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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2444-2446 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose an antenna-coupled microbolometer based on the resistive transition of a high Tc superconducting film as a detector for far infrared and millimeter waves. Such microbolometers can be mechanically stronger, more easily fabricated, and much faster than conventional bolometric infrared detectors. A design analysis shows that a noise equivalent power of 2.5×10−12 W Hz−1/2 is achievable for modulation frequencies up to 10 kHz. The superconducting film must be of high quality with narrow resistive transition and low 1/f noise.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2329-2331 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a novel antenna-coupled low Tc superconducting bolometer which makes use of the thermal boundary resistance and the trapping of quasiparticles at metal-superconducting interfaces. A thin strip of superconductor, whose temperature is regulated at the midpoint of its resistive transition, serves both as a resistive load to thermalize the infrared current from the antenna and as a thermometer to measure the resulting temperature rise. Calculations give a noise equivalent power (NEP)≈7×10−16 T5/2 WHz−1/2 and a time constant τ≈10−8 T−2 s for a 2×2 μm2 thermometer area at temperature T (K). Designs for efficient on-chip rf matching and filter networks with well-defined bandpasses are presented. These detectors can be used to make frequency-multiplexed array receivers for astronomical observations at near millimeter wavelengths.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A design analysis is given for a bolometric infrared detector that uses the resistive transition of a high-temperature superconductor as the temperature sensing element, and liquid nitrogen (LN) as the coolant. It is shown that for highly oriented c-axis films, the measured low-frequency noise causes little or no degradation of the performance. With the incoming radiation chopped at 10 Hz, noise equivalent powers (NEP) in the range (1–20)×10−12 W Hz−1/2 should be achievable. These values compare favorably with the NEP of other detectors operating at or above LN temperatures for wavelengths greater than 20 μm.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1-24 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This review describes bolometric detectors for infrared and millimeter waves. The introduction sketches the history of modern bolometers, indicates how they fit into the more general class of thermal detectors, and describes the types of applications for which they are the optimum solution. Section I is a tutorial introduction to the elementary theories of bolometer response, of thermal radiation, and of bolometer noise. Important results are derived from the laws of thermal physics in the simplest possible way. The more rigorous theories of bolometer response and noise that are required for quantitative understanding and optimization are then summarized. This material is intended to provide the background required by workers who wish to choose the appropriate bolometer technology for a given measurement, or to evaluate a novel technology. Section II, then describes the various components of an efficient bolometer and gives details of the fabrication and performance of modern bolometers. This discussion focuses on composite bolometers with semiconducting thermometers for operation at and below liquid helium temperatures. The tradeoffs involved in using superconducting thermometers at low temperatures are discussed. Finally, a discussion is given of bolometers for operation at liquid nitrogen temperature which use the new high-Tc superconductors as thermometers.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2013-08-31
    Description: Information is given in viewgraph form. Information is given on the characteristics of stressed Ge:Ga, a spring type stress cavity, mounting hardware, materials parameters affecting dark current, and the behavior of low dark current stressed Ge:Ga. It is concluded that detectors exist today for background-limited detection at 200 microns, that researchers are narrowing in on the significant parameters that effect dark current in stressed photoconductors, that these findings may be applied to other photoconductor materials, and that some creative problem solving for an ionizing effect reset mechanism is needed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Ames Research Center, Proceedings of the Third Infrared Detector Technology Workshop; p 5-2
    Format: application/pdf
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  • 7
    Publication Date: 2013-08-31
    Description: We have developed a sensitive bolometric receiver for low background space applications. In a 10 percent bandwidth at 1 THz, this receiver is approximately 100 times more sensitive than a quantum limited heterodyne receiver with a 1 GHz IF bandwidth. This receiver is designed to be used for the long wavelength band (200-700 microns) in the MIPS instrument on NASA's SIRTF satellite. The bolometers are cooled to 100 mK by an adiabatic demagnetization refrigerator. Roughly 60 g of cesium chrome alum salt is partially demagnetized to 100 mK, followed by a slow regulated downramp to compensate for the heat leak. The hold time of the ADR system is about 18 hours with a temperature stability of delta T(sub rms) approx. equals 10 micro-K. The composite bolometers have electrical responsivities of 10(exp 9)V/W and electrical NEP's of about 3x10(exp -17) W/square root of Hz. The bolometer signals are read out by JFET preamplifiers located on the helium plate and operated at 120 K. We have addressed a number of space qualification issues, such as the development of an analog magnet controller, construction of a cryogenic shake-table for bolometers and selection of the paramagnetic salt CCA which can survive a bakeout at 50 C. The receiver is scheduled to be flown in the spring of 1992 on a balloon telescope. This flight has a dual purpose. One is to provide realistic test of the capabilities of the new receiver. The other is to search for anisotropies in the cosmic microwave background on scales of a few degrees.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 678-687
    Format: application/pdf
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  • 8
    Publication Date: 2013-08-31
    Description: We propose a novel adiabatic demagnetization refrigerator (ADR) to produce temperatures as low as 100 mK starting from a high temperature reservoir between 4 and 8 K. The high temperature reservoir for the ADR can be provided by a mechanical cooler or an unpumped liquid helium bath. This refrigerator can be used to cool bolometric infrared detectors for low background astronomy from mountain tops, balloons or satellites as well as to cool cryogenic x-ray detectors. The two-stage ADR consists of a single magnet with a paramagnetic chromic-cesium-alum (CCA) salt pill to produce the low temperature and paramagnetic gadolinium-gallium-garnet (GGG) as the first stage to intercept heat from the high temperature reservoir. Thermal contact between the paramagnets and the reservoir during magnetization is made with a mechanical heat switch. The ADR is suspended with Kevlar chords under tension for high mechanical stiffness and low parasitic heat leak. In a single cycle, the ADR maintains a temperature of 100 mK for 10 to 100 hours. This time depends strongly on the magnetic field and reservoir temperature but not on the volume of the paramagnetic material as long as the heat leak is dominated by the suspension.
    Keywords: ENGINEERING (GENERAL)
    Type: NAS 1.26:192365 , NASA-CR-192365
    Format: application/pdf
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  • 9
    Publication Date: 2013-08-31
    Description: Progress toward a prototype of 100 mK bolometric detection system for the Space Infrared Telescope Facility (SIRTF) is described. Two adiabatic demagnetization refrigerators (ADR's) were constructed and used to investigate the capabilities necessary for orbital operation. The first, a laboratory ADR, demonstrated a hold time at 0.1 K of over 12 hours, with temperature stability approx. 3 micro-K RMS achieved by controlling the magnetic field. A durable salt pill and an efficient support system have been demonstrated. A second ADR, the SIRTF flight prototype, has been built and will be flown on a balloon. Techniques for magnetic shielding, low heat leak current leads, and a mechanical heat switch are being developed in this ADR. Plans for construction of 100 mK bolometers are discussed. Three important cosmological investigations which will be carried out by these longest wavelength SIRTF detectors are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Ames Research Center, Proceedings of the Third Infrared Detector Technology Workshop; p 35-44
    Format: application/pdf
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  • 10
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The specific heat of4He condensed on an evaporated gold surface has been measured for coverages between 0.007 and 0.096 Å−2 and temperatures between 0.4 and 3.0 K. There are at least two types of physisorption site on the gold surface with binding energies −83±7 and −94±7 K. For coverages below 0.06 Å−2 (∼0.5 monolayers), the4He is a two-dimensional classical gas at sufficiently high temperatures. At lower temperatures and higher coverages, the4He forms condensed phases, including liquids, solids commensurate with the gold lattice, and incommensurate solids. The phase diagram of4He/evaporated gold is similar to that for4He/graphite, but the phase boundaries are shifted and not well defined, nor is the diagram as rich in structure.
    Type of Medium: Electronic Resource
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