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Aug 1976

Volume 47, Issue 8, pp. 899-974


Diffraction effects on angular response of x‐ray collimators

R. L. Blake, D. M. Barrus, and E. Fenimore

Rev. Sci. Instrum. 47, 899 (1976); http://dx.doi.org/10.1063/1.1134787 (7 pages) | Cited 3 times

Online Publication Date: 28 August 2008

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Angular responses have been measured for x‐ray collimators with half‐widths ranging from minutes of arc down to 10 arcsec. In the seconds‐of‐arc range, diffraction peaks at off‐axis angles can masquerade as side lobes of the collimator angular response. Measurements and qualitative physical arguments lead to a rule of thumb for collimator design; namely, the angle of first minimum in the Fraunhofer single‐slit diffraction pattern should be less than one‐fourth of the collimator geometrical full‐width at half‐maximum intensity.
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07.85.-m X- and γ-ray instruments
61.05.C- X-ray diffraction and scattering

Asymmetric crystal topographic camera

William J. Boettinger, Harold E. Burdette, Masao Kuriyama, and Robert E. Green

Rev. Sci. Instrum. 47, 906 (1976); http://dx.doi.org/10.1063/1.1134788 (6 pages) | Cited 18 times

Online Publication Date: 28 August 2008

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The practical aspects of asymmetric crystal topography are described. In this technique, asymmetric Bragg diffraction is utilized to obtain a monochromatic and well collimated x‐ray beam large enough to cover the entire area of sample crystals. Thus, the recording of diffracted beams from a sample crystal provides topographic images of the entire sample crystal. Advantages of this technique are simplicity (no scanning device), excellent sensitivity to crystal imperfections (strain fields), and versatility. Information is given on the general alignment of the camera, magnification of the x‐ray beam width, preparation of the first crystal, and divergence of the beam due to the first crystal. The practical aspects of this topographic system are demonstrated using thick Cu and Ni crystals of various degrees of perfection. An inexpensive image intensifier is also described, which is used routinely to aid in the alignment of sample crystals.
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07.85.-m X- and γ-ray instruments
61.05.C- X-ray diffraction and scattering

Pirani manometer with linearized response

H. R. Hidber and G. Süss

Rev. Sci. Instrum. 47, 912 (1976); http://dx.doi.org/10.1063/1.1134789 (3 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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A fast‐reading Pirani manometer with an electronically linearized response for gas pressures between 3×10−4 and 0.5 Torr is described. The time constant of the manometer is 20 msec. Two NTC resistors are used, one for the sensor in the vacuum system and one for the reference at constant pressure. The pressure in the vacuum system is measured by analog computation of the power needed to stabilize the two resistors to equal temperature. By a relatively simple compensation circuit, changes in room temperature within ±10 °C can be eliminated to less than 1 per mille per degree. The manometer is built from inexpensive standard electronic components.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Picosecond resolution, real‐time linear detection system for 10‐μm radiation

A. C. Walker and A. J. Alcock

Rev. Sci. Instrum. 47, 915 (1976); http://dx.doi.org/10.1063/1.1134790 (6 pages) | Cited 3 times

Online Publication Date: 28 August 2008

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A 10‐μm detection system based on up‐conversion in proustite has been developed for the measurement of subnanosecond pulses of CO2 laser radiation. This has involved the development of a ’’stretched‐pulse’’ Q‐switched Nd:YAG oscillator which can be synchronized with the output of a transverse discharge CO2 laser. The 1.06‐μm radiation generated by this oscillator and the incoming 10‐μm radiation pass collinearly through a 0.6‐cm‐long proustite crystal which is oriented for type II phase matching. An investigation of the bandwidth of the up‐conversion process has shown that it should be possible to resolve 10‐μm pulses with durations of ∼5 psec. Using an image converter streak camera to record the 0.96‐μm sum frequency, the overall performance of the system has been investigated with the aid of a mode‐locked CO2 laser operating at a pressure of 12 atm. The results have demonstrated that mode‐locked CO2 pulses as short as ∼75 psec can be generated and that the temporal resolution of the complete detection system corresponds to that of the streak camera.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
06.60.Jn High-speed techniques (microsecond to femtosecond)
42.79.Ls Scanners, image intensifiers, and image converters
42.79.Pw Imaging detectors and sensors
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Interface for a hand calculator and a digital power supply

Charles R. Hummer and Donal J. Burns

Rev. Sci. Instrum. 47, 921 (1976); http://dx.doi.org/10.1063/1.1134772 (3 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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An interface using a simple calculator is described. The calculator display is encoded in BCD and drives the input of a programmable power supply, thus providing a versatile control. This gives the capability of producing a variable step ramp controlled by external clock pulses.
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07.05.Wr Computer interfaces
07.50.Ek Circuits and circuit components

Optical characteristics of the thin‐film scintillator detector

Luis Muga and David Burnsed

Rev. Sci. Instrum. 47, 924 (1976); http://dx.doi.org/10.1063/1.1134773 (4 pages) | Cited 2 times

Online Publication Date: 28 August 2008

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A study of the thin‐film detector (TFD) was made in which various light guide and scintillator film support configurations were tested for efficiency of light coupling. Masking of selected portions of the photomultiplier (PM) tube face revealed the extent to which emitted light was received at the exposed PM surfaces. By blocking off selected areas of the scintillator film surface from direct view of the PM tube faces, a measure of the light‐guiding efficiency of the film and its support could be estimated. The picture that emerges is that, as the light which is initially trapped in the thin film spreads radially outward from the ion entrance/exit point, it is scattered out of the film by minute imperfections. Optimum signals were obtained by a configuration in which the thin scintillator film was supported on a thin rectangular Celluloid frame inserted within a highly polished metal cylindrical sleeve.
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29.40.Mc Scintillation detectors

Polarization modulation for photon‐counting Raman spectroscopy

Herbert Engstrom

Rev. Sci. Instrum. 47, 928 (1976); http://dx.doi.org/10.1063/1.1134774 (4 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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A system combining polarization modulation with digital synchronous detection has been adapted for Raman spectroscopy. The apparatus permits an accurate determination of the polarization of scattered light and offers a number of other advantages over conventional measurements of Raman spectra. Brief derivations of formulas useful for analyzing data are given. The resolution of this apparatus is 87% of the theoretical maximum. The utility of the system is demonstrated by presenting the modulation Raman spectrum of sodium chlorate.
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07.60.Rd Visible and ultraviolet spectrometers
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
33.20.Ea Infrared spectra
33.20.Fb Raman and Rayleigh spectra (including optical scattering)

Optical thickness monitor for sputtered films

D. A. Walsh, G. U. Pukite, and J. R. Fenter

Rev. Sci. Instrum. 47, 932 (1976); http://dx.doi.org/10.1063/1.1134775 (3 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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A modification to a commercial sputtering apparatus to provide real‐time monitoring of the optical thickness of sputtered films is described. The design utilizes a small vacuum window in the center of the targets, permitting the passage of a helium–neon laser beam. Modulation of the beam reflectance by the growing sputtered layer permits in situ thickness measurement.
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81.20.-n Methods of materials synthesis and materials processing
42.79.-e Optical elements, devices, and systems
78.20.-e Optical properties of bulk materials and thin films

Emissionless power cathode

P. C. Stangeby and W. T. Shmayda

Rev. Sci. Instrum. 47, 935 (1976); http://dx.doi.org/10.1063/1.1134776 (3 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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The combination of a weak rf discharge and a plasma current multiplier constitutes an effective dc power cathode which operates without electron emission, elevated materials temperature, or wall bombardment, etc. Such power cathodes may find application wherever filament cathode operation poses difficulties, as with reactive gases, or where filament replacement is undesirable.
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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
07.50.-e Electrical and electronic instruments and components

Digital enhancement of torque magnetometer signals

J. J. Grodski and A. E. Dixon

Rev. Sci. Instrum. 47, 938 (1976); http://dx.doi.org/10.1063/1.1134777 (4 pages)

Online Publication Date: 28 August 2008

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Torque signals from a metal single crystal in a rotating magnetic field and the corresponding angular position of the rotating magnet, for both directions of rotation, were digitally recorded on magnetic tape at equal time intervals, with a maximum recording frequency of 18.8 data pairs per degree of rotation. The signals included induced, background, and de Haas–van Alphen effect torques. Only the induced torque is an odd function of rotation direction, and enhancement of the induced torque signals is achieved by subtracting the data obtained for one rotation direction from that for the other rotation direction. Computer analysis of recorded data yielded enhancement only if prior correction of each angular reading was performed to take into account the finite compliance of the torque magnetometer. The resulting enhanced rotation diagrams were plotted on a Calcomp plotter. The technique is also useful for continuous recording of anisotropy torque data from weakly magnetic samples, since the induced‐torque signals can be cancelled by adding the data from one rotation direction to those obtained from the other direction.
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07.55.-w Magnetic instruments and components
07.05.Bx Computer systems: hardware, operating systems, computer languages, and utilities
75.20.En Metals and alloys

Elastic moduli of NaCl by Brillouin scattering at high pressure in a diamond anvil cell

Charles H. Whitfield, Edward M. Brody, and William A. Bassett

Rev. Sci. Instrum. 47, 942 (1976); http://dx.doi.org/10.1063/1.1134778 (6 pages) | Cited 110 times

Online Publication Date: 28 August 2008

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Instrumentation has been developed to conduct Brillouin scattering measurements on small (0.15 mm) transparent single crystals at hydrostatic pressures up to 35 kilobars in a gasketed diamond anvil cell. Phonon velocities obtained this way can be used to calculate elastic moduli as a function of pressure. Results of measurements made on NaCl yield zero‐pressure values of c11=4.82×1011 dyn cm−2, c12=1.28×1011 dyn cm−2, and c44=1.27×1011 dyn cm−2. The plots of the elastic moduli versus pressure are fitted with straight lines with the following slopes: ∂c11/∂P=11.62, ∂c12/∂P=3.05, and ∂c44/∂P=0.759.
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62.20.D- Elasticity
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Apparatus for measuring pressure–volume–temperature relationships of polymers to 350 °C and 2200 kg/cm2

P. Zoller, P. Bolli, V. Pahud, and H. Ackermann

Rev. Sci. Instrum. 47, 948 (1976); http://dx.doi.org/10.1063/1.1134779 (5 pages) | Cited 66 times

Online Publication Date: 28 August 2008

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An apparatus for determining the specific volume of solid and liquid polymers as a function of pressure (to 2200 kg/cm2) and temperature (30–350 °C) has been constructed. It is based on Bridgman’s bellows method and makes use of a linear variable differential transformer (LVDT) mounted outside the pressure vessel to measure the length changes of the bellows. The off‐null output of the LVDT drives a digital indicator, displaying length changes with an accuracy of 0.01 mm, corresponding to a volume change of 10−3 cm3. Typical samples weigh about 2 g. Volume changes of the sample are calculated from the bellows displacement using the pvT properties of the confining mercury, and by using a calibration function determined in a separate experiment. This apparatus is capable of measuring specific volume changes of polymers with an accuracy of 0.001–0.002 cm3/g. Results for a commercial polystyrene in the glassy and liquid states are given.
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67.25.de Thermodynamic properties
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

Nuclear polarization measurements of oriented 3He gas by ’’frequency jump’’ spectrometry

R. S. Timsit and J. M. Daniels

Rev. Sci. Instrum. 47, 953 (1976); http://dx.doi.org/10.1063/1.1134780 (7 pages) | Cited 1 time

Online Publication Date: 28 August 2008

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An NMR technique capable of yielding measurements of polarization of highly oriented 3He gas without appreciably disturbing the state of nuclear orientation is described. The nuclear polarization is determined through a measurement of dispersive shifts in the frequency of the NMR oscillator as the magnetic field is swept through resonance, rather than from the magnitude of NMR signals.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
33.25.+k Nuclear resonance and relaxation

Apparatus to demonstrate the piezoelectric effect in crystalline powders

A. Battaglia and U. Della Croce

Rev. Sci. Instrum. 47, 960 (1976); http://dx.doi.org/10.1063/1.1134781 (4 pages)

Online Publication Date: 28 August 2008

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An electric instrument for testing the piezoelectric properties of crystalline powders is described. The instrument consists of a rf oscillator, frequency modulated at the rate of 150 Hz with deviation of about 2 kHz. The sample is contained in a capacitor of the oscillator tuning circuit. The oscillator frequency is slowly and continuously shifted in a wide range of frequencies. When one of the resonant frequencies of the microcrystal powder belongs to the range of frequencies swept by the oscillator, the sudden fall of the impedance of the tank circuit appears as an amplitude modulation of the rf carrier. This modulation signal detects the piezoelectricity of the sample.
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77.65.-j Piezoelectricity and electromechanical effects
84.30.Ng Oscillators, pulse generators, and function generators

Aluminosilicate sources of positive ions for use in collision experiments

R. K. Feeney, William E. Sayle, and J. W. Hooper

Rev. Sci. Instrum. 47, 964 (1976); http://dx.doi.org/10.1063/1.1134782 (4 pages) | Cited 39 times

Online Publication Date: 28 August 2008

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Filament sources of all alkali metal and thallium ions have been made using 90% Pt–10% Rh gauze coated with natural or synthetic aluminosilicate materials. Details of the material preparation and emitter fabrication techniques are discussed. The various ion emitters are examined as to total emission, impurity emission, and lifetime. A composite emitter capable of simultaneously producing the several ions is presented.
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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
34.90.+q Other topics in atomic and molecular collision processes and interactions (restricted to new topics in section 34)

Absorber cell for Mössbauer spectroscopy of heterogeneous catalysts at reaction conditions

W. Nicholas Delgass, Ling‐Yuan Chen, and Gilbert Vogel

Rev. Sci. Instrum. 47, 968 (1976); http://dx.doi.org/10.1063/1.1134783 (3 pages) | Cited 4 times

Online Publication Date: 28 August 2008

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A stainless steel cell with external heaters, a Cu gasket seal, vacuum brazed Be windows, and a path length of 80 mm allows in situ collection of Mössbauer spectra for absorber wafers at temperatures up to 800 K and reacting or adsorbing gas pressures up to 1.4×105 Pa (1.4 atm).
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.-d Chemical analysis and related physical methods of analysis

Regulation of arc or emission current in hot cathode ion sources

W. M. Ollison, William A. Peters, and R. James Cross

Rev. Sci. Instrum. 47, 971 (1976); http://dx.doi.org/10.1063/1.1134784 (1 page)

Online Publication Date: 28 August 2008

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Ion currents extracted from hot cathode sources may be stabilized by a simple modification of the filament power supply to regulate the emission current. Simultaneous regulation of both current and voltage in an arc discharge is provided.
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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
84.30.Jc Power electronics; power supply circuits

Solid state surface charge sensor

K. G. Vosburgh and J. F. Schenck

Rev. Sci. Instrum. 47, 972 (1976); http://dx.doi.org/10.1063/1.1134785 (1 page) | Cited 1 time

Online Publication Date: 28 August 2008

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Measurements with a novel solid state sensor show the ability to detect surface charge densities smaller than 0.1 nC/cm2 with an inherent spatial resolution of less than 50 μ. Surface contact is not required, and the sensing process is nondestructive. These devices may be constructed in arrays using present day semiconductor processing technology.
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85.30.Tv Field effect devices
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.50.-e Electrical and electronic instruments and components

Microwave coupler for EPR cavities at 1.3 K

R. A. Isaacson

Rev. Sci. Instrum. 47, 973 (1976); http://dx.doi.org/10.1063/1.1134786 (2 pages) | Cited 6 times

Online Publication Date: 28 August 2008

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This note describes improvements in the commonly used Gordon coupler used in reflection‐type EPR spectrometers. The improvements permit stable, low noise operation in liquid helium at very low modulation frequencies. At microwave powers as high as 10−2 W, the superheterodyne spectrometer noise at 2 Hz is only 2 or 3 times worse than at 100 kHz.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
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