Dilution Refrigeration
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What We Do

In the 75 Fridge Facility we test the particle detectors we receive from Stanford in our 75 microWatt (of heat removal power at 0.1 K) Oxford dilution refrigerator at temperatures near absolute zero before sending them to the mine in Soudan, Minnesota, where they will be used in the CDMS II project to detect dark matter particles directly. We examine their superconductive transition properties and other detector functions. A second function we fulfill is the testing of our cold hardware in the cryostat.

The study of cryogenics is more than a century old, dating back to the end of the 19th century. The application, however, of cryogenic technology to other fields of science and commerce only dates back to the 1960's. Originally, cryogenic refrigerators (or cryostats) were expensive to build and maintain and weren't guaranteed to even work! Since then, cryostats have been improved astoundingly and today are being used in research involving fields from Astrophysics to Oceanography and the Space Sciences, as well as commercially in fields such as Medicine and Global Security.

Recently, cryogenics has been applied to the study of Dark Matter. One of the main benefits of this application is a super-sensitivity that is necessary for detecting dark matter particles -- an excellent candidate for Dark Matter is the WIMP (Weakly Interacting Massive Particle). In the CDMS project we are searching for these WIMPs by trying to detect one of them "crashing" into (or scattering off) one of the nuclei in our large (250g) particle detectors. This amounts to detecting the small recoil energy from the nucleus, hence the need for sensitive instruments. An added benefit is that since we operate at low temperatures, we can exploit the transition properties of superconductivity to make a speedy "Transition Edge Sensor" (TES) from thin-film tungsten. For more information on the particle detectors and the CDMS II experiment itself check out this page.