A view of the inner layers of the cryostat.  The hexagonal holes are the mounting points for the detector assembly and sits at 10 mK during operation.  The surrounding layers are higher temperature stages of the cryostat.  The cryostat is one-of-a-kind and was designed and built by the LBNL-UCB team.  It is constructed entirely of radiopure copper to provide a low-radioactivity environment for the extremely sensitive CDMS detectors. The grey-black layer is a shield made of lead recovered from the ballast of a 18th-century French ship; the age of this lead ensures that the radioisotopes most worrying to CDMS have decayed away.  In recent weeks, a polyethylene shield has been installed inside the lead layer; this new shield will attenuate the neutron flux by ~2.5 while allowing WIMPs to pass through.  The observation of a reduced event rate after installation of this new shield will prove conclusively that CDMS detectors are seeing neutrons, not WIMPs.