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  • American Institute of Physics (AIP)  (9,520)
  • Annual Reviews
  • 2005-2009  (654)
  • 1990-1994  (10,515)
  • 1980-1984
  • 1950-1954
  • 2009  (654)
  • 1993  (10,515)
Collection
Publisher
Years
  • 2005-2009  (654)
  • 1990-1994  (10,515)
  • 1980-1984
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Immunity to Intracellular Bacteria (1993)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 11 (1993), S. 129-163 
    Details
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.iy.11.040193.001021
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  • 2
    Electronic Resource
    Electronic Resource
    The Biochemistry and Cell Biology of Antigen Processing and Presentation (1993)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 11 (1993), S. 403-450 
    Details
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.iy.11.040193.002155
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  • 3
    Electronic Resource
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    The Molecular Cell Biology of Interferon-gamma and its Receptor (1993)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 11 (1993), S. 571-611 
    Details
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.iy.11.040193.003035
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  • 4
    Electronic Resource
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    Dominance and Crypticity of T Cell Antigenic Determinants (1993)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Immunology 11 (1993), S. 729-766 
    Details
    ISSN: 0732-0582
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.iy.11.040193.003501
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  • 5
    Electronic Resource
    Electronic Resource
    rf plasma source using a magnetic line-cusp field (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2434-2439 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large volume cylindrical radio frequency (rf) plasma source using a magnetic line-cusp field has been developed for use in large scale plasma processing. In this type of plasma source, a capacitively coupled 13.56 MHz rf plasma is produced in the presence of a magnetic line-cusp field. Three versions of the plasma source have been constructed and tested. The first version has a pair of peripheral rf electrodes placed outside the ionization chamber and is suitable for preparing a large volume uniform plasma. This plasma source can attain a useful area of plasma with 10% uniformity over a 30-cm-diam region. The second version is featured by parallel doughnut-plate electrodes which form part of the chamber wall and serve as a high current source, where the electron density is proportional to the rf power, being equal to 4×1010 cm−3 at 400 W. The third version is a slab-plasma source, which has a rectangular ionization chamber, a pair of rectangular magnetic coils, and a pair of rectangular rf electrodes, yielding an electron density of the order of 109 cm−3 for a 25 W rf power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143901
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  • 6
    Electronic Resource
    Electronic Resource
    Variable coupling rotational wand for on-line laser beam sampling (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2482-2487 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: As power levels of industrial lasers increase, effective determination of beam profiles over extended operational regimes becomes problematic, due to dynamic range limitations of available detectors. To address this deficiency, a variable coupling rotating wand was developed for on-line monitoring of output radiation from high average power CO2 lasers. The concept features real-time beam sampling adjustment, activated by wand rotational speed change. An associated controller provides appropriate speed regulation of the wand motor drive, via a computer generated setpoint. Design parameters thereby ensure optimal sensor operation at all power levels. A safety override prevents sensor damage by terminating laser operation, if wand speed decreases below a safe value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143907
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  • 7
    Electronic Resource
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    Nanosecond time-resolved vacuum ultraviolet spectrometer for ion diode spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2493-2495 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 1-m normal incidence spectrometer has been modified for use as a diagnostic of ion diode plasmas. To improve instrumental sensitivity, an elliptical mirror images an anode surface plasma onto the entrance slit of an f/10 normal incidence spectrometer. The detector is a time-resolving copper iodide coated microchannel plate stripline framing camera with 60-μm resolution, limiting instrumental resolution to 1 A(ring) with a 600 l/mm grating in first order. Reflectivity of optics and photoelectron efficiency limit the spectral range from 400 to 2000 A(ring). With a 600-l/mm grating the detector spans a 600-A(ring) range. Applications of the instrument may include ion source divergence measurements from Doppler broadening, electric field measurements from Stark splittings or shifts, electron temperature from mean ionization state, and magnetic field measurements on high-power Z pinches from Zeeman splitting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143909
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  • 8
    Electronic Resource
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    Bench top Fourier transform infrared based instrument for simultaneously measuring surface spectral emittance and temperature (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2515-2522 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A bench top instrument has been constructed which allows for the measurements of radiance, directional-hemispherical reflection, and directional-hemispherical transmission from materials at elevated temperatures from 100 to over 2000 °C. The instrument measures these radiative properties over a wide spectral range, in the near- and mid-IR, from 12 500 to 500 cm−1 (0.8–20 μm). These measurements are then processed to determine the spectral emittance of the material and the temperature at the point of measurement. The instrument has applications for (1) industrial quality control of radiative properties of processed materials; (2) research and development of new materials; (3) temperature measurement by optical techniques in the near- and mid-IR; and (4) determination of heat transfer properties of materials. This article describes the instrument and its novel components, and presents measurement results for several materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143913
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  • 9
    Electronic Resource
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    Development of a battery-operated portable synchronous luminescence spectrofluorometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2541-2546 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A battery-operated portable synchronous luminescence spectrofluorometer was developed for on-site analysis of groundwater or hazardous waste sites. The instrument is capable of either emission, excitation, or synchronous fluorescence measurements. The instrument is suited for trace analysis of important pollutants such as polyaromatic hydrocarbons, creosotes, and polychlorinated biphenyls in complex mixtures. The ability to perform synchronous luminescence measurements on these samples can reduce the complexity of fluorescence spectra and help in rapid field site characterization. A description of the instrumental components is given and an evaluation of the instrument using anthracene and several oil samples is provided to illustrate the usefulness of the instrument.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143916
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  • 10
    Electronic Resource
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    High resolution in the soft x-ray range from a toroidal grating monochromator (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2552-2557 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A resolving power, E/ΔE, of ≥13 000 has been achieved with the modified 6 m/160° toroidal grating monochromator (TGM) installed on Beam Line 8-1 at the Stanford Synchrotron Radiation Laboratory. The resolving power of the TGM was increased by replacing the entrance and exit slits with high-precision slits, masking the horizontal part (short radius) of the grating, and improving the TGM scanning mechanisms. To determine the performance of the monochromator, we measured the dependences of resolution and photon flux on the entrance- and exit-slit widths, the exit-slit position, and the masking of the grating. The monochromator resolution in the energy range of 25–65 eV was derived from photoionization measurements of extremely narrow core-excitation resonances in He and Ne. With 10-μm vertical entrance- and exit-slit widths and 32% mask opening of the grating, the monochromator has a resolution (full-width at half maximum) of 5.0±0.7 meV at a photon energy of 64.5 eV and a flux of 2×107 photons/s/100 mA. The results suggest a simple procedure for converting a TGM with moderate resolution into a high-resolution monochromator with a moderate reduction in photon flux due to masking the grating, beyond the reduction attributable to the slit widths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143866
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  • 11
    Electronic Resource
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    Low-energy conversion electron Mössbauer spectroscopy using a chevron microchannel plate detector (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2570-2573 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A detection system for conversion electron Mössbauer spectroscopy is described. A chevron microchannel plate assembly attached to a two-stage electrostatic lens is used to preferentially detect electrons with energies ≤15 eV. Mössbauer spectra collected with these electrons can provide information about a variety of solid-state surface phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143869
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  • 12
    Electronic Resource
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    A linear magnetic field spectrometer for electron energy-loss measurements (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2574-2578 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of electron energy-loss spectrometer has been developed, in which the electrons are confined by a unidirectional magnetic field that extends over a length of 2 m. Magnetic-field-immersed Wien filters are used for energy selection and analysis. The new spectrometer is characterized by a high collection efficiency and hence it is especially suitable for the study of processes that have low cross sections, such as excitation of autoionizing and inner-shell states. Electron energy-loss spectra of inner-shell states of Xe have been obtained with the new spectrometer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143870
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  • 13
    Electronic Resource
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    Using a free-standing thermistor array to measure VUV emission from a tokamak plasma (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2423-2427 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact 15-channel bolometer array composed of discrete thermistors has been installed on the Princeton Beta Experiment tokamak. The response time, fastest for detectors with low thermal capacities, has been optimized by using "free-standing'' detectors. The detector is supported only by thin electrical leads and no thermal substrate is employed. Overheating due to limited heat dissipation is controlled with careful detector biasing. The sensitivity is limited by the systematic errors in the model of the heat transfer from the detector to the electrodes and leads. A two-pole cooling model was found to characterize the detector's thermal decay far better than a simple exponential and resulted in an NEP≈3×10−7 W/(square root of)Hz with a 300-Hz bandwidth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143899
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  • 14
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    Scintillator studies with MeV charged particle beams (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2459-2465 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Thin scintillators used as detectors of escaping fusion products in the TFTR tokamak are studied with Van de Graaf beams of 3-MeV protons and 3.5-MeV alphas. ZnS scintillators are found generally adequate for the D–D experiments performed up to now, marginal for near-term D–T experiments because the emitted light saturates at alpha fluxes greater than 1010 cm−2 s−1, and totally inadequate for future ignited plasmas. Other scintillators have been tested that have lower light efficiencies but much better properties at high fluxes. In particular, the P46 scintillator appears to be an excellent choice for future experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143904
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  • 15
    Electronic Resource
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    Disktron accelerator (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2466-2474 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of low-energy ion accelerator has been developed. It includes an eight-storied Disktron generator, newly developed accelerating tubes which hold up to 4 MV/m, both single and tandem acceleration capability, and a compound negative ion source. The Disktron generates 3.2 MV with a dummy load and 2.2 MV with ion beams, and has a voltage stability better than 10−3 at around 1 MV with a corona feedback stabilizer or a generating voltmeter feedback stabilizer only. The highly stabilized voltage of the Disktron has particularly been allowed to form an ion microbeam of about 1-μm diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143905
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  • 16
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    Truncated cone as a pseudoconjugator in a high-power carbon dioxide laser (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2488-2492 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The incorporation of a retroreflecting, pseudoconjugating cone as a folding element in a double-pass unstable resonator of a high-power carbon dioxide oscillator–amplifier is presented. The concept, when implemented with a truncated cone, has yielded significant improvements in optical energy extraction efficiency, beam quality, and alignment stability. The performance of such a modified clear aperture cone resonator, in comparison with a standard roof prism cavity geometry, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143908
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  • 17
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    Implementation of a dual linear image sensor for measurements of transient absorption spectra in the picosecond time regime (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2504-2507 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to enhance the picosecond absorption spectroscopy, a dual linear image sensor was used for simultaneous intensity measurements of the probing and reference lights by a single polychromator. This detector enabled us to record a fairly well stabilized transient absorption spectrum, and its signal-to-noise (S/N) ratio was much improved. Although the base line spectrum (not averaged) recorded by using a broadband continuum (a self-phase modulation light generated by focusing the fundamental light pulse from a ruby laser into a BK-7 glass block) revealed that the base line fluctuation and drift were less than ±0.04 absorbance units, the five-times spectral average gave rise to the base line fluctuation and drift of less than ±0.01 absorbance units. For an absorption spectrum recorded at a slit width of ≤0.2 mm, the spectral resolution was found to be better than that recorded by a commercial spectrophotometer with a bandwidth of 1.0 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143911
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  • 18
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    Infrared-optical transmission and reflection measurements on loose powders (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2523-2530 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method is described to determine quantitatively the infrared-optical properties of loose powder beds via directional-hemispherical transmission and reflection measurements. Instead of the integration of the powders into a potassium bromide (KBr) or a paraffin oil matrix, which would drastically alter the scattering behavior, the powders are placed onto supporting layers of polyethylene (PE) and KBr. A commercial spectrometer is supplemented by an external optics, which enables measurements on horizontally arranged samples. For data evaluation we use a solution of the equation of radiative transfer in the 3-flux approximation under boundary conditions adapted to the PE or KBr/powder system. A comparison with Kubelka–Munk's theory and Schuster's 2-flux approximation is performed, which shows that 3-flux approximation yields results closest to the exact solution. Equations are developed, which correct transmission and reflection of the samples for the influence of the supporting layer and calculate the specific extinction and the albedo of the powder and thus enables us to separate scattering and absorption part of the extinction spectrum. Measurements on TiO2 powder are presented, which show the influence of preparation techniques and data evaluation with different methods to obtain the albedo. The specific extinction of various TiO2 powders is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143914
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  • 19
    Electronic Resource
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    Phase-locked detection of fluorescence lifetime (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2531-2540 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A newly developed category of signal processing scheme for the detection of fluorescence lifetime is discussed, with application to a number of inexpensive, compact, and reliable fluorescence lifetime-based fiber optic sensors. With phase-sensitive detectors being used to achieve a high noise-suppression ability, the schemes discussed here include some of the features of existing phase and modulation techniques for lifetime measurement. However, they differ from them in several aspects, especially in that they operate in a way rather similar to that of a phase-locked loop. Based on such schemes, the measured lifetime is converted to a repetitive signal whose period is directly proportional to it, and thus a high measurement resolution can be achieved. Such schemes can be operated over a wide consecutive measurement range of fluorescence lifetime, and they are particularly useful for temperature sensor applications using long lifetime ((approximately-greater-than)1 μs) fluorescent media. Illustrations of the applications of these schemes in lifetime-based fiber optic thermometers are presented showing their promising potential for both biomedical and industrial uses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143915
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  • 20
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    Scanning instrumentation for measuring magnetic field trapping in high Tc superconductors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2601-2603 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Computerized scanning instrumentation measures and displays trapped magnetic fields across the surface of high Tc superconductors at 77 K. Data are acquired in the form of a raster scan image utilizing stepping motor stages for positioning and a cryogenic Hall probe for magnetic field readout. Flat areas up to 45 mm in diameter are scanned with 0.5-mm resolution and displayed as false color images.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143875
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  • 21
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    A sensitive interferometric accelerometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2612-2614 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An interferometric accelerometer developed for use in characterizing isolation systems for gravitational wave detectors is described. A Nd:YAG laser is frequency locked to a Fabry–Pérot cavity in which one mirror is flexibly mounted. At 100 Hz the displacement sensitivity is 1.0×10−14 m/(square root of)Hz, 100 times more sensitive than the piezoelectric accelerometers normally used for such measurements. The sensitivity of the accelerometer is limited by the frequency noise of the laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143878
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  • 22
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    Holographic pattern photobleaching apparatus for the measurement of lateral transport processes at interfaces—Design and performance (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2632-2638 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new instrument was developed which allows the detection and characterization of lateral transport processes at the fluid–solid interface. It is based on holographic photobleaching combined with a laterally resolved fluorescence detection by a photon-counting camera. The geometry of the holographic pattern was chosen such that by "on-chip'' integration of photoelectrons in the liquid-nitrogen-cooled camera the images are integrated along the symmetry axis of the pattern and subsequently stored on the chip. Time-dependent changes in the pattern caused by directed motion or by diffusion are then qualified by Fourier analysis. Lateral diffusion coefficients between 10−12 and 10−6 cm2/s and velocities between 10−10 and 10−4 m/s are measurable. In order to discriminate processes at the surface and in the volume, evanescent field illumination can be chosen. The penetration depth of the evanescent field can be varied from 96 to 800 nm. The performance of the instrument is demonstrated on selected examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143882
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  • 23
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    Computer-controlled float zone crystal growth (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2643-2649 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A PC-based computer control system to automate a high-temperature float zone growth of titanium carbide is reported. The control strategy of the computer control system relies on the relations derived from a combination of empirical relations and results from detailed mathematical analysis of the physical transports of the entire float zone assembly. A system control computer program was written to establish real-time determination of the size of the molten zone from a thermal image, control parameters from established relationships, and collected processed data to achieve control objectives. We found that the developed computer control allows the growth process to be operated nearer the stability limit. Any slight variations in growth conditions can be corrected in time to avoid any instability growth, which otherwise cannot be adjusted via manual control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143884
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  • 24
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    Performance and limitations of laser diodes stabilized to the sides of molecular absorption lines of ammonia (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2128-2132 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Performance and limitations of laser frequency stabilization based on the locking to the side of an absorption line are discussed: experimental results of spectroscopic measurements and of the stabilization of 1543-nm DFB laser diodes to ammonia absorption lines are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143948
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  • 25
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    Hyper-resolution Brillouin–Rayleigh spectroscopy with an optical beating technique (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2136-2139 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A system of optical beating spectroscopy has been newly developed for hyper-resolution Brillouin scattering. Frequency resolution as high as 1 kHz was obtained, far beyond the limit of the classical Fabry–Perot interferometer which is commonly used in ordinary experiments. This system is useful over the frequency range from 104 to 109 Hz at present. Experiments for Rayleigh and/or Brillouin spectra were performed in water, toulene, and carbon disulfide to demonstrate the performance of this system.
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    URL: http://dx.doi.org/10.1063/1.1143950
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  • 26
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    Phase-modulated ellipsometer using a Fourier transform infrared spectrometer for real time applications (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2153-2159 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new Fourier transform infrared phase-modulated ellipsometer is presented. It combines the high frequency provided by a photoelastic modulator (37 kHz) with the low frequency of the Fourier transform infrared spectroscopy (〈1 kHz), by means of a numerical data acquisition system. A full spectrum recording (from 900 to 4000 cm−1) can be achieved in 2 s. Thus, it allows its adaptation for kinetic in situ studies. The optical setup and the data reduction procedure are presented. In particular, a self-consistent spectral calibration procedure is described in detail. The precision in Ψ and Δ increases from 0.3° to 0.02° when increasing the integration time from 2 to 760 s. The examples shown in this article illustrate the high sensitivity to identify and analyze the absorption vibration variations of ultrathin films (a few angstroms thick).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143953
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    A double-crystal x-ray monochromator in antiparallel position with a sagittally bent crystal (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2207-2210 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The double-crystal x-ray monochromator (spectrometer) in (+,+) setting is high-resolution equipment. Focusing and a considerable increase of the x-ray monochromatic flux without any lowering of resolution may be reached if one of the crystals is properly bent into conical shape. The parameters of the bending are dependent on the wavelength. This ideal conical bending may be replaced by an easier-realizable cylindrical bending where the virtual source and the focus are located on the axis of the cylinder. In this case the higher monochromatic flux, as compared with the flat crystals, may be reached only for Bragg angles from about 35° to about 60°. The highest flux is for the Bragg angle θ=45° and its nearest neighborhood.
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    URL: http://dx.doi.org/10.1063/1.1143961
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    Optimization of hemispherical electrostatic analyzer manufacturing with respect to resolution requirements (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2190-2194 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electrostatic analyzers with different geometries have been used extensively in space plasma investigations. When the energy resolution requirements are such that ΔE/E≈10% the instrument is rather simple to design and to manufacture. However, when an energy resolution of ≈1% is required, the manufacturing costs increase rapidly. For analyzers with an energy resolution of ≈10% the calibration can also be used to correct for manufacturing errors when they appear. In this paper, it has been shown that to reach an energy resolution ΔE/E=(1.6±0.2)% using a hemispherical electrostatic analyzer with outer and inner radii 101.25 and 98.75 mm respectively and plate thickness 0.4 mm, an accuracy of 25 μm in the alignment of one hemisphere with respect to the other is sufficient. It is also shown that the effect on the energy resolution of an indentation of the surface of one of the conductors can be neglected as long as its depth is less than ≈100 μm. Larger indentations can easily be detected in the manufacturing process. For each case considered, the maximum permitted loss of transmitted particles with respect to the transmission of an ideal instrument has been defined as 10%. Similarly, it has been specified that the deviations in the distributions of entrance angles of transmitted particles shall be less than 0.1°.
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    URL: http://dx.doi.org/10.1063/1.1143958
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    Construction of a transform-limited picosecond time-resolved Raman spectrometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2140-2146 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A pump-probe picosecond time-resolved Raman spectrometer has been constructed using a dye laser synchronously pumped by a cw mode-locked Nd:YAG laser and a high repetition rate (2 kHz) dye amplifier pumped by the frequency doubled output from a cw Nd:YAG regenerative amplifier. Transform-limited picosecond pulses with 3.5 cm−1 wave number width and 3.2 ps temporal width are obtained at the wavelength of 588 nm. The second harmonic of these pulses is generated at 294 nm and is used for pumping, while the remaining visible pulses are used for probing resonance Raman scattering. The cross-correlation time between the pump and probe pulses is 4.1 ps. The temporal profile of the laser pulse is found to be very close to the sech2 shape. The wave number resolution of the system is estimated to be 3.5 cm−1 according to the Tailor criterion. The time resolution is estimated to be 2.2 ps using a criterion newly proposed in the present paper. Time-resolved Raman spectra of S1 trans-stilbene and S1 p-terphenyl are presented to demonstrate the capability of the constructed spectrometer.
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    URL: http://dx.doi.org/10.1063/1.1143951
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  • 30
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    Experimental studies of line shapes from a Balle–Flygare spectrometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2173-2178 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The line shape problem for the Balle–Flygare-type microwave spectrometer is reexamined experimentally using the method of sine and cosine Fourier transforms with a phase correction. Two previous studies [E. J. Campbell, L. W. Buxton, T. J. Balle, M. R. Keenan, and W. H. Flygare, J. Chem. Phys. 74, 829 (1981), and F. J. Lovas and R. D. Suenram, J. Chem. Phys. 87, 2010 (1987)] are reviewed. Those results are combined with new experimental data to obtain a general description of line shapes obtained from this device. Our emphasis here will be on using specific examples to clarify the relationship between the frequency domain representations of experimentally measured time-domain signals and the originating active species distributions.
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    URL: http://dx.doi.org/10.1063/1.1143956
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    Resolution and signal-to-background enhancement in gas-phase electron spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2179-2189 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The most important factors contributing to line broadening and background intensity in electron spectra are identified and new design principles for high quality measurements are presented. It is shown that time-dependent potential gradients in the gas cell are responsible for a large part of the "normal'' line broadening, while scattering processes inside the gas cell are responsible for a large part of the background intensity. By designing the experiment according to these results, gas-phase electron spectra can be recorded routinely at an instrument resolution level of better than 5 meV even at comparatively high gas cell pressures necessary to give high intensity for weak lines, and in principle unlimited counting times, at a much improved signal-to-background level. The resulting improvements in the spectral quality are demonstrated by spectra of Ar and HBr.
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    URL: http://dx.doi.org/10.1063/1.1143957
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    Properties of fixed-position Bragg diffractors for parallel detection of x-ray spectra (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2195-2200 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Advantages of wavelength-dispersive spectrometers over energy-dispersive spectrometers for parallel detection of x rays are discussed and factors involved in the design of wavelength-dispersive spectrometers are reviewed. The dispersion and collection solid angle of fixed-position Bragg diffractors used for parallel detection of x rays are calculated and the properties of four such spectrometers based on singly and doubly curved diffractors are compared with the properties of scanning monochromators. It is concluded that the previously studied parallel-detection spectrometers based on Bragg diffractors are less advantageous than scanning monochromators but they may be preferred when it is necessary to detect many characteristic x-ray lines simultaneously or to avoid the use of moving parts.
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    URL: http://dx.doi.org/10.1063/1.1143959
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    A photoemitted electron-impact ionization method for time-of-flight mass spectrometers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2211-2214 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple and efficient electron-impact ionization method for time-of-flight mass spectrometers is described. This method utilizes the photoelectrons emitted from the accelerating electrode surfaces upon UV laser irradiation as the electron source. Since no modification of the spectrometer is required, it provides a convenient way to perform electron-impact ionization in a time-of-flight mass spectrometer originally designed for laser ionization. The detection sensitivity (∼109/cm3) and mass resolution (∼150) achieved by this method in our apparatus are sufficient for diagnostic purposes for cluster beam experiments. The observed ion intensities suggest that the photoelectron current density produced is comparable to those generated by conventional thermionic emission electron sources. This technique is generally applicable as an ionization method in time-of-flight mass spectrometers and is particularly useful when the available lasers are not suitable for photoionization detection due to wavelength or intensity limitations.
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    URL: http://dx.doi.org/10.1063/1.1143962
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    Photothermal displacement technique: A method to determine the variation of thermal conductivity versus temperature in silicon (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2229-2232 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method to determine the variation of thermal conductivity as a function of temperature in silicon is described. The method is based on the application of a photothermal displacement technique in the temperature range 30–300 K. The results obtained on samples with different types and dopant concentrations are shown to be in good agreement with those reported in the literature.
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    URL: http://dx.doi.org/10.1063/1.1143966
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    Low voltage drop plasma switch for inverter and modulator applications (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2312-2319 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A low forward voltage drop plasma switch has been developed for high-efficiency inverter and modulator applications. The switch, called the HOLLOTRON, is based on a grid-controlled, thermionic hollow-cathode discharge. A low forward voltage drop (10–20 V) is achieved by operating the hollow-cathode discharge in a static gas pressure of xenon. The dense plasma generated in the Ba-oxide dispenser hollow cathode is spread over a relatively large control grid area by a diverging magnetic field superimposed on the discharge. Interruption of the discharge current at high current densities ((approximately-greater-than)4 A/cm2) over the grid area is achieved by biasing the control grid sufficiently negative with respect to the plasma. The HOLLOTRON switch has demonstrated voltage stand-off of up to 20 kV, switching times of ≤0.3 μs, and pulse repetition frequencies of 20 kHz at 50% duty.
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    URL: http://dx.doi.org/10.1063/1.1143927
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    A new powder diffraction method for linear detectors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2201-2206 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article we describe a new type of powder diffractometer that gives a significant improvement in count rate over existing methods. The key to the new technique is the use of a flat, diffracted beam monochromator in combination with a position sensitive detector. The incident x rays fall on a flat plate or capillary sample and multiple diffraction lines are reflected by the monochromator out of the equatorial plane onto a position sensitive detector. Since the monochromator is tuned for the incident beam energy, background from fluorescence or other scattering is eliminated and data can be recorded over a range of several degrees thereby providing a large improvement in counting efficiency over conventional diffractometers. This new method is also compared to a previous article which employed a focusing analyzer crystal and position sensitive detector.
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    URL: http://dx.doi.org/10.1063/1.1143960
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    A low-temperature ultrahigh vacuum scanning tunneling microscope system and tunneling spectra of the Bi2212 superconductor (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2221-2224 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We designed and constructed an ultrahigh vacuum scanning tunneling microscope (UHV-STM) which is available for the measurement of tunneling spectra at low temperature. The sample holder is cooled by thermal conduction to the stage that thermally connects with the refrigerator head. We cleaved Bi2Sr2CaCu2Oy (Bi2212 high Tc superconductor) single crystals under ultrahigh vacuum conditions, and measured tunneling spectra of the Bi–O surface at 35 K. The spectra were smeared due to the fact that the STM tip was at high temperature ((approximately-greater-than)100 K).
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    URL: http://dx.doi.org/10.1063/1.1143964
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  • 38
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    Triple-pendulum vibration isolation system for a laser interferometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2237-2240 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a triple-pendulum vibration isolation system for suspended mirrors used in a laser interferometer for gravitational wave detection. Owing to the passive damping method using high-performance permanent magnets, the system has a very simple, compact structure. We measured the isolation ratio for vibration below 40 Hz and confirmed that the observed and calculated values are in good agreement. The stability of the system has been demonstrated by operating a Michelson laser interferometer incorporated with a mirror mounted on the vibration isolation system.
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    URL: http://dx.doi.org/10.1063/1.1143967
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    Absolute measurement of spatial and spectral characteristics of bremsstrahlung using the photoexcitation of nuclear isomers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2298-2305 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method of obtaining absolute, direct measurements of the spatial and spectral characteristics of bremsstrahlung is discussed. This technique, called x-ray activation of nuclei (XAN) is based on the use of well-known photonuclear reactions which populate long-lived nuclear isomers. These populations sample incident photon continua at discrete excitation energies and effectively store this information for convenient retrieval following the irradiation of gram-sized targets. Recently a series of experiments has been conducted which has significantly expanded the available data for the photoexcitation of a wide range of isomers at higher energies. Thus it has become feasible to extend the use of XAN to energies approaching 4 MeV. The utility of this technique is demonstrated by the characterization of bremsstrahlung from the newly installed research linac at the University of Texas at Dallas.
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    URL: http://dx.doi.org/10.1063/1.1143925
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    The use of silver tips in scanning tunneling microscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2393-2394 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We propose to use silver tips for scanning tunneling microscopy (STM). Silver is the cheapest noble metal that is practically chemically inactive in the air environment. A simple reliable procedure of the tip preparation and resharpening is presented. The procedure is based on two-step electrochemical processing resulting in final tip curvature of less than 200 nm in radius as seen by an electron microscope. The tips show durability for at least a week of daily operation in an air STM.
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    URL: http://dx.doi.org/10.1063/1.1143892
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    Gas pump with a magnetically coupled piston (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2399-2400 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple pump has been constructed which is useful for stirring gas in a sample cell for gas-phase nonlinear optics experiments. It uses a piston and has been operated at gas pressures from 0 to 200 atm, and at temperatures from room temperature to 200 °C.
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    URL: http://dx.doi.org/10.1063/1.1143894
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    A simple profilometer for film thickness measurement (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2405-2406 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple profilometer based upon a commercial strain gauge force transducer is described. It has been used on polymer film coated substrates to determine film thicknesses on the order of 10.0 μm. Measured film thicknesses agree with gravimetrically determined values to within ±0.3 μm.
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    URL: http://dx.doi.org/10.1063/1.1143897
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    Ultrahigh vacuum cold finger for surface reaction studies (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2368-2370 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a cold finger and sample holder for use with a long-strong XYZ manipulator in a multitechnique ultrahigh vacuum chamber is presented. The cold finger design, based on the concept of a cryogenic transfer line, minimizes unwanted cryosorption on the surface of the cold finger. The simple, durable design allows samples to be cooled to below 90 K, rapidly heated to above 1000 K, and quickly returned to low temperatures. The rapid heating and cooling rates coupled with low outgassing make the design ideal for thermal desorption spectroscopy studies.
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    URL: http://dx.doi.org/10.1063/1.1143936
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    A low-power-dissipation broadband cryogenic preamplifier utilizing GaAs MESFETs in parallel (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2373-2378 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A voltage sensitive preamplifier design is presented for operation at 1.6 K. The active device is a Sony 3SK164 dual-gate GaAs metal-semiconductor field-effect transistor (MESFET), which was chosen for its low-frequency noise performance, stability against oscillations, and the inclusion of a gate protection diode. Active devices made from GaAs operate at cryogenic temperatures without carrier "freeze out.'' The main design goal was to keep the power dissipation in the cryostat minimal, while maintaining high bandwidth and low noise. This was achieved by operating four parallel MESFETs at cryogenic temperatures in cascode with a room-temperature Si JFET. Parallel operation gives a higher transconductance-to-power dissipation ratio than with a single device. The input cascode is followed by high-speed, low-noise operational amplifiers. The low-frequency noise corner occurs at 100 kHz. The white voltage noise of the preamplifier referred to the input is 〈0.9 nV/Hz1/2 at 1 MHz with 2 mW dissipated in the cryogenic stage. The power dissipation can be reduced to 1 mW with a moderate increase in noise. The preamplifier noise was found to be dominated by the cryogenic stage. There are two 50-Ω outputs with gains of 39 dB and 59 dB, and the −3 dB points occur at 500 Hz and 10 MHz. The design of the preamplifier is discussed in detail. Noise measurements under a variety of bias conditions are presented along with an analysis of the different noise sources.
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    URL: http://dx.doi.org/10.1063/1.1143938
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    Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2382-2384 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Relative signal response differences are shown between the continuous and the discrete dynode-type detectors for time-of-flight mass spectrometry at increasing pulse repetition rates.
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    URL: http://dx.doi.org/10.1063/1.1143940
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    A low-profile molecular beam source isolation valve for ultrahigh vacuum applications (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2391-2392 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design of a novel low-profile valve to isolate a molecular beam source from an ultrahigh vacuum system. The valve thickness is simply the thickness of a standard double-sided Conflat flange, on which the valve gate and actuation mechanism are assembled in a fully recessed configuration. The valve gate can accommodate a skimmer and/or several source collimating apertures. The manual actuator is mounted radial to the Conflat flange.
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    URL: http://dx.doi.org/10.1063/1.1143891
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    Iodine as a tuning standard for laser ablation–inductively coupled plasma-mass spectrometry (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2395-2396 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For inductively coupled plasma-mass spectrometry analysis of aqueous solutions the plasma and ion optics are optimized (tuned) using elements added to the solution for that purpose, or suitable elements in the dissolved sample. Laser ablation sampling produces transient signals that are difficult to use for tuning. For laser ablation sampling iodine can be used to produce a stable peak at mass 127 for tuning purposes. Iodine is easily introduced into the argon carrier gas stream by room-temperature evaporation of a 1-mm-size grain. The iodine grain should be supported in a glass tube to avoid reaction with plastic or metal. Iodine apparently does not form significant quantities of polyatomic ions such as ArI+ in the plasma, and so does not interfere with the analysis of isotopes having masses (approximately-greater-than)127.
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    URL: http://dx.doi.org/10.1063/1.1143893
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    X-ray generation from a gas-puff z-pinch driven by a pulsed power generator with a self-crowbar switch (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2403-2404 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A self-crowbar switch was operated on the pulsed power generator LIMAY-I and applied to a gas-puff z-pinch load. The radial collapse of the plasma is demonstrated to occur with the aid of the self-crowbar switch after the applied power pulse has turned off. X-ray emission was observed to coincide with radial collapse of the plasma, and the pinched plasma was visually observed by an x-ray pinhole photograph. The x-ray intensity increased with decrease of the puffed gas density.
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    URL: http://dx.doi.org/10.1063/1.1143896
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    A new design of a semiconductor bolometer on rigid substrate for fusion plasma diagnostics (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1714-1717 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new, fast, and very sensitive semiconductor bolometer has been designed and developed for the measurement of radiative energy losses in fusion devices in which the hard radiation level is not too high. Special care was taken in the design of the bolometer to simplify both the construction technology and the installation in fusion devices. The major novelty of this bolometer is the use of a low thermal conductivity rigid substrate, instead of the typical thin foil stretched on a rigid frame. In spite of large detector-substrate contact area, the cooling time constant reaches values as high as 150 ms. The rigid substrate allows the detector to be very robust and reliable; moreover, the monolithic integration of array structures is straightforward. The detector has been fabricated with a thin-film multilayer technology achieving very low thermal capacitance (〈2 mJ/K) and very low response time (〈5 μs). High responsivity (20 V/W) is obtained using GeOx thin film with a high thermal coefficient of the electrical resistance (−4.5%/K) as sensing thermistor.
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    URL: http://dx.doi.org/10.1063/1.1143998
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    Time resolved mass flow measurements for a fast gas delivery system (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1740-1743 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique is demonstrated whereby the delivered mass and flow rate versus time of a short rise-time gas delivery system may be accurately determined. The gas mass M that flows past a point in a gas delivery system by an arbitrary time t=tp may be accurately measured if that point is sealed off with a fast closing valve within a time interval short compared to the mass flow time scale. If the injected mass is allowed to equilibrate in a known volume after being cut off from its source, a conventional static pressure measurement before and after injection, and application of the ideal gas law suffices. Repeating for many different values of tp, and assuming reproducibility, the injected mass time history M(t) characteristic of the system without the fast closing valve may be determined. The flow rate versus time dM(t)/dt may then be determined by numerical differentiation. Mass flow measurements are presented for a fast delivery system for which the flow of argon through a 3.2-mm-i.d., 0.76-mm-thick copper tube is isolated by imploding (θ pinching) the tube using a single turn tungsten magnetic-field coil. Optical measurements of the tube's internal area versus time indicate that the tube is sealed in 7 μs. Results are correlated with piezoelectric probe measurements of the gas flow and 2D axisymmetric numerical simulations of the θ pinch process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144002
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    Effect of trapped ions in a gated time-of-flight apparatus (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1754-1757 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A three-mesh gate is used in a time-of-flight (TOF) apparatus to analyze the velocity of positive ions. Test results and a theoretical description are presented of an effect arising from trapping ions between meshes of a two-gate TOF velocity analyzer. The entrapped ions produce a side peak in the TOF spectra corresponding to faster ions. The onset and relative height of the side peak is dependent on the gating voltage and risetime of the pulsing electronics, while the relative intensity depends upon the velocity being sampled and the ratio of the gate width to duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144005
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    Nd:glass laser control system using intelligent CAMAC crate controllers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1770-1774 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Trident, a TW class Nd:glass laser system has been constructed in the Inertial Confinement Fusion (ICF) Program at Los Alamos National Laboratory for use in x-radiographic imaging of targets and for diagnostic development in support of the ICF program. The laser utilizes intelligent CAMAC crate controllers to provide rapid time response during the charge and fire cycle, while allowing use of an inexpensive desktop computer for the operations station. Operator setup of the laser configuration before a shot and data collection after a shot are performed by the desktop computer, while time critical tasks are handled by the local intelligence. The control system architecture and details of the local control program will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144008
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    A fully automated stage for loss measurements of optical waveguides (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1794-1796 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel test setup for making three-prism or out-of-plane scattering loss measurements for thin-film optical waveguides is described. The test structure is automated and provides quick, convenient and repeatable measurements. The setup is relatively easy to fabricate and employs several unique features which improve the accuracy and repeatability of the measurements including real-time coupling force monitoring.
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    URL: http://dx.doi.org/10.1063/1.1144012
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    Optimization of signal-to-noise ratios in pump-probe spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1775-1778 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Analytic expressions for the signal-to-noise ratio in time resolved pump-probe spectroscopy experiments are presented for two common signal averaging schemes in the presence of strongly correlated laser noise. The case of modulated pump/synchronous probe demodulation ("slow scanning'') is compared to the case of repetitively averaging many scans together ("fast scanning'') without pump modulation. Data are presented from a pump-probe experiment on an amorphous semiconductor thin film which agrees with the simple model developed in this article. The model can be used to predict the optimal scan frequency if the laser noise power spectrum, the magnitude of the signal, and the noise subtraction efficiency are known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144009
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    A high-intensity diffuse light source of ultrashort duration for reflected-light color photography (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1785-1793 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For use in reflected-light color photography a diffuse light source has been developed which has an annular geometry (347×140 mm in diameter) and coaxially surrounds the optical beam of recording. The light source has a luminous peak intensity of 200 Mcd and emits a flash with a duration of 180 ns FWHM. The principle of operation is based on a chain of nine V-shaped light-emitting gliding sparks, each consisting of at least 50 interstitial copper electrodes for the generation of micro gliding discharges. They are all connected in series and driven by a modified nine-stage Marx-surge generator. Substituting each V-shaped gliding spark by two U-shaped Xe-filled flash lamps doubles the light output as well as the flash duration.
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    URL: http://dx.doi.org/10.1063/1.1144011
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    High-sensitivity computer-controlled infrared polariscope (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1815-1821 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-sensitivity computer-controlled infrared polariscope has been developed to measure a small amount of phase retardation, and the principal axes of birefringence induced by residual strains in commercial III-V compound wafers with standard dimensions. In order to check the performance of the polariscope, semi-insulating LEC-grown GaAs (100) wafers, currently used for high-speed integrated circuits, were examined. The residual strain components of ||Sr−St||, ||Syy−Szz||, and ||Syz|| were evaluated from the measured values of the phase retardation and the principal axes of birefringence. It was found that the polariscope developed here was highly sensitive enough to characterize the residual strain components to the order of 10−7 in thin commercial GaAs wafers.
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    URL: http://dx.doi.org/10.1063/1.1144016
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    Polarization analyzing system for x-ray magnetic Kerr rotation in x-ray magnetic resonant scattering (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1825-1830 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We made a new polarization analyzing system for measuring a rotation of major axis of elliptical polarization in x-ray magnetic resonant scattering. This system, based on a two-axis diffractometer, is characterized by introducing a 45° linearly polarized x-ray incident beam. Design and performance of the system are described. The rotation can be measured with precision of 0.2°–0.3° at the vicinity of Gd L3-absorption edge where the maximum rotation is about −2°.
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    URL: http://dx.doi.org/10.1063/1.1144453
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    Quick measurement of NMR-coil sensitivity with a dual-loop probe (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1841-1844 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The radio-frequency coil sensitivity for NMR signal detection can be defined as B1/(square root of)P, which is the magnetic field that the coil induces at a given point per unit supplied power. We propose a new method, based on the reciprocity theorem, to quickly evaluate the sensitivity of a tuned coil. The only requirement of the method is a voltage gain measurement with a small dual-loop probe, without mobilization of the NMR unit. The probe can be used to gauge and map the sensitivity of the coil with good accuracy, while monitoring its tuning frequency ω0 and its quality factor Q. Our method is particularly convenient for development and maintenance of coils for MR imaging, and more generally could be applied to other fields involving radio-frequency characterization of inductive circuits.
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    URL: http://dx.doi.org/10.1063/1.1144020
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    Digital signal processor control of scanned probe microscopes (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1874-1882 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Digital signal processors have made it possible to control scanned probe microscopes using straightforward software emulations of analog circuits. Using a system consisting of a commercially available digital signal processor board interfaced to analog I/O, we have developed algorithms for self-optimizing feedback, raster generation (with hysteresis correction, sample tilt compensation, and scan rotation), lock-in detection, and automatic tip-sample approach. We also discuss an instruction parser that takes advantage of the digital architecture to allow automatic operation for extended periods.
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    URL: http://dx.doi.org/10.1063/1.1144462
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    Analysis of scattering asymmetry statistics when background corrected counts are negative (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1895-1898 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An asymmetry statistic of physical interest is an estimate of the ratio of the difference and the sum of the Poisson rate parameters for two scattering processes. Typically, an additive background signal contributes to measurements of each signal. Background is measured in a third experiment. Data are corrected by subtracting measured background. When the measured background is larger than one of the other measurements, background-corrected counts are negative. For this case, it would seem that no useful information can be extracted from the experiment. Here, asymmetry and an associated uncertainty interval are estimated for such cases using a bootstrap approach.
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    URL: http://dx.doi.org/10.1063/1.1143973
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    A magnetic suspension system with a large angular range (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1910-1917 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to explore and develop technology required for the magnetic suspension of objects over large ranges of orientation, a small-scale laboratory system, the large-angle magnetic suspension test fixture (LAMSTF) has been constructed at NASA Langley Research Center. This apparatus falls into the category of large-gap, actively stabilized magnetic levitation systems. The hardware comprises five conventional electromagnets in a circular arrangement, each driven from a separate bipolar power amplifier. Electromagnet currents are commanded by a digital control system, implemented on a microcomputer, which in turn derives the position and attitude of the suspended element from an infrared optical system. The suspended element is a cylindrical, axially magnetized, permanent magnet core, within an aluminum tube. The element is "levitated'' by repulsive forces, with its axis horizontal, 0.1 m above the top plane of the electromagnet conductor. The element is stabilized in five degrees-of-freedom, with rotation about the cylinder axis not controlled. By mechanical rotation of the sensor assembly, the suspended element can be made to undergo a full 360° rotation about the vertical axis. The controller accommodates the changes in magnetic coupling between the electromagnets and the suspended element by real-time adaptation of a decoupling matrix. This report presents a review of the background to the problem of magnetic suspension over large ranges of orientation. Next, the design and operation procedures adopted for LAMSTF, and the system hardware are described. Finally, some performance measurements are shown, together with illustration that the major design objective—the 360° rotation, has been accomplished.
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    URL: http://dx.doi.org/10.1063/1.1143976
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    High temperature reactor system for study of ultrafast gas-solid reactions (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1989-1993 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-temperature reactor system is developed for studying ultrafast gas-solid reactions. Time-resolved measurements of the reaction kinetics and changes in particle properties can be obtained with this system in the time scale 10–100 ms. The reactor system consists of an electrical furnace and ceramic reactor tubes, a pulse powder feed system, injection and collection probes, and a cascade impactor for in situ particle size classification. The feed system injects solids as short pulses and is capable of handling powders of size 1 μm or less. Hot jet impaction technique is used for rapid heating of the powder to the reaction temperature. The injection and collection probes are equipped with optical systems that are interfaced with a microcomputer data acquisition system, perform particle injection/sampling, reaction quenching, and optical solids monitoring. The most unique feature of the reactor system is its ability, using the probe combination, to directly measure residence times as low as 10 ms for the solids sampled from the high-temperature environment. Sample results are shown for the decomposition of limestone at 975 °C.
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    URL: http://dx.doi.org/10.1063/1.1143987
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    Pulsed laser photoionization technique for recording atomic flux variations during deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2003-2007 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Depositions at rates higher than 1 nm/s show differences in properties when one deposits with a vapor stream that is modulated against those that are deposited with a steady vapor stream. For carrying out investigations along these lines, it was necessary to develop a real-time, noninvasive, and sensitive technique for determining the nature and extent of flux variations in atomic streams close to the deposition plate. A pulsed laser based resonant photoionization technique is proposed for meeting these requirements. The paper describes the method and its application to a case where modulation is caused by residual ripple in high voltage accelerating supply used in the electron gun of the evaporator. The proposed technique overcomes the limitation on sensitivity due to background pressure experienced in the nonresonant approach. Other attractive features are the use of much lower laser intensities for a given sensitivity and the employment of a simpler ion detection system.
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    URL: http://dx.doi.org/10.1063/1.1143990
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    Simple apparatus for the liquefaction of neon directly into a research Dewar (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2023-2026 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple apparatus for liquefying neon is described for use in experiments that require a stable thermal environment at 27 K. This apparatus makes use of a closed-cycle refrigerator attached to an insulated cold finger inserted into a conventional stainless steel Dewar to liquefy a quantity of neon gas stored previously in a tank. The system is inexpensive and easy to use. Furthermore, the neon is recovered for subsequent reuse upon completion of the experiment. Starting with a Dewar holding a small coil that had not been precooled, and using a refrigerator with rated cooling capacity of 15 W at 26 K, approximately 0.5 l of liquid neon was condensed into the Dewar in ∼4 h. The apparatus has been used to measure the critical currents of high Tc oxide tape coils both with and without the application of an external magnetic field.
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    URL: http://dx.doi.org/10.1063/1.1143993
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    Concept of virtual instruments applied in photoacoustic measurements (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2033-2034 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method is presented by which photoacoustic measurements can be done fast and with small effort. All operations are performed by an automatic measurement system based on an IBM PC personal computer. The structure and principles of the system operation are presented. The main advantages of the method described are: short time of measurement, wide chopping frequency range, high accuracy, and low error level. Owing to the computer some operations like hardware averaging, filtering, etc. can be replaced by software. This results in simplicity of the setup.
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    URL: http://dx.doi.org/10.1063/1.1143944
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    Optical pressure transducer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1999-2002 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents the characteristics of an optical pressure transducer using fiber optics. The transducer consists of a cylindrical housing with a reflective mylar diaphragm attached at one end and fiber-optic bundle at the other. The fiber-optic bundle used is the bifurcated type, in which two bundles of randomly distributed fibers are joined at one end to form a Y-shaped geometry. The common end is attached to the end of the transducer housing, opposite to the diaphragm. At the branched ends, one bundle is connected to a dc light source, while the other bundle carries the light reflected from the diaphragm to a photodetector. By keeping the input light source at constant intensity, the amount of reflected light depends on the distortion of diaphragm due to pressure differential across the diaphragm surface. This pressure transducer can measure both the static pressure level and the fluctuating pressure. A simple "homemade'' diaphragm was used in this experiment, and a sensitivity of approximately 10 mV per mm Hg was obtained over a range of 20 mm Hg. The dynamic response was linear to about 2 kHz. Both the sensitivity and the frequency response can be much increased by improving the diaphragm performance.
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    URL: http://dx.doi.org/10.1063/1.1143989
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    Techniques for attainment, control, and calibration of cryogenic temperatures at small single-crystal samples under ultrahigh vacuum (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2013-2022 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: On the basis of detailed considerations of the relevant effects and parameters, we describe techniques which have been developed to accurately set, maintain, and measure the temperature of a small sample (typically a single-crystal disk of about 1 cm in diameter and 1 mm thick) in a strongly nonisothermal surrounding in ultrahigh vacuum, such as required by surface science experiments, in the temperature range from at least 6.5 K up. The resettability and resolution are 30–70 mK and the absolute error is estimated as about 0.7 K at 10 K and about 1.5 K at 100 K. Controlled linear heating with rates from 10−2 to 50 K/s and high constancy (deviations below 0.1 K up to 5 K/s and below 0.5 K up to 50 K/s), and stepwise heating ((approximately-greater-than)100 K/s) without measurable overshoot can be carried out in this whole cryogenic range.
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    URL: http://dx.doi.org/10.1063/1.1143992
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    New method of adjusting and aligning a grazing incidence grating spectrometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2031-2032 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact grazing incidence grating spectrometer with spectral range of 2–32 nm resolution of 0.0005 nm, and about 3.6-kg weight has been manufactured, which can meet the requirements of current x-ray laser experimental research. During the construction, as a new method, we used a 3D measuring machine to finish the adjustment of spectral elements and invented a new method of alignment with a fiducial plane when using the spectrometer in an experiment.
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    URL: http://dx.doi.org/10.1063/1.1143943
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    Time-resolved x-ray absorption spectroscopy on microsecond timescales: Implications for the examination of structural motions (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2035-2036 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We demonstrate a system for collecting high quality x-ray absorption spectroscopy data on microsecond and longer timescales. The method uses a fast-multiscaling board to partition output pulses from a germanium energy resolving detector into a microsecond timebase. Full spectra accumulation and kinetic spectrophotometry are demonstrated for 1–4 mM biological samples. The use of an energy resolving detector promises that the dynamic behavior of a wide range of chemical elements (in conjunction with photochemical, rapid mixing, and temperature jump perturbations) can be observed with this method. We have successfully tested the system by examining the structural evolution of the iron atom of a myoglobin-carbon monoxide complex subsequent to photolysis at low temperature.
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    URL: http://dx.doi.org/10.1063/1.1144461
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    Electron suppression in the H− beam from a Penning surface-plasma source (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1394-1397 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The ratio of electrons to negative ions extracted from Penning surface-plasma sources such as the 8X source is low even before any further steps are taken to suppress the electrons. For the 8X source the e−/H− ratio is typically four or five to one for H− operation and nine to one for D− operation. Because the coextracted e− present a power-loading problem to the 8X-source extraction system, methods to dissipate and/or reduce the power in the e− beam must be developed before extracting a dc H− or D− beam. Thus, we systematically varied the geometry of a cylindrical collar installed in the near-extraction region of the 8X source. The observed dependence of the extracted e− and H− currents on the collar radii and lengths suggests that a conical collar would provide superior electron suppression. The conical collar that we tested lowered the e−/H− ratio to 0.9/1 without reducing the extracted H− current.
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    URL: http://dx.doi.org/10.1063/1.1144049
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    New vaporizing assembly for Q-plasma sources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1407-1409 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and operation of a new vaporizing assembly used for Q-plasma sources are described in this article. The vaporizing system, consisting of two ovens and an effuser, is used to vaporize and direct atoms onto a hot ionizer plate. The hot plate, which may be of tantalum, tungsten, or rhenium, singly ionizes the atoms on contact. The main advantages of this new assembly, compared to previous designs, are the production of higher plasma densities and the control of the radial plasma profile. The heaters of the two atomic beam ovens are independently controlled and monitored so that the gradients of the radial plasma profile can be modified. Plasma production with two ion species can also be performed.
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    URL: http://dx.doi.org/10.1063/1.1144052
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    Optical interferometer for gas bubble vibration measurements with Angstrom sensitivity (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1463-1467 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An optical interferometer which measures the radial pulsations of gas bubbles in liquids with Angstrom sensitivity is described. The gas–liquid interfaces act as mirrors. The interferometer, intrinsically differential, is insensitive to the overall movement of the bubble and to vibrations of the optical components. Examples of the resonance behavior of oxygen bubbles in water are given.
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    URL: http://dx.doi.org/10.1063/1.1144064
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    Scanning x-ray microscopy using a laser-plasma source (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1478-1482 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Previously high-resolution soft x-ray microscopy has only been possible with synchrotron sources. Here, the first successful attempts at using a scanning transmission x-ray microscope with a laser-plasma source are reported. Spatial resolutions were limited to about 650 nm by electrical noise in the detector, but single shot per pixel images were obtained of test and real specimens. The microscope was not optimized to the source since it was designed for use on the undulator beam line of a synchrotron. With an improved system, it is demonstrated that single shot per pixel imaging at high resolution (better than 50 nm) will routinely be possible.
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    URL: http://dx.doi.org/10.1063/1.1144067
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    High-resolution Y-axis readout for delay-line microchannel anodes (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1506-1509 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have devised a method to obtain a high-resolution Y-axis event position determination from microchannel plate delay-line detectors. The method is based on the double-delay-line wedge–wedge charge partition principle of Lampton et al. [M. Lampton, O. H. W. Siegmund, and R. Raffanti, IEEE Trans. Nucl. Sci. 37, 1548 (1990)], where the X axis is read out by a pair of side-by-side delay lines and the Y-axis coordinate is determined by comparing the charges on the two parallel delay lines. However, our new method abandons the common field return path of the two delay lines, and splits them into two adjacent but independent transformer coupled timing circuits having no common ground connection except via the charge-measurement amplifiers. Thus we eliminate the large electrostatic capacitance of the delay lines from the input of the charge-measuring system. Due to the very low output return capacitance of the split delay lines, the Y-axis noise performance is improved enormously. Over its limited working field, the spatial resolution in the Y coordinate can easily equal the resolution provided in the X coordinate by the delay line. Applications to extreme and far ultraviolet photon-counting spectroscopy are envisioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144071
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    A high-temperature Bonse–Hart ultrasmall-angle x-ray scattering instrument (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1510-1514 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A Bonse–Hart ultrasmall-angle x-ray scattering (USAXS) instrument has been designed, constructed, and tested employing a synchrotron x-ray source. The instrument permits experiments ranging from below 0 °C up to about 400 °C, as well as temperature scanning, jumping, quenching, and annealing experiments. The mechanical elements used Super Invar as the basic building material in order to minimize the thermal expansion effect. As the synchrotron beam after the beamline optics is already somewhat collimated and monochromatized, a very fine tuning of the first crystal was necessary. The high-temperature Bonse–Hart instrument increased the performance by a factor of about 10 when compared with our earlier room-temperature Bonse–Hart instrument using the same set of channel-cut germanium crystals. The instrument was tested by using a suspension of polystyrene latex spheres and by combining the USAXS measurement, for the first time, with measurements of the same latex suspension by means of laser light scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144465
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    Vertical two-dimensional piezoelectric inertial slider for scanning tunneling microscope (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1489-1494 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To achieve both high stability during scanning tunneling microscopy (STM) measurements at atomic resolution and long-range imaging of nonhomogeneous samples, we have developed a fully 2D vertical inertial nanopositioner which allows tunneling tip displacements in the 0.01–1000 μm range while keeping high-resolution STM conditions. The inertial sliding of the tip is obtained by overriding the static friction criterion between the tip and its support. By controlling the expansion of the piezotubes and the direction of the applied acceleration, one can obtain displacements as small as 100 A(ring) in the vertical direction. The same piezotubes are also used to scan the sample during conventional STM measurements. Increasing the resonance frequency of the scanner above 10 kHz was essential to ensure good operation. The complete device has not altered the mechanical stability of the microscope; it works in air as well as in ultra-high vacuum conditions. Its reliability is demonstrated by the possibility of obtaining STM images of adjacent areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144068
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    Gold-coated tungsten tips for scanning tunneling microscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1495-1501 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electrochemically etched tungsten scanning tunneling microscope (STM) tips are dc sputter coated with 20 nm of gold (0.04 nm/s and 10 mTorr of argon). Transmission electron microscope (TEM) images of typical etched tips and gold-coated etched tips are presented. The gold layer forms as a series of spherical sections having a mean height of 6.7 nm and mean width of 19.6 nm. STM images are reported for the uncoated W tips, and for gold-coated graphite after coating the tip with gold. We also provide scanning electron microscopy (SEM) and STM images of the surface of a thin CuTCNQ film. The STM image taken with a gold-coated W tip compares very well to the SEM image of the same sample. Gold coating provides a relatively inexpensive and easy way to produce chemically stable tips of well known electronic structure for use in ambient atmosphere STM studies of morphology (structures ≥10 nm) where atomic resolution is not required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144069
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    On the origin of spurious peaks in pseudorandom time-of-flight analysis (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1520-1523 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The pseudorandom time-of-flight analysis overcomes the classic trade-off between resolution and transmission and has become a standard tool in inelastic low-energy neutron and atom scattering. However, systematic errors in the machining of the chopper slots as well as the finite thickness of the chopper disk can lead to the appearance of spurious peaks in the time-of-flight spectrum. These spurious peaks are mirror images of the real time-of-flight distribution shifted in the spectrum by a constant number of channels which is uniquely determined by the nature and length of the chopper-slot sequence. These effects can easily be corrected for and will in general not impede the actual time-of-flight analysis. We report a systematic study of the origin of the spurious peaks and show how one can discriminate between the effects stemming from machining errors or from the finite thickness of the chopper disk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144073
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    A high-stability quartz crystal microbalance electrode for simultaneous solution-phase electrochemistry/microgravitometry (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1530-1535 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A quartz crystal microbalance (QCM) oscillator circuit is described which incorporates a high-gain feedback amplifier controlled by an automatic gain network. Signal level in the oscillator feedback loop is automatically optimized to provide sufficient gain necessary to sustain stable oscillation, but not so much gain as to induce waveform clipping, which would detriment frequency stability. The crystal is driven and loaded by a low-impedance network, and one side of the crystal is held at low impedance to ground. In this way, the microbalance crystal may be used in place of a working electrode in an electrochemical apparatus. Gravitometric studies at the surface of the electrode may be combined simultaneously with cyclic voltammetry, chronocoulometry, chronoamperometry, or any other electrochemical experiment in aqueous and nonaqueous solutions. The QCM signal is heterodyned with a reference signal to produce a difference frequency on the order of a few hundred Hertz. An optional frequency-to-voltage converter is also described so that the beat frequency can be monitored in real time on a chart recorder. The results of a simultaneous electrochemical/microgravitometry experiment involving the growth and redox cycling of a Prussian blue film on the surface of the QCM are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144022
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    A new device for electrical resistivity measurements as a function of temperature (86–700 K) under controlled atmosphere by the four-probe method (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1549-1553 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A device for measuring electrical resistivity as a function of temperature using unsoldered, sharp, and independent contacts has been developed. The probes are fixed on fine ceramic tubes, which are actuated by pressure-sensitive springs. The ceramic tubes are guided by metallic struts that also serve as thermal screens. The device is placed in an enclosure where a primary vacuum is established and introduce a neutral, reducing, or oxidizing gas. Measurement can be performed continually between 86 and 700 K. Materials having resistivities in the 10−8–106 Ω m range have been characterized even when they present resistivity jumps of many orders of magnitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144025
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    Low-current temperature compensated bipolar log-ratio amplifier (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1652-1654 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Numerous instrumentation applications can benefit from the use of logarithmic or exponential signal processing technique. A temperature-compensated bipolar log-ratio amplifier has been designed for measurements of currents of both polarity in the current range 10−11–10−5 A. This amplifier finds its usefulness in signal compression, especially in space-borne instrumentation for the study of various atmospheric parameters, such as electron temperature, where currents of both polarity having large dynamic range are to be measured. Temperature compensation is achieved in the temperature range −10 to +70 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144042
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    Reduced electron multiplier dead time in ion counting mass spectrometry (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1661-1662 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Detector dead time in electron multiplier ion counting applications has been reduced. A first-in first-out buffer allows a traditional ion counting system to accept pulses 10 ns apart. Lower dead time (10 ns) results from elimination of electrical ringing that trails electron multiplier output pulses. The improved system has been tested on 34S/32S isotope ratio measurements.
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    URL: http://dx.doi.org/10.1063/1.1144464
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    Design of an advanced minimum B for electron cyclotron resonance multicharged ion sources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1131-1134 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An advanced configuration of minimum-B field is designed for the electron cyclotron resonance (ECR) multicharged ion sources. The aim is to dramatically increase the efficiency of ion beam extraction by correcting the deformed magnetic flux tube containing hot plasma. The correction is performed by reversing the polarity of successive multipoles in the longitudinal direction. This method enables us to adopt the quadrupole that causes the greatest deformation. In addition, the most intense electron acceleration can be achieved with the quadrupole, since the radial field gradient is the largest of all multipoles.
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    URL: http://dx.doi.org/10.1063/1.1144105
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    Formation of an intense pulsed beam of CH3Cl in the ||111(approximately-greater-than) state using a 2-m electrostatic hexapole field (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1150-1154 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An intense pulsed beam of CH3Cl in the ||111(approximately-greater-than) state without velocity selection was focused using a 2-m electrostatic hexapole field. The beam intensity was estimated to be ∼1×1013 molecules pulse−1, which is much greater than the similar beams in the earlier study of Gandhi et al. by at least two orders of magnitude. The beam had a 3-ms pulse width and was focused with an angular divergence of 0.7 mrad. The improvements in beam intensity and in the divergence of the beam can be mainly ascribable to the efficient pumping of the hexapole field through the cylindrical electrodes, which enables us to employ the helium seeding to have the fast stream velocity, the narrow distribution of velocity, and the aerodynamic effects. Those factors altogether made the velocity selection of the beam unnecessary.
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    URL: http://dx.doi.org/10.1063/1.1144109
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    Series operation of power MOSFETs for high-speed, high-voltage switching applications (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1655-1656 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Series operation of power metal-oxide semiconductor field-effect transistors (MOSFETs) to increase their effective hold off voltage is described. The design procedure presented is a modification of a recently reported [Baker and Johnson, Rev. Sci. Instrum. 63, 5799 (1992)] method. Comments are made on implementing MOSFET stacks in various types of instrumentation.
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    URL: http://dx.doi.org/10.1063/1.1144043
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    A fiber-optic light-scattering spectrometer for dark-colored solutions of macromolecules (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1659-1660 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fiber-optic light-scattering spectrometer with simultaneous operation at wavelengths of 488 and 790 nm is described. The spectrometer can perform both static and dynamic light-scattering measurements, down to a scattering angle of 8°, from dark-colored solutions of macromolecules.
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    URL: http://dx.doi.org/10.1063/1.1144045
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    Repetitive square pulse generation by inductive pulse-forming lines with a field-effect transistor as an opening switch (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1665-1666 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two simple methods of repetitive square-pulse generation by inductive pulse-forming lines with a field-effect transistor as an opening switch are described. The square-pulse output voltages produced by both methods are in good agreement with those predicted for ideal circuits.
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    URL: http://dx.doi.org/10.1063/1.1144047
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    A method for tomography using arbitrary expansions (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1208-1212 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method for reconstructing two-dimensional distributions from a limited number of integrals is presented. The method can be applied for arbitrary expansions of the distribution; thus different types of distributions can be processed with different expansions. The method is numerically simple, and is especially useful for reconstructing time evolution of two-dimensional images. A comparison with maximum entropy tomography and an example of reconstructing tokamak radiation profiles in the case of impurity injection are presented.
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    URL: http://dx.doi.org/10.1063/1.1144118
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    Fourier transform infrared Hadamard tomography of sooting flames (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1213-1221 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An experimental technique is described that combines tomography, Hadamard signal encodement, and a patented Fourier transform infrared (FT-IR) emission/transmission (E/T) technique to perform simultaneous spatially resolved gas species and soot measurements during combustion. Tomographic analysis of line-of-sight FT-IR data allows spatially resolved measurements to be made. Hadamard encodement of the tomographic sections increases the overall signal throughput, improving the signal to noise (S/N) ratio for each measurement. The Hadamard technique leads to a major simplification in the tomographic apparatus in that the scanning apparatus that would normally be required is eliminated, and focusing of the infrared light is much easier. An experiment demonstrating Hadamard data processing as applied to FT-IR tomography is described. Deconvolution of the encoded data is shown to be accurate and gives the predicted improvement in S/N ratio. The FT-IR Hadamard tomography is performed to measure soot in a fuel-rich diffusion flame. Spatially resolved concentration measurements agree well with previous data, and clearly show striking three-dimensional features that could not normally be measured by simple line-of-sight techniques.
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    URL: http://dx.doi.org/10.1063/1.1144119
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    A broadband nuclear magnetic resonance spectrometer: Digital phase shifting and flexible pulse programmer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1235-1238 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple, low-cost pulse nuclear magnetic resonance (NMR) spectrometer is described. There are two key features of the instrument: (1) all radio frequency phase shifting is done digitally with a new-generation frequency synthesizer and (2) the pulse programmer is based on a high-speed 32-bit parallel interface card in a desktop computer. The spectrometer is well suited for single-frequency channel experiments such as nuclear quadrupole resonance and deuterium quadrupole echo NMR experiments. Because the rf phase shifting is done digitally, the spectrometer operates easily over a wide frequency range, here 10–300 MHz. The pulse programmer and other software functions are written in LabView, a graphical programming language.
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    URL: http://dx.doi.org/10.1063/1.1144122
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    Self-cleaning Langmuir probe (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1253-1256 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A contamination-free Langmuir probe of novel design is described. Surface contaminants, which lead to erroneous evaluation of plasma parameters by distortion of the probe's current-voltage characteristic, are removed by the indirect heating of the probe tip with separate heating elements running parallel to the probe wire in multibore alumina tubing. This configuration minimizes magnetic field perturbations, while maintaining the compact profile and construction ease of an unheated probe. The design and operating characteristics of such a probe are reported. Temperatures at the probe tip, as measured by a subminiature thermocouple, can exceed 500 °C. Experiments determining the effect of probe temperature, Tprobe, on the characteristic have been performed in a Q-machine plasma (Ti≈Te≈0.2 eV). We find that for Tprobe〈250 °C, the measured electron temperature is up to several times too large, indicating the presence of a contamination layer. This contamination layer is removed for Tprobe ≥300 °C, and accurate electron temperatures are recovered.
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    URL: http://dx.doi.org/10.1063/1.1144074
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    Design of a multistage 250 kJ capacitor bank for ohmic transformer of tokamak "ADITYA'' (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1263-1267 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Tokamaks require toroidal loop voltage for breakdown of the neutral gas, current rise, and the flat top phase. The temporal profile of the loop voltage established by the change of flux linked by the ohmic transformer has to be a noncosine waveform. In this paper a multistage capacitor bank is described which was used to energize the ohmic transformer in tokamak ADITYA with a major radius of 0.75 m, minor radius of 0.25 m, and a toroidal field of 1.5 T at the plasma center. A combination of capacitors charged to different voltages are switched in at appropriate times, to realize an experimental demand for initial high loop voltage followed by a lower sustaining loop voltage. Theoretical prediction for the duration of the secondary loop voltage as a function of circuit parameters, for a fast bank operation of 6 kV, slow bank, 4–4.5 kV, and slow bank, 2–2.5 kV yield t0=1.25 mS, t1=4.95 mS, and t2=24.1 mS. These values are in close agreement to the measured values of t0=1.39 mS, t1=5.7 mS, and t2=23.7 mS. The trigger delays to the various capacitor bank sections are parameter dependent. To avoid repetitive adjustments in the delays, a novel scheme for consistent triggering is also highlighted.
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    URL: http://dx.doi.org/10.1063/1.1144076
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    Measurement of frequency response in short thermocouple wires (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1280-1286 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Experimental measurements are made for the steady-state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire (type K) and a two material wire (type T) with unequal material properties across the junction. The data for the amplitude ratio and phase angle are correlated to within 10% with the theoretical predictions of Fralick and Forney (1992) for a laser-heated junction with no bead. This is accomplished by choosing a natural frequency ωn for the wire data to correlate the first-order response at large gas temperature frequencies. Moreover, it is found that a large bead size (roughly twice the wire diameter) will increase the amplitude ratio at low frequencies and distort the phase angle. In the latter case, it is necessary to increase the thermocouple wire length by 20% in the theory to correlate the data when the junctions have beads (silver soldered).
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    URL: http://dx.doi.org/10.1063/1.1144080
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    Identification of toroidal field errors in a modified betatron accelerator (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1425-1431 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A newly developed probe, having a 0.05% resolution, has been used to detect errors in the toroidal magnetic field of the NRL modified betatron accelerator. Measurements indicate that the radial field components (errors) are 0.1%–1% of the applied toroidal field. Such errors, in the typically 5 kG toroidal field, can excite resonances which drive the beam to the wall. Two sources of detected field errors are discussed. The first is due to the discrete nature of the 12 single turn coils which generate the toroidal field. Both measurements and computer calculations indicate that its amplitude varies from 0% to 0.2% as a function of radius. Displacement of the outer leg of one of the toroidal field coils by a few millimeters has a significant effect on the amplitude of this field error. Because of uniform toroidal periodicity of these coils this error is a good suspect for causing the excitation of the damaging l=12 resonance seen in our experiments. The other source of field error is due to the current feed gaps in the vertical magnetic field coils. A magnetic field is induced inside the vertical field coils' conductor in the opposite direction of the applied toroidal field. Fringe fields at the gaps lead to additional field errors which have been measured as large as 1.0%. This source of field error, which exists at five toroidal locations around the modified betatron, can excite several integer resonances, including the l=12 mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144056
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    A new concave electrostatic lens with periodic electrode configuration (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1432-1436 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To obtain a large aperture lens with outstanding focal length homogeneity, a concave electrostatic quadrupole lens with a periodic configuration of the electrodes was developed and its performance was numerically studied. By adjusting the azimuthal angle (θc) of the electrode to an adequate periodic function along the lens axis, the integration of the field gradient along the axis, for a period (∫φdz/∫dz), becomes equal to an ideal quadrupole field distribution. To verify the usefulness of the lens, the beam spot distortion of the paraxial beam, which had an initial beam diameter of 90% of the lens radius, was calculated. The results revealed that the error of the focal length inside 90% of the lens radius was only 0.012% when the lens has nine period per unit length. Also, by considering the characteristics of the modified Bessel function, a simple formula for the uniformity of the focal length was obtained, and this expression agreed well with the simulation results.
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    URL: http://dx.doi.org/10.1063/1.1144057
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    A versatile laser beam deflection sensor utilizing optical fibers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1451-1455 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact, fast (τ≈10 ns) and sensitive (δ≈0.1 μrad) laser beam deflection sensor has been developed. The device consists of a passive fiber optic sensor head and a separate detector and amplifier unit. Subsequent signal processing is performed using a fast digital storage oscilloscope. The sensor head can be adjusted according to the probe beam spot size to optimize the deflection measurement sensitivity. The passive sensor head having no electrical components makes the system especially suitable for applications where rf noise pickup may constitute a problem. A differential operating principle is utilized to reduce common-mode noise such as probe laser intensity fluctuations. The possibilities of high-pass filtering and averaging of the deflection signal to enhance the measurement sensitivity are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144061
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    Improved furnace temperature control for the PARC vibrating sample magnetometer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1365-1366 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Temperature control of furnaces to be used with the PARC vibrating sample magnetometer can be greatly improved if a separate temperature controller is utilized. A control circuit that allows easy temperature programming and ramping is described, as well as sample holder modifications which permit accurate measurement of the sample temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144097
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  • 98
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    Simple system for high-pressure FTIR measurements of supercritical fluid mixture (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1369-1370 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple system for high-pressure FTIR measurements was designed and tested. This system can be applied to physicochemical measurements and in situ analysis of chemical reactions in supercritical fluids. The principle of the high-pressure IR optical cell proposed in this study was based on that of the cylindrical internal reflectance. This system was tested by measuring the IR spectra of supercritical CO2 and of naphthalene dissolved in supercritical CO2 .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144099
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  • 99
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    Electronic Resource
    Calibration technique of time lag between nonsynchronous, ultrafast digitizers for dual homodyne spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1021-1025 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In situ calibration technique of time lag between nonsynchronous, ultrafast wave form digitizers with a sampling frequency of 1.35 GHz has been developed for application to the dual homodyne receiver system for the ion Thomson scattering experiment. By making use of the proposed calibration technique, time lag between two nonsynchronous digitizers is measured with an accuracy of ±0.015 ns. The present calibration method is applicable to any other multichannel digitizers system for simultaneous measurements, such as cross-correlation diagnostics between high frequency, broadband signals, or measurement of ultrashort pulse wave forms in a single shot.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144172
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  • 100
    Electronic Resource
    Electronic Resource
    High frequency measurement technique for patterned soft magnetic film permeability with magnetic film/conductor/magnetic film inductance line (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1034-1037 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes a new technique in the 1 MHz to 1 GHz range for measuring the permeability of patterned soft magnetic films. An inductance line with a magnetic film/conductor/magnetic film structure makes it possible to measure permeability at frequencies of up to 1 GHz because of the low stray capacitance and high resonance frequency of the electric circuit. The magnetic film pattern is designed so that the demagnetizing field can be ignored, and the absolute permeability value is estimated by analyzing the magnetic circuit. No anomaly, which may be caused by a magnetic charge at the pattern edge or a dimensional resonance, is observed using this pattern. Also, the relative permeability μ′r(0) and ferromagnetic resonance frequency fk measured with this technique, are confirmed to be in good agreement with the values calculated from static magnetic properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144479
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