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Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P. |
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First 1.3 THz observations at the APEX telescope |
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2009 |
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Proc. 20th Int. Symp. Space Terahertz Technol. |
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54-61 |
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balanced HEB mixer noise temperature APEX telescope stability Allan variance aperture efficiency |
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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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Shaha, Jagdeep; Pinczukb, A.; Gossardb, A. C.; Wiegmannb, W. |
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Hot carrier energy loss rates in GaAs quantum wells: large differences between electrons and holes |
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1985 |
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Phys. B+C |
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134 |
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1-3 |
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174-178 |
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2DEG, GaAs/AlGaAs, heat flow, electron-phonon, hole-phonon, carrier-phonon, interactions |
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The first direct and separate determination of the hot electron and hot hole energy loss rates to the lattice shows unexpectedly large differences between electrons and holes in GaAs quantum wells. This large difference results from an anomalously low electron energy loss rate, which we attribute to the presence of non-equilibrium optical phonon rather than the effects of reduced dimensionality or dynamic screening. A model calculation of hot phonon effects is presented. |
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634 |
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de Lange, Gert; Krieg, Jean-Michel; Honingh, Netty; Karpov, Alexandre; Cherednichenko, Sergey |
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Performance of the HIFI flight mixers |
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2008 |
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Proc. 19th Int. Symp. Space Terahertz Technol. |
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98-105 |
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HEB mixer applications, HEB applications |
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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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Beck, M.; Klammer, M.; Lang, S.; Leiderer, P.; Kabanov, V. V.; Gol’tsman, G. N.; Demsar, J. |
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Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy |
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2011 |
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arXiv |
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NbN thin film, energy gap dynamics |
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Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. |
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Duplicated as 641 |
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1388 |
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Семенов, А. В.; Девятов, И. А.; Рябчун, С. А.; Масленников, С. Н.; Масленникова, А. С.; Ларионов, П. А.; Воронов, Б. М.; Чулкова, Г. М. |
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Поглощение терагерцового электромагнитного излучения в “грязной” сверхпроводниковой пленке при произвольном виде спектральных функций |
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2011 |
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Ж. Радиоэлектрон. |
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10 |
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7 |
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terahertz electromagnetic radiation; superconductors; detectors of terahertz range |
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A problem of absorption of high-frequency electromagnetic field in dirty superconductor is treated within Keldysh technic. Expression for the source term in the kinetic equation for quasiparticle distribution function is derived. The result is significant for deriving a consistent microscopic theory of superconducting detectors for terahertz frequency range, perspective detectors on kinetic inductance of current-biased superconducting strip and on Josephson inductance of tunnel.
В технике Келдыша рассмотрена задача о поглощении мощности высокочастотного электромагнитного поля в сверхпроводнике, удовлетворяющем условию грязного предела. Получено выражение для члена источника в кинетическом уравнении для функции распределения квазичастиц, справедливое при произвольном виде спектральных функций. Этот результат имеет значение для развития последовательной микроскопической теории сверхпроводниковых детекторов излучения терагерцового диапазона, в частности, перспективных детекторов на кинетической индуктивности смещённой током сверхпроводниковой полоски и джозефсоновской индуктивности туннельного контакта. |
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RPLAB @ gujma @ |
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713 |
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