Dark Matter Detector Takes Shape in South Dakota

Homestake Mine, the deepest such structure in the western hemisphere, was until 200 2 the home of a massive gold exploitation, that produced billions of dollars for North America. Now, it is being re-purposed as one of the most advanced dark matter detectors in the world.

Locate in Black Hills, that large mine is now being converted to a state of the art facility, which could help physicists identify weakly-interacting massive particles (WIMP), the basic hypothesized components of dark matter.

One of the reason mines or other similar underground facilities need to be used for this job is that the elusive particles making up this form of matter are in the habit of not interacting with ordinary matter.

Connections develop only at a large scale, and only then indirectly. Galaxies are for example held together by the gravitational attraction of huge dark matter clouds. The stuff may also be responsible for channeling some galaxies into superclusters.

In addition to WIMP, elementary particles such as neutrinos are also very bad at interactions. These building block can pass through regular matter without wavering, and have no electric charge.

Underground detectors are the most suitable places to install detectors, and Homestake is especially good for such studies. The location was selected because the mine is as deep as Mount St. Helens is high, at a depth of around 8,000 feet.

The Sanford Underground Laboratory at Homestake (SULH) was selected as the site of a new underground detector back in 2007, Wired reports. The decision was announced by the US National Science Foundation (NSF).

Since then, physicists that are conducting the assembly of the new Deep Underground Science and Engineering Lab (DUSEL) have come a long way.

They are treading in the footsteps of astrophysicist Raymond Davis, who used a detector installed in this particular mine to prove that neutrinos indeed have mass. His work won him the 2002 Nobel Prize in Physics.

The Davis Cavern at the SULH will now house: a 770-pound tank of liquid xenon called the LUX (Large Underground Xenon) experiment, whose main function will be to house WIMP interactions.

Detectors placed around LUX will keep an eye on the collisions taking place within, and hopefully be able to detect if a rare neutrino or WIMP is produced within.

The photon-collecting tubes at the top of the tanks are the most important detectors. Work on their assembly has already started, and the entire lab is scheduled for completion by December 2011.

One of the things researchers working here like to joke about is how the detector uses so much xenon that they project single-handedly increased the market price of the chemical by thousands of dollars.