bluuebunny/crossref_metadata_2025 huggingface dataset:
X-Ray Method for Study of Explosively Accelerated Metal Systems Using a 7-Mev Electron Linear Accelerator
Authors: Hess Wilmot N. , Martin Marvin D. , McFarland George C. , Rutz Wesley A. , Welch Jasper A.
Published: February 2005

A new x-ray technique for the study of explosively accelerated metal systems is described. X-rays from a 7-Mev electron linear accelerator operated with a pulse length of 10 μsec pass through the assembly under study and are detected by NaI scintillators viewed by photomultipliers. Collimation is used to achieve time resolution of 0.2 μsec and space resolution of 0.025 cm parallel to the direction of motion and 1 cm perpendicular to the motion.
Spectrum Generator for Testing of Pulse-Height Analyzers
Authors: Draper J. E. , Alston W. J.
Published: February 2005

A voltage pulse spectrum generator is described which delivers the following distributions of pulse heights: (1) delta function distribution; (2) uniform distribution; or (3) triangular distribution. The pulses are available at either a regular rate or a random rate. The delta function distribution is calibrated and continuously variable over the ranges 0–100 v and 0–0.1 v. The duration of the pulses is adjustable over 1–4 μsec.
Small Magnetic Field Mapping Probes of Thin Semiconducting Films
Authors: Buttrey John W.
Published: February 2005

The Hall effect in thin semiconducting films has been employed to produce a magnetic field mapping probe of very small active area. Germanium probes having active areas of approximately 10 square microns were found to have a sensitivity of approximately 100 oe. Results obtained on thin InSb films indicate small area probes of this material should be sensitive to fields smaller than five oersteds.
Time-to-Pulse Height Converter of Wide Range
Authors: Fischer Joachim , Lundby Arne
Published: February 2005

A time-to-pulse height converter covering the range from millimicroseconds to minutes is described. A simple 5-component passive circuit for scanning times above 50 μsec is included also. The converters can measure several events per time scan related to one starting event. They are designed as plug-in units for an oscilloscope, and utilize its sweep and other circuits. The use of the converters is discussed and includes scanning of negative time and inverted operation for reduction of counting losses. Notes on testing, calibration, and dead times are given, as well as examples of nuclear experiments to which they have been applied.
Use of the Four-Inch Liquid Hydrogen Bubble Chamber as a Fast-Neutron Spectrometer
Authors: Adelson Harold E. , Bostick Hoyt A. , Moyer Burton J. , Waddell Charles N.
Published: February 2005

The 4-in. hydrogen bubble chamber has been used as a neutron spectrometer in the 5- to 30-Mev region. A fast data-reduction system for the analysis of the recoil-proton tracks was developed, utilizing a commercial electronic coordinate-measuring device, the IBM punch-card system, and the IBM 650 digital computer. The resolution of the entire spectrometer system was determined by measuring the monoergic (14.1-Mev) neutron spectrum from the t(d, n)He4 reaction with different neutron collimators. The full width at half maximum of the measured peak was 10% of the peak energy.
Lithium Hydride Bremsstrahlung Beam ``Hardener''
Authors: Hart E. L. , White D. H.
Published: February 2005

The attenuation of the low energy component (below 50 Mev) of the bremsstrahlung beam of a high energy electron accelerator by several low-Z absorbers is studied. In particular, the advantages and construction of a lithium hydride absorber are described. The experimentally measured attenuation is compared with that calculated from a single interaction model, and several further suggestions are offered.
Temperature-Regulated Ignition Source
Authors: Preston John , Ashman Leland E.
Published: February 2005

The temperature controller described here is capable of heating a fine wire (of the order of a few mils in diam) to some temperature between 700°C and the melting temperature, and holding the temperature constant to within a few degrees.

The detector is a photomultiplier that monitors radiation from the center of the wire; changes in radiation result in compensating changes in the current. The controller responds within a millisecond to sudden changes in the environment of the wire. This rapid response is useful for detecting the onset of ignition in reactive gases and perhaps for measuring the thermal properties of nonreactive gases.
Separated 1.17-Bev/c K− Meson Beam
Authors: Eberhard Phillippe , Good Myron L. , Ticho Harold K.
Published: February 2005

This report describes the design and testing of a 1.17-Bev/c separated K− beam designed in the fall of 1958 in connection with a 15-in. hydrogen bubble chamber experiment. At the target the K−/π− ratio was 1/140. At the chamber, 4.0 K−-meson decay lengths from the target, and after two stages of electromagnetic separation, the K−/π− ratio was 12.5, corresponding to a total pion suppression by a factor of about 105. The K− flux at the chamber was 0.87 K− mesons per 1010 protons impinging on the target.
An Analysis of the Circuit of Dauphinee and Mooser for Measuring Resistivity and Hall Constant
Authors: Pauw L. J. V. D.
Published: February 2005

The Dauphinee and Mooser circuit [Rev. Sci. Instr. 26, 660 (1955)] for the measurement of resistivity and the Hall effect is liable to certain systematic errors due to capacitive effects in the switches. The magnitude of these errors is estimated, and it is shown how they may be eliminated by the use of suitably placed trimming capacitors and by a suitable switching sequence. The sensitivity of the circuit is also calculated.
Efficient Production of Multiply Charged Positive Ions by Low Energy Stripping in Helium Gas
Authors: Allison S. K. , Cuevas J. , Garcia-Munoz M.
Published: February 2005

``Low energy'' as used in this report means ionic and atomic beam velocities from approximately 5×107 to 2×108 cm/sec. In this velocity region an ion beam brought to charge equilibrium in helium gas has a much greater content of components of high positive charge than does the same beam charge equilibrated in other gases. To achieve this effect, however, the pressure of helium gas in a charge stripper or converter cell placed in the beam path must be much higher than in other gases. The predicted effect, calculated from the charge changing cross sections, is verified by experiments on the stripping of Li+ to Li++ in air and helium. In a qualitative experiment the proton beam of the Chicago synchrocyclotron was increased 100% by equilibrating the hydrogen constituent in a 90–10 HeH2 mixture before issuing it from the ion source into the acceleration chamber.
Improved “Twin” Scintillation Fast Neutron Detector
Authors: Berlman I. B. , Grismore R. , Oltman B. G.
Published: February 2005

Improvements are presented in the use of the ``twin'' scintillation detector described in an earlier paper. Conditions are specified under which the fluorescence yield is maximized and the proton to electron ratio equalized in both solutions. For a neutron energy of 2.19 Mev the instrumental line width is 23%. The estimated lower limit of its potential range is ¼ to ⅓ mev. Other improvements in sensitivity have permitted the measurement of background neutron fluxes of the order of those produced by cosmic rays.
Measurement of Ratio of Absorptivity of Sunlight to Thermal Emissivity
Authors: Gordon G. D.
Published: February 2005

Direct measurements of the ratio of the surface absorptivity of sunlight to the thermal emissivity have been made, and the apparatus is described. A thin plate to be measured is suspended in a vacuum, surrounded by walls cooled by liquid nitrogen, and illuminated by an arc light, which simulates solar radiation. The desired ratio is determined from the equilibrium temperature, which ranged from 0° to 250°C for the samples measured. Possible errors in the procedure have been analyzed theoretically, and corrections introduced where necessary. Intensity fluctuations in the present light source have limited the accuracy to 10%, but this is not a fundamental limitation in the method. Values of the thermal emissivity are also obtained from the rate of change of sample temperature.
Fast Transistorized Time-to-Pulse-Height Converter
Authors: Culligan G. , Lipman N. H.
Published: February 2005

A transistorized time-to-pulse-height converter is described which has a timebase range of 0 to 15 nsec, and a stability of 10−10 sec. The circuit has been used for the mass analysis of particle beams by time-of-flight. Time resolutions of 10−9 sec were obtained using conventional scintillation counters. The circuit has a short dead time (3×10−7 sec), contains a gating facility, but is of simple design. It has been in use at CERN for the previous six months, and functions satisfactorily under experimental conditions.
Capacitance Transducers for Muscle Research
Authors: Schilling Myron O.
Published: February 2005

Apparatus has been developed for the measurement of shortening and tension of isolated muscle using variable capacitance methods. An isotonic transducer is described which will measure up to 2.5 cm of shortening with a minimum of inertial loading with 1% linearity. An isometric transducer is described which will measure tensions up to 100 g with not more than 5-μ displacement from 0 to 200 cycles/sec. Simple modifications provide other ranges of tension.
Extraction of Tritium Present in Helium-3
Authors: Elliott M. J. W.
Published: February 2005

The concentration of tritium present in 10 liters of He3 has been reduced to the order of 10−11 by absorption of the tritium in pyrophoric uranium. This purity was required in order that the resolution of a gridded ionization chamber neutron spectrometer containing the He3 should not be adversely affected by the tritium. Details of the purification system and method are given. The assay of the tritium by introduction of samples of the He3 into Geiger counters is discussed.
Theory of a High Dispersion Double Focusing Beta-Ray Spectrometer
Authors: Daniel H. , Laslett L. Jackson
Published: February 2005

A ``flat'' high dispersion double focusing beta-ray spectrometer is proposed and results of computations are presented. The high dispersion is achieved by making the electrons orbit around the field axis more than once. The source and detector are displaced radially, in opposite directions, from the stationary circular orbit. A suitable baffle is mounted between the source and detector to shield the detector against unwanted electrons. The electron-optical properties are almost the same as for the π2 spectrometer except that the dispersion is increased. Numerical results are presented for two instruments with focusing angles of 565.88° and 909.02°, with respective dispersions of 21.5 and 50.6, to be compared with a dispersion of 4 for the π2 spectrometer.
Transmission Optics of Focused Ion Beams Used in Mass Spectrometry
Authors: Dietz Leonard A.
Published: February 2005

Current density profiles and angular spreading of low intensity positive ion beams are measured with scanning slits in an evacuated beam analyzer. Experimental measurements are made of spherical aberration and transverse thermal velocity at a crossover focused by an ion gun. Spherical aberration is determined by an extrapolation technique which apparently has not been used before. Beam constants were evaluated for an ion gun used with V-type, flat ribbon, and multiple filaments. Each type of surface ionization filament produces a beam of elliptical cross section. Expressions are given for the variations of current density in a plane normal to and moved along the beam axis in field-free image space, and for the beam fraction transmitted through a rectangular aperture. Application of the results to estimate the degree of voltage and mass discriminations is briefly discussed.
Design of Mutual Inductance Bridge for Cryogenic Measurements
Authors: Jennings L. D.
Published: February 2005

It is shown that a mutual inductance bridge may be designed whose components are small and which allows a magnet to be placed around the unknown with no loss in sensitivity and accuracy. An instrument which embodies these principles is described, and techniques are given for obtaining accurate and rapid measurements of the real and imaginary components of the unknown.
Instrument to Measure Fluorescence Lifetimes in the Millimicrosecond Region
Authors: Bennett R. G.
Published: February 2005

An instrument to measure fluorescence lifetimes of the order of millimicroseconds is described. Following excitation by a hydrogen flash lamp, the fluorescence is observed stroboscopically with a gated photomultiplier. The method of gating is novel and achieves a time resolution comparable with fast oscilloscopes (1.8×10−9 sec). The data are presented in the form of a chart record.
Detectors for Microwave Spectrometers
Authors: Long Maurice W.
Published: February 2005

The sensitivity of detectors used in sample modulated microwave spectrometers is investigated. Characteristics of crystal diodes and barretters as functions of microwave power are compared with an ideal detector operating at room temperature. A spectrograph is described which was used to measure a CFCl3 line having a calculated absorption coefficient of 3.9×10−11 cm−1. The relationship between recorder deflection and absorption coefficient is discussed.
Floating Zone Crystals Using an Arc Image Furnace
Authors: Poplawsky R. P. , Thomas J. E.
Published: February 2005

A floating zone technique for growing crystals of medium high melting point materials with an arc image furnace is presented. This technique has been successfully applied to silicon. The oxygen concentration, resistivities, and dislocation densities of resulting crystals were determined to make possible a comparison with crystals obtained by standard methods. In general this comparison is favorable. Considerations of floating zones, maximum power, and flux distribution indicate that floating zone techniques combined with an arc image furnace are promising in connection with the growth of good quality crystals of a variety of high melting point materials.
Method of Studying Travel Time Anomalies of High Frequency Radio Waves
Authors: Lerfald Gordon , Scheibe Paul
Published: February 2005

A device utilizing pulse techniques has been built for automatic measurement of changes in radio wave travel times. The equipment uses a combination of amplitude, time, and frequency selection for discrimination against unwanted signals. The received signals from U. S. time standard station WWV are sampled at 1-sec intervals to measure changes in the time of reception of the 1-sec timing pulses transmitted by WWV. The changes in travel time can give information on the vertical velocity of a virtual reflection point in the ionosphere and other factors of interest in the study of the ionosphere.
Velocity Modulation and Related High Frequency Deflection Errors of the Traveling Wave Deflection System
Authors: Goldberg Jacob
Published: February 2005

The potential and electric field distributions in a traveling wave deflection system are derived for a sinusoidal deflecting signal. They are then generalized for application to arbitrary deflecting signals. It is shown that a longitudinal field exists and depends on the odd derivatives of the signal. This component of the field modulates the velocity of the beam and gives rise to errors in focusing and time axis position. The velocity modulated beam is then dispersed by the time axis deflection system. The nonuniformity which must exist in the deflecting component of the field is shown to depend on the even derivatives of the deflecting signal. The nonuniformity gives rise to dispersion and errors in deflection of the beam by the traveling wave deflection system. Generalized expressions for these errors are derived, and the errors are evaluated for a representative set of conditions.
Simple Apparatus for the Growth of Germanium Dendrites
Authors: Lever Reginald F. , Powers John K. , Richards John L. , Sirgo Harry V.
Published: February 2005

A description is given of a simple resistance-heated apparatus for pulling germanium dendrites. Two distinct types of growth are obtainable. When the correct conditions are achieved, growth may continue indefinitely. A typical product is a 2 m length of essentially uniform ribbon 1.5 to 3 mm in width, and 0.1 mm thick.
A Deformation Calorimeter
Authors: Williams Robin O.
Published: February 2005

A calorimeter has been constructed which adiabatically deforms metals with a known mechanical energy. The energy which is stored in the sample as a result of the deformation is the difference between the supplied energy and the heat which is found by the increase in sample temperature. It is also possible to follow subsequent energy releases which take place immediately following the deformation; for some materials this release can be an appreciable fraction of the stored energy. The results for the stored energy are considered to be accurate to approximately 10%.
Modified Coaxial Powder X-Ray Camera
Authors: Fisher D. Jerome
Published: February 2005

Herewith is described a modified form of the x-ray powder camera that employs a flat specimen mounted normal to the direct beam which proceeds along the axis of the cylindrical film, as first constructed by L. L. Hawes [Acta. Cryst. 12, 443 (1959)]. Also presented are details of the techniques for mounting specimens, measuring films, and correcting these for errors. Theoretical discussion of the advantages and disadvantages of this type of camera, together with a simplified least-squares technique for interpreting the data, are given in two papers by Hawes now in press. An example of the high accuracy obtained with this camera is described in Hawes.
High-Speed Bolometer
Authors: Stubbs H. E. , Phillips R. G.
Published: February 2005

A description is given of a high-speed bolometer intended for measuring the radiation from nuclear fireballs. The bolometer is made by successive depositions of an insulating layer and a gold sensing element upon a copper block which serves as a heat sink. An analysis of the bolometer's performance indicates that it has a response time of approximately 50 μsec.
New Apparatus for Measuring Flow Birefringence
Authors: Janeschitz-Kriegl H.
Published: February 2005

In the present paper a description is given of the design of an apparatus for measuring flow birefringence; the pertinent theory has been published previously [Physica 22, 1197 (1956); J. Polymer Sci. 23, 181 (1957)]. In this apparatus glass cylinders are used, instead of the usual metal cylinders. A slow convention stream which moves parallel to the cylinder axis, removes part of the frictional heat generated in the annular gap. In that way a rising temperature distribution throughout the cross section of the gap, as was described by Y. Björnståhl [Z. Physik 119, 245 (1942)], is prevented. This temperature distribution, as is well known, causes the divergence of the light beam and, consequently, reflection at the walls of the cylinders. However, in the apparatus described in this paper, no reflections occur and, as a consequence, the appearance of a parasitic double refraction is avoided.

Some results of measurements on solutions of cellulose nitrate in cyclohexanone are communicated.
Use of a Platinum Filament in the Electron Microscope
Authors: Bishop Francis W.
Published: February 2005

A platinum filament covered with a mixture of oxides has been used to replace the tungsten filament in the RCA model EMU-2 electron microscope. This unit originally was used on an Akashi electron microscope. Since the filament operates at a low temperature, evaporation of the filament itself is very slow. The electron source is very small. The drift of illumination is small and the field of illumination is quite uniform.
Ultra-High-Pressure, High-Temperature Apparatus: the ``Belt''
Authors: Hall H. Tracy
Published: February 2005

Equipment is described for maintaining pressures of 100 000 atmos at temperatures in excess of 2000°C for long periods of time. The equipment makes use of conical Carboloy pistons that push into each end of a specially shaped Carboloy chamber. Both chamber and pistons receive lateral support from stressed binding rings. Axial motion of the conical pistons in and out of the chamber is accomplished (while still maintaining a pressure seal) by the use of a specially shaped sandwich gasket made up of naturally occurring pyrophyllite and a steel cone. The arrangement gives a multistaging effect in a single stage. Pyrophyllite in addition to its use in the gasket is also used as pressure transmitting medium, thermal insulation, and electrical insulation. The sample is heated by passage of an electric current through a metal or graphite tube. Methods of pressure and temperature calibration as well as construction details are discussed.
Follow-Through Plate Holder for Nuclear Track Microscopes
Authors: Dyson A. E.
Published: February 2005

The follow-through plate holder is a device for following nuclear tracks from one emulsion plate to another. This is accomplished by placing one plate above the other in such a way that the upper plate may be moved horizontally together with the lower one or independent of it, while either is viewed in the microscope.
Digitron—A Digital Time Analyzer for Microsecond Intervals
Authors: Swanson R. A.
Published: February 2005

A system is described which measures microsecond time intervals by counting pulses from a 10-Mc ringing circuit. The data are accumulated in a magnetic core memory. The measured standard deviation of channel widths is ≤0.15%, and the drift in absolute time calibration is <0.1% for periods of several days.
Experimental Calibration of Scintillation Pulse Heights of Thin CsI Crystals
Authors: Worth D. C. , Haste G. R.
Published: February 2005

The pulse-height response of three thin CsI crystals has been determined for protons from B10(d,p) and C12(d,p) reactions, using Al foils to vary the energy of the incident protons. Three points on the range-energy curve for CsI have been determined and compared with the range-energy curve for silver.
Solenoid Pair for Production of a Seventh-Order External Field
Authors: Jungerman J. A. , Patten C. G.
Published: February 2005

The magnetic field is calculated for a coaxial pair of solenoids having an external axial field which decreases as the inverse seventh power of the distance from the solenoid centers. The effect of finite coil thickness is discussed.
Scintillation-Bubble Chamber
Authors: Minehart Ralph C. , Milburn Richard H.
Published: February 2005

A solution of 33 g of naphthalene and 133 mg of PBD phosphor in a liter of liquid propane has been found to perform as a liquid scintillation counter at temperatures of 65−75°C. This solution also functions comparably to pure propane as a bubble chamber filling. Scintillations have been obtained from 100–145-Mev protons as well as from minimum-ionizing particles. This precludes Čerenkov radiation as the dominant scintillation mechanism, and shows that the processes of scintillation and bubble nucleation are compatible in the propane solution. Using a gated photomultiplier system, a number of chamber-scintillation-controlled photographs have been made of cosmic-ray tracks.
Liquid-Helium Goniometer-Mounted Cryostat for a Single Crystal Automatic Neutron Diffractometer
Authors: Abrahams S. C.
Published: February 2005

An all-metal cryostat capable of maintaining a single crystal at liquid helium temperatures is described. One filling of liquid helium lasts over 10 days. Crystal orientation is obtained by mounting the cryostat on a large goniometer head and tilting the entire cryostat to the required position. The maximum semi-vertical angle is 20°. The complete assembly is used with SCAND for routine measurement of the diffracted neutron intensities from single crystals in the temperature range between ca 4.6° and 1.5°K.
Mass Separation of High Energy Particles in Quadrupole Lens Focusing Systems
Authors: Courant E. D. , Marshall L.
Published: February 2005

In systems for mass separations of high energy particles, the separation achieved depends not only on the applied electric field but also on the characteristics of the systems of magnetic lenses which may be used to contain and focus the beam of particles. Quantitative relations for the mass separation and momentum dispersion are derived. It is shown that systems can be designed involving a module of magnetic lenses and electric field such that, when the module is repeated indefinitely, the mass separations at successive foci increase linearly with the number of modules.
Preparation of Thin Self-Supporting Carbon Films
Authors: Dearnaley G.
Published: February 2005

A method is described for the preparation of self-supporting carbon films of thickness between 4 μg/cm2 and 1 mg/cm2 and areas up to 1.5 cm2. These have many applications as targets and backings, and have been used as beam strippers in the Harwell Tandem Generator.
Automatic Q-Meter Peaking Circuit
Authors: Wanlass Frank M.
Published: February 2005

A circuit is presented that, when used with an ordinary Q meter, automatically will enable the Q and the capacitance of a low loss sample in parallel across the Q-meter tank circuit to be measured rapidly and continuously without the necessity of constant hand tuning of the tank circuit to resonance. Employing this circuit, it is possible to observe Q and capacitance changes that have a time constant of 0.3 sec or greater.
High Speed Spectrograph Shutter
Authors: Camm John C.
Published: February 2005

An electromechanical shutter is described which will open and close a 20-μ spectrograph slit in 5 μsec after a delay of 20 μsec. The shutter incorporates a movable slit which is propelled across the stationary spectrograph slit by the thermal expansion of a Joule-heated hairpin-shaped Nichrome wire.
Control and Calibration of the Betatron Energy Scale
Authors: Geller K. N. , Muirhead E. G.
Published: February 2005

A new system for control of the x-ray energy from a 25-Mev betatron is described. Modifications in the method of energy control and orbit expansion lead to improved operation. Calibration of the energy scale is based on reaction thresholds for D(γ,n), Bi209(γ,n), Cu63(γ,n), and the threshold for excitation of the 15.116-Mev state in C12. The resulting energy scale is linear with respect to electron momentum to better than ±20 kev.
Microwave Thickness Detector
Authors: Beyer James B. , Van Bladel J. , Peterson Harold A.
Published: February 2005

A device is described which is capable of continuously measuring the thickness of moving conducting materials. The details of two independent methods, one utilizing the amplitude and one the phase of reflected microwave energy, are explained and compared. Experimental results verify that increments of the order of 1/40 mm are clearly detectable.
Design Problems in Ebulliometry of Polymers
Authors: Blackmore W. R.
Published: February 2005

There are two fundamental problems in ebulliometry. The first is to find a detector with sufficient sensitivity to measure the very small boiling point elevations obtained with dilute solutions of high polymers. This problem is solved easily with thermistor bridges and modern high gain amplifiers. The second problem is that of random thermal fluctuations or background noise in the ebulliometer itself. When this study began, it was considered that there were three probable sources of noise, viz., (1) superheated liquid from the Cottrell pump, (2) pressure fluctuations and differences within the ebulliometer, and (3) the presence of foam which usually appears when a polymer solution is maintained at the boil. However, the tests carried out with the ebulliometers described here seem to indicate that the difficulties may be inherently associated with the polymer solutions themselves.
High Precision Large Current Regulator
Authors: Brog K. C. , Milford F. J.
Published: February 2005

A versatile high current regulator using transistors for the series regulating element and capable of accuracies of a few parts per million is described. A solid state dc power supply capable of delivering 50 amp at 50 v also is described. The performance of the system as a magnet current regulator is discussed briefly.
Dewar System for Low Temperature Experiments
Authors: Zahn C. T.
Published: February 2005

A special system of glass Dewars for experiments at low temperatures is described in which the liquid nitrogen shield consists of two separate parts, one dipping into the other. The upper shield is constructed with three walls rather than the usual two, since it must be open at the bottom. The liquid helium Dewar fits fairly closely inside this extra wall, with a thin air space between the two, and extends downward into the lower shield. The upper shield thus is mechanically isolated from the liquid helium Dewar. Access to a cold spot of the liquid helium flask is provided by a tube passing upward through the bottom of the lower shield and coupled to the liquid helium flask by means of a spherical ground-glass joint. Various advantages of this system and possible modifications thereof are discussed.
Device for Ultra-High-Pressure High-Temperature Research
Authors: Wilson W. B.
Published: February 2005

A new device has been developed for materials research at high pressures and high temperatures. The unit may be described as an extension of the Bridgman ``anvil,'' modified to permit internal heating. The principle of ``massive support'' is retained with pressure being achieved through the elasticity of multiple binding rings, rather than through the ``compressible'' gasket effect. The unit has been calibrated to pressures beyond 100 000 atm with temperature to 2000°C. The operational characteristics of the device and problems associated with high-pressure high-temperature research are discussed.
Superconducting Electromagnets
Authors: Autler S. H.
Published: February 2005

Experiments or devices requiring the joint use of liquid helium and magnetic fields can make use of superconducting electromagnets. Solenoids capable of producing up to 4300 gauss in large volumes are described. Higher fields, up to 14 kilogauss, have been produced by iron-core superconducting magnets. A small power supply may be used to energize one of these magnets and then disconnected after a persistent current has been set up. A stable magnetic field is thus maintained for many hours if the magnet is kept cold.
Low Background Thin-Wall Flow Counters for Measuring Beta Activity of Solids
Authors: Lal Devendra , Schink David R.
Published: February 2005

The construction and performance of disk-shaped thin-walled flow counters suitable for measuring very small beta activities of solids is described. The circular faces, which serve as the cathode, consist of conducting films. Either a single pear-shaped loop of wire whose plane is parallel to that of the faces, or a group of straight wires stretched across the midplane serves as the anode. The counters are operated in the Geiger region. Samples can be counted against both faces of the counter. Performance data are given for counters having active volumes ranging from 0.2 to 7 cc, and having active areas from 1.6 to 23 cm2. Counting efficiencies for natural potassium (mounted on Lucite) vary from 30% to 47%, depending on the relationship of sample area to counter dimensions. Inside a 20-cm steel shield and an anticoincidence ring the background counting rates varied approximately as 1 count/hr/cm2 of counting area. Backgrounds as low as 1 count/hr were obtained.

The disk geometry permits the use of a smaller metal and anticoincidence shield than is possible with cylindrical geometry. Counters shielded successively with 1.9-cm mercury, 5-cm steel, and 5-cm lead, and operated with a flat multiple-anode anticoincidence counter (15 cm2), actually gave lower background than with the 20-cm steel and anticoincidence ring assembly. An integral counter assembly, consisting of ∼2-cm diam disk-shaped counter and a disk-shaped guard counter (∼7-cm diam), was constructed and gave satisfactory results.
Rapid Cycling Bubble Chamber
Authors: Vernon Carl Wayne
Published: February 2005

The operation of a 500-cc compressed nitrogen driven propane bubble chamber at cycling rates up to 15 cps is described. A vapor pressure of 310 psi is found as optimum with a 540-psi compression pressure and a 7% volume change. The chamber was expanded into a 170-psi exhaust chamber. Excessive boiling and sensitive time are related to the cycling rate and expansion time.
Millimicrosecond Triggering of High Voltage Spark Gaps
Authors: Theophanis G. A.
Published: February 2005

Pulse transformers often are employed in circuits which are used to trigger spark gaps. There are limitations in the use of this type of generator when a high degree of accuracy is desired. When operating light sources in conjunction with Kerr cell shutters, synchronization of the light source and shutter must be accomplished with a jitter of no more than a few millimicroseconds. Pulse requirements and spark gap conditions for millimicrosecond triggering are defined. Several transformerless trigger pulse generators are described. One of these has been used to trigger 50-kv spark gaps with jitter times as low as 2 mμsec. A number of techniques for synchronizing the firing of spark gaps are discussed and some uses of these techniques are given. Several methods for pulsing Kerr cells using accurately triggered spark gaps also are described.
Rugged Film Resistor Thermometer for the Measurement of Surface Temperatures
Authors: Thun R. E. , Caudle G. F. , Pasciutti E. R.
Published: February 2005

A resistor thermometer element is described consisting of a nickel or palladium film protected by an SiO or didymium fluoride coating. The films are vacuum deposited on a glass substrate with imbedded Kovar contacts. The element is capable of withstanding accelerations up to 100 000 G. It is shown that nickel or palladium films can be obtained with a temperature coefficient of resistance (TCR) considerably higher than previously reported. When corrected for the anomalous skin effect, a resistivity and a TCR approaching the bulk values were measured on films deposited at a rate of about 200 A/sec and annealed for 20 min at 450°C.
Sensitive Flux Measurement of Thin Magnetic Films
Authors: Oguey H. J.
Published: February 2005

The two main difficulties encountered in the design of a sensitive hysteresis loop tracer for thin magnetic films are the flux calibration and the reduction of noise. The aim of this paper is to examine their nature and to show the possible solution for the design of very sensitive hysteresis loop tracers. The study of the flux distribution around a thin magnetic film specimen permits determination of the merits of various pickup coil configurations, as well as the form which optimizes the signal-to-noise ratio. The various disturbing voltages and the ways to eliminate them are examined. Optimization of the amplifier noise figure, proper choice of the integration network, dc restoration, and hum synchronization are described for the reduction of the output noise after integration and amplification. Two instruments built according to these principles are outlined. The first has a single wire pickup and is well suited for measurement of the flux distribution around a thin magnetic film and for experiments in vacuum at elevated temperatures; the second is more flexible and sensitive. By using different pickup coils covering a frequency range from 50 cps to 10 kc, its sensitivity is sufficient to measure flux values of 2×10−12 v-sec at a frequency of 500 cps.
Mechanical Model for Uniaxial Magnetic Anisotropy
Authors: Oguey H. J.
Published: February 2005

A mechanical model has been constructed as a means of understanding certain properties of anisotropic thin films. The model renders possible direction finding of the magnetization for a given amplitude and direction of the magnetic field vector lying in the plane of the film, provided rotational processes only are considered. The magnetic field is represented by the position of a small knob, and can be set in its amplitude and direction. A pointer then indicates the orientation of the magnetization vector. Jump phenomena can be easily observed, the locii of which form the critical curve for the uniaxial anisotropy.
Hard Gallium Alloys for Use as Low Contact Resistance Electrodes and for Bonding Thermocouples into Samples
Authors: Harman George G.
Published: February 2005

A new family of low contact resistance electrodes is described. These are hard alloys of gallium, prepared at room temperature in a manner similar to that of dental amalgams. They may be packed into cavities in semiconductors or in some cases applied to a flat surface and allowed to harden under pressure. These alloys can also be used to bond wires and thermocouples into samples. The maximum operating temperatures range from 250° to about 900°C for various alloys. The electrical characteristics, when used on ferrites and controlled valency semiconductors, are similar to those of the frequently used semiliquid indium-mercury and indium-gallium electrodes.
Precise Automatic Inexpensive Buret Reader
Authors: Farquharson J.
Published: February 2005

An instrument has been developed to find automatically the level of a colorless liquid in a glass tube and to indicate the volume on a digital register. The instrument is applied to volumetric measurements required in a chemical titration. The first model has a range of 40 ml, a precision of ± 0.02 ml on a single determination (95% confidence level), and a bias of 0.1%. A photocell detector with a cable and drum elevating and measuring mechanical system is employed.
Method for Obtaining a Component of Approximately Collimated Fast Neutrons in a Reactor
Authors: Levy Paul W.
Published: February 2005

By locating a uranium slug in the reflector of a graphite reactor, at the edge of the loading, an approximately collimated fast neutron flux is obtained which is at least twice the random background fast flux. The relative intensity of the collimated flux is determined by the separation between slug and sample. Close to the slug the directed flux is high and the collimation poor, and by increasing the separation, the collimation is increased but at the expense of intensity. The fast flux in the region where samples are located was determined using the U238 fast fission reaction. The spatial dependence of the directed flux can be approximated by an inverse square expression.
Rapid Scanning Microspectrofluorimeter
Authors: Olson Rodney A.
Published: February 2005

An apparatus is described in which spectra of microscopic objects can be continuously scanned. An adjustable linear spiral slit rotated at 2 rps provides an oscillographic presentation of either emission or absorption spectra. The apparatus was developed primarily for the study of fluorescent structure in connection with the photochemistry of living cells. An alternate modification provides the simultaneous recording of the time course of spectral changes at several selected wavelengths. Performance data and examples of biological application are presented.
Neutron-Insensitive Proportional Counter for Gamma-Ray Dosimetry
Authors: Caswell Randall S.
Published: February 2005

A gamma-ray dosimeter with low sensitivity to neutrons has been developed for radiation dosimetry in mixed fields of neutrons and gamma rays. Neutron sensitivity in a 2.5- to 3-Mev H2(d,n)He3 neutron field has been shown experimentally to be ≤1.2% on the basis of first collision dose in tissue. Gamma-ray sensitivity is independent of energy to within ±5% from 1.25 Mev (Co60) to 200 kev and to within ±20% down to 47 kev. The instrument is a proportional counter which may be used as a dosimeter for gamma rays in the presence of neutrons by pulse-height integration of the small pulses due to secondary electrons produced by gamma rays and rejection of the large pulses due to heavy particle recoils from neutrons.
Improved Slotted Disk Type Velocity Selector for Molecular Beams
Authors: Hostettler Hans U. , Bernstein Richard B.
Published: February 2005

A slotted disk type mechanical velocity selector, 10 cm long and 16 cm in diameter, consisting of six disks has been constructed and tested. The velocity resolution corresponding to the half-intensity width is 0.047; no velocity sidebands are transmitted. The effective fractional open time to the incident beam is 0.35. At the highest rotor speed used (17 000 rpm) the transmitted velocity is 1.05×105 cm/sec. A general theoretical analysis of the transmission and resolution of selectors with disks of finite thickness is presented. The velocity distribution is reported for a molecular beam effusing from an oven equipped with Zacharias corrugated foil exit canals.
Detection of the α-γ Iron Phase Transformation by Differential Thermal Conductivity Analysis
Authors: Claussen Walter F.
Published: February 2005

A method of phase change detection in solids involving differential thermal conductivity analysis is described. This method is applied to the α-γ transformation of iron at various pressures up to 100 000 atm. This transformation temperature was found to drop continuously with increasing pressure down to 605°C at 100 000 atm.
New Method of Testing Divided Circles
Authors: Kühne Christoph
Published: February 2005

The residual uncertainties of angular measurements due to the circle graduation testing methods presently used are touched upon. A new method is described, and its mathematics elucidated. Theoretically, the method permits one to obtain exactly equidistant angular intervals even if the master circles used have errors in their graduations. The method suggested enables division errors of diameters to be measured directly. Further, it is shown how the measurement procedure may be rendered automatic by suitable technical means which would permit determination of the totality of division errors for all graduated circles without prohibitive cost.
Nomographic-Type Slide Rule for Obtaining Spectral Blackbody Radiation Directly
Authors: Reid Charles D.
Published: February 2005

A nomographic type of slide rule is described from which spectral radiant emittance can be obtained directly and from which the exponential power at which the spectral radiant emittance is changing with temperature for any value of wavelength and temperature can be read. The usual quantities available on radiation slide rules are also obtainable.
A Soft X-Ray Spectrometer using a Flow Proportional Counter
Authors: Holliday J. E.
Published: February 2005

A soft x-ray spectrometer operating in the wavelength region of 30–200 A has been built in order to study the electronic properties of metals and alloys. The detector is a flow proportional counter with a 1000 A cellulose nitrate window. The window sets the upper limit of the spectrometer and will transmit only 17% of the radiation at 200 A. By using an aluminized replica grating of 600 lines/mm, the resolution was calculated to be 0.7 A for a wavelength of 64 A. The M4, 5 emission spectra of Mo and Nb, and the K emission bands of C and Be, have been investigated. The K emission band of Be had a peak intensity of 475 counts/sec and a peak-to-background ratio of 20 to one for a beam current of 4 ma and a potential of 1900 v. The carbon K emission band had a peak intensity of 700 counts/sec with a peak-to-background ratio of 30 to one for a beam current of 2 ma and a potential of 2000 v.
Variable-Slope Pulse Line for Synchrotron Injector
Authors: Wells D. Kenneth , Johnson Rudin
Published: February 2005

An injector pulse-forming network for the 300-Mev synchrotron at the University of California has been developed which can be adjusted to produce a pulse to match the acceptance energy of the machine at any energy. This device and a method to determine the acceptance energy curve are described here.
Multiple Coincidence Circuit
Authors: Chase Robert L.
Published: February 2005

A general purpose “fast-slow” multiple coincidence circuit is described. Three independent sets of fast coincidence conditions and three independent sets of slow coincidence conditions, involving up to five input signals, can be imposed simultaneously using a plug board and a set of patch cords. Coincidence pulse timing is accomplished with the aid of a unique discriminator circuit which can be used either to detect an early point on the rise of the input signals or the time of input signal zero transition. The discriminator bias can be varied over a wide range without affecting the circuit recovery time. The ``fast'' coincidence resolving time can be adjusted from 0 to 0.18 μsec, and signal delays can be adjusted over a 0.3-μsec range. The ``slow'' coincidence resolving time is fixed at approximately 2 μsec. Semiconductor active elements have been used exclusively.
Adiabatic Calorimeter for Small Samples
Authors: Tunnicliff D. D. , Badley J. H.
Published: February 2005

A relatively simple adiabatic calorimeter has been developed for measuring the thermal properties of 0.5-g samples of stable liquids or fusible solids over the temperature range of −130° to +200°C. Adiabatic conditions are automatically maintained during a run by means of a control system based on the use of resistance thermometers and a modified commercial electronic thermoregulator. Fifteen determinations on four pure compounds show that the heat of fusion can be determined to an accuracy of about 1%. Because of the simple semi-automatic operation, the apparatus is particularly suited to the determination of the purity of organic compounds by the calorimetric method.
Effect of Crystal Thickness and Geometry on the Alpha-Particle Resolution of CsI (Tl)
Authors: Martinez Prudencio , Senftle Frank E.
Published: February 2005

The resolution of CsI(Tl) for Po210 alpha particles has been measured as a function of crystal thickness. The best resolution of a ½-in. diam cylindrical crystal was obtained for a thickness of 0.38 mm, and the effect of thickness on the resolution is discussed. Based on the proposed model, a conical crystal was designed, which yielded a line width of 1.8% for Po210 alpha particles with a selected photomultiplier tube.
Simple Transistor Marginal Oscillator for Magnetic Resonance
Authors: Donnally Bailey , Sanders T. M.
Published: February 2005

A transistor marginal oscillator circuit for nuclear magnetic resonance measurements is described. The circuit is self-contained, simple, nonmicrophonic, and noncritical and has been used in a variety of measurements in both research and instructional laboratories. The sensitivity of the device is approximately one-half that of a Pound-Knight-Watkins system.
Ultralinear Cathode Follower
Authors: Read Philip L.
Published: February 2005

The design of a modified cathode follower circuit which possesses an extremely linear response and a voltage gain of essentially unity is presented. Analysis of the circuit shows that, in principle, the harmonic distortion may be made arbitrarily small, and at the same time the voltage gain may be made arbitrarily close to unity. The modification is applied to a White cathode follower where the increase in linearity and gain is accompanied by a decrease in the output impedance. A practical modified White follower having a measured intermodulation distortion of 2×10−5%, a calculated voltage gain of (1−10−6), and a calculated output impedance of 2×10−3 ohms is given.
Transparent Indium Contacts to CdS
Authors: Sihvonen Y. T. , Boyd D. R.
Published: February 2005

Diffusion and sputtering techniques are described for applying low resistance, highly transparent, antireflecting, electrical contacts to CdS. The diffusion process entails heating CdS for several minutes in the presence of indium vapor. The resulting crystal surface resistance has been adjusted to range as low as 12 ohms/square without any observable crystal discoloration. The sputtering process employs an 82–18% indium-tin alloy that is placed onto the crystal surface using oxygen as the sputtering atmosphere. The resulting film is Sn-doped In2O3, measuring 100–150 ohms/square, and showing 80–100% transmittance from 4600 to 20 000 A.