bluuebunny/crossref_metadata_2025 huggingface dataset:
Constant-Temperature Hot-Film Anemometer as a Tool in Liquid Turbulence Measurements
Authors: Bankoff S. G. , Rosler R. S.
Published: February 2005

The application of the Ling hot-film anemometer to measurements of free liquid turbulence has been studied. Probe drift due to electrolysis and scale formation, which heretofore has been a troublesome problem, was eliminated by maintaining the water resistivity above 106 Ω/cc. Mean velocity distributions, intensities and scales of turbulence, and spectral energy distributions were obtained which were in good agreement with corresponding measurements due to Corrsin in an air jet. On the other hand, turbulent intensity measurements in air were low by a factor of two to three, possibly due to insufficient compensation for the heat conducted into the glass backing.
Double-Beam Spectrofluorimeter
Authors: Melhuish W. H. , Murashige R. H.
Published: February 2005

A single-beam spectrofluorimeter was converted to a double-beam instrument by adding a quartz beam splitter and a second photomultiplier. Exciting light fluctuations were thus reduced from 10 to 0.5%. True excitation spectra could also be recorded and, provided the exciting light did not change by more than a factor of 10, accuracies were of the order of 10%.
Apparatus for Obtaining X-Ray Extinction Micrographs of Single Crystals
Authors: MacCrone R. K.
Published: February 2005

An apparatus for obtaining x-ray extinction micrographs (Berg-Barrett micrographs) of single crystals is described. A simple method to orient the crystal for reflection for a predetermined plane is discussed. Finally, a selection of micrographs illustrating the high resolution of the apparatus is presented.
Electron Cloud Annealing Furnace
Authors: Chandrasekhar B. S. , Flinn P. A.
Published: February 2005

An electron bombardment annealing furnace has been constructed for annealing refractory metal samples in high vacuum up to about 2800°C. The furnace is designed to accept small rods or plates, not over about 3 in. in the largest dimension. Provision is included for quenching in water (or other liquid) directly from the annealing temperature. The maximum power input to the sample is about 600 W.
A 25-Input Pulse-Height Recording System
Authors: Groom D. E. , Marshall J. H.
Published: February 2005

A general description is given of a data recording system which provides a link between counter experiments in high-energy physics and a high-speed digital computer. The instrument described can accept as many as 25 simultaneous photomultiplier tube signals and pulse-height analyze them into 100 channels each. Six bits of digital data may be substituted for any unused pulse-height input. The usual output is perforated paper tape with a binary coded decimal format for use with a Burroughs 220 computer. Identification words can be set up and recorded on the tape. The speed of the paper tape perforator limits the rate of analysis to one event per second. If the output data are fed directly into a computer memory, then the recording rate can be increased to 60 events per second. The instrument has been in operation since December 1961, and results obtained with it using both particles produced by the Caltech synchrotron and pulsers are given. Only solid-state components have been used, including nearly 1700 transistors and an equal number of diodes.
A Thermal Neutron Fission Counter for Nuclear and Analytical Measurements
Authors: Gray James , Hagemann French
Published: February 2005

A fission counter which has been used at the Argonne CP-5 reactor is described. It has been applied to the measurement of thermal neutron fission cross sections and to the determination of very small quantities of fissionable materials. The counting system consists of a dual chamber fission counter, the associated electronic apparatus, a mechanism for positioning the counter in the thermal column, and the protective neutron shielding. The design and performance of the system and the operating procedures are discussed in detail.
Plasma and Ion Beam Characteristics of the Dynamag Ion Source
Authors: Kellogg Edwin M. , Eklund Karl E.
Published: February 2005

A description of an ion source of the duoplasmatron type is given. Experimental results related to the plasma density distribution in the region between the intermediate electrode and the anode are given and discussed. Ion beam behavior in the extractor region as a function of extraction potential and total current has been studied. Also, ion beam space-charge neutralization by secondary electrons has been looked for, but not observed under present conditions.
Duoplasmatron as a Vacuum Ultraviolet Light Source
Authors: Samson James A. R. , Liebl Helmut
Published: February 2005

The radiation emitted from a duoplasmatron ion source has been investigated between 500 and 2000 Å. When the ion source is operated with hydrogen, the familiar hydrogen continuum is produced down to 1650 Å, followed by the many-lined spectrum down to 900 Å, including the atomic Lyman alpha and beta lines at 1215.7 and 1025.7 Å, respectively. With argon the source emits a line spectrum down to 550 Å originating from excited neutral, singly, and doubly ionized argon atoms.
Tunnel Diode Decade Counter
Authors: Rabinovici B.
Published: February 2005

A decimal coded binary counter is described which employs four tunnel diodes to achieve ten stable states and a transistor circuit for reset amplification and readout of the carry. The tunnel diodes must satisfy certain relationships between their peak and valley currents and final voltages. The principle of operation is discussed and the circuit of the decade counter described. The paper presents the required conditions for the diode parameters and gives experimental results obtained on a laboratory model.
X-Band Resonant Cavity for Optical Studies at Liquid Helium Temperatures
Authors: Rieckhoff K. E. , Weissbach R.
Published: February 2005

A detailed description of a cylindrical reflection cavity operating in the TE112 mode in the X band is given. The special features of the cavity design are provision for the passage of a beam of light through the region of maximum magnetic field in any direction perpendicular to the axis of the cavity, and an integral crystal mounting arrangement that allows optical alignment of the crystal around two perpendicular axes while the cavity is immersed in a liquid helium bath under reduced pressure.
Calculation of the Optimum Dimensions of Collimators for Neutron Diffraction
Authors: Jones Ian R.
Published: February 2005

If the horizontal angular divergence and total width of the aperture are preset, the neutron intensity transmitted by a primary Soller collimator will vary with the number of channels. For a given set of collimator system dimensions there is an optimum number of collimating channels, and a corresponding maximum in the transmitted intensity. For a broad range of system dimensions, it is possible to calculate both of these quantities explicitly. This provides a simple and rapid means of comparing alternatives in collimator design and location, for both optimal and nonoptimal configurations.
Display of Rotational Switching Characteristics of Magnetic Thin Films
Authors: Smith J. P.
Published: February 2005

The apparatus and techniques for displaying both rotational critical curves and rotational hysteresis curves are described. The use of large values of 20-kc control fields and linear circuitry enables the oscilloscope display of these curves to be directly related to the rotation of thin-film magnetization. The degree of deviation of switching properties of actual magnetic films from those of the theoretical model can conveniently be determined from the oscilloscope display.
High-Voltage Pulse Measurement with a Precision Capacitive Voltage Divider
Authors: Brady M. M. , Dedrick K. G.
Published: February 2005

The capacitive voltage divider can be designed to have an accurately known division ratio over a wide range of operating frequencies. A coaxial, guard-ring type geometry is described, and an analysis of possible errors due to geometrical anomalies and temperature variations is given. Due to the particular method of construction used, the division ratio of the divider itself is essentially independent of the dielectric constant of the dielectric oil used. Bridge circuits and their pertinent equations for calibrating the divider are presented. An experimental divider designed to operate on pulsed voltages up to 350 kV is described, having an over-all division ratio of 1042.3±6.0 with an expected temperature dependence of 0.01%/°C.
Instrument for Observation of Magnetization Vector Position in Thin Magnetic Films
Authors: Bader Clifford J. , Ellis David M.
Published: February 2005

An instrument is described which relates magnetization vector position in a thin film to rf mixing behavior under a crossed-wire probe. The high sensitivity possible with tuned rf amplification permits nondestructive observation of small areas of the film and affords an angular resolution on the order of one-tenth degree. Accurate location of the film easy axis and direct indication of magnetization vector rotation under the influence of a static field are obtained.
High Temperature Thermobalance
Authors: Woerner P. F. , Wakefield G. F.
Published: February 2005

A thermobalance was designed and constructed that operated up to 3000°K in vacuum or inert atmosphere. The temperature was limited by the power supply. Its utility was first demonstrated by measuring the vapor pressure of niobium. A unique heater uses standard tungsten welding rods with a tantalum expansion joint. This design allows efficient transfer of metal vapor to the cooler shields.
Pressure Measurement in Nonbaked Ultra-High Vacuum Systems
Authors: Santeler D. J.
Published: February 2005

The use of high-speed cryogenic pumping systems has resulted in the obtaining of pressures in the ultra-high vacuum region without the use of a bakeout. Under these conditions two new pressure-measurement problems are introduced due to directional pressure effects and outgassing of the gauge tubulation. These effects can cause reading errors in excess of one decade. This paper discusses these effects. A solution is presented which eliminates both types of errors and hence allows for improved pressure measurement in nonbaked ultra-high vacuum systems.
Method for Tensile Testing of Brittle Materials
Authors: Sedlacek Rudolf , Halden Frank A.
Published: February 2005

A method of tensile testing is described in which hydrostatic pressure, acting radially against the internal wall of a cylindrical specimen, is utilized to create a uniform tangential tensile stress in the specimen wall. The method is applicable to brittle materials because it eliminates nonaxial stresses due to misalignment and localized stress concentrations which normally arise from gripping or supporting the test specimens. Standard deviations of 1.1 to 2.6% were obtained on plastic and aluminum oxide specimens. The method and apparatus are described, and the results are presented.
Use of the Reciprocal Lattice for the Development of a New Pole Figure Technique
Authors: Meieran Eugene S.
Published: February 2005

A new pole figure technique employing a composite specimen is developed by means of the reciprocal lattice theory. An entire quadrant of the pole figure can be obtained in a single determination, using a spiral track goniometer and Schulz geometry. Advantages of the method are ease of specimen preparation and data recording, and accuracy of the pole figure, since variations between ``surface'' and ``inside'' textures are properly averaged over the entire pole figure.
Use of a Large Thermocouple Junction to Locate Temperature Disturbances
Authors: Jackson Philip L.
Published: February 2005

A temperature disturbance within a large thermocouple junction produces a voltage which decreases with distance from the disturbance. Resulting voltage residues can be compared at two or more points on the junction to indicate positions, magnitudes, and sizes of temperature disturbances. Useful measurement applications result.
New Large Area CdS Photoconductor
Authors: Wendland Paul H.
Published: February 2005

A CdS photoconductive cell, combining the mechanical properties of powder-binder type layers with photoconductive properties exhibited by sintered layers, is described in this report. The preparation process requires a single air firing and subsequent pressure-temperature molding with an acrylic. Data presented on the characteristics of these cells includes: photocurrent as a function of illumination intensity and electrical field, speed of response, spectral response, and mechanical properties.
New Method for Producing Platinum Preshadowed Carbon Substrates
Authors: Cook C. F.
Published: February 2005

A novel approach to the evaporation of platinum and carbon is described. The technique is capable of producing routinely preshadowed carbon replicas with a resolution of better than 20 Å. The technique consists of evaporating platinum from a specially shaped carbon rod which later is evaporated to coat the shadowed specimen without the necessity of opening the vacuum chamber or rotating specimen.
Automatic Data Recording System for Semiconductor Research
Authors: Duga J. J. , Freundlich J. J. , Bate R. T.
Published: February 2005

A completely programmable automatic data recording system has been constructed and is described in detail. Being originally designed for the measurement of the resistivity and Hall coefficient of semiconductors as functions of temperature, the system features: (1) a 100-step temperature detector to initiate a measurement cycle at a preselected temperature; (2) a 100-step input selector which can choose from up to 17 different voltages in a preprogrammed sequence and, in addition, can control environmental conditions; (3) a high-precision voltage amplifying and measuring system; and (4) an output selector containing appropriate binary-code translation circuitry and a combination typewriter-tape punch. The data are typed and simultaneously punched on tape in a desired format, and the tape information is converted to cards for data processing by a digital computer. The operation of each subsystem is described, and the over-all versatility is demonstrated by several different types of applications.
Magnetic Balance for Ferromagnetism
Authors: Hofer L. J. E. , Toor E. W.
Published: February 2005

A Mathieu-type pendulum magnetic balance is described that employs the Faraday principle for measuring the specific magnetization of ferromagnetic materials. The balance can be operated automatically, or deflections may be read optically. The sensitivity of the balance can be varied twenty-fold by changing the weight distribution, and the calibration remains constant for years. Specific magnetizations are obtained with a precision of ±0.3%. Field strengths up to 10 000 oe can be held constant within ±0.3% for several hours. Specimens can be heated to 800°C or cooled to −180°C, and the temperature can be held constant to ±1.0°C for isothermal measurements. Automatic heating of the specimen at constant rate is provided.
Nanosecond Coincidence Circuit Using Tunnel Diodes
Authors: Whetstone A. , Kounosu S.
Published: February 2005

A tunnel diode coincidence circuit which is versatile and simple is described. It is intended to serve as the elemental block for building up complicated fast logic schemes which are frequently required in high energy physics experiments. Performance results are given as well as discussions of numerous possible variations on the design.
Ion Source for Low-Energy Negative Ions
Authors: Muschlitz E. E. , Randolph H. D. , Ratti J. N.
Published: February 2005

A negative ion source is described which is capable of producing negative ion beams of moderate intensity, but with relatively narrow spread in ion energy. The source consists essentially of a jet of gas intersected by an electron beam. The pressure in the vicinity of the thermionic electron source is kept low by differential pumping. Although ion currents are not as high as those obtained with discharge sources, the present source produces ion beams particularly free of noise and instability.
Fast Ion Gauge for the Measurement of Neutral Gas Density in the Presence of Magnetically Confined Plasma
Authors: Lewin Gerhard , Martin George
Published: February 2005

A hot filament ion gauge with a calculated time constant of 130 μsec for D2 at room temperature has been developed to measure neutral gas density near a magnetically confined plasma. The plasma contribution to the collector current is determined by operating the device with the filament cold. The influence of emission, gas pressure, and magnetic field on gauge sensitivity is given. Measurements taken on a stellarator demonstrate the use of the gauge.
Operation of a Bayard-Alpert Ionization Gauge
Authors: Winters H. F. , Denison D. R. , Bills D. G.
Published: February 2005

The conditions existing in a Bayard-Alpert gauge and the effect of varying these conditions are reviewed. It is shown that several accounts of nonlinearity in gauge operation are due to variation in these conditions during the test and not to any intrinsic nonlinearity in the gauge itself. Furthermore, it is shown that if pumping effects and conductances are taken into account, good agreement is obtained between pressure measurements made in different regions of a system containing a single gas type with gauges operating at various emission currents. In addition, it is shown that many problems are substantially reduced by the simple expedient of operating the gauge at reduced electron emission and filament temperature.
Reversal of the Spin of Polarized Thermal Neutrons Without Depolarization
Authors: Abrahams K. , Steinsvoll O. , Bongaarts P. J. M. , De Lange P. W.
Published: February 2005

An inexpensive and versatile magnetic guide field for polarized thermal neutrons is described. Methods are discussed to turn the polarization vector of a beam of polarized thermal neutrons in space and with respect to a magnetic guide field in the wavelength region of 1.0 to 2.0 Å. Within an experimental error of 2% no depolarization was found.
New Emission X-Ray Microscope
Authors: Yoneda Y.
Published: February 2005

A new x-ray microscope described here uses x rays emitted by substances under electron bombardment. A pinhole formed by four knife edges is used for the projection. The purpose of this microscope is similar to that of the scanning electron microscope. The resolving power of about 0.45 μ was obtained by a comparatively simple apparatus. The construction, operation, resolution, and contrast of photographs obtained with the microscope are discussed, and, for comparison, examples of photographs are shown together with conventional optical micrographs.
Analog Computation of Respiratory Response Curve
Authors: Murphy T. W. , Crane R.
Published: February 2005

A special purpose analog computer is designed to study the normal human ventilatory response to increasing concentrations of carbon dioxide. An infrared analyzer and a pneumotachograph and strain gauge are the transducers. Standard chopper-stabilized operational amplifiers and one nonlinear (divider) element are used. A relay system synchronizes the timing and readout of the signals to produce an x-y plot of alveolar ventilation and alveolar carbon dioxide tension. This relation is used as a measure of the sensitivity of the respiratory center and of its depression by narcotic drugs.
Cylindrical Spark Chamber
Authors: Wahlig M. A. , Buffington A. , Frisch D. H. , Hill D. A. , Sodickson L.
Published: February 2005

A spark chamber consisting of eight coaxial cylindrical gaps around a liquid hydrogen target has been built and used. The sparks are viewed by a single camera looking axially up into the chamber. Stereo information is provided in the same view by reflections of the sparks from tilted mirrors at the top of the chamber.
Thin Semiconductor Transmission-Counter System for Nuclear Particle Detection
Authors: Elliott Jack H. , Pehl Richard H.
Published: February 2005

Sturdy silicon transmission counters as thin as 0.0012 in. were produced and used in conjunction with a passive pulse-adder circuit which combined the dE/dx and E pulses so that the nonuniformity and energy straggling in the transmission counter would not decrease the resolution of the energy spectra. Construction and performance of these counters are described.
Calorimetric Probe for the Measurement of Extremely High Temperatures
Authors: Grey Jerry , Jacobs Paul F. , Sherman Martin P.
Published: February 2005

A water-cooled gas sampling probe capable of steady-state operation at 15 000°K and one atmosphere has been developed. Temperature is measured by a calorimetric technique which can provide high-accuracy calibration under arcjet conditions. The probe also measures velocity and chemical composition and, because of its small size (∼⅛ in. o.d.), is capable of accurate local measurements in the presence of severe gas-stream property gradients. Calibrations in the partially ionized argon-helium environment of an arcjet exhaust indicated an average agreement with mass and energy balance criteria within ½%, and a standard deviation from the mean of less than 3%.
Electroluminescent Pressure Gauge
Authors: Ziegler C. A. , Bird L. L. , Chleck D. , Carnevale E. H.
Published: February 2005

This report describes work undertaken to design and build a pressure gauge utilizing a unique pick-off which couples the phenomena of electroluminescence and photoconductivity to obtain a completely solid-state device having a low impedance output capable of detecting very small mechanical displacements (microinches) of bellows and diaphragm pressure sensors. Advantages of this device as applied to pressure measurement are small size and weight, very high resistance to shock and vibration, and continuous resolution over a wide dynamic range. A prototype pressure gauge capable of measuring pressures from 0 to 800 mm Hg and having an electrical output of 1 to 5 V when operated from a 28-V dc power source is described.
Electrostatic Quadrupole Lens Pair for Mass Spectrometers
Authors: Lu Chih-Shun , Carr Howard E.
Published: February 2005

The focusing properties of a quadrupole lens pair have been studied under conditions to produce a wedge-shaped ion beam for a mass spectrometer. The lens equations have been analyzed numerically and resulting graphs are given for the determination of various lens parameters.
Slotted-Disk Velocity Selector of Extended Range
Authors: Trujillo S. M. , Rol P. K. , Rothe Erhard W.
Published: February 2005

A slotted-disk, mechanical velocity selector has been constructed and tested. It is similar to that reported by Hostettler and Bernstein, but may be used at velocities more than five times higher (to 6000 m/sec). Its velocity spread is somewhat less (3.4%), and its fractional open time is about the same (34.8%) as the Hostettler-Bernstein instrument. A lithium beam has been velocity analyzed and found to be in agreement with the calculated distribution.
Photographic Detectors for Neutron Diffraction
Authors: Berger Harold
Published: February 2005

Although new boron- and lithium-loaded scintillators yield very fast photographic response for thermal neutrons, it is pointed out that reciprocity-law failure responses will complicate intensity analyses of diffraction pattern films made with these techniques. The magnitude of this effect for a B10-loaded scintillator and type F x-ray film is such that the response is decreased by a factor of at least 4 times at a neutron intensity of 3×103 neutrons/cm2- sec when compared to the response at a neutron intensity 100 times higher. This objection, and that of image nonuniformities, can be eliminated by using slower response metal screens and film detectors. A rhodium-gadolinium screen combination used with a fast x-ray film such as type KK is shown to be a fast technique which will yield diffraction patterns having useful intensity information.
High Efficiency Low-Pressure Ion Source
Authors: Carlston C. E. , Magnuson G. D.
Published: February 2005

A magnetically confined, oscillating electron bombardment source has been designed which delivers high currents of noble gas ions in the 1- to 10-keV energy range. The energy spread of the beam was 2±1 eV using an anode potential of 45 V. Pressure in the source chamber was measured during source operation so that accurate gas efficiency measurements could be made. The optimum gas efficiency obtained for argon at 5-kV extraction potential and an operating pressure of 4×10−4 Torr was 59%. Mass analysis of source output showed that when the source was operated with research grade argon (99.999% pure) impurity ions in the beam consisted of only 0.50% N2+, 0.75% O2+, 0.75% H2O+, and 0.70% Ar++. Filament life is extremely long, well over 750 h. Analysis of ion production rate and plasma density shows that a large contribution to electron emission is made by the secondary electrons produced at the tungsten filament due to positive ion bombardment. The secondary electron emission current was found to be as much as 30% of the true thermionic emission current and is not negligible as previous investigators have assumed.
Nonparallel Light, Plane Grating Monochromator
Authors: Dalton Murphy L.
Published: February 2005

A high speed plane grating monochromatic illuminator intended for the vacuum ultraviolet and using nonparallel light is described. The light undergoes only two reflections between entrance slit and exit slit. Entrance slit and exit slit are on the principal axis of an ellipsoidal mirror, thereby eliminating astigmatism and spherical aberration.
Instrumentation for the Measurement of Fluctuations in Amplitude and Phase of Pulsed Radio Signals
Authors: Sawchuk Walter
Published: February 2005

This paper describes instrumentation for automatically measuring the phase and amplitude of randomly fluctuating pulsed radio signals reflected by the ionosphere. The phase detecting system is based on the null principle of servo-mechanics, wherein the phase difference between transmitted and received signals is considered as an error to be annulled. The equipment is designed for pulsed operation at a carrier frequency of 60 kc, pulse width of 100 μsec, and a repetition rate of 12 pulses/sec. Amplitude and phase data are presented on a dual channel pen recorder.
Programmed Electronic X-Ray Automatic Diffractometer
Authors: Abrahams S. C.
Published: February 2005

A high-speed, high-reliability, automatic diffractometer based on equi-inclination geometry is described. Precomputed instructions are supplied on punched paper tape. The Miller indices of each reflection are recorded, both counter and initial crystal angles are set and recorded, the diffracted intensities at the required angular intervals in a fixed counter-moving crystal stepwise scan are measured, and the final crystal angle is recorded automatically, all on punched paper tape. Angles are set to 0.01°. The output tape is processed to give the resulting corrected structure amplitudes on a common scale.
Direct-Reading Diaphragm-Type Pressure Transducers
Authors: Cope J. O.
Published: February 2005

An analysis is given of a direct-reading system for micron range differential-capacity type diaphragm manometers. It is shown that electrostatic compensation of diaphragm displacement by feedback produces a linear pressure calibration when control system gain is sufficient. It is also shown that adjustment can be provided for unavoidable inequalities in the manometer capacities without changing the calibration. An experimental direct-reading gauge is described with deviations from linearity less than 1% in the pressure range 0 to 500 μ.
Delineation of Tracks of Heavy Cosmic Rays and Nuclear Processes Within Large Crystals of Silver Chloride
Authors: Childs Charles B. , Slifkin Lawrence M.
Published: February 2005

Tracks of energetic charged particles, such as heavy primary cosmic rays and the products of nuclear collisions, have been made visible within the interior of large, transparent crystals of silver chloride. The tracks are delineated by photoelectric formation of metallic silver along them. This technique may be useful as a convenient and distortion-free method for the study of heavy primaries and fission fragments.
Ion Energy Analyzer for Plasma Measurements
Authors: Eubank H. P. , Wilkerson T. D.
Published: February 2005

Flux measurements of low-energy, neutral and charged particles provide direct knowledge of plasma composition and energy distribution. We describe a particle analyzer for the energy range between a few electron volts and several thousand electron volts, which is sensitive to single ions and has an inherent time resolution of less than 50 mμsec. Experimental results are given for both energy and mass analysis of positive ions ejected by a pulsed-arc plasma gun. Significant variations in composition and energy distributions are observed with variations in gun voltage. Preliminary results are presented on the detection of low-energy neutral particles.
Monopole Spectrometer, a New Electric Field Mass Spectrometer
Authors: Von Zahn Ulf
Published: February 2005

The monopole spectrometer uses an rf electric field between a two-electrode configuration for analyzing ions of different e/m. One electrode has a right-angle cross section, the other has a circular cross section whose center is located on the bisector of the right angle. The properties of the spectrometer are derived from an approximate equation for the ion motion. An instrument is described which achieves a sensitivity of 0.3 mA/mm Hg at m/Δm=190 with good peak shape, using an analyzing field of 27-cm length.
Electrostatic Voltmeter for the Measurement of Surface Potentials
Authors: Ashcraft T. L. , Riney John , Hackerman N.
Published: February 2005

The apparatus contains a reference surface (gold) and provision for evaporating the experimental surface onto a rotating metal plate. Circuits used to measure the surface potential difference between the two metal surfaces are described. The apparatus has a rapid and continuous response to changes in the surface potential difference (SPD) between an experimental and a reference surface. As a result, the resolution of the initial variation of the SPD on sorption of oxygen on evaporated iron has been materially increased. The apparatus can be modified to allow SPD measurement on single crystals or catalyst surfaces.
Tunable, High Stability, Microwave Oscillator
Authors: Poynter R. L. , Steffensen G. R.
Published: February 2005

This paper describes a microwave oscillator which is phase stabilized to a high-order microwave harmonic from a stable frequency standard, and which may be conveniently tuned through any selected 200-Mc band in the microwave frequency range. One form of this oscillator has a stability of a few parts in 108 throughout the 200-Mc tuning range, while a slightly more complex form has a stability of a few parts in 109 through a reduced tuning range. While this oscillator has only been applied to a high resolution microwave spectrometer and to the spectrum analysis of stable cw microwave signals, it is also well adapted to gas beam maser spectroscopy.
Apparatus for Light Efficiency Measurement
Authors: Cheroff G. , Lanza C. , Triebwasser S.
Published: February 2005

Motivated by a desire to determine the quantum efficiency of a relatively large number of GaAs injection lasers in order that some understanding of the relation between performance and structural parameters could be derived, a simple system for measuring the total light emission from such devices was sought. The method finally employed (and described herein) is generally applicable to any enclosure in which the walls are reasonably good diffuse reflectors. The calibration of the transfer efficiency of light from the source to a detector is effected by introducing a light absorbing element of known relative absorption coefficient and area.
Anomalous Residual Currents in the Ultrahigh Vacuum Use of Bayard-Alpert Ionization Gauges
Authors: Hartman Thomas E.
Published: February 2005

Anomalously high residual collector current is observed with a Bayard-Alpert ionization gauge after the gauge has been exposed to a relatively high pressure gas which will chemisorb on the grid of the gauge. The evidence indicates that the principal portion of the anomalous residual current results from the subsequent release of the adsorbed species as high velocity ions. A small fraction of the fast ions collide with the collector resulting in a positive charge flow from the grid to the collector which is pressure independent. The more strongly chemisorbed gases are found to replace those which have been previously adsorbed. Oxygen results in the largest and most persistent anomalous residual current.
Effect of Absorption and Incoherent Scattering on X-Ray Line Profiles
Authors: Bragg Robert H. , Packer Charles M.
Published: February 2005

Formulas are derived for correcting observed x-ray line profiles for distortion caused by low specimen absorption coefficient in both the asymmetrical Bragg and Laue cases. In the symmetrical Bragg case (incident and reflected x-ray beams make equal angles with the specimen surface) the present results reduce to those obtained by Keating and Warren. By making suitable approximations, all of the usual intensity formulas for the Bragg and Laue cases are obtained. It is shown that the absorption corrections for the integrated intensity can be obtained directly from measurements of the background radiation.
Study of Contamination Rates in an Electron Microscope
Authors: Patterson R. L. , Wayman C. M.
Published: February 2005

A study of contamination rates in a Hitachi HU-11 electron microscope under various conditions was made. A decontamination device is described which lowers the contamination rate by more than a factor of two. The construction of this apparatus is such that accessories like a multiaxis tilting stage and specimen tensile straining device can be used concurrently.
Heat Flow in Connected Media of Different Temperature-Dependent Conductivities
Authors: Lazarus R. B.
Published: February 2005

In slab or cylindrical geometry, it is shown that the total heat flow through parallel, homogeneous channels is the same, regardless of the state of thermal contact between them, even if the channels have conductivities which are different functions of temperature.
Fatigue and Saturation in Photomultipliers
Authors: Keene J. P.
Published: February 2005

The characteristics of some EMI photomultipliers when operated continuously with large cathode and collector currents are described. It is shown that cathode currents up to about 10 μA/cm2 are possible with some types of tubes, the only limitation being cathode deterioration under intense illumination. In other types surface resistivity and space charge prevent operation above about 0.02 μA/cm2. Data on collector saturation are given and the effect of dynode heating by large currents with consequent reduction in secondary emission factor is also described.
Design and Construction of High Magnetic Field Traveling Wave Lines
Authors: Lidsky L. M. , Rose D. J.
Published: February 2005

A pulsed, capacitively loaded helical line capable of generating 5000-G pulses is described. The line velocity is 15 cm/μsec. Titanate ceramics are used as the dielectric elements. The analysis and design take into account the often overlooked effect of inductive coupling between line elements. A formalism suitable for numerical computation of complicated systems is illustrated. The design can be extended to give a variable velocity 9-kG line.
Simple Automatic Frequency Control System for Reflex Klystrons
Authors: Waring R. K.
Published: February 2005

A simple automatic frequency control system for reflex klystrons is described. A sample of the microwave power is reflected from a reference cavity that has a modulated resonant frequency. The detected signal is phase sensitively demodulated in a transistorized demodulator that can be inserted directly into the reflector lead of the klystron.
Streak Camera for Laser Emission Studies
Authors: Helfrich James L. , Blizard Gordon F.
Published: February 2005

An inexpensive streak camera was designed and built with the specific purpose of examining laser emissions. A 10-ft sweep radius and a 6-ft film plane provided good spatial resolution and at the same time recorded the entire event. Sweep rates were variable to greater than 0.5 in./μsec. Periodic self-modulation, mode variations, and changes in emitting points have been observed.
Precision Measurement of the Cleavage Plane Grating Spacing of Potassium Acid Phthalate
Authors: Bearden Alan J. , Huffman F. N.
Published: February 2005

The clevage plane grating spacing of potassium acid phthalate (KAP) has been measured in nine orders of diffraction and d∞ found to be (13289.51±0.05 xu) at 26°C. The use of these crystals as diffraction elements for the wavelength range 6 to 25 Å is discussed. Measurement of the lattice spacing is by diffraction angle determinations in many orders with Cu Kα1 radiation. An angular precision of 0.1″ is attained. The index of refraction was calculated from the crystal constants and is consistent with the observed orders of diffraction.
Multiplication and Logarithmic Conversion by Operational Amplifier-Transistor Circuits
Authors: Paterson William L.
Published: February 2005

Multiplier and log converter circuits in the literature which are based on junction diodes have in common the requirement that the junction employed have a constant slope of the log I vs V characteristic. When current components of the Cutler-Bath and Sah-Noyce-Shockley types are considered, it is found that the range over which any one component becomes dominant, permitting application of the junction for logarithmic conversion, is narrow. The transfer conductance yFB of silicon diffused transistors is shown to exhibit the desired logarithmic characteristic over many decades. The use of an operational amplifier to impose the required bias conditions is discussed, together with performance limitations imposed by the amplifier. Circuits are given illustrating the application of the technique to vacuum gauges, transistor testing, and to an analog multiplier having a dynamic output range of five decades. A commercial electrometer is converted to logarithmic indication by the addition of only two components.
Automated Contact Resistance Probe
Authors: Antler Morton , Auletta L. V. , Conley J.
Published: February 2005

A probe is described that will determine (a) contact resistance with continuously increasing pressure from 0–1000 g, (b) contact resistance as a function of wipe distance at fixed normal load, and (c) the current-voltage properties of films from 0–200 V. In pressure and voltage modes, specimen positioning is entirely automatic and programmable. The probe locates the test surface on an X-Y plane, goes through the selected mode, and then automatically repositions and repeats the measurement according to test schedule. The wipe mode is performed manually. Resistance, current, voltage, load, wipe distance, and location of the specimen are read out on an oscillographic recorder. Contact resistance is measured by the four-point technique from 10−4 to 103 Ω. The resistance span is divided into six ranges which change automatically, from high to low, when the resistance decreases to a preset percentage of the scale. The open circuit dc voltage of the resistance measuring circuit is 10−2 or 5×10−2 V, depending on resistance range.
Determination of the Dynamic Shear Modulus of a Composite Solid Propellant
Authors: Layton Lionel H. , Sheppard G. A. , Bennett S. John
Published: February 2005

Structural analyses of large solid propellant motors subjected to an environment of transportation and handling must include the contribution of the solid propellant. More accurate propellant mechanical properties are needed for this purpose than are presently being obtained. The test method described is for determination of the dynamic shear modulus in the frequency range 0.10 to 1000 cps. The specimen consists of two concentric metal rings carried by a flat plate of propellant. The high frequency data (70–1000 cps) are obtained by applying a known sinusoidal motion to the outer ring and measuring the response at the center. The transducer and center mounting are used as an inertial mass and are included in the analysis of the viscoelastic plate. The low frequency data (0.10–45 cps) are obtained by applying a known sinusoidal motion to the center of the specimen with the outer edge in a clamped position. The applied force and displacement are both measured at the center of the specimen. The theoretical response of a plate with the dimensions of the specimen is determined by using plate theory [J. H. Baltrukonis, W. G. Gottenberg, and R. H. Schreiner, Space Technology Lab. Tech. Rept. STL/TR-60–0000–19331 (1960)] and assuming a complex Poisson's ratio of 0.5+i(o). An IBM computer is used to reduce the high frequency data; however, for the low frequency data an approximate solution [A. I. Soler and M. A. Brull, Repts. No. 61–012 and 61-A-014 under contract U-60–11305, Dyna/Structures, Inc., Springfield, Pennsylvania (1961)] makes possible the reduction of results by a simple hand computation. Typical results for the complex dynamic shear modulus with its real and imaginary parts as well as the loss tangent are given for a composite solid propellant. These data indicate a precision of approximately ±10%.
Zero-Point Detector for the Dauphinee-Mooser Circuit
Authors: Soonpaa H. H. , Motchenbacher C. D. , Dahl H.
Published: February 2005

The Dauphinee-Mooser circuit has been improved by incorporating into it a transistorized null detector. The effective noise level has been cut down to, and possibly below, the chopper noise level by picking only the portion of signal that is observed while the contacts are closed. Pickup of external stray signals has been cut down to the level where they are virtually imperceptible. A complete description of the amplifier circuit is included.
Parafocusing Diffractometry
Authors: Ogilvie R. E.
Published: February 2005

A variable bent diffracting device is described which will fit on the Norelco diffractometer. The object of this device is to provide a coupling to the rotation of the diffracting element about the goniometer axis and to bend the element automatically so that its radius of curvature has a constant value over its surface and in particular the correct value at each diffraction angle. With such a device it has been demonstrated that it is possible to eliminate the major source of error in peak displacement and, in particular, improve the resolution of low angle lines.
Equipment and Techniques for Low Temperature Electron Irradiations
Authors: Lowe L. F. , Jimenez C. , Burke E. A.
Published: February 2005

A system is described for making low temperature electron bombardment studies. A liquid helium Dewar is used in conjunction with a 1.2-MeV Dynamitron electron accelerator. Cooling is by conduction, and annealing is accomplished by balancing the helium flow rate through the cooling coils with a heater located within the cooling head. Details of the sample mount are given along with the beam positioning and monitoring devices.
Optically Pumped Nuclear Magnetometer
Authors: Schearer L. D. , Colegrove F. D. , Walters G. K.
Published: February 2005

A continuous recording total earth's field magnetometer has been demonstrated which utilizes optical pumping in He3 and the resultant polarization of the nuclear spins. The device operates as a ``self-oscillator'' at the Larmor frequency of the ground state atoms. The oscillator has a ``Q'' of 104 in a 0.5-G field. The sensitivity of the instrument to fluctuations in the magnetic field is presently several microgauss. The characteristics and operating principles of the instrument are described. The application of the device to the measurement of the absolute value of the total external magnetic field is discussed.
Probe System for Plasma Research
Authors: Chapuk J. M. , Corso V. L. , Foote V. S. , Harries W. L. , Sinclair R. M. , Upham J. L. , Yoshikawa S.
Published: February 2005

A probe system for studying the plasma of a stellarator is described. Such a fully ionized plasma can have a density ∼1013 cm−3 and a temperature ∼50 eV. The probe translator can carry various probes (we take as an example a simple Langmuir electrostatic probe) and forms part of an ultrahigh vacuum system. The associated circuitry for probe biasing, control, position indicating, and data handling and display must meet various requirements of accuracy, bandwidth, and personnel safety. Some experimental results obtained with the system are discussed, and compared with those obtained by other methods.
Thermal Conductivity of Some Amorphous Dielectric Solids Below 1°K
Authors: Anderson A. C. , Reese W. , Wheatley J. C.
Published: February 2005

The thermal conductivities of nylon, Teflon, Kel-F, hard rubber, Epibond 100A, Epibond 104, and Pyrex have been measured below 1°K, generally in the range 0.8 to 0.1°K. In all cases the thermal conductivity decreases more rapidly than linearly with decreasing temperature. If this temperature dependence is assumed to result from intrinsic structure scattering and a single temperature independent scattering length, the resulting scattering lengths fall in the range 10−3 to 10−4 cm. Several of the materials studied, particularly Teflon, Epibond 104, and nylon, have significantly lower thermal conductivities in the temperature range investigated than does Pyrex, the material most commonly used for thermal isolation in the design of demagnetization cryostats.
Velocity Servo Drive for a High Precision Mössbauer Spectrometer
Authors: Flinn P. A.
Published: February 2005

A Mössbauer effect spectrometer utilizing a servomechanism to provide a constant velocity drive has been developed. The apparatus is useful to velocities up to 1 cm/sec, and provides velocities known to one part in 103. The moving portion is relatively massive and can be used to move a small furnace or cryostat.
Thin Film Thickness Measurement Using Silver-Modified Newton's Rings
Authors: Stern Barry J.
Published: February 2005

Many interference techniques have been employed for the thickness measurement of thin films. An interference technique which is inexpensive and easy to operate consists of a silvered lens placed over a stepped film with silver overlay. The resultant interference pattern when viewed in reflection is a series of sharp dark rings against a bright background, modified Newton's rings. The step in the film to be measured causes a shift in the rings from which the thickness is calculated. Step heights in silver films, vacuum deposited on fire-polished microscope slides, of 160 and 780 Å were measured.
Multiple-Gap Magnetic Spectrograph for Charged-Particle Studies
Authors: Enge H. A. , Buechner W. W.
Published: February 2005

A spectrograph has been designed that simultaneously records broad-range, charged-particle spectra at twenty-four different reaction angles, 7.5° apart, from 0 to 172.5°. At each angle, the spectrograph records a spectrum with a total energy range of about 2.3:1 and with a resolving power exceeding R=E/ΔE=1000, where ΔE is the full width at half-maximum of a peak. The recorders are seventy-two 2×10 in. nuclear-track plates, which are developed and scanned under a microscope after the exposures. When half-millimeter strips across the nuclear-track plates are scanned, the information contained on the nuclear-track plates after one exposure corresponds to about 36 000 data points. A typical exposure time with about a 0.5-μA beam is of the order of 2 to 3 h.