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Proceedings Paper

THUMPER: the 200-um photometer for ground-based astronomy
Author(s): Richard J. Walker; Derek Ward-Thompson; Rhodri Evans; Sarah J. Leeks; Peter A. R. Ade; Matthew J. Griffin; Walter K. Gear; Brian Kiernan; Fred C. Gannaway; Stephen A. Rinehart; Henrique Araujo
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Paper Abstract

Atmospheric modelling predicts that a window at 200-μm occurs under very dry conditions at high altitude sites. The transmission can reach up to 30 % in the driest conditions, but also exists for as many as 80 nights per year at Mauna Kea. A 200-μm photometer, THUMPER, is currently under construction at Cardiff University for use at the JCMT to exploit this atmospheric window. THUMPER consists of a seven-element hexagonal array of stressed Ge:Ga photoconductors cooled to liquid helium temperature. Initial laboratory testing suggest an NEFD of (formula available in paper)should be possible, under conditions of 0.5-mm pwv. A dichroic splits the beam between SCUBA and THUMPER, allowing simultaneous observations with THUMPER effectively acting as a third SCUBA array. Photometric measurements at 200-μm, in conjunction with SCUBA, will provide valuable information on cold dust sources in the temperature range 10 to 50 K. Since SCUBA fails to sample the peak of the Planck function at these temperatures, it is not possible to differentiate between temperature and density variations across a source using SCUBA data alone. THUMPER will provide these additional data at the same spatial resolution as SCUBA. This will provide an unprecedented combination of wavelength coverage and resolution when imaging sources such as protostars and pre-stellar cores.

Paper Details

Date Published: 17 February 2003
PDF: 11 pages
Proc. SPIE 4855, Millimeter and Submillimeter Detectors for Astronomy, (17 February 2003); doi: 10.1117/12.459153
Show Author Affiliations
Richard J. Walker, Univ. of Wales/Cardiff (United Kingdom)
Derek Ward-Thompson, Univ. of Wales/Cardiff (United Kingdom)
Rhodri Evans, Univ. of Wales/Cardiff (United Kingdom)
Sarah J. Leeks, Univ. of Wales/Cardiff (United Kingdom)
Peter A. R. Ade, Univ. of Wales/Cardiff (United Kingdom)
Matthew J. Griffin, Univ. of Wales/Cardiff (United Kingdom)
Walter K. Gear, Univ. of Wales/Cardiff (United Kingdom)
Brian Kiernan, Univ. of Wales/Cardiff (United Kingdom)
Fred C. Gannaway, Univ. of Wales/Cardiff (United Kingdom)
Stephen A. Rinehart, NASA Goddard Space Flight Ctr. (United States)
Henrique Araujo, Imperial College of Science, Technology and Medicine (United Kingdom)

Published in SPIE Proceedings Vol. 4855:
Millimeter and Submillimeter Detectors for Astronomy
Thomas G. Phillips; Jonas Zmuidzinas, Editor(s)

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