12 research outputs found
A New 100-GHz Band Front-End System with a Waveguide-Type Dual-Polarization Sideband-Separating SIS Receiver for the NRO 45-m Radio Telescope
We developed a waveguide-type dual-polarization sideband-separating SIS
receiver system of the 100-GHz band for the 45-m radio telescope at the
Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho-mode
transducer and two sideband-separating SIS mixers, which are both based on the
waveguide technique. The receiver has four intermediate frequency bands of
4.0--8.0 GHz. Over the radio frequency range of 80--120 GHz, the
single-sideband receiver noise temperatures are 50--100 K and the image
rejection ratios are greater than 10 dB. We developed new matching optics for
the telescope beam as well as new IF chains for the four IF signals. The new
receiver system was installed in the telescope, and we successfully observed
the 12CO, 13CO and C18O emission lines simultaneously toward the Sagittarius B2
region to confirm the performance of the receiver system. The SSB noise
temperature of the system, including the atmosphere, became approximately half
of that of the previous receiver system. The Image Rejection Ratios (IRRs) of
the two 2SB mixers were calculated from the 12CO and HCO+ spectra from the W51
giant molecular cloud, resulting in > 20 dB for one polarization and > 12 dB
for the other polarization.Comment: 10 pages, 13 figures, Accepted for publication in PASJ, version with
high resolution figures is available via
http://www.nro.nao.ac.jp/library/report/list.htm
New 60-cm Radio Survey Telescope with the Sideband-Separating SIS Receiver for the 200 GHz Band
We have upgraded the 60-cm radio survey telescope located in Nobeyama, Japan.
We developed a new waveguide-type sideband-separating SIS mixer for the
telescope, which enables the simultaneous detection of distinct molecular
emission lines both in the upper and lower sidebands. Over the RF frequency
range of 205-240 GHz, the single-sideband receiver noise temperatures of the
new mixer are 40-100 K for the 4.0-8.0 GHz IF frequency band. The image
rejection ratios are greater than 10 dB over the same range. For the dual IF
signals obtained by the receiver, we have developed two sets of acousto-optical
spectrometers and a telescope control system. Using the new telescope system,
we successfully detected the 12CO (J=2-1) and 13CO (J=2-1) emission lines
simultaneously toward Orion KL in 2005 March. Using the waveguide-type
sideband-separating SIS mixer for the 200 GHz band, we have initiated the first
simultaneous 12CO (J=2-1) and 13CO (J=2-1) survey of the galactic plane as well
as large-scale mapping observations of nearby molecular clouds.Comment: 15 pages, 15 figures, Accepted for publication in PASJ, version with
high resolution figures is available via
http://www.nro.nao.ac.jp/~nakajima/vst1_2sb.pd
The Atacama Large Millimeter/submillimeter Array (ALMA) Band-1 Receiver
The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers
the 35-50 GHz frequency band. Development of prototype receivers, including the
key components and subsystems has been completed and two sets of prototype
receivers were fully tested. We will provide an overview of the ALMA Band 1
science goals, and its requirements and design for use on the ALMA. The
receiver development status will also be discussed and the infrastructure,
integration, evaluation of fully-assembled band 1 receiver system will be
covered. Finally, a discussion of the technical and management challenges
encountered will be presented
First light demonstration of the integrated superconducting spectrometer
Ultra-wideband 3D imaging spectrometry in the millimeter-submillimeter
(mm-submm) band is an essential tool for uncovering the dust-enshrouded portion
of the cosmic history of star formation and galaxy evolution. However, it is
challenging to scale up conventional coherent heterodyne receivers or
free-space diffraction techniques to sufficient bandwidths (1 octave) and
numbers of spatial pixels (>). Here we present the design and first
astronomical spectra of an intrinsically scalable, integrated superconducting
spectrometer, which covers 332-377 GHz with a spectral resolution of . It combines the multiplexing advantage of microwave kinetic
inductance detectors (MKIDs) with planar superconducting filters for dispersing
the signal in a single, small superconducting integrated circuit. We
demonstrate the two key applications for an instrument of this type: as an
efficient redshift machine, and as a fast multi-line spectral mapper of
extended areas. The line detection sensitivity is in excellent agreement with
the instrument design and laboratory performance, reaching the atmospheric
foreground photon noise limit on sky. The design can be scaled to bandwidths in
excess of an octave, spectral resolution up to a few thousand and frequencies
up to 1.1 THz. The miniature chip footprint of a few
allows for compact multi-pixel spectral imagers, which would enable
spectroscopic direct imaging and large volume spectroscopic surveys that are
several orders of magnitude faster than what is currently possible.Comment: Published in Nature Astronomy. SharedIt Link to the full published
paper: https://rdcu.be/bM2F
ALMA Band 1 Optics (35–50 GHz):Tolerance analysis, effect of cryostat infrared filters and cold beam measurements
\u3cp\u3eThe Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35–50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance.\u3c/p\u3