Cryogenic Dark Matter Search: The Detector
CDMS Detector Located in Soudan Mine Lab
The CDMS detectors are very pure hockey-puck sized disks of germanium, pictured left, inside their hexagonal holder. The key to understandng how the CDMS detector works is in understanding temperature. Temperature is a measure of the net kinetic energy of an object, which is a measure of the amount of motion in an object. The Cryogenic Dark Matter Search rests at a temperature of 0.05 K or about -490 degrees Farenheit; which is to say there is very little motion inside the detector. If a WIMP were to pass through the detector and hit a Germanium nucleus it would cause the nucleus to move, thereby vibrating the whole crystal and raising the temperature of the system.
More common particles such as electrons and photons tend to merely disturb the electrons surrounding the germanium nucleus releasing a charge that is detected separately from temperature. The ratio of charge release to temperature change of a given event indicates whether the nucleus was hit (like in a WIMP event) or if the electrons surrounding the nucleus were brushed.