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Author Tong, C.-Y.E.; Meledin, D.V.; Marrone, D.P.; Paine, S.N.; Gibson, H.; Blundell, R.
Title Near field vector beam measurements at 1 THz Type Journal Article
Year 2003 Publication IEEE Microw. Compon. Lett. Abbreviated Journal
Volume 13 Issue 6 Pages 235-237
Keywords HEB, mixer, waveguide, LO power, local oscillator power, saturation effect, dynamic range
Abstract We have performed near-field vector beam measurements at 1.03 THz to characterize and align the receiver optics of a superconducting receiver. The signal source is a harmonic generator mounted on an X-Y translation stage. We model the measured two-dimensional complex beam pattern by a fundamental Gaussian mode, from which we derive the position of the beam center, the beam radius and the direction of propagation. By performing scans in the planes separated by 400 mm, we have confirmed that our beam pattern measurements are highly reliable.
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ISSN 1531-1309 ISBN Medium
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Notes Approved no
Call Number RPLAB @ lobanovyury @ Serial 574
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Author Wei, Jian; Olaya, David; Karasik, Boris S.; Pereverzev, Sergey V.; Sergeev, Andrei V.; Gershenson, Michael E.
Title Ultrasensitive hot-electron nanobolometers for terahertz astrophysics Type Journal Article
Year 2008 Publication Nature Nanotechnology Abbreviated Journal Nature Nanotech
Volume 3 Issue 8 Pages 496-500
Keywords HEB, Ti/NbN, single terahertz photons, detection
Abstract The submillimetre or terahertz region of the electromagnetic spectrum contains approximately half of the total luminosity of the Universe and 98% of all the photons emitted since the Big Bang. This radiation is strongly absorbed in the Earth's atmosphere, so space-based terahertz telescopes are crucial for exploring the evolution of the Universe. Thermal emission from the primary mirrors in these telescopes can be reduced below the level of the cosmic background by active cooling, which expands the range of faint objects that can be observed. However, it will also be necessary to develop bolometers – devices for measuring the energy of electromagnetic radiation—with sensitivities that are at least two orders of magnitude better than the present state of the art. To achieve this sensitivity without sacrificing operating speed, two conditions are required. First, the bolometer should be exceptionally well thermally isolated from the environment;

second, its heat capacity should be sufficiently small. Here we demonstrate that these goals can be achieved by building a superconducting hot-electron nanobolometer. Its design eliminates the energy exchange between hot electrons and the leads by blocking electron outdiffusion and photon emission. The thermal conductance between hot electrons and the thermal bath, controlled by electron–phonon interactions, becomes very small at low temperatures (10-16 WK-1 at 40 mK). These devices, with a heat capacity of 10-19 J K-1, are sufficiently sensitive to detect single terahertz photons in submillimetre astronomy and other applications based on quantum calorimetry and photon counting.
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ISSN 1748-3387 ISBN Medium
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Notes Approved no
Call Number Serial 576
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Author van't Klooster, K.; Myasnikova, S. E.; Parshin, V. V.; Kasparek, W.
Title Results of reflection loss measurements of sample material for radio astronomy telescope antenna for Planck Project Type Conference Article
Year 2004 Publication Proc. 14th international crimean conference on microwave and telecommunication technology Abbreviated Journal
Volume Issue Pages 753-755
Keywords mirror, reflection index, emissivity, Fabry-Perot interferometer, space observatory, terahertz, THz
Abstract Advanced radio telescope antennas for space applications are realised by the use of stable composite materials, which are lighter in general than various metal realisations. Reflectivity measurements have been carried out on high technology samples for the Planck radio telescope. Highly accurate results have been obtained at the Applied Physics Institute in Nizhny Novgorod, and an independent measurement with a totally different setup at the University of Stuttgart confirmed that one of the samples showed a strange behaviour. Moreover, it confirmed the high accuracy of the testing method.
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Notes Approved no
Call Number Serial 579
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Author Shitov, S. V.; Inatani, J.; Shan, W.-L.; Takeda, M; Wang, Z.; Uvarov, A. V.; Ermakov, A. B.; Uzawa, Y.
Title Measurement of emissivity of the ALMA antenna panel at 840 GHz using NbN-based heterodyne SIS receiver Type Conference Article
Year 2008 Publication Proc. 19th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 263-266
Keywords SIS mixer, reflection, emissivity, mirror, space telescope, space observatory
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Call Number Serial 580
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Author Kasparek, W; Fernandez, A.; Hollmann, F; Wacker, R.
Title Measurements of ohmic losses of metallic reflectors at 140 GHz using a 3-mirror resonator technique Type Journal Article
Year 2001 Publication Int. J. Infrared and Millimeter Waves Abbreviated Journal
Volume 22 Issue 11 Pages 1695-1707
Keywords mirror, reflection index, emissivity, Fabry-Perot interferometer, subterahertz, subTHz
Abstract The reflectivity of metallic mirrors in the millimeter wave region does not only depend on the material, but also on the structure and roughness of the surface. We have performed measurements of the reflectivity of various plane and grooved metallic and graphite samples at 140 GHz. The technique is based on the comparison of the quality factor of a 2-mirror reference resonator with the quality factor of a 3-mirror resonator which has identical dimensions and includes the mirror to be tested. After a brief presentation of the theory, the set-up is described and the reflection loss for various aluminium and copper mirrors as well as vacuum compatible materials for applications in thermonuclear fusion experiments are presented and discussed.
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Notes Approved no
Call Number Serial 581
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