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Sep 1964

Volume 35, Issue 9, pp. 1105-1241

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Method of Continuous Shock Front Position Measurement

M. Heusinkveld and F. Holzer

Rev. Sci. Instrum. 35, 1105 (1964); http://dx.doi.org/10.1063/1.1718974 (3 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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A method (called ``slifer'') for continuously measuring the position of a shock front in a solid, opaque medium has been developed. The sensing element is a shorted transmission line which forms part of the inductance of an oscillator. As the stress wave moves along the line, it crushes the cable progressively, thus changing the cable inductance and the oscillator frequency. The oscillator output is recorded as a function of time. This frequency record is converted to uncrushed cable length, and finally to a position versus time relation.

Assembly and Performance of a Double‐Beam Microscope Spectrophotometer from Commercial Instruments

Heyman C. Duecker and Ellis R. Lippincott

Rev. Sci. Instrum. 35, 1108 (1964); http://dx.doi.org/10.1063/1.1718975 (5 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A microscope spectrophotometer assembled from commercially available instruments has been used to obtain visible and near‐infrared spectra on selected specimen areas as small as 1 μ2. A commercial spectrophotometer is coupled to a research microscope equipped with a photometer tube to which the photodetector of the spectrophotometer is attached. The miscroscope spectrophotometer can be assembled easily, quickly, and in a very compact form with a minimum of machine work. The performance characteristics are discussed, as well as some applications. The instrument was designed for spectral investigations of substances under pressure, but is equally well suited to the study of conventional microscope specimens. The incorporation of cameras and polarizing optics makes the instrument particularly suited to phase studies as well. Applications discussed are the shift of absorption bands with pressure, the determination of the pressure gradient in the diamond high pressure cell, and the determination of the spectra of microsections of stained biological specimens.

Novel Method of Measuring Elastic and Anelastic Properties of Solids

D. B. Fraser and R. C. LeCraw

Rev. Sci. Instrum. 35, 1113 (1964); http://dx.doi.org/10.1063/1.1718976 (3 pages) | Cited 37 times

Online Publication Date: 29 December 2004

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A technique has been devised whereby the elastic and anelastic properties of solids can be measured both as a function of frequency and temperature. A small sphere, of the order of a few millimeters in diameter, is placed without bonding on a shear mode transducer. The transducer is driven with a pulse at one of the sphere's resonant frequencies and the free decay of the sphere's vibrations is observed by switching the transducer to a receiver. From the decay of the vibrations, the internal friction Q−1 may be calculated. Various modes may be excited and from comparison with the computed mode spectra of an isotropic solid, the Lamé constants, λ and μ, and Poisson's ratio may be calculated directly. Measurements have been made over a range of temperatures from 1.4 to near 400°K, the present upper limit being set by the solder connections to the transducer. Several materials have been tested and the results for two single‐crystal nonmagnetic garnet spheres are given as representative of the capabilities of the technique for reasonably isotropic substances. The values of Q−1 for these garnets lie between 3×10−7 and 2×10−5 at a frequency of approximately 2 Mc.

Correlated Energy and Time‐of‐Flight Measurements of Fission Fragments with Semiconductor Detectors: System Design and Performance

C. W. Williams, W. E. Kiker, and H. W. Schmitt

Rev. Sci. Instrum. 35, 1116 (1964); http://dx.doi.org/10.1063/1.1718977 (8 pages) | Cited 11 times

Online Publication Date: 29 December 2004

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A system for the measurement of correlated energies and times‐of‐flight of fission fragments has been developed. This system, adaptable for use with other charged particles as well, includes a fast‐response transformer coupling scheme in which the charge originating in a solid‐state detector passes through the transformer primary to a low noise charge‐sensitive amplifier; the fast timing signal is obtained from the transformer secondary. Noise thereby added to the linear energy signal is negligible. The measured time resolution of the system for particles in a narrow band of energies was ≲0.4nsec, full‐width at half‐maximum. The design of the system is described, and the detailed results of performance tests, including tests with coincident 252Cf spontaneous fission fragments and energy‐time correlation measurements for bromine and iodine ions (artificial fission fragments), are given.

Gas Reactor for Hot Stage Transmission Electron Microscopy

E. J. Gallegos

Rev. Sci. Instrum. 35, 1123 (1964); http://dx.doi.org/10.1063/1.1718978 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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An apparatus is described by which in‐microscope gas‐specimen reactions are possible without recourse to gas containment or aid of an auxiliary vacuum system. The existing hot stage for the JEM‐6A electron microscope in combination with the liquid nitrogen trap normally used with the cooling attachment is converted into a heated stage gas specimen reactor for transmission electron microscopy. The apparatus is described and preliminary results on the controlled oxidation of copper, iron, and nickel metal and the reduction of their oxides are discussed.

Simple Determination of the Angular Deviation Between a Prepared Crystal Surface and the Crystal Plane

F. F. Lange

Rev. Sci. Instrum. 35, 1125 (1964); http://dx.doi.org/10.1063/1.1718979 (2 pages)

Online Publication Date: 29 December 2004

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A method is described to measure the angular deviation between a prepared crystal surface and the crystallographic plane in question. The method employs a simple device used in conjunction with a Laue camera, thus eliminating cumbersome optical techniques prevalent in other methods. The deviation angle can be determined directly from the Laue photograph by a simple calculation.

High Speed Decade Pulse Counting

R. S. Foote and D. Johnson

Rev. Sci. Instrum. 35, 1126 (1964); http://dx.doi.org/10.1063/1.1718980 (4 pages)

Online Publication Date: 29 December 2004

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A high speed decade counter has been developed for pulse counting from single pulse to repetition rates greater than 50 Mc. The circuit incorporates a ladder of five tunnel diodes integrated with a rapid reset, followed by a countdown of two. Direct indicator tube readout of the pulse count is accomplished by voltage‐to‐digital conversion.

Technique for Measuring Burning Rates of Solid Propellants

J. R. Osborn and H. E. Bethel

Rev. Sci. Instrum. 35, 1130 (1964); http://dx.doi.org/10.1063/1.1718981 (5 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A technique for measuring the burning rate of solid propellants inside rocket motors is described. The technique consists of embedding wires in a specimen of solid propellant and then casting or bonding the specimen to the propellant in the rocket motor. The wires employed were made of 0.0045‐in.‐diam lead‐antimony which has a low melting point, a low thermal diffusivity, and a moderate electrical resistance. The technique involves measuring the time interval between successive interruptions of the wires caused by the burning surface of the propellant. The distance between these wires is determined from an x‐ray picture of the specimen prior to placing it in the rocket motor and prior to burning. Thus, with both the distance burned and the burning time known, the burning rate can be determined. When this technique is properly employed, it does not influence the burning rate, nor does it affect the flow field. Furthermore, it can be employed to study the influence on the burning rate of the port shape of a propellant grain inside a rocket motor, since the small specimen of solid propellant containing the resistance‐wire network can be cast into the grain of a solid rocket at any position in the port. This will permit measuring burning rates at selected locations and times in the rocket motor.

Scanning and Measuring Projector

P. G. Davey, R. I. Hulsizer, W. E. Humphrey, J. H. Munson, R. R. Ross, and A. J. Schwemin

Rev. Sci. Instrum. 35, 1134 (1964); http://dx.doi.org/10.1063/1.1718982 (13 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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The Scanning and Measuring Projector (SMP) is a semiautomatic device for making rapid and accurate measurements on bubble chamber or other photographs. The SMP, its human operator, and a general purpose digital computer work together in an integrated system. The operator scans the film and specifies the approximate path of the points to be measured, and the points are accurately digitized by a novel apparatus that sweeps the specified portion of the image across a fixed lattice of reference marks. This paper describes the SMP digitizing mechanism and process, and the configuration of the over‐all system. Also discussed are the pattern‐recognition and time‐sharing aspects of the associated computer program, and its error‐correcting capabilities.

Automatic Thin Film Vacuum Deposition System of High Stability

R. B. Brownell, W. D. McLennan, R. L. Ramey, and E. J. White

Rev. Sci. Instrum. 35, 1147 (1964); http://dx.doi.org/10.1063/1.1718983 (4 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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An automatic thin film vacuum deposition system is described which permits films of preselected thickness, in the range of 50 to 1500 Å, to be deposited automatically at selected rates between 0.1 and 10 Å∕sec. The long time repeatability of the system lies within ±10 Å of the selected thickness.

Time‐Shared Time‐of‐Flight Analysis by Computer

R. E. Chrien, S. Rankowitz, and R. J. Spinrad

Rev. Sci. Instrum. 35, 1150 (1964); http://dx.doi.org/10.1063/1.1718984 (7 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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A time‐shared computer‐centered data collection system has been placed into operation at the Brookhaven Graphite Research Reactor. The system provides simultaneous data collection and sorting for two physically unrelated neutron time‐of‐flight experiments in time‐share with a general computation facility. A general purpose stored‐program digital computer with a 4096 word, 24‐bit memory is the heart of the system. The computer system provides, for the ``fast neutron chopper'' experiment, a 1024‐channel time analyzer for total or partial neutron cross section experiments, three elapsed‐time clocks, three total events scalers, two monitor scalers, and a chopper tachometer. At the same time, for the ``slow neutron chopper'' experiment, the system provides a 256‐channel time analyzer, a clock, a total events scaler, a monitor scaler, and a chopper tachometer. The two experiments are independent of one another and are controlled by the typing of four‐letter mnemonic codes on the system typewriter. A live cathode‐ray tube display of either experiment is present at all times except when the time‐shared computational facility is being used. Connections between the computer and the external analog‐to‐digital converters are made on a patchboard, allowing convenient control of data format. The system has been designed to facilitate expansion to multiparameter data handling.

Cube‐Root Coordinate Color‐Difference Computer

M. E. Faulhaber and P. D. Schnelle

Rev. Sci. Instrum. 35, 1157 (1964); http://dx.doi.org/10.1063/1.1718985 (4 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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An electromechanical analog computer is described which automatically converts tristimulus values directly to visually compatible color differences, ΔL, Δa, Δb, and ΔE, in the cube‐root coordinate system. The range of this computer is suitable for color arrangement and formulation purposes, and its accuracy and reproducibility meet the requirements for critical industrial color control applications. The equations solved by the computer are derived from the cube‐root coordinate system; analog methods for generating these equations are outlined; typical operating procedures are illustrated; and technical specifications are detailed.

Ionization Method of Measuring Contact Potential Differences

K. W. Bewig

Rev. Sci. Instrum. 35, 1160 (1964); http://dx.doi.org/10.1063/1.1718986 (3 pages) | Cited 6 times

Online Publication Date: 29 December 2004

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A modification of the ionization method of measuring the contact potential difference between two surfaces is described which permits remote separation between the source electrodes and the indicating meter. Elapsed time recording is easily accomplished. The errors resulting from large separation between the electrodes are analyzed.

System for Displaying Thin‐Film Plated Wire Switching Characteristics Under Disturbed Conditions

Bruce A. Kaufman

Rev. Sci. Instrum. 35, 1163 (1964); http://dx.doi.org/10.1063/1.1718987 (4 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A simple and rapid test system for displaying the switching characteristics of thin‐film plated wire computer memory elements under disturbed write conditions is described. The characteristics are displayed on an oscilloscope, eliminating the need for manual plotting of data. The instrument design and construction is described and typical results are presented.

Spin Decoupler for NMR

Joseph H. Noggle

Rev. Sci. Instrum. 35, 1166 (1964); http://dx.doi.org/10.1063/1.1718988 (4 pages) | Cited 15 times

Online Publication Date: 29 December 2004

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A homonuclear spin decoupler has been developed which, in conjunction with a Varian HR60 nuclear magnetic resonance spectrometer system, may be used for frequency sweep single or double resonance or for field sweep double resonance.

New Type of Flux Meter for the Measurement of High Magnetic Fields at Low Temperatures

J. R. Houck and R. Bowers

Rev. Sci. Instrum. 35, 1170 (1964); http://dx.doi.org/10.1063/1.1718989 (3 pages) | Cited 11 times

Online Publication Date: 29 December 2004

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A flux meter is described which is convenient for high field measurements at low temperatures. The device is based on a magnetoplasma resonance and produces an audio‐frequency signal whose frequency is proportional to the magnetic field. The device has a linearity of better than 1% between 10 and 80 kG.

Electrostatic Torsion Balance for Magnetic Film Measurements

W. T. Siegle and W. R. Beam

Rev. Sci. Instrum. 35, 1173 (1964); http://dx.doi.org/10.1063/1.1718990 (3 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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An automatic torsion balance has been built for measurement of magnetic film properties. The use of electrostatically generated restoring torques results in a substantial simplification of the suspension system over previous arrangements. Furthermore, the reduced sensitivity of this system to background vibrations has made the attainment of 3×10−4 dyn‐cm sensitivity fairly simple.

Instrumentation for Measuring the dc Conductivity of Very High Resistivity Materials

D. S. Dorcas and R. N. Scott

Rev. Sci. Instrum. 35, 1175 (1964); http://dx.doi.org/10.1063/1.1718992 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Instrumentation for measuring the dc conductivity of alkali halide crystals, and other high resistivity materials, in the temperature range 20–200°C is described. Conductivity as low as 2×10−18 Ω−1 cm−1 has been measured with an estimated accuracy of 5%. A vibrating reed electrometer is used, together with a special test fixture. The latter has provision for temperature measurement and control and for maintaining the specimen in an inert atmosphere. Electrodes are applied to the specimen with colloidal graphite in alcohol or, preferably, vapor‐deposited gold electrodes are used. Contact pressure between the specimen electrodes and the gold‐plated electrodes of the fixture is maintained by gravity, the latter electrodes being free to move in a vertical direction.

Reference Tables for Platinum 20% Rhodium∕Platinum 5% Rhodium Thermocouples

R. E. Bedford

Rev. Sci. Instrum. 35, 1177 (1964); http://dx.doi.org/10.1063/1.1718993 (14 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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Reference tables have been set up for platinum 20% rhodium∕platinum 5% rhodium thermocouples over the temperature range 0–1800°C based on measurements made in air with thirteen thermocouples from four wire lots. The thermocouples were calibrated by comparison with standard platinum 10% rhodium∕platinum thermocouples from 0 to 1500°C; by freezing point determinations of zinc, antimony, silver, and gold; by melting point determinations of palladium and platinum by the wire method; by comparison with an optical pyrometer from 1200 to 1800°C; and by intercomparisons (with each other) from 0 to 1750°C. The accuracy obtained in the use of the tables is discussed, and data relating to the stability and reproducibility of these thermocouples is presented. Expanded versions of the tables are available as NRC Report No. 7930. A description of a high temperature vacuum furnace is given in the Appendix.

Precision Controlled Thermoelectric Temperature Chamber

Allan L. Wennerberg

Rev. Sci. Instrum. 35, 1191 (1964); http://dx.doi.org/10.1063/1.1718994 (3 pages)

Online Publication Date: 29 December 2004

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A precision thermoelectric temperature control system composed of a thermoelectric heat pump and a fully proportional bidirectional controller is described. This system maintains a chamber temperature at 25±0.2°C, while the ambient varies from −29 to 85°C.

Electrical Conductivity Cell for Organic Semiconductors

Paul M. LaFlamme

Rev. Sci. Instrum. 35, 1193 (1964); http://dx.doi.org/10.1063/1.1718995 (4 pages) | Cited 7 times

Online Publication Date: 29 December 2004

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This report describes the construction, calibration, and performance of a simple electrical conductivity cell for use in measuring the electrical conductivity: temperature relationship of organic semiconductors and related materials. The cell allows operation in a vacuum or inert gas atmosphere over a temperature range adequate to make rapid and reliable measurements of ρ, ρ0, and Δ EG for powdered organic semiconductor samples. Resistivities in the range of 1<ρ<108 Ω‐cm may be measured with an estimated error of ±1.2%.

Relativistic Equations and Tables for Ion Energy Determination by the Crossover Technique

Rodman Smythe

Rev. Sci. Instrum. 35, 1197 (1964); http://dx.doi.org/10.1063/1.1718996 (4 pages) | Cited 21 times

Online Publication Date: 29 December 2004

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A relativistically exact equation is derived for the scattering angle at which ions elastically scattered from one kind of nuclei have the same energy as they do when inelastically scattered from heavier nuclei. Tables are presented for protons, deuterons, and alpha particles using the 4.433‐ and 9.629‐MeV levels of 12C. The tables include incident energies from approximately 5 to 60 MeV.

Versatile Light Scattering Photometer

B. Chu

Rev. Sci. Instrum. 35, 1201 (1964); http://dx.doi.org/10.1063/1.1718997 (5 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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A photometer has been built for fluctuation studies of liquid mixtures near the critical point with thermostats controlled to 0.001°. The instrument has provisions for a choice of light sources and detection systems, and is capable of absolute scattered intensity measurements of dilute polymer solutions over a wide temperature range. It can also be converted to a spectrophotometer with a variable angular acceptance for the phototube, so that the effect of forward scattering on turbidity measurements may be examined.

Infrared Techniques for Fused Salts

Alan Bandy, J. Paul Devlin, Ronald Burger, and Billy McCoy

Rev. Sci. Instrum. 35, 1206 (1964); http://dx.doi.org/10.1063/1.1718998 (2 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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By capitalizing on the unusual properties of ultrapure silicon, two methods of measuring the infrared spectra of molten salts have been developed. Silicon is used as a cavity cell in one method, while in the second method a silicon reflecting prism allows the measurement of attenuated total reflection spectra. The two methods combined permit routine measurement of the infrared spectra of many molten salts for path lengths greater than the wavelength of the radiation. The utility of these techniques is exemplified by data for fused lithium nitrate.

Double‐Probe Method for Unstable Plasmas

Francis F. Chen

Rev. Sci. Instrum. 35, 1208 (1964); http://dx.doi.org/10.1063/1.1718999 (5 pages) | Cited 12 times

Online Publication Date: 29 December 2004

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In order to check the accuracy of electron temperature measurements by the Langmuir probe method in a plasma with large fluctuations in space potential, a method has been used which employs a floating probe in addition to the usual biased probe. The results show that the oscillations do not noticeably affect temperatures found by the standard method, so that it is not usually necessary to use this two‐probe time‐resolved method even in the presence of fairly large oscillations. Furthermore, the usefulness of this method in the case of an inhomogeneous plasma is illustrated.
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