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  • 1990-1994  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4097-4102 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Double-barrier niobium tunnel junctions with the middle electrode thinner than the London penetration depth were fabricated. Their I-V curves, annealing behavior, response to external magnetic field, and response to 230 and 350 GHz irradiation in mixer experiments is discussed. Junctions with an integrated tuning circuit designed for the 230 GHz frequency range gave double-sideband receiver noise temperatures of 100 K. Vertically stack arrays can be attractive for various applications. Compared to single-barrier devices possible drawbacks were noted. The I-V curve indicates heating and/or nonequilibrium effects. Double-barrier devices became nonuniform after thermal annealing at 200 °C. The response to the external magnetic field is more complex and considerably larger flux densities are needed to suppress Josephson effects.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The y-ray source Geminga (2CG195 + 04) was first seen by the SAS-2 satellite (refs 2-4) in observations made roughly 20 years ago. Then, as now, it was one of the three strongest high-energy y-ray sources in the sky, the other two being the Crab and Vela pulsars PSR0531 + 21 and ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Following the SAS-2 and COS-B high-energy y-ray observations of the Crab (0531 + 21) and Vela (0833-45) pulsars1'2, searches were made for additional y-ray pulsars3'5. No other positive results were then found, but calculations have indicated that y-ray emission is likely from other ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 77 (1993), S. 61-64 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht SIS-Tunnel-Kontakte sind die zur Zeit besten Mischerelemente bei einer Wellenlänge zwischen 0.5 und 3 mm. Der Vortrag behandelt einen SIS-Empfänger für 0.86 mm Wellenlänge (345 GHz), der bisher viermal mit gutem wissenschaftlichen Ergebnis am für diese Wellenlänge größten Radioteleskop installiert war. Der Empfänger ist als sog. “offene Struktur” ausgeführt. Der SIS-Kontakt ist in einer planaren Dipolantenne auf einem dünnen Quarzsubstrat integriert. Bandsperrende Filter zur Einkopplung einer Vorspannung und Auskopplung der Zwischenfrequenz sind auf dem gleichen Substrat als supraleitende Dünnschichtschaltungen realisiert. Die Submm-Strahlung vom Radioteleskop und vom lokalen Oszillator (LO) werden durch eine asphärische Substratlinse aus Kristallquarz eingekoppelt. Der LO überdeckt mit einem Stellbereich von 324 bis 363 GHz gut das atmosphärische Fenster. Die Doppelseitenband (DSB)-Empfängerrauschtemperatur ist bei ausgewählten Frequenzen 〈80 K und liegt im größten Teil des Abstimmbereichs unter 100 K.
    Notes: Contents SIS tunnel junctions are at present the best mixer elements at wavelengths between 0.5 and 3 mm. This talk reports about a SIS receiver for 0,86 mm wavelength (345 GHz) which was used at the 30 m telescope on the Pico Veleta (Spain). The receiver was implemented in an “open structure” concept. The SIS tunnel junction is integrated into a planar dipole antenna on a quartz substrate. The submm radiation arriving from the radiotelescope and from the local oscillator (LO) is coupled to the planar dipole by an aspheric substrate lens made of crystal quartz. The LO has a tuning range of 324 to 363 GHz covering the atmospheric window. The double sideband (DSB) receiver noise temperature is 〈80 K at selected frequencies and 〈100 K in a large part of the tuning range.
    Type of Medium: Electronic Resource
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