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Semiconductors and the Search for Dark Matter

Just a quick note on another use of semiconductor manufacturing technology for physics instrumentation.  A research group here at Texas A&M University is involved in the search for dark matter as part of the Cryogenic Dark Matter Search, (CDMS).  They’re using silicon and germanium detectors with aluminum and tungsten circuit elements to search for elusive dark matter particles, (see picture to the left).  In contrast to traditional semiconductor manufacturing, the detectors are built on top of quite thick discs, (around six mm and up). The massiveness of the disc provides more material for dark matter particles to interact with.  Many of the detectors are being built right here at Texas A&M using fab equipment provided by Maxim Integrated.

What is Dark Matter?
As far back as the 1930′s, astronomical measurements have detected discrepancies between gravitational effects in galaxies and the amount of observable matter that should account for the mass and therefore the available gravity in a given galaxy.  One example of this is the rotational speed of galaxies.  Based on the observed matter distribution of galaxies, their rotational speed should be slower near the edge of the galaxy than at the center.  Instead, astronomers observe a roughly constant rotational speed with respect to the distance from the center of a galaxy.  To account for this discrepancy, physicists and astronomers have proposed the existence of weakly interacting massive particles, (WIMPs), also known as dark matter.  While WIMPs have not yet been detected, it is theorized that they account for up to 23% of the mass of our universe.

 

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