Detectors and cryostat design for the SuMIRe Prime Focus Spectrograph (PFS)

James E. Gunn*a, Michael Carra, Stephen A. Smeeb, Joe D. Orndorffb, Robert H. Barkhouserb, Charles L. Bennettb, Jenny Greenea, Timothy Heckmanb, Hiroshi Karojid, Olivier Le Fevrec, Hung-Hsu Lingf, Laurent Martinc, Brice Ménardb,d, Hitoshi Murayamad, Eric Prietoc, David Spergela, Michael A. Straussa, Hajime Sugaid, Akitoshi Uedae, Shiang-Yu Wangf, Rosemary Wyseb, Nadia Zakamskab

aDepartment of Astrophysical Sciences, Princeton University, Princeton, NJ, 08544, (USA)
bDepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, (USA)
cLAM – Laboratoire d’Astrophysique de Marseille, Traverse du siphon, 13376 Marseille, (France)
dKavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Tokyo, (Japan)
eNational Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, (Japan)
fAcademia Sinica Institute of Astronomy and Astrophysics, Taipei 10617, (Taiwan)

We describe the conceptual design of the camera cryostats, detectors, and detector readout electronics for the SuMIRe Prime Focus Spectrograph (PFS) being developed for the Subaru telescope. The SuMIRe PFS will consist of four identical spectrographs, each receiving 600 fibers from a 2400 fiber robotic positioner at the prime focus. Each spectrograph will have three channels covering wavelength ranges 3800 Å – 6700 Å, 6500 Å – 10000 Å, and 9700 Å – 13000 Å, with the dispersed light being imaged in each channel by a f/1.10 vacuum Schmidt camera. In the blue and red channels a pair of Hamamatsu 2K x 4K edge-buttable CCDs with 15 um pixels are used to form a 4K x 4K array. For the IR channel, the new Teledyne 4K x 4K, 15 um pixel, mercury-cadmium-telluride sensor with substrate removed for short-wavelength response and a 1.7 um cutoff will be used. Identical detector geometry and a nearly identical optical design allow for a common cryostat design with the only notable difference being the need for a cold radiation shield in the IR camera to mitigate thermal background. This paper describes the details of the cryostat design and cooling scheme, relevant thermal considerations and analysis, and discusses the detectors and detector readout electronics.


James E. Gunn et al., “Detectors and cryostat design for the SuMIRe Prime Focus Spectrograph (PFS)”, Ground-based and Airborne Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki Takami, Editors, Proc. SPIE 8446 (2012).

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