The Hobby-Eberly Telescope (HET) is an existing innovative large telescope of 9.2 meter aperture, located at the
McDonald Observatory in West Texas. The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) requires a
major upgrade to the HET, including a substantial increase in the telescope field of view, as well as the development and
integration of a revolutionary new integral field spectrograph called VIRUS. The Visible Integral-Field Replicable Unit
Spectrograph (VIRUS) is an instrument comprising approximately 150 individual IFU-fed spectrographs which will be
mounted on the telescope structure. Each spectrograph has a CDD camera detector package which must be cryogenically
cooled during scientific operation. In order to cool each of these camera systems a liquid nitrogen system has been
proposed and design study completed. The proposed system includes: a liquid nitrogen source, vacuum jacket
distribution system, local storage on the telescope, and distribution under a thermal siphon to the individual
spectrographs and local thermal connectors.
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