton.

From their analysis, they believe that there is a 75 percent chance that both events are WIMPs, and a 25 percent chance that they might both be false-positives caused by stray radiation.
ANI



First Published: Saturday, December 19, 2009 - 12:50

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