We are currently involved in two research projects, CDMS II and XENON
The CDMS II experiment uses germanium and silicon detectors cooled to about 20 mK to look for the extremely rare events in which a dark matter particle will elastically scatter off a nucleus. The experiment is located in the Soudan Mine in Northern Minnesota,about half a mile beneath the earth's surface to prevent cosmic rays from interacting in the detectors. It is also shielded by several layers of low radioactivity lead and polyethylene against radiation coming from the Soudan rock.CDMS II measures both the phonon (or lattice vibration) and the small charge signal produced in a particle interaction in the silicon or germanium material. The ratio of the two can tell us whether the interaction was caused by dark matter, or just by background radiation. A more detailed description can be found on the official CDMS website.
The XENON experiment is also designed to look for dark matter particles. In this case, the detection medium is liquid Xenon, and the measured signals are electrical charge and xenon scintillation light. As for CDMS, the ratio of light to charge is used to differentiate WIMP signals from background induced events. Liquid xenon has a high density and the experiment can be relatively easy scaled to large masses. While a first 100 kg module is currently in planning, the proposed final experiment will contain 1 tonne of liquid xenon. Such an experiment will not only have a fair chance of detecting dark matter, but will also be able to measure the interaction rate with high precision. For a detailed description see the official XENON website.
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