The upcoming Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) has provided motivation for upgrading the Hobby-Eberly Telescope (HET) at the McDonald Observatory. This upgrade includes an increase in the field-of-view to accommodate the new and revolutionary Visible Integral-field Replicable Unit Spectrograph (VIRUS). VIRUS is the instrument designed to conduct the HETDEX survey and consists of 150 individual integral-field spectrographs fed by 33,600 total optical fibers covering the 22 arc-minute field-of-view of the upgraded HET. The spectrographs are mounted in four enclosures, each 6.0×3.0×1.4 meters in size. Each spectrograph contains a CCD detector that must be cryogenically cooled, presenting an interesting cryogenic and vacuum challenge within the distribution system. In this paper, we review the proposed vacuum jacketed, thermal siphon, liquid nitrogen distribution system used to cool the array of detectors and discuss recent developments. We focus on the design, prototyping, and testing of a novel "make-break" thermal connector, built from a modified cryogenic bayonet, that is used to quickly detach a single spectrograph pair from the system.

Date Published: 20 July 2010
PDF: 15 pages
Proc. SPIE 7735, Ground-based and Airborne Instrumentation for Astronomy III, 773576 (20 July 2010); doi: 10.1117/12.857362

Published in SPIE Proceedings Vol. 7735:
Ground-based and Airborne Instrumentation for Astronomy III
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)