New Detector for Dark Matter
Neutron Detector
An MIT team led by Jocelyn Monroe has found a new, more efficient method of detecting the weakly-interacting massive particle (WIMPs) that are thought to make up dark matter, which comprises up to 23% of the Universe’s total mass.
Dark matter has been an area of research recently. In particular, many are working to identify and detect the common yet elusive particles that are thought to make up the majority of it. Some scientists work from the theoretical side, producing and analyzing models that describe and put constraints on dark matter. Others are trying to observe these particles using various experiments.
The experiments that are currently underway work by detecting the light that results from dark matter colliding with normal matter. However, these flashes of light are rare and hard to differentiate from collisions of purely normal matter. That is why large tanks of liquid, usually some sort of fluorine or chlorine based molecule, are set deep underground with a surrounding field of photomultipliers. When a dark matter particle reacts with the liquid, the photomultipliers detect the resultant flash. While most normal matter particles with interact with other normal matter particles in the ground around the tank, a few make it through and interact with the liquid to produce a false detection. These few particles far outnumber the dark matter particles, though: “…ordinary collisions should happen about 10 billion billion times (19 orders of magnitude) more often than the dark-matter collisions.”
That is why Monroe’s team proposes placing a second detector, which only detects neutrons from normal matter collisions, to characterize the background. This background noise is then compared to the collisions detected by the large tank of liquid and photomultiplier tubes, and all collisions due to normal matter are subtracted from the data. This then allows one to count only those collisions due to dark matter.
Although there are many dark matter particle candidates, experimentalists have yet to directly observe such a candidate in one of these detectors. The few possible observations of dark matter collisions that have occured are as of yet unconfirmed. However, Monroe stated, “I think probably in the next five years, someone will see a candidate.”
Sources:
http://web.mit.edu/newsoffice/2008/dark-matter-tt1210.html
This entry was posted on Wednesday, December 10th, 2008 at 9:55 pm and is filed under Astrophysics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
