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Proceedings Paper

Z-Spec, a broadband millimeter-wave grating spectrometer--design, construction, and first cryogenic measurements
Author(s): C. Matt Bradford; Peter A. R. Ade; James E. Aguirre; James J. Bock; Mark Dragovan; Lionel Duband; Lieko Earle; Jason Glenn; Hideo Matsuhara; Bret J. Naylor; Hien T. Nguyen; Minhee Yun; Jonas Zmuidzinas
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Paper Abstract

We present the design, integration, and first ryogenic testing of our new broad-band millimeter-wave spectrometer, Z-Spec. Z-Spec uses a novel architecture called WaFIRS (Waveguide Far-IR Spectrometer), which employs a curved diffraction grating in a parallel-plate waveguide propagation medium. The instrument will provide a resolving power betwee 200 and 350 across an instantaneous bandwidth of 190-310 GHz, all packaged within a cryostat that is of order 1 meter in size. For background-limited astronomical observations in the 1mm terrestrial window, Z-Spec uses 160 silicon nitride micro-mesh bolometers and the detectors and waveguide grating are cooled to ~0.1 K. Our first cryogenic measurements at 225 GHz show resolving power greater than 200, and the end-to-end throughput is estimated to be greater than 30%, possibly as high as 40%. Z-Spec represents the first systematic approach to cosmological redshift measurement that is not based on optical or near-IR identifications. With its good sensitivity and large bandwidth, Z-Spec provides a new capability for millimeter-wave astrophysics. The instrument will be capable of measureing rotational carbon monoxide line emission from bright dusty galaxies at redshifts of up to 4, and the broad bandwidth insures that at least two lines will be simultaneously detected, providing an unambiguous redshift determination. In addition to Z-Spec's observations over the next 1-3 years, the WaFIRS spectrometer architecture makes an excellent candidate for mid-IR to millimeter-wave spectrometers on future space-borned and suborbital platforms such as SPICA and SAFIR. The concept is dramatically more compact and lightweight than conventional free-space grating spectrometers, and no mirrors or lenses are used in the instrument. After the progress report on Z-Spec we highlight this capability.

Paper Details

Date Published: 8 October 2004
PDF: 11 pages
Proc. SPIE 5498, Millimeter and Submillimeter Detectors for Astronomy II, (8 October 2004); doi: 10.1117/12.552182
Show Author Affiliations
C. Matt Bradford, Jet Propulsion Lab. (United States)
Peter A. R. Ade, Cardiff Univ. (United Kingdom)
James E. Aguirre, Univ. of Colorado/Boulder (United States)
James J. Bock, Jet Propulsion Lab. (United States)
Mark Dragovan, Jet Propulsion Lab. (United States)
Lionel Duband, Commissariat a l'Energie Atomique (France)
Lieko Earle, Univ. of Colorado/Boulder (United States)
Jason Glenn, Univ. of Colorado/Boulder (United States)
Hideo Matsuhara, Institute of Space and Astronautical Science (Japan)
Bret J. Naylor, California Institute of Technology (United States)
Hien T. Nguyen, Jet Propulsion Lab. (United States)
Minhee Yun, Jet Propulsion Lab. (United States)
Jonas Zmuidzinas, California Institute of Technology (United States)

Published in SPIE Proceedings Vol. 5498:
Millimeter and Submillimeter Detectors for Astronomy II
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington, Editor(s)

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