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| Author |
Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P. |
| Title |
First 1.3 THz observations at the APEX telescope |
Type  |
Conference Article |
| Year |
2009 |
Publication |
Proc. 20th Int. Symp. Space Terahertz Technol. |
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Pages |
54-61 |
| Keywords |
balanced HEB mixer noise temperature APEX telescope stability Allan variance aperture efficiency |
| Abstract |
The Atacama Pathfinder EXperiment (APEX) 12m telescope is operating on the Llano Chajnantor, Chile, since 2003 and a set of state of the art sub-millimeter receivers have been installed for frequencies spanning from 150 GHz to 1500 GHz. In 2008, a balanced 1.3 THz Hot Electron Bolometer (HEB) receiver was installed for the atmospheric window 1250-1380 GHz. This instrument is part of a 4-channel receiver cryostat with the other channels being 211-275 GHz, 275-370 GHz and 380-500 GHz Sideband Separating (SSB) SIS receivers. This paper presents the first observations obtained so far with the 1.3 THz band during its first months of operation. The sky measurements were taken during opportunistic commissioning and science verification phases, when the weather conditions were sufficiently good with a Precipitable Water Vapor (PWV) below 0.25 mm, which was the case only a few nights during these months. We present the first observations of the molecular transition CO J=(11-10) line on different sources such as Orion-FIR4, CW-Leo and SgrB2(M). We describe the many challenges and difficulties encountered for achieving successful THz observations from a large sub-millimeter ground-based telescope. |
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619 |
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| Author |
de Lange, Gert; Krieg, Jean-Michel; Honingh, Netty; Karpov, Alexandre; Cherednichenko, Sergey |
| Title |
Performance of the HIFI flight mixers |
Type |
Conference Article |
| Year |
2008 |
Publication |
Proc. 19th Int. Symp. Space Terahertz Technol. |
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Pages |
98-105 |
| Keywords |
HEB mixer applications, HEB applications |
| Abstract |
We summarize the technology and final results of the superconducting heterodyne SIS and HEB mixers that are developed for the HIFI instrument. Within HIFI 7 frequency bands cover the frequency range from 480 GHz to 1910 GHz. We describe the different device technologies and optical coupling schemes that are used to cover the frequency bands. The efforts of the different mixer teams that participate in HIFI have contributed to an instrument that will have unprecedented sensitivity and frequency coverage. |
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Groningen |
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1074 |
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| Author |
Lobanov, Y.; Tong, C.; Blundell, R.; Gol'tsman, G. |
| Title |
A study of direct detection effect on the linearity of hot electron bolometer mixers |
Type |
Conference Article |
| Year |
2009 |
Publication |
Proc. 20th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 20th ISSTT |
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Issue |
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Pages |
282-287 |
| Keywords |
HEB mixer, direct detection effect |
| Abstract |
We have performed a study of how direct detection affects the linearity and hence the calibration of an HEB mixer. Two types of waveguide HEB devices have been used: a 0.8 THz HEB mixer and a 1.0 THz HEB mixer which is ~5 times smaller than the former. Two independent experimental approaches were used. In the ΔG/G method, the conversion gain of the HEB mixer is first measured as a function of the bias current for a number of bias voltages. At each bias setting, we carefully measure the change in the operating current when the input loads are switched. From the measured data, we can derive the expected difference in gain between the hot and cold loads. In the second method (injection method [1]), the linearity of the HEB mixer is independently measured by injecting a modulated signal for different input load temperatures. The results of both approaches confirm that there is gain compression in the operation of HEB mixers. Based on the results of our measurements, we discuss the impact of direct detection effects on the operation of HEB mixers. |
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RPLAB @ gujma @ |
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724 |
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| Author |
Lobanov, Y. V.; Tong, Cheuk-Yu E.; Hedden, A. S.; Blundell, R.; Gol'tsman, G. N. |
| Title |
Microwave-assisted슠measurement슠of the슠frequency슠response슠of슠terahertz슠HEB슠mixers슠with a슠fourier슠transform슠spectrometer |
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Conference Article |
| Year |
2010 |
Publication |
21st International Symposium on Space Terahertz Technology |
Abbreviated Journal |
21st ISSTT |
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420-423 |
| Keywords |
HEB mixer |
| Abstract |
We describe a novel method of operation of the HEB direct detector for use with a Fourier Transform Spectrometer. Instead of elevating the bath temperature, we have measured the RF response of waveguide HEB mixers by applying microwave radiation to select appropriate bias conditions. In our experiment, a microwave signal is injected into the HEB mixer via its IF port. By choosing an appropriate injection level, the device can be operated close to the desired operating point. Furthermore, we have shown that both thermal biasing and microwave injection can reproduce the same spectral response of the HEB mixer. However, with the use of microwave injection, there is no need to wait for the mixer to reach thermal equilibrium, so characterisation can be done in less time. Also, the liquid helium consumption for our wet cryostat is also reduced. We have demonstrated that the signalto-noise ratio of the FTS measurements can be improved with microwave injection. |
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RPLAB @ gujma @ |
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725 |
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| Author |
Shurakov, Alexander; Tong, Edward; Blundell, Raymond; Gol'tsman, Gregory |
| Title |
Microwave stabilization of HEB mixer by a microchip controller |
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Conference Article |
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2012 |
Publication |
IEEE MTT-S international microwave symposium digest |
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1-3 |
| Keywords |
HEB mixer stability, microwave injection, Allan variance, Allan time |
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The stability of a Hot Electron Bolometer (HEB) mixer can be improved by the use of microwave injection. In this article we report a refinement of this approach. We introduce a microchip controller to facilitate the implementation of the stabilization scheme, and demonstrate that the feedback loop effectively suppresses drifts in the HEB bias current, leading to an improvement in the receiver stability. The measured Allan time of the mixer's IF output power is increased to > 10 s. |
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Montreal, QC, Canada |
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857 |
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Khosropanah, P.; Merkel, H.; Yngvesson, S.; Adam, A.; Cherednichenko, S.; Kollberg, E. |
| Title |
A distributed device model for phonon-cooled HEB mixers predicting IV characteristics, gain, noise and IF bandwidth |
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Conference Article |
| Year |
2000 |
Publication |
Proc. 11th Int. Symp. Space Terahertz Technol. |
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474-488 |
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HEB mixer numerical model, diffusion cooling channel, diffusion channel, distributed HEB model, distributed model |
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A distributed model for phonon-cooled superconductor hot electron bolometer (HEB) mixers is given, which is based on solving the one-dimensional heat balance equation for the electron temperature profile along the superconductor strip. In this model it is assumed that the LO power is absorbed uniformly along the bridge but the DC power absorption depends on the local resistivity and is thus not uniform. The electron temperature dependence of the resistivity is assumed to be continuous and has a Fermi form. These assumptions are used in setting up the non-linear heat balance equation, which is solved numerically for the electron temperature profile along the bolometer strip. Based on this profile the resistance of the device and the IV curves are calculated. The IV curves are in excellent agreement with measurement results. Using a small signal model the conversion gain of the mixer is obtained. The expressions for Johnson noise and thermal fluctuation noise are derived. The calculated results are in close agreement with measurements, provided that one of the parameters used is adjusted. |
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University of Michigan, Ann Arbor, MI USA |
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893 |
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Ynvesson, K. Sigfrid; Kollberg, Erik L. |
| Title |
Optimum receiver noise temperature for NbN HEB mixers according to standard model |
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Conference Article |
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1999 |
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Proc. 10th Int. Symp. Space Terahertz Technol. |
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566-582 |
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HEB mixer model, standard model, electro-thermal feedback, self-heating parameter, heating efficiency |
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895 |
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Leisawitz, David T.; Danchi, William C.; Dipirro, Michael J.; Feinberg, Lee D.; Gezari, Daniel Y.; Hagopian, Mike; Langer, William D.; Mather, John C.; Moseley, Jr. Samuel H.; Shao, Michael; Silverberg, Robert F.; Staguhn, Johannes G.; Swain, Mark R.; Yorke, Harold W.; Zhang, Xiaolei |
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Scientific motivation and technology requirements for the SPIRIT and SPECS far-infrared/submillimeter space interferometers |
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Conference Article |
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2000 |
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Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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4013 |
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36-46 |
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HEB applications |
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Far infrared interferometers in space would enable extraordinary measurements of the early universe, the formation of galaxies, stars, and planets, and would have great discovery potential. Since half the luminosity of the universe and 98% of the photons released since the Big Bang are now observable at far IR wavelengths (40 – 500 micrometers ), and the Earth's atmosphere prevents sensitive observations from the ground, this is one of the last unexplored frontiers of space astronomy. We present the engineering and technology requirements that stem from a set of compelling scientific goals and discuss possible configurations for two proposed NASA missions, the Space Infrared Interferometric Telescope and the Submillimeter Probe of the Evolution of Cosmic Structure. |
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909 |
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Klapwijk, T. M.; Barends, R.; Gao, J. R.; Hajenius, M.; Baselmans, J. J. A. |
| Title |
Improved superconducting hot-electron bolometer devices for the THz range |
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Conference Article |
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2004 |
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Proc. SPIE |
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Proc. SPIE |
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5498 |
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129-139 |
| Keywords |
HEB mixer distributed model, numerical model |
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Improved and reproducible heterodyne mixing (noise temperatures of 950 K at 2.5 THz) has been realized with NbN based hot-electron superconducting devices with low contact resistances. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, has been used to understand the physical conditions during the mixing process. We find that the mixing is predominantly due to the exponential rise of the local resistivity as a function of electron temperature. |
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Invited talk, Recommended by Klapwijk |
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912 |
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Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Golts'man, G.; Gershenzon, E.; Voronov B. |
| Title |
Superconductive NbN hot-electron bolometric mixer performance at 250 GHz |
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Conference Article |
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1996 |
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Proc. 7th Int. Symp. Space Terahertz Technol. |
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Proc. 7th Int. Symp. Space Terahertz Technol. |
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331-336 |
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NbN HEB mixers |
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Thin film NbN (<40 A) strips are used as waveguide mixer elements. The electron cooling mechanism for the geometry is the electron-phonon interaction. We report a receiver noise temperature of 750 K at 244 GHz, with / IF = 1.5 GHz, Af= 500 MHz, and Tphysical = 4 K. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator (LO) power is 0.5 1.tW with 3 dB-uncertainty. The mixer is linear to 1 dB up to an input power level 6 dB below the LO power. We report the first detection of a molecular line emission using this class of mixer, and that the receiver noise temperature determined from Y-factor measurements reflects the true heterodyne sensitivity. |
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945 |
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