The liquid nitrogen cryostat is the most important and least appreciated component in assuring reliable long term performance of a germanium detector system. Mirion manufactures its own cryostats to exacting quality standards to ensure long detector life.
There are two basic types of cryostats in use: the dipstick, in which the detector occupies a vacuum chamber having a dipstick-like tail which is inserted into the neck tube of a Dewar, and the integral, in which the detector chamber and Dewar share a common vacuum.
The standard configuration comes with a radial O-ring seal. A metal face seal is available as an option on detectors with a 3.0 in. (76 mm) diameter endcaps only. Metal seals are more rugged and, in general, provide a longer life time of the detector vacuum.
Flanged cryostats can be fitted with a Remote-Detector Chamber (RDC). This RDC option separates the detector chamber from the Dewar and preamplifier and allows the use of a backshield so lead shielding that completely surrounds the detector element can be installed.
This significantly reduces the radiation background on the detector. Standard lengths for the RDC option are 2, 4, 6, 8 and 10 inches. Custom lengths are available on request.
End cap dimensions depend on detector size. The chart below shows the typical efficiency range vs. end-cap diameter. End cap lengths are also greater for larger detectors. Consult the factory if end-cap size is critical in your application.
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