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Proceedings Paper

Cooling the Dark Energy Camera instrument
Author(s): R. L. Schmitt; H. Cease; D. DePoy; H. T. Diehl; J. Estrada; B. Flaugher; S. Kuhlmann; Birce Onal; A. Stefanik
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Paper Abstract

DECam, camera for the Dark Energy Survey (DES), is undergoing general design and component testing. For an overview see DePoy, et al in these proceedings. For a description of the imager, see Cease, et al in these proceedings. The CCD instrument will be mounted at the prime focus of the CTIO Blanco 4m telescope. The instrument temperature will be 173K with a heat load of 113W. In similar applications, cooling CCD instruments at the prime focus has been accomplished by three general methods. Liquid nitrogen reservoirs have been constructed to operate in any orientation, pulse tube cryocoolers have been used when tilt angles are limited and Joule-Thompson or Stirling cryocoolers have been used with smaller heat loads. Gifford-MacMahon cooling has been used at the Cassegrain but not at the prime focus. For DES, the combined requirements of high heat load, temperature stability, low vibration, operation in any orientation, liquid nitrogen cost and limited space available led to the design of a pumped, closed loop, circulating nitrogen system. At zenith the instrument will be twelve meters above the pump/cryocooler station. This cooling system expected to have a 10,000 hour maintenance interval. This paper will describe the engineering basis including the thermal model, unbalanced forces, cooldown time, the single and two-phase flow model.

Paper Details

Date Published: 9 July 2008
PDF: 11 pages
Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 70146O (9 July 2008); doi: 10.1117/12.786794
Show Author Affiliations
R. L. Schmitt, Fermi National Accelerator Lab. (United States)
H. Cease, Fermi National Accelerator Lab. (United States)
D. DePoy, The Ohio State Univ. (United States)
H. T. Diehl, Fermi National Accelerator Lab. (United States)
J. Estrada, Fermi National Accelerator Lab. (United States)
B. Flaugher, Fermi National Accelerator Lab. (United States)
S. Kuhlmann, Argonne National Lab. (United States)
Birce Onal, Fermi National Accelerator Lab. (United States)
A. Stefanik, Fermi National Accelerator Lab. (United States)


Published in SPIE Proceedings Vol. 7014:
Ground-based and Airborne Instrumentation for Astronomy II
Ian S. McLean; Mark M. Casali, Editor(s)

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