The 1.1 THz multi-pixel heterodyne receiver will be mounted in the Nasmyth A cabin of the 12 m APEX telescope on the Chajnantor plateau, 5000 meters altitude in northern Chile. The receiver will cover the spectral window of 1000 - 1080 GHz, where important spectral lines like CO 9-8 at 1036.9 GHz, a tracer of warm and dense gas and OH+ at 1033 GHz and NH+ at 1012.6 GHz, both important for the study of chemical networks in the ISM, are located. The multi-pixel receiver greatly enhances the science output under the difficult observing conditions in this frequency range. Two 9-pixel focal plane sub-arrays on orthogonal polarizations are installed in easily removable cartridges. We developed a new thermal link to connect the cartridges to the cryostat. Our thermal link is an all-metal design: aluminum and Invar. All the optics is fully reflective, thus avoiding the absorption and reflection losses of dielectric lenses and reducing standing waves in the receiver. To guaranty internal optics alignment, we employ a monolithic integrated optics approach for the cold optics and the Focal Plane Unit (FPU) optics modeled after the CHARM (Compact Heterodyne Array Receiver Module) concept. The receiver uses synthesizer-driven solid-state local oscillators (LO) and the mixers will be balanced SIS mixers, which are essentially based on the design of the on-chip balanced SIS mixers at 490 GHz developed in our institute. Singleended HEB mixers are used for the laboratory tests of the optics. The LO power distribution is accommodated behind the FPU optics. It is composed of the LO optics, which includes a collimating Fourier grating, and an LO distribution plate to supply LO signal to each of the 9 pixels of the sub-array. Different options for the LO coupling design and fabrication are being analyzed and will be based on in-house hybrid waveguide/planar technology. We summarize the receiver project with emphasis on the cryogenics and the optics and present laboratory test results of the cryogenics, including the thermal link's performance. Beam pattern measurements of the receiver optics are scheduled for the coming days, but unfortunately could not be included in the current paper.
Supercam is a 345 GHz, 64-pixel heterodyne imaging array for the Heinrich Hertz Submillimeter Telescope
(HHSMT). By integrating SIS mixer devices with Low Noise Ampliers (LNAs) in 8 - 1x8 pixel modules, the
size needed for the cryostat and the complexity of internal wiring is signicantly reduced. All subsystems
including the optics, cryostat, bias system, IF boxes, and spectrometer have been integrated for all 64 pixels. In
the spring of 2012, SuperCam was installed on the HHSMT for an engineering run where it underwent system
level tests and performed rst light observations. In the fall of 2012 SuperCam will begin a 500 square degree
survey of the Galactic Plane in 12CO J=3-2. This large-scale survey will help answer fundamental questions
about the formation, physical conditions, and energetics of molecular clouds within the Milky Way. The data
set will be available via the web to all interested researchers.
The Stratospheric TeraHertz Observatory (STO) is a NASA funded, Long Duration Balloon (LDB) experiment designed to
address a key problem in modern astrophysics: understanding the Life Cycle of the Interstellar Medium (ISM). STO will
survey a section of the Galactic plane in the dominant interstellar cooling line [C II] (1.9 THz) and the important star
formation tracer [N II] (1.46 THz) at ~1 arc minute angular resolution, sufficient to spatially resolve atomic, ionic and
molecular clouds at 10 kpc. STO itself has three main components; 1) an 80 cm optical telescope, 2) a THz instrument
package, and 3) a gondola . Both the telescope and gondola have flown on previous experiments [2,3]. They have been reoptimized
for the current mission. The science flight receiver package will contain four [CII] and four [NII] HEB mixers,
coupled to a digital spectrometer. The first engineering test flight of STO was from Ft. Sumner, NM on October 15, 2009.
The ~30 day science flight is scheduled for December 2011.
We report on both laboratory and telescope integration results from SuperCam, a 64 pixel imaging spectrometer
designed for operation in the astrophysically important 870 micron atmospheric window. SuperCam will be used to
answer fundamental questions about the physics and chemistry of molecular clouds in the Galaxy and their direct
relation to star and planet formation. The SuperCam key project is a fully sampled Galactic plane survey covering over
500 square degrees of the Galaxy in 12CO(3-2) and 13CO(3-2) with 0.3 km/s velocity resolution
In the past, all heterodyne focal plane arrays have been constructed using discrete mixers, arrayed in the focal plane.
SuperCam reduces cryogenic and mechanical complexity by integrating multiple mixers and amplifiers into a single
array module with a single set of DC and IF connectors. These modules are housed in a closed-cycle cryostat with a
1.5W capacity 4K cooler. The SuperCam instrument is currently undergoing laboratory testing with four of the eight
mixer array modules installed in the cryostat (32 pixels). Work is now underway to perform the necessary modifications
at the 10m Heinrich Hertz Telescope to accept the SuperCam system. SuperCam will be installed in the cassegrain cabin
of the HHT, including the optical system, IF processing, spectrometers and control electronics. SuperCam will be
integrated with the HHT during the 2009-2010 observing season with 32 pixels installed. The system will be upgraded to
64 pixels during the summer of 2010 after assembly of the four additional mixer modules is completed.
We report on the development of SuperCam, a 64 pixel imaging spectrometer designed for operation in the
astrophysically important 870 micron atmospheric window. SuperCam will be used to answer fundamental questions
about the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation.
The Supercam key project is a fully sampled Galactic plane survey covering over 500 square degrees of the Galaxy in
12CO(3-2) and 13CO(3-2) with 0.3 km/s velocity resolution.
We report on the development of SuperCam, a 64 pixel, superheterodyne camera designed for operation in the astrophysically important 870 μm atmospheric window. SuperCam will be used to answer fundamental questions about
the physics and chemistry of molecular clouds in the Galaxy and their direct relation to star and planet formation. The
advent of such a system will provide an order of magnitude increase in mapping speed over what is now available and
revolutionize how observational astronomy is performed in this important wavelength regime.
Unlike the situation with bolometric detectors, heterodyne receiver systems are coherent, retaining information about
both the amplitude and phase of the incident photon stream. From this information a high resolution spectrum of the
incident light can be obtained without multiplexing. SuperCam will be constructed by stacking eight, 1×8 rows of fixed
tuned, SIS mixers. The IF output of each mixer will be connected to a low-noise, broadband MMIC amplifier integrated
into the mixer block. The instantaneous IF bandwidth of each pixel will be ~2 GHz, with a center frequency of 5 GHz.
A spectrum of the central 500 MHz of each IF band will be provided by the array spectrometer. Local oscillator power
is provided by a frequency multiplier whose output is divided between the pixels by using a matrix of waveguide power
dividers. The mixer array will be cooled to 4K by a closed-cycle refrigeration system. SuperCam will reside at the
Cassegrain focus of the 10m Heinrich Hertz telescope (HHT). A prototype single row of the array will be tested on the
HHT in 2006, with the first engineering run of the full array in late 2007. The array is designed and constructed so that
it may be readily scaled to higher frequencies.
In November 2003 the heterodyne receivers WANDA (polarization diplexed 492/810 GHz) and PoleSTAR (2x2 810 GHz array) of AST/RO (Antarctic Submillimeter Telescope and Remote Observatory, located at the South Pole) were upgraded with new 810 GHz SIS (Superconductor-Insulator-Superconductor) waveguide mixers from KOSMA. Profiting from device development for the HIFI (Heterodyne Instrument for the Far-Infrared) Band 2 SIS mixers of the Herschel Space Observatory, a factor of approx. 2 improvement in receiver noise temperature (from 1100 K to 550 K DSB) was achieved with WANDA. The SIS mixer devices employ low-loss NbTiN-Al tuning circuits and are fabricated using electron beam lithographic junction area definition and CMP (Chemical Mechanical Polishing) of the tuning circuit dielectric.
With the South Pole being one of the best possible sites for ground-based submillimeter astronomy, the 1.7 m telescope currently makes AST/RO well suited for sensitive, large scale spectral line mapping at 810 GHz. Low atmospheric opacity (tau < 1) and, consequently, very low system noise temperatures (< 3000 K) are regularly achieved at 810 GHz, making AST/RO an extremely sensitive observatory at these frequencies.
"First light" astronomical measurements made with the upgraded 810 GHz channel of WANDA towards the galactic HII region NGC 3576 in CO J=7-6 (806.65 GHz) and the neutral carbon [CI] 3P2-3P1 (809.3 GHz) lines are presented.