New detector will help search elusive dark matter

December 12th, 2008 - 4:50 pm ICT by ANI  

Washington, Dec 12 (ANI): Physicists at the MIT have built a calibration tool that will aid in the search for dark matter, by revealing when hypothetical particles are detected.

Several research projects are underway to try to detect particles that may make up the mysterious dark matter, believed to dominate the universes mass.

But the existing detectors have a problem.

They also pick up particles of ordinary matter - hurtling neutrons that masquerade as the elusive dark-matter particles the instruments are designed to find.

Now, MIT physicist Jocelyn Monroe and her students have built a detector that should identify all of the ordinary neutrons that come along, leaving anything else that the other detector picks up as a strong candidate for the elusive dark matter.

Dark matter experiments are very hard, explained Monroe, who worked on the project with undergraduates Dianna Cowern and Rick Eyers and with graduate students Shawn Henderson and Asher Kaboth.

They are looking for a tiny signal, from a phenomenon that happens very rarely, namely the collision of a dark-matter particle with one of ordinary matter, producing a tiny, brief flash of light, she added.

Such flashes can be detected by putting a tank of liquid deep underground to shield it from most stray particles, then lining the tank with photomultiplier tubes that can pick up even the faintest bursts of light.

The problem is, even buried a mile underground, calculations show such detectors will pick up far more collisions from particles of ordinary matter than from those made of the still-unknown particles of dark matter.

To be precise, the ordinary collisions should happen about 10 billion billion times more often than the dark-matter collisions.

So, learning how to rule out those ordinary collisions is the key to finding the unknown matter.

Were really trying to characterize the background, Monroe explained. Were making a precise measurement of the energy spectrum of the neutron background, she added.

By understanding the nature and intensity of this background, it will be possible to design more effective shielding material to keep them away from the detectors.

By running the two detectors at the same time, anytime a signal is seen in the neutron detector, any signal seen simultaneously in the dark-matter detector can be safely ignored.

Only when the dark matter detector sees something and the neutron detector doesnt will there be a chance that one of the elusive dark-matter particles has been found.

I think probably in the next five years, someone will see a candidate for a dark-matter particle, Monroe said. (ANI)

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