bluuebunny/crossref_metadata_2025 huggingface dataset:
First- and Second-Order Magnetic Optics of a Circular-Pole Uniform-Field Magnet. I.
Authors: Brown K. L.
Published: February 2005

A calculation has been made of both the first- and second-order optics of a uniform-field circular-pole magnet, using the impulse approximation for the fringe-field effects. From this, the first- and second-order resolution has been derived over the entire focal plane of the magnet as a function of the angle of deflection and the momentum of the particle.
Hysteresis Loop Tracer for Thin Films in Ultrahigh Vacuum
Authors: Copeland J. A. , Kuo C. K. , Scheibner E. J.
Published: February 2005

The hysteresis loop tracer described in this paper has two unique features: first, the pickup coil leaves one face of the film exposed thus allowing the film to be deposited while the pickup coil is in place; secondly, the high sensitivity (noise equivalent to 5×10−13 Wb) allows measurements to be made on very thin films or on films having a very small saturation magnetization. The construction of the hysteresis loop tracer is discussed in detail and its effectiveness evaluated.
Magnetic Field-Tracking Nuclear Resonance Gaussmeter
Authors: Maki August H. , Volpicelli Richard J.
Published: February 2005

A feedback system is described by means of which a marginal oscillator may be referenced to the frequency of a nuclear resonance occurring in a magnetic field, and is thus useful as a magnetic field tracking nuclear resonance gaussmeter. An instrument is described which uses the proton resonance in water to track fields in the vicinity of 3500 G. The tracking range of the oscillator is 2 Mc about a center frequency of 14.5 Mc with an estimated tracking error of ±5 cps over this range at low tracking speed. A tracking rate as high as 50 kc/sec2 is possible with a tracking error of about 20 cps. A digital-to-analog conversion of the oscillator frequency has been used to present EPR spectra on an x axis linear in magnetic field, thus compensating for poor magnetic field regulation.
Zeolite Gettering for the Production of an Ultrahigh Vacuum
Authors: Batzer Thomas H. , McFarland Robert H.
Published: February 2005

During the past four years, two groups at the Lawrence Radiation Laboratory have extended, independently, the uses of zeolite gettering devices toward the production of an ultrahigh vacuum. This paper discusses their collective results.
Precision Measurement of Lattice Imperfections with a Photographic Two-Crystal Method
Authors: Bearden J. A. , Henins Albert
Published: February 2005

A photographic two-crystal spectrometer method employing the penetrating W Kα1 line has been developed. In the present investigation this technique was used to test large crystals with areas up to 25×50 mm in reflection and volumes up to 25×3.5×5 mm in transmission; angular deviations in the lattice as small as 0.5″ were detected. The first crystal was a nearly perfect calcite 30×70×10 mm used in the second order and located 100 cm from the tungsten x-ray tube and also 100 cm from the second crystal (one tested) which was usually set in the −2 order. The 200-cm distance from the focal spot to the second crystal separated the α1α2 lines and allowed the α2 line to be blocked out when testing a calcite crystal. In most tests the crystals were of different d∞'s, and a small dispersion resulted, but essentially gave the rocking curve expected from the Darwin-Prins single-crystal diffraction pattern. A NaI detector and a scaler were used to locate the peak and half-intensity points of the rocking curve. A photographic film was placed between the detector and test crystal, and an exposure of 5 to 20 min was made at each of the three positions. Structure in the image gave a measure of the imperfections and their location on the surface of the test crystal. Approximately 100 samples of calcite, quartz, silicon, and germanium crystals have been tested, of which only six or seven approximated perfection. The sensitivity and speed of the method appear superior to any thus far developed, and it provides not only an excellent test procedure for selecting crystals for precision x-ray wavelength measurements and high resolving power studies, but also for further perfecting synthetic crystal -growing techniques.
Piezoelectric Gauge for Measuring Cylinder Drag in a Fluctuating Airstream
Authors: Hanson A. R.
Published: February 2005

A piezoelectric gauge is described which is capable of measuring directly the fluctuating drag on a circular cylinder in an airstream whose velocity varies periodically. The gauge will measure forces in the milligram range having frequencies from 15 to 1000 cps. Design features of the gauge are discussed. A few results are given for the Reynolds number range of 1.5 to 115.
Temperature Effects on Flow of Low Pressure Gas
Authors: Herb R. G.
Published: February 2005

A simple proof is given of the phenomenon that in the molecular flow region gas flow through a conductance tube is independent of tube temperature.
Dipping Electrode Electrical Conductance Instrument for Use to 1700°C
Authors: Riebling E. F. , Logel P. C.
Published: February 2005

An electrical conductance instrument has been constructed for use with molten oxides at temperatures up to 1700°C. The principle of operation involves a measurement of the resistance between two partially immersed wire electrodes. The dependencies of cell constant on liquid depth, immersion depth, frequency, and resistance are described. An unusual relationship between cell constant and melt resistance appears to be associated with the geometry of the electrode arrangement. The calibration scheme involves the use of a series of standard solutions of varying conductance and a log-log plot of κstd. vs Ωmeas.. The instrument has been successfully used at temperatures up to 1700°C.
Properties of Inclined-Field Acceleration Tubes
Authors: Purser K. H. , Galejs A. , Rose P. H. , Van De Graaff R. J. , Wittkower A. B.
Published: February 2005

The avoidance of the ``total-voltage effect'' in acceleration tubes, by the use of plane electrodes with their normal inclined to the tube axis, is described. This inclined-field structure serves to sweep nonbeam charged particles out of the acceleration region soon after their formation and to reduce the probability of regenerative multiplication. A summary is presented of experiments which illustrate the major properties of this type of tube.
Application of Charged Coaxial Cables to the Measurement of Projectile Velocity and Impact Time in a Compressed Gas Gun
Authors: Ingram G. E.
Published: February 2005

An application of charged coaxial pulse-forming cables to measurements on rapidly moving electrically conductive projectiles when accelerated in a compressed gas gun is presented. Two quantities associated with high stress impacting of materials, time and instantaneous velocity at impact, are determined. Electrical signals with risetimes of less than 3 nsec are obtained and used as fiducials to determine the precise location of moving surfaces in time and space. Average velocities over three short intervals are measured to within ±0.08%. Impact and event timing to ±10 nsec is accomplished.
Ion Cyclotron Resonance Spectrometer
Authors: Wobschall Darold
Published: February 2005

A sensitive ion cyclotron resonance spectrometer designed to study low energy ion-molecule interactions in a weakly ionized gas is described. It is capable of determining simultaneously the collision frequency and average concentration of ions having a particular charge-to-mass ratio. General design considerations discussed include sensitivity, linewidth, resolution, and line broadening at high E/P. Effects of electron buildup are also discussed. The measurement chamber is intended to operate within a 1500 G, 102 cm long solenoid. Ion sources and electrode arrangements are described. Power absorption is detected by a narrow band, derivative type system for which circuit diagrams are given. The spectrometer has a resolution of about 3% and can detect an average concentration of 1–10 ions/cm3.
Nonlinear Network for the Operation of Inductive Transducers
Authors: Földvári Tibor L. , Lion Kurt S.
Published: February 2005

A nonlinear circuit is presented for the conversion of inductance variation of inductive or eddy current transducers into analogous current and voltage signals. The circuit provides high level dc output at low impedances without amplification. The sensitivity is high, values of 13 V/mH or 6 mA/mH have been observed experimentally. When the network is operated near its maximum sensitivity the output is practically independent of variations of the supply frequency.
Fast Single-Channel Pulse-Height Analyzer
Authors: Welter Leonard M.
Published: February 2005

A circuit description and performance evaluation are presented for an analyzer capable of processing pulses with risetimes as fast as 7 nsec and widths as narrow as 10 nsec. An integral nonlinearity of ±0.15% and a differential nonlinearity of ±3.5% were obtained over its dynamic range of 100:1. The maximum input repetition rate for the lower and upper level thresholds was 13 and 5 Mc, respectively, when using a 12 nsec input pulse width. The entire analyzer is mounted on a single-sided 11.4×17.8 cm printed circuit board.
Sensitive Absorption Spectrophotometer for Use as a Split Beam or as a Dual Wavelength Instrument
Authors: Rikmenspoel Robert
Published: February 2005

The spectrophotometer described in this paper is constructed to operate either as a spectrum-scanning or as a dual wavelength instrument. The advantages of combining these two modes of operation in a single instrument are discussed. The described spectrophotometer has a limit of detectibility as (1) dual wavelength spectrophotometer of 1 to 2×10−4 O.D. (O.D. is optical density) in the visible range (400–650 mμ), (2) as spectrum scanning instrument of 2×10−4 O.D. in the same wavelength range. A dynamic correction system using magnetic tape memory for obtaining a baseline flat within ±2×10−4 O.D. is described. The instrument is designed to measure optical densities with an accuracy of 2% in the range −0.3 to +1.0 O.D.
Method for the Rapid Calibration of Precision Potential Dividers While Being Operated Under Normal Conditions of Voltage, Current, and Environment
Authors: Lewis Robert N.
Published: February 2005

One of the more difficult tasks in developing and using high precision-high potential dividers is that of accurate calibration. It appears that greater confidence is possible when calibration is performed with the divider connected to its normal operating circuit voltages and exposed to its normal operating conditions. This paper describes a method for the rapid accurate calibration of dividers under their normal conditions of voltage, current, and environment. This is accomplished without making direct measurements on the majority of the individual resistors. Furthermore, the method requires so little time to perform that a calibration check may be made each time operating conditions are changed. It appears now that, when used with a divider of appropriate design, calibration accuracies of 0.001% should be practical.
Water Vapor Jet Target for the Charge Changing of Fast Ion Beams
Authors: Roos M. , Rose P. H. , Wittkower A. B. , Brooks N. B. , Bastide R. P.
Published: February 2005

A water vapor jet was used in the terminal of a tandem Van de Graaff accelerator as a stripping medium. The design of this jet system, which passed a beam 2.6 cm in diameter, is described. When used experimentally, the jet converted negative ions into positive ions with an efficiency >90% and a maximum proton current of 180 μA was measured at a beam energy of 2 MeV. This jet has also been used for the production of negative ions at low energies and the equilibrium fractions for a hydrogen ion beam in water vapor are listed.
Response of Plastic Scintillators to Cosmic Ray Air Showers
Authors: Bray A. D. , Crawford D. F. , Jauncey D. L. , McCusker C. B. A. , Melley D. , Nelson D. , Poole P. C. , Rathgeber M. H. , Seet S. H. , Ulrichs J. , Wand R. H. , Winn M. M.
Published: February 2005

The response of plastic scintillators to the flux of particles occurring in cosmic ray air showers has been measured at various distances from the center of showers of various sizes. The number of ``scintillator particles'' S obtained by dividing the observed pulse height by the mode of the pulse-height distribution due to single fast muons has been compared with the number of incident ionizing particles G seen by Wilson cloud chambers and Geiger counters. The ratio S/G is always greater than unity. It increases with increasing number of charged particles per square meter, being 1.1 for 100 scintillator particles per m2 and 4.0 for 10 000 scintillator particles per m2. It varies with radial distance from the shower center and with shower size, being 1.2 on average at 30 m from the center of showers of ∼105 particles and greater than 4 near the center of large showers. The increase in S/G is partly due to cascading of the electromagnetic component within the plastic scintillator but mostly to nuclear interactions produced in the scintillator by strongly interacting particles.
Modular Optical Test Instrument for 1700–11 000 Å
Authors: Pellicori S. F. , Roland E. H. , Teska T. M.
Published: February 2005

A laboratory instrument is described which is capable of precise measurements of refraction, transmission, polarization, and reflection from 1700 to 11 000 Å. The instrument consists of eight modular units that can be bolted together in various serial arrangements as required for the particular test. A goniometer specimen chamber and specimen carriage of unusual design are described. The specimen chamber utilizes a transit dial and is readable to 20″.
Synchronous Integrator and Demodulator
Authors: Frater R. H.
Published: February 2005

A demodulator system has been developed where integration is performed prior to demodulation. This allows a simple demodulator to be used to obtain a high level output with large dynamic range. A complete demodulator is described which gives a maximum dc output of 10V with an input rms signal-to-noise ratio as low as — 10 dB. The output zero drift is less than 50 μV/°C. The system is designed for radio astronomy applications, but is widely applicable for the recovery of signals ``buried'' in noise.
Tunneling Junction Diode Pressure Gauge
Authors: Cohen Marvin M. , Horn Leon
Published: February 2005

Tunneling junction diodes were designed specifically for use as miniature pressure gauges. They were fabricated from arsenic doped germanium of resistivity 0.001 Ω-cm and tested under hydrostatic pressures up to 700 kg/cm2. Gauge factors of 350 were achieved and the change in ``peak'' current with pressure was shown to be comparable with that of Esaki diodes. These diodes differ from ordinary tunnel diodes in that the peak-to-valley ratio has been reduced to 1 or less by increasing the excess and diffusion currents via high temperature alloying and increased alloying times. A negative resistance region appears only at low temperatures. This type of flat-characteristic, two-terminal device is useful as a variable range pressure gauge by utilizing the pressure dependence of the tunneling current. These diodes have the advantage that they need not satisfy the strict stability requirements of the amplifier mode as does the tunnel diode when it is used in this manner; furthermore, bulky low inductance mounting is no longer needed. It is now possible to take full advantage of the extremely small size of these diodes, the working area of which may be as small as 0.076 mm in diam.
Detailed Planar Magnetic Anisotropy Evaluation from Flux Sensing Measurements
Authors: Beam W. R. , Siegle W. T.
Published: February 2005

A method is described for accurate measurement of the variations of magnetic anisotropy energy with magnetization orientation in the plane of a magnetic thin film. The result, when properly chosen bias fields are applied, is shown to be identical in form to the torque curves obtained by mechanical means. The method is suitable for study of non-uniaxial as well as uniaxial anisotropies. For uniaxial films, values of Hk can be obtained with far greater sensitivity than is possible in conventional switching-type measurements. A major advantage of the technique is that it can be applied to small areas of large films, for local anisotropy variation studies.
Signal and Noise Characteristics of the PKW Marginal Oscillator Spectrometer
Authors: Howling D. H.
Published: February 2005

Results are presented of an experimental investigation into the signal and noise characteristics of a Pound-Knight-Watkins marginal oscillator spectrometer used for nuclear magnetic resonance studies. Both the wide band and the narrow band spectral noise distribution of the oscillator have been examined. Noise curves for various oscillator tubes are presented. The signal and noise response as a function of the modulation frequency of a Watkins' calibrator and the rf oscillator level has been studied. The noise distribution studies show that at low and high rf oscillation levels 1/f frequency components are always present. At intermediate levels a region of white noise is obtained between 20 cps and 1 kc. Over the range of rf levels investigated (0.6 V rms and below), the results show that for maximum signal/noise ratio the oscillator should be operated at the highest rf level. Some gain in signal/noise is obtained by using modulation frequencies in the 500 cps region. At different modulation frequencies NMR traces confirm these results.
Sensitivity Comparison of Transduction Mechanisms
Authors: Wilner L. Bruce
Published: February 2005

By using as sensitivity the ratio of output power to input mechanical energy, comparisons are made between self-generating (e.g., piezoelectric) and strain gauge type mechanisms. The comparisons indicate the frequencies below which the strain gauge mechanisms are more sensitive than the self-generating mechanisms.
Proton Magnetometer and Stable Oscillator for Remote Measurement of Strong Magnetic Fields
Authors: Garwin R. L. , Patlach A. M.
Published: February 2005

A simple apparatus for proton-resonance magnetic-field measurement permits remote location of the rf source and indicator. A high stability variable-frequency oscillator is also described.
Stored Program Computer as an Associative Radiation Analyzer
Authors: Souček Branko
Published: February 2005

A system design based on the use of a stored program on-line computer is presented here. The system is used as an associative radiation analyzer. The channel capacity of the system is 20 bits (one million channel analyzer). The data storage program is based on a threaded list (tree) algorithm. The number of different events which will be measured during a particular experiment can be assigned for each experiment. The count capacity is 4096 counts per channel, but can be extended. Two alternatives are discussed, depending on whether a fast or medium speed computer is used. The mean input rates are 5000 or 1000 events per second alternatively. In both cases the resolution between two events is determined mainly by the analogue-to-digital converters used. There is a good flicker-free display on the CRT. The display can be in map, isometric, or curve form. The display format (grid, unblanking, etc.) as well as the experimental conditions are under typewriter control.
Cell for Dielectric Measurements on Hygroscopic Materials
Authors: Nanassy A. J.
Published: February 2005

A cell for the measurement of dielectric parameters of hygroscopic materials over the frequency range from 0 to 100 Mc and at temperatures from −50 to 150°C is described. Provision is made for measurement of humidity inside the cell.
Noise Tests of an Airborne Microwave Refractometer System
Authors: Thompson M. C. , Grant W. B.
Published: February 2005

An airborne microwave refractometer system was tested to determine its noise spectrum and the distribution of this noise within the system. Samples of atmospheric turbulence spectra are shown from about 180 to 1800 m above ground [about 1800 to 3300 m above msl (mean sea level)]. Total noise in a 0.03–15 cps passband is found to be about 0.04 ppm rms and to be approximately ``white.''
Pairs of CdS Crystals with Matched Photoresponses
Authors: Snyder Donald D.
Published: February 2005

This paper is a report of a study undertaken to ascertain the feasibility of developing identically photoresponsive CdS crystals for x-ray monitoring applications. Of the crystals studied nearly one half could be matched into pairs with very nearly identical photoresponse to changes in visible and x-ray (30 kV) irradiation intensity.
Technique for Measuring the Absorption Coefficient of a Plasma
Authors: Braun W. G.
Published: February 2005

Instrumentation for determining the absorption coefficient in a plasma in the optical wavelength region has been developed for the study of a hydrogen arc discharge. The arc column is scanned with a beam of its own radiation emitted from the central zone which usually displays the highest brightness. The accuracy of the attenuation measurements near the edges of the plasma column is significantly increased over the accuracy obtainable with the double-path method. The described instrumentation produces a lateral scan of the plasma in digital form suitable for the computation of the spatial distribution of the absorption coefficient.
Elevated Temperature Metallographic Facility for Deformation and Fracture Studies
Authors: Kasen M. B. , Ford P. W. , Taggart R. , Polonis D. H.
Published: February 2005

A metallograph has been constructed so as to permit the microstructural examination of the surface of metallurgical specimens during deformation and fracture at elevated temperature in a controlled environment. Auxiliary instrumentation provides for the recording of specimen elongation, load, load transients, and temperature on a time base. The rate of specimen elongation may be controlled independently of the load. Microstrain can be measured from the relative displacement of surface markings at the same time as the microstructural appearance is observed and photographed. Cine photography can be employed to record deformation or fracture sequences. In all circumstances a careful correlation is maintained between all the measured parameters.
Analysis of Gas Pressure and Composition in a Helium-Neon Laser Discharge
Authors: Turner R. , Van Der Hoeven C. J.
Published: February 2005

A method of analyzing the gas constitution of a helium-neon laser discharge is described. The analysis was made in terms of the relative intensities of three spectrum lines in the light emitted from the side of the laser discharge tube. A graph is given relating these intensities to the laser gas constitution and also to the laser output power. Results on gas clean-up and relative laser output power during the lifetime of a helium-neon laser are also included.
Versatile Electron Microscope Reflection Stage and Its Applications
Authors: Koehler H. , Cooper G.
Published: February 2005

Design details of an electron reflection stage are described together with various applications. A unique feature of the use of this stage is a low energy secondary electron gun which is used to ``flood'' the specimen. This permits immediate surface imaging of insulator surfaces without prior specimen surface preparation. With this technique semiconductor surfaces and glass surfaces were inspected.
Large Collecting Area Sealed Proportional Counter
Authors: Bowyer C. Stuart
Published: February 2005

A large collecting area proportional counter for soft x-ray spectroscopy is described. The counter is a sealed instrument designed for inclusion in a rocket borne instrumentation package. The counter has an 82 cm2 collecting area and is sensitive from 1 to 8 Å. The energy spread of the counter with an 55Fe source is 34%.
Simple Automatic Scanner for Spark Chamber Photographs
Authors: Rust D. R. , Sinclair C. K. , Talman R. M.
Published: February 2005

An automatic scanner useful for analyzing the photographs of some spark chamber systems is described. The images of all spark chamber gaps must be aligned with the edge of the film. The film is transported at constant speed and spark positions are recorded as the times the sparks pass fixed sensors; one per gap. Digitization along the gaps is accomplished by interpolating with clock pulses between marks on a uniform scale photographed on each frame. Output is on punched cards but conversion to magnetic tape is planned.
Hydraulic Constant-Velocity Transducer for Mössbauer Effect Measurements
Authors: Kocher C. W.
Published: February 2005

A hydraulic constant-velocity Mössbauer effect transducer is described which features low cost, low noise, and a high degree of precision and accuracy, using off-the-shelf components. This unit was designed and used as a research instrument, but because of its simplicity of construction and operation it could serve well as the basis for a demonstration unit for an undergraduate laboratory. The description includes specification of important components and block diagrams of the spectrometer. Results of Mössbauer effect measurements in Armco iron and some stainless steels are presented to show the performance of the instrument.
Automatic Electrolytic Tank and Digital Computer Program for Calculations of Ion Trajectories in Crossed Electric and Magnetic Fields
Authors: Reiser Martin , Kopf John
Published: February 2005

This paper describes an automatic electrolytic tank facility and a digital computer program for studies of ion trajectories in a time-varying electric field with superimposed magnetic field. The electrolytic tank system features a probe, the motion of which is motor controlled to allow automatic measurements of electric fields in the form of two dimensional arrays of data points rather than equipotential lines. The voltage at each point of the rectangular grid is automatically balanced to ground by a self-balancing bridge and the value punched on an IBM card. The computer program is written in FORTRAN and integrates the relativistic equations of motion in Cartesian coordinates numerically by the Runga-Kutta method. The electric field is carried as a rectangular grid of potential values as obtained from the tank measurements. Magnetic field information is represented in the form of a Fourier series in azimuth, with average field and Fourier coefficients tabulated at radial increments. The program was written for orbit calculations in the center of a cyclotron, but it can be used or adapted for many other problems of charged particle motion in crossed electric and magnetic fields.
Thermal Conductivity of Electrically Conducting Liquids
Authors: Mallon C. E. , Cutler M.
Published: February 2005

The necked down sample method, which has been previously used for measuring the thermal conductivity of electrically conducting solids at high temperatures, is extended in application to liquids. The special problems engendered in the application to liquids are the design of a cell to contain the liquid in the appropriate configuration and suppression of convection. The solutions of these and other problems are discussed in the paper, and experimental results for the thermal conductivity of mercury are compared with literature data obtained by other methods.
Neutron Crystal Spectrometer with Range Extended to Subthermal Energies
Authors: Rustad B. M. , Melkonian E. , Havens W. W. , Taylor T. I. , Gould F. T. , Moore J. A.
Published: February 2005

A neutron crystal spectrometer is described which has the following features: (1) a useful range from 0.1 to 11.5 Å, (2) exceptional reproducibility for high precision experiments, (3) complete automatic control for measuring sample transmission as a function of wavelength, (4) a temperature regulated sample changer with range from −196 to 300°C, and (5) direct recording of data on punch cards, and a FORTRAN program for the statistical analysis of the data on a digital computer. Three alternate techniques were investigated and developed for extending the range of the spectrometer to wavelengths longer than 1 Å where the relative intensity of higher order Bragg reflections becomes large. In two of the methods, crystalline filters are used to attenuate shorter wavelength neutrons in the beam. In the third, a mechanical neutron velocity selector is used which transmits only the desired first order reflection. The residual higher order contamination in the spectrometer beam was measured to be less than 0.5% over the useful range of each technique. Examples of cross section measurements on V, Gd, and crystalline and fused quartz are presented. The total cross section of vanadium, which is used as a reference standard in many neutron scattering experiments, was determined to be σT=(4.93±0.02)+(2.78±0.01)λ(Å) barns in the region from 0.1 to 4.0 eV (0.92 to 0.145 Å). The total cross section of normal gadolinium measured at thermal energy (0.0253 eV) is 50 400±500 b.
Performance of a Thermistor Anemometer in Constant Density Shear Flow
Authors: Niiler Pearn P.
Published: February 2005

A mathematical model is proposed for calculating the steady state performance of a constant power dissipating thermistor in a laminar shear flow. It is assumed that the fluid is dissipationless and that forced convection is negligible. Explicit values of the excess temperature of a small thermistor, above that of the impinging fluid temperature, have been calculated for asymptotically small and large values of shear velocity.
Method for the Measurement of the Pyroelectric Coefficient, dc Dielectric Constant, and Volume Resistivity of a Polar Material
Authors: Lang Sidney B. , Steckel F.
Published: February 2005

A method is described for measuring the pyroelectric coefficient, dc dielectric constant, and volume resistivity of a polar material over a broad temperature range. The technique is based on the observation of the capacitive charging of a pyroelectric sample by the pyroelectric current generated during a continuous temperature change. This method has the advantages of requiring neither a heat flux measurement nor the attaining of isothermal conditions and does not alter the domain structure of a ferroelectric material. Values of the above properties were measured for Clevite PZT-5 (lead-zirconate-titanate ceramic) over the temperature range from −200 to 200°C. The pyroelectric coefficient of Clevite PZT-4 (lead-zirconate-titanate ceramic) was measured by a simplified method over the temperature range of 25 to 75°C.
Solution Polishing of Oriented Single Crystals
Authors: Deslattes Richard D. , Simson Bert G. , Horton Avery T.
Published: February 2005

Techniques for the x-ray alignment and solution polishing of oriented single crystals are described. These are shown to yield strain-free surfaces which are closely parallel to the atomic planes and reasonably flat.
Hot Wire Anemometer in Liquid Mercury
Authors: Sajben Miklos
Published: February 2005

A hot wire system has been developed which is suitable for operation in liquid mercury at speeds from 1 to 12 cm/sec. The wire was 38 μ diam tungsten with 2.5 μ thick enamel coating, used with 2 A heating current in constant current operation. The Nusselt number was determined experimentally as a function of Péclet number in the range 0<Pé<1.2, and was found to be compatible with available theory. Fluid impurities posed a serious problem which was countered with a special calibration procedure. The associated bridge circuit is described. Manipulation of bridge signal is made difficult by the low frequencies associated with low speeds, but can be handled by available techniques.
Air Film Blocked Electrode for Space Charge Measurement in Benzene Solution
Authors: Prock Alfred
Published: February 2005

An equilibrium capacitance method is described for investigating the extent of interfacial space charge in a highly resistive electrolyte solution. It employs an air layer blocked electrode, produced by suspending a conducting optical flat above the liquid surface. By the technique described, stable air layers with thickness of the order of 30 μ are readily prepared. The method is applied to calculation of ionic concentration in solutions of a quaternary picrate in benzene, with apparent dc specific resistance in the range 2.9×1011 to 1.1×1013 Ω cm.
Instrument for Making Small Spherical Crystals
Authors: Schuyff A. , Hulscher J. B.
Published: February 2005

A device is described for grinding small spheres of fragile crystals by blowing them around a circular tunnel, the outer wall of which is lined with emery paper. The smallest sphere diameter obtainable with the instrument is around 0.15 mm.
High Temperature Cell Compartment for the Unicam SP 700 Spectrophotometer
Authors: Bailey R. A. , McIntyre J. A.
Published: February 2005

A furnace which permits simultaneous heating of sample and reference compartments, and which can be readily installed or removed from the unmodified instrument, is described for the Unicam SP 700 spectrophotometer. A technique for preparing air sensitive melts is included. The spectrum of Nd+3 in the LiCl-KCl eutectic is shown to illustrate the performance of the instrument.
Silicon-Controlled-Rectifier Long-Pulse Driver for Injection Lasers
Authors: Teich M. C. , Berkley D. A. , Wolga G. J.
Published: February 2005

A pulser capable of driving injection lasers with long pulses (>30 μsec), high duty cycle, and currents of up to 20 A has been designed and operated. Higher currents may be obtained by increasing the power capabilities of the circuit components. Special features of the pulser are its low cost, simplicity of construction, and laser overload protection.
High Temperature, Small Diameter, Radial Heat Flow Thermal Conductivity Apparatus
Authors: Glassbrenner C. J.
Published: February 2005

A high temperature thermal conductivity apparatus has been designed and built. The apparatus employs a cylindrical geometry and radial heat flow and is accurate to ±5%. The thermal conductivities of germanium and silicon from 300°K to their respective melting points were measured with this apparatus. The special problems of high temperature measurements encountered with the apparatus are reviewed and discussed. In solving the high temperature measurement problems the eutectic temperatures of two germanium alloys (on the germaniumrich side of the phase diagram) were measured to about ±3°C. These are 909°C for germanium-iridium, and 932°C for germanium-tantalum. Germanium and molybdenum did not react noticeably.
Pulsed Field Gradients for NMR Spin-Echo Diffusion Measurements
Authors: Tanner J. E.
Published: February 2005

Construction parameters are given for coils to produce field gradients for use in NMR spin-echo diffusion studies. The coils are shaped to give the greatest field gradient homogeneity in the region of the sample, taking into account image currents in the magnet pole faces. A circuit diagram of the current supply is given, including a transistor switch for pulsing the current.
Electromagnetic Flowmeter
Authors: Cushing Vincent
Published: February 2005

In this paper we augment earlier electromagnetic flowmeter theory to provide for wide area curvilinear detection electrodes. An expression is derived for the flowmeter's internal impedance. It is shown that with one certain amount of positive feedback in the detection circuitry, the EM flowmeter measures volumetric flowrate irrespective of the electrical properties of the metered fluid; with a second certain amount of feedback, the EM flowmeter measures mass flowrate for dielectric fluids which satisfy the Clausius-Mossotti relationship. Experimental results, using transformer oil as the metered fluid, are reported.
Simple Force Magnetometer
Authors: Harvey Robert L.
Published: February 2005

The fixed position pendulum magnetometer described here uses a commercial electromechanical transducer for indicating the change of intensity of magnetization of magnetic materials as a function of specimen temperature. The resultant data of thermal coefficient of magnetization and Curie temperature are displayed on an X-Y recorder. The instrument requires no coils, is inexpensive to build, is essentially automatic in operation, and can accommodate samples of most forms and shapes.
Sensitive ac Hall Effect Circuit
Authors: Guthrie G. L.
Published: February 2005

A description is given of a Hall effect circuit which uses a constant magnetic field and a 270 cps alternating current source supplying the driving current to the sample. Provision is made for canceling voltages caused by misalignment of the Hall voltage probes as well as other unwanted voltages induced from the driving circuit. The cancelation of the unwanted voltages is accomplished within the sample by controlling the current distribution so that the unwanted voltages never appear at the Hall voltage probes. This allows the detector circuitry to be kept simple, keeps shielding problems to a minimum, and eliminates the necessity for using balancing resistors in the low level Hall voltage circuit. Sensitivity compares favorably with other ac methods.
Nonlinear Bridge for Electrothermal Measurements
Authors: Rosenthal Louis A.
Published: February 2005

If an ac bridge contains one arm which is capable of responding to the instantaneous cyclic power, it will exhibit a residual third harmonic voltage at balance. This voltage magnitude is related to the electrothermal parameters of the nonlinear arm and the phase angle is related to the ability to follow instantaneous power. A practical measurements system based on these principles is described.
Discharge Chamber Sensitive Time
Authors: Strelzoff A. , Pondrom L. , Kloeppel P. , Fassnacht S. , Limon P.
Published: February 2005

Wide gap discharge chambers have been exposed to proton beams of 2×106/sec. It was found that the chamber could handle about 3 extra particles/μsec without obscuring the event of interest. The spatial response of the chamber would render it useful as a detector at high energy accelerators in intense beams where simultaneous tracks at large opening angles must be observed.
High Voltage Cathode Temperature Measurement
Authors: Forgacs R. L. , Parafin B. A. , Eichen E.
Published: February 2005

The problem of making accurate measurement of temperature of a high voltage cathode in an emission microscope is discussed. Temperatures to 1300°C with voltages to 50 kV were measured within approximately ±5°C. Radiation sensing measurement schemes were dismissed, primarily on the basis of limited accuracy due to emissivity variations. In the developed system the entire temperature measurement and control system consisting of a Pt/Pt-10 Rh thermocouple, a recorder, controller and power amplifier, are floated at cathode potential to 50 kV. The presence of high voltage, about 109 times greater than the permissible thermocouple error voltage, produces negligible effect on indicated temperatures; the entire thermocouple circuit is enclosed in a shield at cathode potential. A high voltage insulated isolation transformer provides line power to the measurement and control system and insulated shaft extensions permit safe manipulation of all controls with high voltage applied. The accuracy of ±5°C achieved for temperature measurements was determined by utilizing the known temperature of metallurgical phase transformations. The recorder is about as safe and convenient to use as a normal grounded recorder.
High Performance Phase Fluorometer Constructed from Commercial Subunits
Authors: Müller Alexander , Lumry Rufus , Kokubun Hiroshi
Published: February 2005

Using new commercial equipment including a Pockels-effect light modulating device, a phase fluorometer with the following characteristics has been constructed: high intensity light with a high degree of modulation (typically m=43% at 1 kV modulating voltage and 462 mμ); pure sine modulation of variable frequency (14.0110, 21.0170, 27.0040 Mc); narrow wavelength regions for excitation and emission; very small contamination of detected light with exciting light (<1%); spectral range of the modulated light from 200 to 1000 mμ. The phase difference between fluorescent light and scattered light is measured with a high precision wide band phasemeter employing fixed and variable coaxial delay lines. The output of the phase detector is recorded and precise phasenull found graphically. Maximum time resolution is 0.02 nsec. The average over-all precision in general use is Δτ/τ=2% in the range from 2 to 63 nsec; a wider range can be measured with slightly reduced precision. Systematic errors caused particularly by electron transit time in the photomultipliers depending on voltage, exposed area of photocathode, wavelength, and photocurrent are investigated for two photomultipliers (EMI 9558B and RCA 6217), and procedures to control these errors are described. Measurements of fluorescence liftetimes of five organic compounds at very low concentrations show a lack of dependence of the results on type of photomultiplier tube, photocurrent, multiplier voltage, type of scatterer, modulating frequency, and emission wavelength. This suggests that the accuracy of the measurements is very nearly equal to precision and is limited by the experimental error in sample preparation rather than the accuracy of the measurements themselves. Some lifetime results reported are 10−6 M fluorescein in 0.01 M KOH, τ=(3.83±0.01) nsec; 10−5 M 9,10-diphenylanthracene in 95% ethanol, τ=(7.91±0.02) nsec; acridone in water (0.01×saturated solubility), τ=(15.54±0.05) nsec; 1.3×10−6 M safranin T in pyridine containing 5% water, τ=(2.29±0.01) nsec; 3×10−7 M chlorophyll-a in 95% ethanol, τ=(5.55±0.03) nsec. Some effects of oxygen quenching and concentration are also reported. The instrument allows analysis of complex decay kinetics by varying the excitation modulation frequency and selecting narrow wavelength intervals in the emission. A wide range of excitation and emission intensities can be employed for studies of intensity dependence of liftetimes as is necessary in studies of natural photosynthesis.
Calorimeter with Peltier Compensation and with Multiple Sample Bulbs for Measuring Heats of Solution
Authors: Friedman Harold L. , Wu Yung-Chi
Published: February 2005

A calorimeter has been constructed for measuring heats of solution of salts in various solvents near room temperature and at large solvent/salt ratio. The instrument consists of a sealed tantalum vessel housing an externally driven stirrer and suspended in an evacuated submarine immersed in a constant temperature bath. The heat of stirring is compensated by a Peltier cooling device. Up to four samples of salt can be dissolved in an experiment without opening the calorimeter. A germanium resistance thermometer is used to compare the temperature change produced by the dissolving salt with that produced by electrical heating.
Stable Current Regulator for Superconducting Solenoids
Authors: Fietz W. A.
Published: February 2005

A zero to twenty-five ampere controller for use with a superconducting solenoid is described. The controller drift is less than one part in 106 per hour and the low frequency peak-to-peak noise is less than one part in 106 of the maximum current output. In addition, the controller contains circuitry to maintain the solenoid terminal voltage at a value which may be programmed as a decreasing function of solenoid current in order to vary the magnetic field to any desired value without exceeding the allowable terminal voltage of the solenoid.
Nitroguanidine Explosive Plane-Wave Generator for Producing Low Amplitude Shock Waves
Authors: Benedick W. B.
Published: February 2005

An explosive plane-wave generator is described in which low-density nitroguanidine is used to reproducibly generate low amplitude plane shock waves. The nitroguanidine density was varied to change the shock wave amplitude. Most of the results are for a plane-wave generator 7.1 cm in diameter; however, it is shown that scaling to a 10 cm diam is valid. For a 7.1 cm diam plane-wave generator, the detonation wavefront planarity is within ±0.03 μsec over a 5 cm diameter. Based on quartz gauge measurements of propagated shock wave amplitudes in aluminum and brass, an approximate analysis indicates detonation pressures of about 9 and 12 kbar, respectively, for nitroguanidine densities of 0.30 and 0.40 g/cc.
Inexpensive Low Temperature Cell for Visible and uv Spectra
Authors: Rose W. B. , Nebgen J. W. , Metz F. I.
Published: February 2005

A simple low temperature Dewar and cell for visible and uv spectroscopic studies of liquids are described. The unit can be used with most spectrophotometers with little or no modification of the instruments. Advantages and disadvantages of the Dewar are discussed.
Programmed Temperature Controller and Cryostat
Authors: McSweeney D. , Levy P. W. , Townsend P. D.
Published: February 2005

A cryostat and programmed temperature controller has been developed to heat solid samples from liquid helium temperature to room temperature (4 to 300°K) so that their temperature increases according to a specified function of time. It can be operated at various heating rates and has been tested using linear heating rates of 0.5 to 20°K per minute. The desired temperature profile is obtained as a voltage from a function generator. This voltage is compared to the emf from a sensing thermocouple and the difference signal used to adjust the sample compartment heater. Any arbitrary monotonic temperature vs time function may be obtained by adjusting resistors in the function generator.
Regulated Light Source
Authors: Rosenthal Louis A.
Published: February 2005

The light output from a small incandescent lamp can be regulated by employing a photoconductive cell in a feedback loop. Two systems are described and analyzed. Drifts less than 0.07% are achievable.
Low Frequency Field Modulation Differential Magnetometer; Applications to the De Haas-Van Alphen Effect
Authors: Goldstein A. , Williamson S. J. , Foner S.
Published: February 2005

Low frequency field modulation techniques (FMT) for measurements of differential magnetic susceptibility are discussed and specific applications to the de Haas-van Alphen effect are analyzed. The method utilizes a small ac modulating field which is superimposed on a large applied dc magnetic field. Differential changes in magnetization of the sample are synchronously detected with the aid of a suitable arrangement of pickup coils. The FMT is applicable to a wide variety of magnetic measurements and is particularly valuable for de Haas-van Alphen or magnetic transition studies at high magnetic fields. Advantages of this technique include: simplicity, versatility, direct applicability to axial high field water-cooled and superconducting solenoids or transverse magnets, high differential sensitivity (dσ/dB=3×10−6 emu/gG), convenient access to the sample environment, and use of standard commercially available electronic components. Details of the detection coil assembly, sample rotation devices, and low temperature accessories are presented along with a general discussion of the data processing techniques. Modifications for transverse field modulation and accurate orientation of the dc or modulation field with respect to the sample are also discussed.
Measuring the Submicrosecond Response of Shock Loaded Materials
Authors: Linde Ronald K. , Schmidt David N.
Published: February 2005

Methods for high precision transient measurements using simple techniques for instrumentation and target alignment are described. Techniques are discussed in terms of application to a gas gun used to study the response of materials to dynamic loading. Results indicate that tilts of about 0.01° between impacting surfaces, projectile velocity measurements to about 0.1%, and time correlations to within 0.01 μsec are readily obtainable.
Null Method of Measuring Microwave Phase Shifts
Authors: Gardner Andrew L.
Published: February 2005

A companion paper by Gardner and Hawke described a microwave phase shifter, with constant output, capable of rapid phase control by the bias voltage applied to varactor diodes. This paper describes the application of this device to measure phase shifts in a cw microwave system by a null method. If phase and amplitude variations are not too fast, standard oscilloscope components can provide most of the required circuitry. Examples are given, including the measurement of 0.003° phase shift at 9 Gc in a plasma experiment.