bluuebunny/crossref_metadata_2025 huggingface dataset:
MURA 50-MeV Electron Accelerator—Design Study and Choice of Operating Point. II
Authors: Cole F. T. , Haxby R. O. , Sessler A. M. , Snyder J. N.
Published: February 2005

The design study which led to the MURA 50-MeV electron accelerator is described. Choice of accelerator type, energy and operating point, computer studies, tolerances to field errors, and design of the shaped pole are discussed.
Design and Construction of the Magnets and Magnet Support Structure for the MURA 50-MeV Electron Accelerator. III
Authors: Haxby R. O. , Day E. A. , Mulady J. R. , Pruett C. H. , Wallenmeyer W. A. , Winter W. R.
Published: February 2005

Design and construction of the magnets and magnet support structure of the MURA 50-MeV electron accelerator are discussed. The choice of the basic magnet structure as determined by the accelator parameters and methods of matching the magnets and winding the coils to produce magnets with uniform properties are described.
Main Magnet Power Supplies of the MURA 50-MeV Electron Accelerator. IV
Authors: Berndt Martin M.
Published: February 2005

The main magnet power supplies for the MURA 50-MeV electron accelerator consist of motor generator sets for producing the direct current, a transistor filter in series with the load to absorb transients, and a high gain regulator to provide long term stability. Two 70-A, 50-kW power supplies with stability of 0.002% and two 14-A, 4-kW power supplies of 0.01% stability are required. In addition, it is necessary to be able to turn the supplies on slowly, reproducibly, and with a minimum of overshoot.
Tolerances and Effects of Field Perturbations for the MURA 50-MeV Electron Accelerator. V
Authors: Parzen G.
Published: February 2005

The operating point of the MURA 50-MeV electron accelerator lies near three linear perturbation resonances. The effect of each of these resonances is examined and the tolerances due to each resonance are determined. Results are also given for the effects of perturbations at the two-way operating point.
Vacuum System for the MURA 50-MeV Electron Accelerator. VIII
Authors: Owen C. W. , Lee G. M. , McGruer J. N.
Published: February 2005

Details of the design, fabrication and assembly, and operating experience are given for the vacuum system of the MURA 50-MeV electron accelerator. A vacuum envelope constructed of ⅜-in.-thick aluminum alloy is evacuated to pressures of the order of 10−7 Torr by two 280-liter/sec getter-ion pumps. Viton-A elastomer gaskets are used throughout for both fixed and sliding seals.
Radio-Frequency Acceleration System for the MURA 50-MeV Electron Accelerator: Theoretical Considerations and Description. XI
Authors: Symon K. R. , Rowe E. M. , Swenson D. A. , Johnston L. H.
Published: February 2005

Theoretical considerations pertinent to the design of the radio-frequency acceleration system for the MURA 50-MeV electron accelerator are presented. Parameters of the acceleration system are developed on the basis of these considerations. Theoretical limitations of the maximum stacked beam obtainable with this acceleration system are given.
Betatron Acceleration in the MURA 50-MeV Electron Accelerator. XII
Authors: Peterson F. L. , Radmer C. A.
Published: February 2005

Four transformer cores symmetrically placed around the FFAG electron accelerator are used to accelerate particles from an injection energy of approximately 100 keV to about 2 MeV, which is well above the transition energy of 1.13 MeV. This type of acceleration during the early part of the operating cycle provides flexibility and simplification for the injection process, eliminates the complications required by an rf program suitable for accelerating particles through the transition energy, and is a useful analyzing tool for certain types of experiments. Detailed operation of the betatron system and its associated components is described. The construction parameters of the cores and a description of the associated pulsed power supply and integrator circuits are also discussed.
Radio-Frequency Acceleration System for the MURA 50-MeV Electron Accelerator: Design and Construction. XIII
Authors: Rowe E. M. , Hilden R. H. , Stump R. F. , Swenson D. A.
Published: February 2005

The design, construction, and operation of the accelerating and holding rf systems of the MURA 50-MeV electron accelerator are described and discussed. Qualitative results of experiments with the systems are given.
Beam Measurement Probes for the MURA 50-MeV Electron Accelerator. XV
Authors: Lee G. M. , McGruer J. N. , Mills F. E. , Owen C. W. , Peterson F. L. , Radmer C. A. , Rowe E. M. , Swenson D. A.
Published: February 2005

The design and construction of probes to measure beam size, orbit shape, betatron oscillation frequencies, and beam intensity are described, together with the mechanical and electrical aspects of the probe drives which move the probes.
Nanosecond Pulse Amplifiers
Authors: Lunsford James S.
Published: February 2005

A group of fast amplifiers has been developed primarily for use with fast semiconductor detectors in time-of-flight experiments. They have risetimes of approximately 1 nsec, gains of 100, and dynamic ranges of 50:1.
Piezo-Faraday Effect at 25 kbar
Authors: Skaggs F. L. , Broersma S.
Published: February 2005

The magneto-optic rotation has been investigated at 25 kbar using a diamond press and an electromagnet. The optical aperture does not impose intensity limitations. The sample area is 0.4 mm2 and its thickness about 20 μ. The Verdet constants of ferric polysaccharides were measured at a wavelength of about 0.65 μ. Raising the pressure to 25 kbar, the rotation decreases, in general, reversibly by about 65%. The piezo-Verdet constant, defined as σ=(Vp−Vo)/Vop, is −27×10−6bar−1. This is the same relative change as that found for the magnetic susceptibility below 1 kbar.
High Sensitivity Faraday Susceptibility Apparatus
Authors: Soule D. E. , Nezbeda C. W. , Czanderna A. W.
Published: February 2005

A high sensitivity Faraday susceptibility apparatus employing a quartz beam microbalance is described. With this apparatus, it is possible to measure the susceptibilities of small samples (0.2 mg) and adsorbed gases, to adequately account for ferromagnetic impurities by the Honda-Owen method, and to carry out measurements over a range of ambient atmospheres and temperatures (80–700°K). An automated null technique was developed for continuous operation in time dependent studies. In practice, the error obtained with this apparatus is 0.1% for precision and ≤1% for accuracy and it is possible to obtain, under favorable conditions, an ultimate sensitivity of ±0.001×10−6 emu/g.
Čerenkov Counter Monitor for Separated Bubble Chamber Beams
Authors: Horwitz Nahmin , Webster Medford
Published: February 2005

The construction and performance of a simple, reliable threshold gas Čerenkov counter is described. When the discrimination level is well below one photoelectron, the counter efficiency rises from 0.1 to 0.9 for a change in particle velocity of Δβ=0.0006. The counter has been very useful in setting up and monitoring a separated beam used with the Brookhaven 80-in. bubble chamber.
Laboratory System for the Transfer of 4.2°K Liquid Helium into a Below-λ Region
Authors: Madden Hannibal H. , Bohm Henry V.
Published: February 2005

A laboratory system for the transfer of 4.2°K liquid helium into a below-λ region is described. The device operates on the principle of ``flash-evaporation'' of 4.2°K liquid through a needle valve into a region of below-λ temperature. It is designed for easy installation on most experimental cryostats. Factors affecting transfer efficiency, currently greater than 20%, are discussed.
Hydraulic Tension-Compression Fatigue Machine
Authors: Pelloux Regis M. N. , Brooks S. D.
Published: February 2005

A tension-compression fatigue machine has been designed and built which permits fatigue testing under controlled uniaxial stress or strain amplitudes with zero, positive, or negative mean stress or strain. Stress control is available in three load ranges up to 1000 lb. Strain amplitudes can be measured and controlled by a differential transformer extensometer which covers up to 0.1-in. displacement in its 1.0-in. gauge length, in three ranges. The accuracy in the maximum range is ±100 μin. Larger displacements, up to 1.0 in., are controlled through ram instrumentation. Stress or strain amplitude, as well as frequency of cycling, can be varied continuously during the test in order to perform increasing stress or strain amplitude fatigue tests. Recording of the stress or strain level versus time or recording of the stress-strain hysteresis loop is accomplished by means of an oscilloscope or X-Y recorder.
Spark Chamber Pulsing System
Authors: Lavoie Louis , Parker Sherwood , Rey Charles , Schwartz Daniel M.
Published: February 2005

A spark chamber pulser is described in which several avalanche transistors and a step-up transformer drive directly an air spark gap whose trigger electrode is surrounded by barium titanate dielectric. Output pulses of from 1 to 25 kV with a risetime of 1 nsec and an output impedance of less than 1 Ω can be obtained. The total delay from the 1-V input pulse to the high voltage output pulse ranges from 17 to 65 nsec depending on the desired voltage and the mode of operation of the spark gap. Jitter times are less than 3 nsec. When Elkonite-tipped electrodes are used, the gap life is in excess of 5 000 000 pulses. Methods are given for reducing the delay to less than 25 nsec at 20 kV and the recovery time to less than 200 μsec at 10 kV.
Self-Supporting Calcium, Potassium, and Lithium Targets
Authors: Maxman Stephen H.
Published: February 2005

The methods of vacuum evaporation of calcium, potassium, and lithium are discussed for the production of self-supporting targets in the thickness range of ∼100 to 1500 μg/cm2.
High Temperature Differential Thermal Analysis Apparatus
Authors: Hopkins Maxwell M.
Published: February 2005

The design and construction of a recording differential thermal analysis (DTA) apparatus capable of operating in an arbitrary ambient atmosphere or in a vacuum from room temperature to 1500°C is described. The temperature program is continuously variable from 1.5 to 20°C/min with the furnace temperature controlled to 0.1% or better. The system uses a calorimeter type sample holder described by Boersma with the sample and reference material held in individual cups. Quantitative measurements of heats of reaction and transition temperatures can be made. The low heat capacity system has a sensitivity of ±0.1 cal. Recording of the thermograms is automatic and all components are commercially available.
Apparatus for Measuring Crush Strength of Microspheres
Authors: Griffo Joseph S. , Lonadier Frank D. , Baston Mose
Published: February 2005

An apparatus was designed and built which can measure the force required to crush a single particle 0.1 to 0.38 mm in diameter. The sensing element consists of two strain gauges attached to a strain bar. The force applied to a particle placed at one end of the strain bar is detected by the strain gauge, and the resulting signal is amplified and recorded on a 1-mV recorder. The instrument was standardized using weights from the National Bureau of Standards, and is used to measure crush strengths between 0.5 and 500 g.
Method of Using a Compensated Gradient to Improve Time Response of an Animal Calorimeter
Authors: Sherebrin M. H. , Burton A. C.
Published: February 2005

Rapid response of a gradient calorimeter can be achieved by reducing changes of heat stored in the wall and by using an air flow circuit to facilitate heat transfer. A servomechanism controls the power to a heater on the inner surface of the wall to maintain constant the temperature gradient and heat flow through the wall. The 98% response to a step change from an electrical heat source requires 2.5 min with servo-control compared to 12 min without the feedback circuit. The reason for this decreased time of response is discussed.
Kerr Constant Evaluation of Organic Liquids and Solutions
Authors: Lee S. M. , Hauser S. M.
Published: February 2005

We have examined a variety of organic liquids, liquid-liquid, and liquid-solid combinations, and have found several having Kerr constants greater than nitrobenzene, including a formulation which has yielded a relative Kerr constant greater by a factor of 80% than that of nitrobenzene.
Model Surface Pressure Instrumentation for a Hypersonic Shock Tunnel
Authors: Jenkins Richard C. , Hopkins Harold B.
Published: February 2005

The design and construction of piezoelectric pressure transducers to meet model surface pressure instrumentation requirements for the Grumman Research hypersonic shock tunnel are described. An accurate method for calibrating the gauges is given. The gauge response to calibration pressures and to pressures measured in the tunnel is analyzed to account for the relatively short time constant of this system.
Simple Display System for Recording Time-Resolved Mass Spectra
Authors: Lincoln Kenneth A.
Published: February 2005

An uncomplicated photographic readout for recording rapidly changing mass spectra (of the order of milliseconds) generated by a time-of-flight instrument is achieved by a combination of two oscilloscopes equipped with Polaroid Land cameras. One of the oscilloscopes is operated by established techniques to display, quantitatively, peak height versus time for any one of the preselected mass peaks. Simultaneously, the second oscilloscope in the system displays a raster presentation of approximate peak height of all peaks in the spectrum as a function of time. In the latter case, the discrete m/e values are displayed on the horizontal axis as dots and the magnitude of the ion peaks is displayed qualitatively by z-axis modulation (intensification of the dots), while time is presented as the trace is displaced vertically by a raster voltage which is synchronized with the time base of the first 'scope. The z-axis circuitry has been employed to further advantage by applying it to the monitoring oscilloscope during the customary time-of-flight spectral presentation (ion-peak height versus m/e) to intensify all the peaks of the oscilloscopic display, thus enhancing visual observation and photographic recording for all operations of the mass spectrometer.
High Resolution, Low Energy Electron Spectrometer
Authors: Simpson J. Arol
Published: February 2005

An electron spectrograph consisting of an electron source, an electron monochromator, a gas cell, and an electron energy analyzer is described. The electron energy spread from the monochromator as seen by the analyzer is 0.005 eV at 3.35 eV primary energy. It is shown that space charge within the beam requires operation of the energy selectors at the lowest possible energy if high current, together with high resolution, is required.
Device for Generating an Alkali Plasma in Thermodynamic Equilibrium (PETER)
Authors: Enriques L. , Magistrelli F.
Published: February 2005

A device for generating an alkali plasma in thermodynamic equilibrium is described. It consists of a cylindrical tantalum cavity which is made incandescent by means of electron bombardment. The plasma obtained by contact ionization on the walls has a density varying from 1010 to 1012 cm−3 at a temperature of 2600°K, and is free from temperature, density, and potential gradients. A series of coaxial tantalum screens surrounds the cavity with the purpose both of limiting the supplied power and of making the cavity temperature uniform. The testing of the apparatus by means of a hot probe is also described.
30–40 Megawatts rf Line Pulse Generator
Authors: Lietti Alfredo
Published: February 2005

The construction of this apparatus follows an initial investigation which has been reported by Weibel. The generator delivers 10 periods of 30 MW at 1.5 Mc to a 10-Ω load. Alternatively it can give 40 MW at 2 Mc. The technical feasibility of producing hundreds of megawatts for a longer time, as required in some plasma-physics experiments, is examined.
Statistics of Single-Electron Multiplication
Authors: Baldwin G. C. , Friedman S. I.
Published: February 2005

Measurements of the pulse-height distribution from electron multipliers excited by single electrons are interpreted in terms of the Poisson statistics to give the secondary emission coefficient and detection efficiency. It is shown that silver-magnesium dynodes are characterized by a distribution of local values of the secondary emission coefficient.
Photoelectric Yield of Aluminum from 300 to 1300 Å
Authors: Samson James A. R. , Cairns R. B.
Published: February 2005

The photoelectric yield of aluminum type 5086-H32 containing 94% Al and 4% Mg has been measured at wavelengths between 300 and 1300 Å. At 584 Å the yield increased by 50% when the angle of incidence was changed from 0 to 50°. At 1026 Å the yield remained nearly constant for such a rotation. In general the yield was a function of the wavelength, the angle of incidence, and the degree of polarization of the incident radiation. The photoelectric yields were found to be stable and reproducible.
Scanning Photomultiplier for Studying Chemiluminescent Reactions in Flow Systems
Authors: Allen Eric R. , Grahek Frank E. , Cadle Richard D.
Published: February 2005

A continuous vertical scanning photosensitive device is described which is capable of monitoring the radiation intensity of chemiluminescent reactions in cylindrical flow reactors. The output from the photomultiplier is fed to a conventional millivolt recorder to obtain a plot of intensity as a function of time. This enables calculations to be made of concentrations and rate constants of reaction for the species taking part in the chemiluminescent reaction, if the reactions occurring are well understood. The system increases the accuracy of measuring rates of reaction, greatly shortens the time required to carry out an experiment, and is inexpensive to construct.
Stroboscopic Shutter for Visually Studying Plasma Oscillations
Authors: Alexeff I. , Jones W. D. , Neidigh R. V.
Published: February 2005

A military surplus ``Snooperscope'' has been converted into a stroboscopic shutter for the study of plasma oscillations. Some modification of the surplus item plus the adaptation of commercially available electronic gear has given a device with which periodic fluctuations in the light output of a plasma in the frequency range 103 to 106 cps can be stroboscopically ``stopped'' and studied. The electric circuits permit a ``lock on'' to a reference signal obtained from the plasma. In this fashion, the stroboscopic shutter will operate even though the plasma oscillations have a frequency jitter greater than 10%. An example of how the device has been used in an investigation of moving striations is given. Other possible uses in the study of plasmas are suggested.
Simplified Apparatus and Technique for the Determination of Crystal Orientation by Ion Bombardment
Authors: Cunningham R. L. , Ng-Yelim Joyce
Published: February 2005

The ion bombardment camera, designed specifically for orientation determinations, is machined from clear acrylic plastic and incorporates an ion source of the glow discharge type. A plastic orienting sphere, illuminated from within, has engraved on it the low index directions of cubic crystals. Hemispherical collectors, bearing ejection patterns, are positioned on the sphere and the orientation of the crystals may then be immediately observed.
Determination of Stress in Films on Single Crystalline Silicon Substrates
Authors: Glang R. , Holmwood R. A. , Rosenfeld R. L.
Published: February 2005

A convenient method to determine stress in thin films deposited on single crystalline silicon wafers is described. The film is treated as an elastic membrane attached to the edges of a thin circular disk. Due to the stress forces of the film, the substrate deforms elastically and assumes a parabolic curvature. This parabolic deflection is determined by measuring the substrate profile on the surface with a light section microscope. Knowing the curvature and the elastic constants of the substrate wafer, one can calculate the stress forces exerted by the film. The experimental accuracy of the method is about ±10%.
Means of Reducing Ringing Times in Pulsed Nuclear Magnetic Resonance
Authors: Spokas John J.
Published: February 2005

Two auxiliary circuits are described for incorporation in a pulsed nuclear magnetic resonance system to reduce the deadtime of the system following an rf exciting pulse. The function of one, a driven balanced clamp, is to reduce the Q of the detecting circuit for a controlled time after each pulse. The other, a symmetric damping circuit requiring little operating power, works in conjunction with the transmitter to ``square-up'' the rf pulses generated. The circuits presented here represent certain improvements in established techniques of clamping and damping. Additionally, it is pointed out that there is a particular advantage, with respect to minimizing the deadtime in a coherent system, of using timing pulses which are phase locked to the rf reference.
Fixed Point Calibrations of Pressure Gauges
Authors: Boren M. Dale , Babb Stanley E. , Scott Gene J.
Published: February 2005

Manganin gauges were calibrated at five fixed points, and the resulting calibration compared with that obtained at a single fixed point, or at three fixed points. For most work three points are sufficient. The nonlinearity is 0.135%/kbar. Manganin gauges intercompared agree within one bar to 10 kbar. Pressures of the H2O L-III-V, L-V-VI triple points and melting pressure of VI at 25°C were determined. It was not found possible to prepare a gold-chromium coil which was free of hysteresis.
Superconducting Magnet Facility for Plasma Physics Research
Authors: Roth J. Reece , Freeman Donald C. , Haid David A.
Published: February 2005

A superconducting magnet facility has recently been built and operated as an adjunct to a plasma physics experiment. The facility consists of two superconducting coils in a variable-spacing, horizontal-axis, split-pair configuration. Both coils are enclosed in Dewars that allow a working magnetic field diameter of 17.8 cm at the necks of the magnetic bottle. Each coil is capable of producing a maximum field of 25 kG on its axis. The operating characteristics of the coils, the Dewars, and the facility described are superior to conventional magnets of the same field strength and geometry on grounds of economy, convenience, and flexibility.
Hall Effect Magnetic Field Inverter for Use in Fermi Surface Measurements
Authors: Higgins R. J.
Published: February 2005

An analog circuit is described for producing a voltage proportional to inverse magnetic field 1/H over a field range of 20 to 1, for use in recording de Haas-van Alphen oscillations and similar measurements on an X-Y recorder. Linearity of the device was determined by the Hall probe used, and was in this case within 0.3% from 25 to 30 kG. Short term stability was better than 0.05%. Long term stability was better than 0.5%, the instability being due to temperature changes in the Hall probe which was mounted without temperature stabilization on the pole faces of the electromagnet.
Simple Device for Luminescence Petrography
Authors: Sippel Robert F.
Published: February 2005

Thus far, all reported work on luminescence petrography has been accomplished by use of the microprobe, a very expensive instrument beyond the grasp of most petrographers. A simple device is described here which attaches to an ordinary petrographic microscope and permits luminescent observations as well as ordinary white or polarized light observations. The instrument has the advantages of short pump down time (two min), large area of illumination by the electron beam (1×3 cm), and a minimum of charging and sparking problems. In addition, ordinary uncoated rock or mineral thin sections may be used. The instrument has proven to be superior to the microprobe for luminescent observations of geological specimens. Other (nongeological) applications in fields such as ceramics and solid state physics are also likely.
Shock Tube Induction Flowmeter
Authors: Croce Paul A.
Published: February 2005

Shock tube gas velocities have been monitored accurately by means of a transverse-field induction flowmeter. Experiments were performed in a hydrogen-driven shock tube using argon as the test gas; shock Mach numbers were varied from 6 to 12, initial pressures from 0.5 mm Hg to 50 mm Hg, and magnetic field strengths from 0 to 1100 G. The flowmeter was calibrated by comparing measured induced voltages to theoretical values of induced voltage based on measured shock velocities. Three electrode configurations were tried and yielded similar results. Satisfactory results (less than 10% deviation from theoretical values) were obtained for initial pressures between 0.5 mm Hg and approximately 30 mm Hg. This range includes, for a given drive burst pressure, the low pressure limitation of the shock tube, i.e., extremely short test times, and the high pressure limitation, i.e., the increased flowmeter internal impedance resulting from low shock Mach numbers. Pressure losses due to magnetic drag in the end regions of the flowmeter were found to be negligible.
Linearization of Nonlinear Analog Data
Authors: Coffey William L.
Published: February 2005

A circuit for linearizing nonlinear analog data in a specific application is described. Nonlinear analog data are coupled to the input of an operational amplifier and associated circuitry and converted to linear analog data. The output data can be read out on a strip-chart recorder, integrated, or put into digital form. Information pertinent to performance evaluation, application, and accuracy is presented.
Application of Pile-Up Distortion Calculations
Authors: Souček Branko
Published: February 2005

Factors of interest to an experimenter who feels that his measurement may be distorted by pile-up effects are: relative distortion of the distribution peak (peak position, as well as peak count); distortion of the distribution shape; influence of the detector output waveform on spectral distortion; influence of radiation source intensity (pulse rate) on spectral distortion; influence of detector resolution (dimensions and type of detector) and amplifier resolution (noise, drift); discontinuities in spectra produced by pile-up, etc. This paper gives quantitative answers to such questions in the form of curves. Results are obtained on the basis of recently developed theories of pile-up effect. The domain of validity of results is shown, as well as a comparision between different approaches (analytical and numerical) for calculation of spectral distortions due to pile-up effect.
Tensile Hot Stage for Metallographic Examination
Authors: Kirchner R. L. , Ripling E. J.
Published: February 2005

An elevated temperature, controlled atmosphere, and metallographic stage for observing flow and fracture on a microscopic scale is described. A load cell in series with the test specimen allows measurement and control of the applied loads. The specimen is enclosed in a sealed chamber so that the test environment can also be controlled by regulating the composition and pressure of the chamber atmosphere. Elevated temperatures are obtained with a Nichrome or tungsten heater, the selection depending on the temperature and atmosphere required. The apparatus has been used to study the hot salt stress corrosion cracking of titanium alloys.
Method for Preparing Electron Microscopy Specimens from Selected Details and its Applications
Authors: Koehler H. , Mattern D.
Published: February 2005

A selected area specimen preparation technique suitable for single stage, double stage, and triple stage replication techniques as well as for transmission specimen preparation is presented. Applications of the technique are illustrated on various types of specimens. Principles for appropriate choice of particular replica techniques are discussed and comparison of several replica techniques is made.
High-Speed Rotating Disk Electrode Unit
Authors: Hintermann H. E. , Suter E.
Published: February 2005

A rotating disk electrode assembly is described for interchangeable electrodes of 1–1000 mm2 exposed surface area. In aqueous solutions the speed of rotation can be varied between 50 and 40 000 rpm for the smallest, and between 50 and 5000 rpm for the largest electrode diameters. The standard deviation from the nominal value of the revolutions per unit time is less than ±0.05%. At maximum speed, the eccentricity of the free end of the electrode is ±2.5 μ. At 40 000 rpm and a current of 0.5 A the noise voltage at the electric contact on the shaft of the electrode is less than 0.2 mV.
Noncontact Technique for the Local Measurement of Semiconductor Resistivity
Authors: Bryant C. A. , Gunn J. B.
Published: February 2005

A method is described for finding the local resistivity of a semiconductor crystal by measuring the radio frequency spreading resistance of a small probe placed on a flat surface of the sample. The method is nondestructive and does not require the attachment of electrical contacts. The resistivity measured is that of the material lying within a hemisphere of about 1 mm radius; measurements have been made over the range 0.1–100 Ω cm with good accuracy above 0.5 Ω cm.
Alloy Evaporating System
Authors: Bis R. F. , Rodolakis A. S. , Zemel J. N.
Published: February 2005

A dual beam evaporating system has been designed for producing single crystal alloy films and has shown improved performance over an earlier model. The main features of the system are the individually pumped source and evaporation chambers and a water-cooled baffle between the two source ovens. These features eliminate the problem of cross contamination and facilitate achievement of any desired alloy composition ratio.
Advanced High Temperature Thermal Analysis Apparatus Employing Derivative and Differential Techniques
Authors: Rupert George N.
Published: February 2005

The techniques of thermal analysis, derivative thermal analysis, differential thermal analysis, and a new function, thermal derivative thermal analysis (temperature vs derivative of temperature curves), are combined in this apparatus. High sensitivity is available for detecting small heat effects (less than 0.2 cal/sec) produced by rapid phase transitions in cooling or heating samples, and accurately determining their temperatures. Light from the incandescent sample s is sensed by photoconductive diodes. (Thermocouples with suitable amplifiers may be used for lower temperature studies.) The diode currents after processing are displayed on a dual-trace storage oscilloscope. The temperatures of the samples, which are heated indirectly by induced radio frequency currents, are measured using a calibrated beam splitter and optical pyrometer. A description of a light source used to demonstrate the various displays by simulating thermal arrests in the cooling or heating curve of an incandescent sample is included. Illustrations are given for typical thermal analysis displays in the Nb-C, Ti-C, and V-C systems.
Automatic Optometer for Use with the Undrugged Human Eye
Authors: Roth Niles
Published: February 2005

An automatic optometer that relies on phase detection as opposed to amplitude detection offers the advantage of relative independence of refractive measurements from changes in photodetector signal amplitude. Thus, phenomena that affect signal amplitude such as changes in test source output, variations in pupil size, eye movements, and photodetector and amplifier instabilities have negligible or greatly reduced effects on refractive measurements. The foregoing properties permit high resolution refractive measurements without the need for a pupil dilating drug and also allow the recording of pupil size changes in the same eye with minor additions to the existing apparatus.
Instrumentation for the Direct Measurement of Outer Space Short Circuit Current of Solar Cells
Authors: Lambert Robert J.
Published: February 2005

An electro-optical system is described for automatically measuring the spectral response of a photosensitive material or device and its output under an arbitrary light spectrum. The system has been used to obtain the spectral response and the short circuit current of solar cells in outer space sunlight. A comparison of the outer space short circuit current of n-p silicon solar cells measured by this system and by a commercially available solar simulator shows an agreement of better than 2.1%.
Multiple Watt Submicrosecond High Repetition Rate Light Source and Its Application
Authors: Mackey R. C. , Pollack S. A. , Witte R. S.
Published: February 2005

A light source is described for generation of intense constant shape pulses of width as short as 20 nsec at demonstrated repetition rates up to 5 kc. The radiated power in the violet-green region (3000–5000 Å) of the spectrum was measured at 0.5 W/sr perpendicular to the lamp axis. Lamp configuration, pulser circuitry, and applications to spectroscopy and optical radar are discussed. A simple computer to facilitate the determination of fluorescent lifetimes is described.
Sensitive Voltage Measurement and Recording System
Authors: Cairns E. J. , Tevebaugh A. D.
Published: February 2005

A direct current voltage measuring and recording system having high sensitivity (0.02 μV) and high accuracy has been developed using commercially available components. The performance of the system exceeds the nominal specifications of the individual portions of the system because of selection of components and careful shielding, guarding, and grounding practices.
Optical Method for Absolute Velocity Calibration of Mössbauer Spectrometers
Authors: De Waard H.
Published: February 2005

The variable ``moiré pattern,'' formed when a 1:1 image of an 8 μ grating connected to a Mössbauer drive is reflected back onto itself, is utilized to measure the instantaneous velocity of the drive. A photodiode converts the intensity modulated light from the pattern into an electrical signal. From this signal pulses are derived that correspond to shifts of the grating by multiples of 2 μ. These pulses can be applied to a multichannel analyzer used as a part of the Mössbauer spectrometer and thus yield a velocity calibration spectrum. Instantaneous velocities can be measured with accuracies down to about 1 μ/sec.
Compressibility Measurement at High Pressures by the Inductance Coil Method
Authors: Giardini A. A. , Poindexter E. H. , Samara G. A. , Barnett J. D.
Published: February 2005

Volume compression of isotropic solids at high pressure may be determined by measurement of the inductance of a coil wound tightly around the sample. For isotropic compression of a coil, inductance is exactly proportional to the cube root of coil volume. Cores of tungsten, strontium titanate, cadmium sulfide, and sodium chloride were compressed to 55 kbar to test coil performance. The reproducibility of compression values varied from ±5 to ±15%. The observed compressions agree closely with other published results on compression and elastic constants. For nonconductive samples, no corrections need be applied to the volumetric data.
Anemometric Characteristics of a Wire-to-``Plane'' Electrical Discharge
Authors: Nygaard Kaare J.
Published: February 2005

This work describes an electric discharge in air at atmospheric pressure between a thin wire and a cathode with an elliptical cross section. The short axis of the ellipse was so small that the cathode surface facing the thin anode wire could be approximated by a plane. The cathode was split in two parts with the split parallel to the wire. When this discharge was exposed to a wind blowing perpendicular to the wire and parallel to the plane, it was found that the average displacement of the positive ions was directly proportional to the free-stream velocity. The actual displacement could be determined by moving the wire to an upstream position such that the two parts of the cathode carried the same current. The measurements were made in a wind tunnel with velocities from about 1 to 18 m/sec.
Design of the Deflector for the rf Beam Separator at the Brookhaven AGS
Authors: Hahn H. , Halama H. J.
Published: February 2005

The design of the iris-loaded deflector for the Panofsky type rf beam separator now under construction at the Brookhaven AGS is presented. General expressions for the transverse momentum acquired by an ultrarelativistic particle traversing the deflector are derived from the field equations. Useful figures of merit (shunt impedance R, series impedance Z, quality factor Q, R/Q, etc.) are defined. Computational results for the aperture radius a, the guide radius b, Q, R/Q, and R as functions of group velocity vg, the number of irises per wavelength N, and iris thickness d/w are presented for structures with the phase velocity vp=c. They are compared with experimental results reported from deflection tests. The design procedure of a deflector is developed for the realistic case that the shunt impedance varies with group velocity. Optimization of operating frequency fπ/2, deflector length l, vg, d/w, and N is carried out. Higher order modes in iris-loaded waveguides are investigated and methods for the suppression of mode degeneracies are outlined. The effect of the mechanical tolerances on the phase shift per cell Φ is considered. The chosen deflector structure has λ0=10.495 cm, N=4, Φ=½π, d/w=0.8, 2a=48.13 mm, 2b=116.71 mm, l=3.07 m, rounded iris edges, and lateral rods as mode stabilizers. ``Cold'' measurements on cavities and waveguides are described, and a precise R/Q perturbation method is detailed. Pertinent results are fπ/2=2856.35 Mc, Q=8700, phase error per cell ΔΦ=2.7° rms, R/Q=1.41 kΩ/m, vg/c=−0.0204, αl≈0.5. It is concluded that a klystron pulse of ≥14 MW is sufficient to give a 1 mrad peak deflection of 18 GeV/c particles.
Correlator-Amplifier for Very Low Level Signals
Authors: Brophy James J. , Epstein Max , Webb Samuel L.
Published: February 2005

A correlator-amplifier system based on a Hall multiplier improves the sensitivity of low level amplifiers by two to three orders of magnitude. The system is assembled largely from commercial instruments, with the exception of the Hall element itself. Over the frequency interval from 10 cps to 10 kc, the equivalent input noise level ranges from 5×10−15 to 10−19 V2/cycle. The system is capable of detecting correlated signals presented to both inputs in the presence of uncorrelated noise two to three orders of magnitude greater.
Construction and Calibration Techniques of High Frequency Magnetic Probes
Authors: Phillips R. C. , Turner E. B.
Published: February 2005

The details of the construction and calibration of high frequency magnetic probes, used to measure the transient magnetic fields in a linear pinch device, are described. A simple and reliable calibration technique, using conventional laboratory electronic equipment, was developed to measure the absolute sensitivity of magnetic probes in the frequency range of 1–50 Mc. Factors affecting the frequency response of magnetic probes are considered, and high frequency design and construction are discussed. A double probe, which measures two magnetic field components simultaneously is described. The use of these probes is briefly mentioned.
Longitudinal Space-Charge Effects in Standing Wave Linacs
Authors: Morton P. L.
Published: February 2005

The repulsive longitudinal space-charge forces between particles being accelerated in a linac weaken the total phase-focusing force which arises from the rf accelerating field. The stable longitudinal phase-space area decreases as the particle phase-space density increases. In this paper the techniques used in Nielsen and Sessler's treatment of the longitudinal space-charge problem in circular accelerators are applied to the longitudinal space-charge problem in linacs. A method for determining the dependence of the available longitudinal phase-space area on the beam current is outlined. An example is worked out using the parameters of a linac designed at MURA for various values of stable phase angle, drift-tube hole radius, and beam radius. Numerical results show that there is a significant decrease in stable longitudinal phase-space area for instantaneous beam currents larger than about 100–200 mA.
Elimination of Undesirable Undershoot in the Operation and Testing of Nuclear Pulse Amplifiers
Authors: Nowlin C. H. , Blankenship J. L.
Published: February 2005

The techniques of modern network theory have been applied to some of the problems of pulse shaping in nuclear pulse amplifiers. A technique referred to as pole-zero cancellation has been evolved which permits a system designer to specify the pulse decay time at the amplitude-limiting section of the system and the pulse shape at the final output as completely independent parameters. The deadtime of the amplifier system can be reduced by orders of magnitude without degrading the signal-to-noise ratio. In addition, the usual charge-injection system has been examined, and a simple, linear lumped-element network has been evolved which makes possible an improved evaluation of the amplifier response to detector charge pulses.
Rolling Ball Viscometer for Use at Temperatures to 400°C under Pressures to 5 Kilobar
Authors: Harrison D. E. , Gosser R. B.
Published: February 2005

The rolling ball technique of measuring viscosity was adapted for use at temperatures up to 400°C under pressures up to 5 kbar. At 75°C, log10 viscosity of glycerol was found to increase linearly with pressure up to 5 kbar.
New Mass Spectrometer Ion Source for Solids
Authors: Čobić B. , Perović B. , Tošić D.
Published: February 2005

An ion source with magnetron geometry for mass spectrometric analysis of low vapor pressure materials is constructed. Using the magnetron configuration of this source a new method for obtaining the ion beams of low vapor pressure elements is developed. The material to be analyzed is fixed to the hot cathode, so that the cathode can be used simultaneously as a hot support for charge material and as a source of electron emission. The vapor of the material is produced by the combined effect of filament heating of charge material and cathode sputtering by the ions of carrier gas. The method was successfully applied in obtaining ions of Cr, Fe, Ti, Ir, La, Ta, Nd2O3, Re, Ce2O3, and ZrO2. The collector ion currents range up to 10−11 A. The energy spread is measured by means of both the retarding potential and the beam deflection methods. It is found that there was no difference in the energy spread of this source and a classical Nier's ion source for mass spectrometry. The advantages of the source are also described.
High Frequency Recording with Electrostatically Deflected Ink Jets
Authors: Sweet Richard G.
Published: February 2005

A high speed oscillograph, using ordinary ink and paper, has been developed that provides a new approach to the old problem of producing instantly visible, high frequency records with inexpensive writing materials. A high speed jet of ordinary fountain-pen ink is divided into a uniform procession of drops, each of which is independently charged in proportion to an input-signal voltage. After projection through a constant transverse-deflecting field, the charged drops are collected on a moving chart to form an instantly visible, permanent record of the input signal. Drops are typically formed at a rate of 100 000/sec; each has an independent trajectory and makes an individual mark representing an independent sample of the input waveform. The ink stream may be switched on or off at high speed by providing, between the drop-launching point and the record surface, a collector that intercepts drops having a specific trajectory. Besides oscillography, which is discussed in detail, the technique has applications in other fields requiring marking at high speed or marking without pressure or physical contact.
Two Electrical Contactor Pin Designs
Authors: Dick Richard D. , Gould Thomas E.
Published: February 2005

Simple designs for a coaxial electrical contactor pin and an insulated single conductor pin for measuring shock velocities are described. The coaxial pin consists of a hypodermic tube for the outer conductor with an insulated wire inside which is setback one mil. A formed silver foil cap covers the recessed end. The single conductor pin has a Mylar film over one end and insulated tubing covering the length. Both types of pins have performed satisfactorily over a wide pressure range at ambient and liquid nitrogen temperatures.
Cosmotron Pole Face Windings Generator System Permitting Long Beam Spill
Authors: Cottingham J. G. , Pellegrin J.-L.
Published: February 2005

A scheme is described for maintaining a constant current in the magnetic field correction windings of the Cosmotron, during the process of beam ejection and long spill-out. A solid-state switch is used to apply compensation for the vanishing induced voltage in these correction windings. It is shown how this method could be applied in the event beam ejection and long spill-out would be performed at two different energies.
Analog Representation of Two-Dimensional Potential Fields in Nonhomogeneous Media
Authors: Peters C. J.
Published: February 2005

This paper describes an analog method for representing two-dimensional potential fields in regions where the material properties vary from point to point. The region is represented by a current flow model made by depositing thin metallic films on a glass substrate. In some cases the metallic films may consist of several layers of different materials such as gold on top of Nichrome. The shape of each layer is determined by masking during the deposition process to conform to the body that the layer represents. By varying the thickness and the conductivity of the layers a wide range of material properties can be represented. These models can be used to determine such quantities as capacity, inductance, thermal resistance, etc. They can also be used to determine the potential distribution. The definition is given for the conjugate model in which the equipotentials correspond to the flow lines of the original model.
``Floating Wire'' Technique for Testing Magnetic Lenses
Authors: Vogel Uriel
Published: February 2005

Improvements in the well-known technique of using a current-carrying wire to simulate particle trajectories in a magnetic field are described. As presently used, the parameters of magnetic lenses can be determined for a resolution in momentum as large as 104.
Electron Injection Technique for Investigating Conduction Processes in Insulating Liquids and Solids
Authors: Watson P. K. , Clancy T. M.
Published: February 2005

A dielectric test cell has been constructed in which the cathode of a conventional cell is replaced by a scanning electron beam. This apparatus has been used to study conduction processes in dielectrics, principally liquids, in the absence of the complicating factors normally introduced by a metal cathode. In this apparatus an electron beam is used to inject a uniform electron charge pattern into the top layer of the dielectric. As the charge builds up, the resultant field causes a current to flow through the liquid to the substrate; this current is measured by an electrometer. The surface potential of the liquid is measured by observing the deflection of a second electron beam which passes parallel to the dielectric surface about 7 mm above it. This ``electrometer'' beam can also be used to time-resolve the build up and decay of charges in the dielectric. The injected charges give rise to a mechanical force, which tends to compress the dielectric, so that it is necessary to monitor the thickness of the liquid during a test. This is done optically by using a light slit technique for relatively thick films, and an interferometric method for films thinner than 0.04 mm. Typical results for a hydrocarbon liquid are presented to illustrate the use of the apparatus for dielectric measurements.
Use of Prism Pairs for Precise Pointing of an Optical Axis
Authors: Stubbs H. Eugene
Published: February 2005

The use of a pair of prisms to achieve precise pointing of an optical axis is analyzed. A sextant using prism pairs having an accuracy of 0.2″ is comfortably within the present state of the art. Even higher accuracies can be achieved at the expense of a limited maximum range in the sextant.