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Proceedings Paper

First light of DESHIMA on ASTE: on-chip filterbank spectrometer for submillimeter wave astronomy (Conference Presentation)
Author(s): Akira Endo; Kenichi Karatsu; Yoichi Tamura; Shun Ishii; Tatsuya Takekoshi; Tai Oshima; Akio Taniguchi; Tsuyoshi Ishida; Koyo Suzuki; David Thoen; Robert Huiting; Toshihiko Kobiki; Tom Bakx; Kaui Chin; Kazuyuki Fujita; Vignesh Murugesan; Sjoerd Bosma; Ozan Yurduseven; Tetsutaro Ueda; Masato Naruse; Shunichi Nakatsubo; Akira Kouchi; Jun Maekawa; Stephen Yates; Nuria Llombart; Teun Klapwijk; Ryohei Kawabe; Shin'ichiro Asayama; Paul van der Werf; Kotaro Kohno; Jochem Baselmans

Paper Abstract

An ultra-wideband, large field-of-view (sub)millimeter wave imaging spectrometer is imperative for uncovering the evolution of dust-enshrouded cosmic star formation rate, galaxy evolution, and structure formation, over cosmic time. Here we report the first on-sky demonstration of DESHIMA. DESHIMA (Deep Spectroscopic High-redshift Mapper) is a new type of submillimeter wave spectrometer, which uses a superconducting filterbank on a chip to achieve a very wide instantaneous bandwidth. Compared to an optical spectrometer with equivalent performance, such an on-chip spectrometer is not only compact, but also offers a higher degree of potential scalability to multiple spatial pixels. On the filterbank spectrometer chip of DESHIMA, the signal captured by the lens-antenna travels through a coplanar waveguide made of superconducting NbTiN, from which planar NbTiN bandpass filters branch out to divide the signal into frequency channels. At the output of each filter is a NbTiN/Al hybrid kinetic inductance detector (KID). These KIDs are operated at 120 mK with a 2-stage adiabatic demagnetization refrigerator (ADR), and their response is read out using the SpaceKIDs readout electronics. Being in its phase-1 configuration, DESHIMA currently covers the 330-370 GHz band with 49 spectral channels, offering a spectral resolution F/dF = 400, or dV = 700 km/s. This design is intended as a scalable prototype towards the phase-2 DESHIMA instrument, which targets at 240-720 GHz instantaneous band coverage with a resolution of F/dF = 500 (dV = 600 km/s), and >2 spatial pixels. In the laboratory, the sensitivity and frequency response of DESHIMA was characterized using a black-body calibration source and a THz photo-mixer source, respectively. The sensitivity is photon-noise limited at a detector loading power of ~1 pW, with a photon-noise limited optical Noise Equivalent Power of 1-2 x 10^-16 W Hz^-0.5. From October to November 2017, DESHIMA was installed on the Atacama Submillimeter Telescope Experiment (ASTE), a 10 m diameter antenna in the Atacama Desert of Chile. The sensitivity of DESHIMA measured inside the ASTE cabin is similar to lab results. At the time of submission of the abstract, DESHIMA has successfully detected multiple astronomical sources, in both continuum and line emission. At the conference we will report the lessons learned in the first actual operation of an on-chip filterbank spectrometer on a telescope, including the influence of thermal cycles on the filters, system susceptibility to telescope environment and motion, on-sky beam pattern, and sensitivity to continuum and line emission.

Paper Details

Date Published: 10 July 2018
Proc. SPIE 10708, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, 107080N (10 July 2018); doi: 10.1117/12.2309804
Show Author Affiliations
Akira Endo, Technische Univ. Delft (Netherlands)
Kenichi Karatsu, SRON Netherlands Institute for Space Research (Netherlands)
Yoichi Tamura, Nagoya Univ. (Japan)
Shun Ishii, National Astronomical Observatory of Japan (Japan)
Tatsuya Takekoshi, The Univ. of Tokyo (Japan)
Tai Oshima, National Astronomical Observatory of Japan (Japan)
Akio Taniguchi, The Univ. of Tokyo (Japan)
Tsuyoshi Ishida, The Univ. of Tokyo (Japan)
Koyo Suzuki, Nagoya Univ. (Japan)
David Thoen, Technische Univ. Delft (Netherlands)
Robert Huiting, SRON Netherlands Institute for Space Research (Netherlands)
Toshihiko Kobiki, National Astronomical Observatory of Japan (Japan)
Tom Bakx, Cardiff Univ. (United Kingdom)
Kaui Chin, The Univ. of Tokyo (Japan)
Kazuyuki Fujita, Hokkaido Univ. (Japan)
Vignesh Murugesan, SRON Netherlands Institute for Space Research (Netherlands)
Sjoerd Bosma, Technische Univ. Delft (Netherlands)
Ozan Yurduseven, Technische Univ. Delft (Netherlands)
Tetsutaro Ueda, Nagoya Univ. (Japan)
Masato Naruse, Saitama Univ. (Japan)
Shunichi Nakatsubo, Japan Aerospace Exploration Agency (Japan)
Akira Kouchi, Hokkaido Univ. (Japan)
Jun Maekawa, National Astronomical Observatory of Japan (Japan)
Stephen Yates, SRON Netherlands Institute for Space Research (Netherlands)
Nuria Llombart, Technische Univ. Delft (Netherlands)
Teun Klapwijk, Technische Univ. Delft (Netherlands)
Ryohei Kawabe, National Astronomical Observatory of Japan (Japan)
Shin'ichiro Asayama, National Astronomical Observatory of Japan (Japan)
Paul van der Werf, Leiden Univ. (Netherlands)
Kotaro Kohno, The Univ. of Tokyo (Japan)
Jochem Baselmans, SRON Netherlands Institute for Space Research (Netherlands)
Technische Univ. Delft (Netherlands)

Published in SPIE Proceedings Vol. 10708:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX
Jonas Zmuidzinas; Jian-Rong Gao, Editor(s)

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