bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Insertion Device for Coaxial Attenuators
Authors: Rumfelt A. Y. , Como R. J.
Published: February 2005

A rapid insertion device for coaxial attenuators is described. This device is used as an alignment aid when making insertion loss measurements of fixed coaxial attenuators at frequencies up to 6 kMc. It provides a quick connect and disconnect feature, maintains axial alignment of the connectors during joining and separation, and reduces cable flexure. The improved repeatability and accuracy of insertion loss measurements is shown by comparative data with different alignment techniques.
High-Voltage, Low-Inductance Switch for Megampere Pulse Currents
Authors: Baker William R.
Published: February 2005

A switch is described that will handle pulse currents of several millions of amperes and stand off dc supply voltages of over thirty kilovolts. It is useful in powering fast pinch devices such as those used in thermonuclear research.
Differential Microfluorimeter for the Localization of Reduced Pyridine Nucleotide in Living Cells
Authors: Chance Britton , Legallais Victor
Published: February 2005

This paper describes a differential microfluorimeter suitable for quantitative measurement and localization of the reduced pyridine nucleotide of the intact cell by means of its fluorescence emission band at 443 mμ. Applications of the method to different types of biological material are described.
Technique for Liquid Phase Spectrophotometry at Elevated Temperatures and Pressures
Authors: Waggener W. C.
Published: February 2005

A standard Model 14M Cary recording spectrophotometer has been equipped with a special cell assembly for studies of the liquid state, particularly of water and radioactive aqueous solutions over a working range of 0 to 250°C and 0 to 1000 psia. The stability and reproducibility of measurements are comparable to those obtainable at room temperature.
Simultaneous Detonation Along a Line
Authors: Erkman J. O.
Published: February 2005

Some experiments for studying the effects of explosively induced shock waves require that the detonation front lie in a straight line in a thin sheet of explosive. Since explosives are conventionally point initiated, a device must be used to convert the curved detonation front into a straight front. This conversion has been achieved in a practical fashion by point initiating a thin sheet, properly shaped, of easily molded explosive. Some satisfactory shapes which can be produced by standard shop methods are described.
Determination of Turbulence Characteristics of Solid Particles in a Two-Phase Stream by Optical Autocorrelation
Authors: Soo S. L. , Tien C. L. , Kadambi V.
Published: February 2005

Application of optical autocorrelation techniques enables determination of Lagrangian correlation, scale, and intensity of turbulent motion of solid particles in a two-phase stream. This method allows measurement of both longitudinal and transverse correlations.
Sampling Oscilloscope for Millimicrosecond Pulses at a 30-Mc Repetition Rate
Authors: Farber Arnold S.
Published: February 2005

A sampling oscilloscope with a rise time of 3×10−10 sec is described. It may be used with carrier or noncarrier periodic signals having a high fixed repetition rate. A novel coincidence circuit employed in the device for displaying the envelope of 1-mμsec bursts of 10-kMc energy is also presented.
Precise Measurement of Density and Surface Tension at Temperatures up to 1000°C in one Apparatus
Authors: Janz George J. , Lorenz Max R.
Published: February 2005

A method for the precise measurement of surface tension and density of molten salts in one apparatus at temperatures up to 1000°C is reported. The essential features of the apparatus are a density bob of special design to enable surface tension data to be obtained simultaneously, and a continuously variable height crucible arrangement for the liquid sample. A description of the apparatus and the calibration procedures are given in detail. The results for molten potassium nitrate up to 470°C are reported to illustrate the method.
Gamma-Ray Pinhole Television Camera
Authors: Cohen Abraham E.
Published: February 2005

An experimental camera has been devised capable of viewing a gamma-ray or x-ray source both statically and dynamically with a kinescope readout suitable for quantitative measurements. Experiments are described indicating sensitivities to x-rays of about 1 to 2 r/hr.
Arc-Image Furnace for Growth of Single Crystals
Authors: De La Rue Robert E. , Halden Frank A.
Published: February 2005

A carbon arc-image furnace has been designed and employed for the growth of single crystals of refractory compounds. The image furnace is a unique facility for this application since it provides a sharply defined hot zone, excellent atmosphere control, and complete freedom from contamination during crystal growth. General operating and performance characteristics of this furnace are described.
Injection of Fast Neutral Beams into the Three-Stage Tandem Accelerator
Authors: Rose P. H. , Bastide R. P. , Wittkower A. B. , Webb D. L. , Goldie C. H. , Shaw J.
Published: February 2005

An experiment is described in which a beam of fast neutral atoms was injected into the terminal of a tandem accelerator. A second tandem was arranged in line with the first. By taking advantage of charge-exchange mechanisms these atoms were accelerated to 15 Mev by a three-stage process.
The Stilbene Scintillation Crystal as a Spectrometer for Continuous Fast-Neutron Spectra
Authors: Broek H. W. , Anderson C. E.
Published: February 2005

A method is described for measuring neutron spectra in the energy range 1 to 10 Mev. The pulse-height spectrum of scintillations produced in a stilbene crystal by recoil protons originating in the crystal is analyzed to yield the incident neutron energy distribution. Insensitivity to gamma rays and electrons is achieved by utilizing differences in the pulse shapes of light pulses produced by electrons and protons. This spectrometer is useful for both group and continuous spectra and has been tested by measurement of the spectra from a Pu-Be neutron source and from the spontaneous fission of Cf252. Both measurements are consistent with previous data. The Pu-Be data definitely confirm a peak at 9.7 Mev that was suggested by previous data.
Transistor Switch Stimulus Isolator
Authors: Fein H.
Published: February 2005

The instrument described provides rectangular pulses separated from ground by less than 20 pf capacity and essentially infinite resistance. The transistor switch provides pulses at low output impedance, from a floating battery, of 0 to 80 v in amplitude and variable in duration by the width of a triggering stimulus from a conventional stimulator or pulse generator. The device is of particular use in biological experiments where isolation of a stimulating pulse from ground is required.
Punched Tape Readout for a Multichannel Pulse-Height Analyzer
Authors: Brotzman Jack
Published: February 2005

An instrument for transferring information from a magnetic core memory to punched paper tape is described. When used with a 100-channel pulse-height analyzer with a capacity of 105 counts per channel, total readout time for all 100 channels is less than 17 sec.
A Method for Detecting Hydrogen in Gas Mixtures
Authors: Young J. R. , Whetten N. R.
Published: February 2005

The selective diffusion of hydrogen in palladium has been employed to determine the presence of hydrogen qualitatively and quantitatively in different gas mixtures. It was found possible to determine concentrations of hydrogen from 100% to 0.001%, or about ten parts per million, in nitrogen, with ease. Also it was found possible to detect the presence of hydrogen at a partial pressure of 10−7 mm Hg. This would indicate that it is possible to determine the presence of hydrogen in concentrations of one part in 1010 in a gas at atmospheric pressure. There is reason to believe that this technique could be extended even further perhaps to one part in 1014 with proper care and presently existing high vacuum techniques.
Small General Purpose Double Focusing Mass Spectrometer
Authors: Nier Alfred O.
Published: February 2005

A small high performance double focusing mass spectrometer employing a 90° electrostatic analyzer and a 60° magnetic analyzer is described. The radius of curvature of ion paths in the magnetic analyzer is 2 in. As a laboratory instrument for making gas or isotope analyses, its sensitivity and resolution make it competitive with instruments several times as large employing only a magnetic analyzer. With a permanent magnet the weight and power consumption are both low, making it attractive for applications where these factors may be of importance.
Temperature Control Method for Use between 4.2° and 77°K
Authors: Flournoy John M. , Baum Lillian H. , Siegel Seymour
Published: February 2005

A simple system is described for maintaining controlled experimental temperatures between the normal boiling points of helium and nitrogen. No special apparatus is involved other than that normally required for the handling of liquid helium and the measurement of low temperatures. The technique has been used to control the temperature of a resonant cavity to within ±0.2°K, for T>20°K, using a copper-Constantan thermocouple and a variable range recording potentiometer to measure temperature.
Counter Torque Quartz Fiber Adaptation of the Curie-Chéneveau Type Magnetic Balance
Authors: Day M. C. , Hulett L. D. , Willis D. E.
Published: February 2005

A mechanically simple magnetic balance having sufficient sensitivity to measure diamagnetic susceptibilities has been developed using a permanent magnet. Its operation is based on the twisting of a quartz or Vycor fiber in a direction such as to overcome the effects of the magnetic field. The magnetic field strength is dependent on the position of the magnet with respect to the sample and can be varied by using different magnet settings.
Full and Partial Particle Replication Technique for Electron Microscopy
Authors: Leonhard F. , Cook C. F. , Anderson F. R.
Published: February 2005

The state of the art, and the principal problems of particle replication techniques have been reviewed. The objective was to obtain the highest reliability as well as the maximum geometrical and contrast resolution for the replication technique. To this end, further improvements and complementary developments of the now-known techniques of particle replication were made. The essential stages consist of: (1) preshadowing of the sample by a refractory alloy (Pt:10%Rh) evaporated in high vacuum from a carbon rod; (2) utilizing a residual gas scattering evaporation technique (carbon in an argon atmosphere of 10−3 mm Hg) at twice the mean free path of the carbon (this forms a thin uniform carbon coating layer as a supporting layer which gives a minimum of contrast in the electron microscope); (3) utilizing an auxiliary strengthening layer of a subliming material (sulfur) to protect effectively the replica from deformation or fracture during the preparation procedure (the auxiliary layer can later be removed by sublimation); (4) development of an easy to do partial-particle replication technique, utilizing a thermoplastic embedding technique to restrict replication to only one side of a particle which will give superposition free images.
On the Use of 2N504 Transistors in the Avalanche Mode for Nuclear Instrumentation
Authors: Fullwood Ralph
Published: February 2005

Philco 2N501, 2N502, and 2N504 transistors have been operated successfully in the avalanche mode as fast discriminators on photomultiplier tubes and as the pulse generating element in pulse generators. They exhibit the property of a fast rise time (≲1 nsec) and sharp discriminating characteristics but have the disadvantage of a long recovery time (∼80 nsec).
High Temperature Mass Spectrometer Sample System
Authors: Shin H. M. , Hahm H. K. , Kwon S. I. , Jo S. H. , Hong S. B.
Published: February 2005

A General Electric analytical mass spectrometer, which was originally designed only for gaseous samples, has been modified so that the sample system can be converted for application to solid samples at elevated temperatures up to 1000°C. Conversion is accomplished by the complete replacement of the sample system by a magnetically operated device and a cavity furnace, the heater of which is thermally attached to the furnace body and servo-controlled to keep to the predetermined temperature within a fraction of a degree. The furnace body is a silica tube, 5 mm i.d. Replacement of the sample can be done within 10 min without breaking the major vacuum. Advantages and disadvantages compared to the Knudsen cell are also discussed.
Low Scatter High Current Gas Target for D-D Neutrons
Authors: Richardson Allan C. B.
Published: February 2005

A target for the production of neutrons by the D(d,n) He3 reaction is described. The target gas is circulated to cool the foils used as entrance and exit windows for the incident deuteron beam. Low mass construction is employed to minimize the scattering of neutrons.
Simple Versatile Volumeter
Authors: Wiegand Oscar f. , Schrank A. R.
Published: February 2005

The design and principles of operation of a direct reading Lucite volumeter for use in the study of respiration, photosynthesis, and gas exchange reactions is described. The detection and compensation device consists of two rigidly coupled pistons driven by a knurled nut; as one piston is moved to compensate for a volume change in the compensation chamber, the displacement is magnified by the larger piston and can be observed as fluid displacement in a graduated pipette. The chambers, pistons, and manometer assembly are exchangeable to permit selection of the relative sensitivity and amplification, in keeping with the temperature control and the absolute magnitude of the volume increments to be detected. With temperature control of ±0.05°C, a thermal stability of 0.2 μl/hr may be achieved and rates of 2.0 μl/hr resolved at 5-min intervals. Absolute measurements of 0.1 μl may be made. The respirometer is provided with gassing vents. A simple pump may be used for the agitation of the respiration chamber atmosphere to accelerate equilibrium and improve the response time of the instrument. Representative measurements are included.
Transistorized Ratemeter Design
Authors: Marvin James F. , Miller William D. , Loken Merle K.
Published: February 2005

Extensively increasing adaptation and use of radioactive isotopes for in vivo studies of the circulatory system has dictated improvement in the electronic instrumentation necessary to detect and measure progress of the isotope through the system. Inasmuch as the time intervals of circulatory studies are rather short (not over 30 sec), speaking on a gross scale, measurements at several different checkpoints must be accomplished with duplicate immobilized detectors rather than a single movable unit. A transistorized ratemeter featuring lower power requirements, smaller space consumption, superior reliability and durability together with the stability of vacuum tube circuits in ac operation has been developed to make practicable multiple channel in vivo counting systems for use in the modern x-ray or operating room.
NaI(Tl) Summing Compton Spectrometer
Authors: Takekoshi H.
Published: February 2005

The paper describes a new method of measuring gamma-ray energy by using two sodium iodide crystals. The sum of two pulses is to be taken: one from a crystal which scatters gamma rays by the Compton effect, and the other from a second crystal which receives the scattered photon. In comparison with the scintillation Compton spectrometer hitherto developed, this method is good both in efficiency and in resolution.
Constant Current Supply for Very High Resistance Loads
Authors: Haisty Robert W.
Published: February 2005

A solid-state constant current supply which operates in the current range of 1 to 100 μa with load resistances up to several hundred megohms is described. The system is battery operated, and allows one side of the load resistance to be grounded. The current is controlled by a gallium arsenide photoresistor in series with the load. The load current is balanced against a standard current and the difference is fed to a chopper-amplifier which drives a small lamp focused on the photoresistor. The gain of the amplifier is sufficiently high that a very small unbalance in current will drive the lamp to full output; thus, the photoresistor keeps the load current very near the standard current for any value of load resistance from zero up to the dark resistance of the photoresistor, typically about 8×108 ohms.
Magnetic Susceptibility Measurements of Single Small Particles
Authors: Gill S. J. , Malone C. P. , Downing M.
Published: February 2005

A method for measuring the diamagnetic or paramagnetic susceptibilities of small particles of diameters of 1 to 100 μ is described. Theoretical considerations are given for the design of the apparatus and for the interpretation of measurements. Susceptibility determinations of polystyrene latexes and red blood cells show the use of the method.
Low Frequency Underwater Sound Velocity Meter
Authors: Shaffer John D.
Published: February 2005

An underwater sound velocity meter is described which employs an open-end heavy-walled tube for a resonant cavity. The water column is excited into vibration by a sound source near one end, while a hydrophone probe at the tube center registers the pressure amplitude. A sharp resonance (Q=450) permits making relative measurements with an uncertainty of less than 0.2 m/sec when the fundamental mode (f≈570 cps) is used.
Total Absorption Gamma-Ray Spectrometers Utilizing Anticoincidence Shielding
Authors: Perkins R. W. , Nielsen J. M. , Diebel R. N.
Published: February 2005

Two total absorption gamma-ray spectrometers utilizing anticoincidence shielding are described. One of these consists of a 5-in. diam by 5-in. thick NaI(Tl) well crystal enclosed in a 26-in. diam by 30-in. high plastic phosphor. The plastic phosphor serves as the anticoincidence guard. The second spectrometer consists of a 3-in. diam by 3-in. thick NaI(Tl) crystal with a 9⅜-in. diam by 8½-in. thick NaI(Tl) well crystal as its anticoincidence guard. With the anticoincidence shielding, and a point source in the well of the 5×5-in. crystal, the Compton portion of the Zn65 spectrum is reduced by a factor of about 5, while the Compton portion of the Co60 spectrum (below 1 Mev) is reduced by factors of 20 to 25. With these point sources on top of the 3×3-in. solid crystal, these Compton regions are reduced by factors of about 4 and 14, respectively. These anticoincidence shielding arrangements also provide background reductions of a factor of 2 to 5 in the energy region below 3 Mev. The response of these spectrometers to other gamma-ray energies is included. The photomultiplier mounting arrangements for the large NaI(Tl) and plastic phosphors, and the resolutions of the plastic and NaI(Tl) crystal are discussed.
Precision Zeeman Modulation Microwave Spectrometer
Authors: Zimmerer Robert W.
Published: February 2005

A high-precision Zeeman modulated microwave spectrometer was developed to measure the rotational fine structure of oxygen. The transitions lie between 50 and 65 kMc. Direct measurement of the line widths was made at pressures from 20 to 500 μ. The Zeeman components were resolved and compared with the theoretical expectation for the N−=3 line. Twelve lines were measured to better than 0.01 Mc and 11-line breadth parameters were measured to 0.1 Mc/mm. Of particular interest is the use of transistor circuits to achieve design simplification and improvement.
Techniques of Cathode Temperature Measurements as Applied to Commercial Cathode-Ray Tubes
Authors: Coppola P. P.
Published: February 2005

Thermocouple, optical pyrometer, and retarding potential techniques for the measurement of cathode temperatures in commercial cathode-ray tubes have been investigated to determine their relative merits, limitations, and corrections.

The thermocouple method is accurate and reliable provided necessary lead loss corrections are made. Application of this method to commercial tubes is limited by the expense involved. The optical pyrometer method is questionable when applied to an oxide-cathode coating due to considerable spread in spectral emissivity data; however, the method is reliable when applied to the cathode base nickel. The retarding potential method shows good correlation to the other methods and is directly applicable to commercial tubes with no modifications required. However, limitations are imposed by a number of factors, notably the stability of cathode emission and leakage current levels.
Improved Circuit for the Measurement of the Dielectric Constants of Gases
Authors: Gauss E. J. , Gilman Theodore S.
Published: February 2005

Chien's apparatus for the measurement of dielectric constants has been modified by the use of a Clapp oscillator. The measuring cell and the technique used to detect capacitance differences of about 10−3 pf are described.
Square-Wave Generator for the Study of Exploding Wires
Authors: Tucker T. J.
Published: February 2005

A 100-kv coaxial cable square-wave generator producing a 2000-amp, 3-μsec duration, 6-mμsec rise time, current pulse has been constructed for the study of exploding wires. Unlike conventional capacitor current sources the circuit behavior is described by algebraic rather than nonlinear differential equations, thus allowing easier and surer interpretation of results. Using coaxial-cable techniques for the entire system also provides mμsec resolution of current and voltage wave forms. The system features an output timing pulse, occurring 1.5±0.005 μsec prior to the beginning of the wire explosion which provides triggering for oscilloscopes and for a 5-mμsec exposure time Kerr-cell camera. The electrical isolation of the output trigger pulse from the monitored signal also eliminates wave form distortion produced by trigger circuit loading and signal delay.
Continuous Oscillographic Method for Measuring the Velocity and Conductivity of Stable and Transient Shocks in Solid Cast Explosives
Authors: Amster Adolph B. , Kendall Paul A. , Veillette Leo J. , Harrell Burton
Published: February 2005

The continuous monitoring of the position and relative conductivity of reactive shock waves in confined cast explosives is made possible by a new technique. A fine Nichrome wire is cast within and parallel to the long axis of the sample. A record of its resistance during detonation serves to locate the ionization front associated with detonation. The measurement is recorded on an oscillograph. From the photograph of this record, instantaneous detonation velocities are measured to within ±2%. Attenuation of the initiating shock causes a delay in the establishment of a stable detonation in the acceptor. The distance and time required for this transition is confined charges can be measured. The simultaneous use of independent Nichrome and copper wire sensors furnishes additional information about the conductivity of the predetonation zone. Failure of a propagating detonation can also be studied; this permits the measurement of critical diameters, i.e., that diameter below which detonation will not propagate in an unconfined charge. Examples of each use are presented.
Development of a Compact Evacuated Pulsed Neutron Source
Authors: Gow J. D. , Pollock H. C.
Published: February 2005

A pulsed neutron source has been developed whose principal element is a sealed-off vacuum tube in which a discharge between titanium tritide surfaces produces tritons, which then are accelerated to a deuterium-loaded target. The construction of a tube producing approximately 107 neutrons in microsecond pulses and having a life of several thousand pulses is described.
Direct Reading Resistance Thermometer Bridge. Part I
Authors: Dauphinee T. M. , Preston-Thomas H.
Published: February 2005

The paper describes the basic circuitry required for a high precision direct reading resistance thermometer with dials calibrated in degrees C and any standard platinum resistance thermometer as sensing element. A circuit has been developed which, through linear variations of the resistance elements, gives a quadratic law having the form R=R0(1+AT+BT2), where B is negative, as is required for a platinum thermometer. At the same time it allows separate adjustments for slope A and curvature B or B/A of the resistance vs temperature relation of the particular thermometer being used and also for the ice point resistance R0. The auxiliary circuitry is given for comparing the computing circuit with the thermometer and for maintaining a constant recorder sensitivity of all temperatures; stability requirements for work to 0.001°C over a 700°C range are discussed.
Resistance-Heated High Vacuum Furnace for Temperatures to 1400°C
Authors: Cohen Julius
Published: February 2005

An experimental high vacuum furnace with a platinum-rhodium resistance heating element is described; it is operable also in oxygen or other gases up to pressures of at least 10−3 mm Hg. The furnace is assembled from readily obtainable equipment, and knife-edge vacuum seals are used throughout. The uniform hot zone is approximately 1932 in. in diameter and 2 in. long. The power required for 1400°C, the maximum safe operating temperature, is about 1 kw; at this temperature the pressure is ∼10−8 mm Hg. This furnace is suitable for electrical conduction studies as well as for heat treatment, etc.
Pulse Height Distribution of Čerenkov Counters
Authors: Wagner Richard J.
Published: February 2005

The problem of determining the distribution of path lengths of an isotropic flux of particles passing through a cylinder is solved analytically. The distribution function is shown graphically for cylinders of various height-to-diameter ratios and the mean path length is calculated in each case. The distribution function for some special cases of shielded cylinders also is discussed.
Test Set for Displaying the Volt-Ampere Characteristics of Tunnel Diodes
Authors: Goodman Alvin M.
Published: February 2005

A test set is described which permits the display of the V-I (volt-ampere) characteristic of a tunnel diode on an oscilloscope. The circuit instabilities which usually exist when a negative resistance device is tested on a V-I curve tracer are suppressed in the unit described. The principles of design, construction, and operation are presented.
Sensitive Thermal Conductivity Gas Analyzer
Authors: Purcell John R. , Keeler R. N.
Published: February 2005

A thermal conductivity gas analyzer has been designed using ac excitation for the thermal conductivity cell. This has greatly reduced drift and has increased sensitivity. The unit has a minimum range of 200 ppm N2 in H2 for full scale deflection.
Self-Supporting Heating Element
Authors: Rothstein Jerome
Published: February 2005

A heating element design is described, applicable to graphite or sheet metal, which has an electrical resistance comparable to a helix and a structural rigidity comparable to a cylinder. Incomplete cuts perpendicular to the axis create a number of electrically long paths in parallel, each with relatively short distances between regions of mechanical support.
Forced Periodic Changes of Kinetic Energy of Gas Molecules as a Means of Vacuum Measurement
Authors: Schwarz Helmut
Published: February 2005

Gas molecules in a container, under pressure lower than that attained when the mean free path is equal to or greater than the geometrical dimensions of the container, may impinge on a solid surface, the temperature of which can be made to change periodically. The frequency of this change is made equal to the mechanical resonant frequency of a membrane held at constant low temperature. Depending on the time phase at which the gas molecules reach the hot surface, their kinetic energy varies with the same frequency. This membrane will then vibrate up to large amplitudes when hit by the gas molecules coming from the periodically heated surface. The amplitude is a measure of the gas pressure. If a phase-sensitive lock-in amplifier system is employed, much greater sensitivity can be achieved than is possible with the generally used Knudsen-type vacuum gauges. A general solution for the temperature function and the radiometric force is given, and numerical curves for one example are calculated.
Fractional Order Slide Rule for Interferometric Length Measurement
Authors: Hart K. H.
Published: February 2005

A description is given of a slide rule of special design for use with the method of exact fractions in interferometry. The instrument computes lengths from measured excess fraction orders.
Apparatus for the Study of the Dielectric Properties of Macromolecular Solutions under Flow
Authors: Jerrard H. G. , Fisher T. A. , Simmons B. A. W.
Published: February 2005

Some solutions show a change in value of their dielectric constant and specific conductance when subjected to shearing stresses produced by a velocity gradient established within them. A detailed account is given of an apparatus which has been used for studying this effect. The solution to be investigated is placed in the annular space between two concentric cylinders. The gap between the cylinders varies from about 0.5 to 0.9 mm and has an average radius of about 9.8 mm. The outer cylinder can rotate at speeds up to 5000 rpm and, with aqueous solutions, gradients of the order of 3500 π sec−1 can be obtained without turbulence. Higher values are possible. The rotation is controlled by a Velodyne unit, which gives a continuously variable drive and, for any setting, gives a constant speed independent of load changes. Speeds are accurately determined by an electronic tachometer. The outer cylinder is of metal and the inner cylinder is made from an insulating material in which an electrode in the form of a narrow band is inserted. The metal cylinder and the electrode form a concentric cylinder capacitor or cell so that an electrical field can be applied in a direction perpendicular to the stream lines. The impedance of the cell filled with the solution under test can be determined over the frequency range 0.03 to 20 Mc using a Schering bridge and a twin-T bridge for the low and high frequency ranges, respectively. A cooling system, controlled by thermostats, is provided to maintain the liquid at a constant temperature. The method of use of the apparatus is briefly described and the precision with which measurements may be made is fully discussed.
Hypervelocity Precision Impact Instrument
Authors: Allen William A. , Meloy Gerald E. , Rogers James W.
Published: February 2005

This paper reports the development of a hypervelocity precision impact instrument. The device consists of a specially designed 0.50-caliber smooth-bore gun with an attached projectile guide to ensure collision of the projectile with its target at a prescribed geometrical orientation. Hypervelocity is defined roughly as velocity in excess of 0.15 cm/μsec. Conventional propellants are used. Velocities in excess of 0.30 cm/μsec are obtained. The instrument is designed so that experiments can be performed in a 0.1 μ vacuum. The projectile guide and an associated system of baffles eliminate the likelihood of the propellant gases preceding the projectile to the target. The instrument has been used to check equation of state information on the metal involved in the impact; to investigate the phenomenon of crater formation; and to produce hypervelocity fluid flow for a unique wind tunnel.
Optical Methods for Negative Ion Studies
Authors: Smith Stephen J. , Branscomb Lewis M.
Published: February 2005

A high vacuum crossed-beam apparatus for the study of photodetachment of electrons from negative ions is described, with emphasis on (1) the optical system which transmits a filtered high intensity photon beam, (2) a high transmission mass selector and associated ion optics, and (3) the sensitive ac preamplifier, amplifier, and phase sensitive detector used for measuring the photodetached electron current. The methods used for calibrating and operating the apparatus are discussed.
Apparatus for the Study of Recrystallization Rates
Authors: Leighly H. P.
Published: February 2005

The recrystallization apparatus described was constructed to permit the determination of metal recrystallization rates at elevated temperatures. The experiment is accomplished by diffracting an x-ray beam from a specific crystallographic plane in a deformed single crystal and detecting with a scintillation counter. When the deformed material recrystallizes, the newly formed crystals have different orientations from that of the original crystal which prevents diffraction of the x-ray beam. By repeating this test at different points a known distance apart on the specimen, the rate of recrystallization can be calculated.
Improved Square Wave Inductance Bridge
Authors: Howland Bradford
Published: February 2005

This paper describes an ac bridge useful for comparing an inductance coil with its dual equivalent circuit so as to determine, with one square wave null measurement, the values of the inductance, the equivalent series and shunt resistances, and the distributed capacitance. This circuit, which features a wide band transformer of novel but simple construction, has the important advantage that one terminal of both the inductor and its dual circuit are at ground potential. Shielding problems are thereby minimized, and laboratory-type decade boxes and precision variable condensers may be used to synthesize the dual equivalent circuit or to adjust the distributed capacitance of the inductor. A prototype bridge circuit, operating in the frequency range 0.1 to 350 kc, and incorporating compensation for errors due to residual elements is given, together with a simple alignment procedure and the results of a sample measurement of a standard inductor. It is shown that the frequency limitations of the present bridge circuit are not fundamental; an improved high frequency compensation scheme using the concept of the distributed transformer should permit operation in the vhf range. The resulting transmission line bridge circuit may also have application as a precision wide band pulse reflectometer.
Double Modulation Photometer
Authors: Kalmus Henry P.
Published: February 2005

A radio-frequency signal, gated at an audio rate, is applied to a bridge circuit. One arm of the bridge circuit is a phototube or a photomultiplier; the corresponding arm is a capacitor. The bridge is balanced in the absence of photocurrent, unbalanced in its presence, with the degree of unbalance being proportional to the average value of the photocurrent. (Dark current is canceled by an auxiliary circuit.) The null detector is an ac amplifier having a bandpass centered at the audio gating frequency, followed by a synchronous detector tuned to the same frequency. The circuits require no critical adjustments; impedances are well below the levels used in electrometer circuits, and the ultimate sensitivity is limited only by the statistical fluctuations in the dark current. At room temperature, the stability of the zero level is determined by the constancy of the mean level of the dark current. The new method makes it possible to produce stable instruments with a maximum full-scale sensitivity of 4×10−9 lu whereby, with a bandwidth of 1 cps, a signal-to-noise ratio of 100 is maintained.
Measurement of the Sheet Resistivity of a Square Wafer with a Square Four-Point Probe
Authors: Keywell Frank , Dorosheski George
Published: February 2005

The sheet resistivity of a thin sample of semiconductor may be measured by the placement of four probes on the surface of the sample. When current is passed between two of the probes, the potential difference between the other two probes is proportional to the current and the sheet resistivity of the sample. Sheet resistivity is then proportional to PD÷current, the proportionality or correction factor being dependent on the geometry of the sample and the probe. Calculations have been made for the correction factors in the case of a square probe array placed symmetrically on a square wafer. The correction factors for conversion of PD÷current to sheet resistivity are given for square dimensions, in units of probe spacing, over the range one to 50. The data include the special case d/s=1 wherein the probe points are on the corners of the square.
Atomic Beam E-H Gradient Spectrometer
Authors: Bederson B. , Eisinger J. , Rubin K. , Salop A.
Published: February 2005

A novel atomic beam magnetic substate selector is described. A potential difference is applied to the insulated pole faces of an inhomogeneous magnet. The resulting E and H fields are then approximately congruent throughout the gap region. A beam atom experiences forces due to its effective magnetic moment and induced electric moment which can be made to balance for particular magnetic substates, independent of the atomic velocity. State-selected beams of reasonable intensity and purity can thus be obtained.
Instrumentation for Medium Energy Gamma-Ray Scattering Measurements
Authors: Garwin E. L. , Penfold A. S.
Published: February 2005

A system for the energy analysis of scattered gamma rays of up to 70-Mev energy is described. A 5-in. diam, 4-in. long NaI(Tl) crystal was the energy sensitive element. The net amplification between the ten-stage photomultiplier output and the pulse-height analyzer input was 1.8. The pulse-height-to-channel transfer characteristic of the system departs from linearity by less than 0.05 channel between the 50th and 16th channel and by one channel between the 16th and sixth. It is demonstrated that the light-to-voltage transfer characteristic of the photomultiplier is linear up to at least 30-v output levels. Provision for direct determination of the effect of superposed pulses (pileup) is incorporated into the system. Careful shaping of the pulses reduced pileup to a minimum, commensurate with obtaining good resolution from the NaI(Tl) crystal. Some typical pulse-height spectra are given, and the novel features of the circuits are described.
Application of Analog Computers to ESR Spectroscopy
Authors: Randolph M. L.
Published: February 2005

By coupling an analog computer to a conventional high-sensitivity electron spin resonance (ESR) spectrometer, the total absorption of ESR spectra, which is essentially proportional to the total number of resonances present, is obtained automatically with a typical standard error of 8% for uncorrected data or 2% for simply corrected data. Other considerations inherent in the combination of such equipment are also discussed. An experimental check of the linear dependence of first moment of the usual spectrometer output on field modulation is given.
Frequency Stabilization Scheme for the Pound-Watkins Rf Spectrometer
Authors: Jeener J.
Published: February 2005

A scheme is described for locking the frequency of a marginal oscillator rf spectrometer to that of an external standard. This makes it convenient to use such a spectrometer for high resolution NMR work.
A 30-Kilowatt, 500-Microsecond Vacuum Tube Pulser
Authors: Kawcyn Robert A.
Published: February 2005

A vacuum tube pulser which was developed for the operation of gas discharge tubes used in plasma research is described. It is capable of supplying a load with rectangular current pulses of as much as 12 to 15 amp for durations from 30 to 500 μsec with a voltage drop across the load up to 3500 v. The maximum duty cycle at high currents is 0.005.
Arc Source for High Temperature Gas Studies
Authors: Shumaker John B.
Published: February 2005

A wall-stabilized water-cooled copper ring type arc source is described which operates stably in apparently any gas for periods of an hour or more at currents up to 100 amp. Arc temperatures obtained spectroscopically by absolute line intensity and line profile methods are given for the arc in nitrogen at 92 amp.
Stepless Variable Resistor for High Currents
Authors: Yokley C. R. , Shumaker J. B.
Published: February 2005

A variable-area water rheostat has been applied to the problem of current control in electric arc and plasma generating equipment. Resistance between 0.5 and 30 ohms can be obtained by adjusting the height of circulating water which surrounds pairs of fixed vertical aluminum plates. The electrolyte is ordinary city water which is circulated through the tank and discharged. No special filtering, pumping, or other treatment is used. The unit is located in the open air outside the laboratory and all control functions are operated from a remote switching panel. The unit has been operated using a maximum of 125 amp at 400 v dc and 1000 amp at 230 v dc.
A 100-db Microwave Semiconductor Switch
Authors: Feldman D. W. , McAvoy B. R.
Published: February 2005

A dual-diode microwave switch providing in excess of 100-db switched attenuation with low insertion loss is described. Switching time of the device, limited by the diodes, is 3×10−7 sec. Application of the switch in a 9000-Mc superheterodyne magnetic resonance spectrometer as a mixer crystal protector and as a microwave signal blanker is described.
Simulator for High Density Ion Guns
Authors: Fox Raymond
Published: February 2005

A simulator for an ion gun is used to predict the ion trajectories in the gun for a given electrode geometry. One simulator control is used for the space charge simulation of the entire ion beam. The beam is divided into cells of different areas in such a manner that each cell has the same space charge. Potential measurements are made at the boundaries of the cells where the accuracy of the space charge simulation is the greatest. A trajectory plotter is described which consists of a miniature tricycle, a voltage balancing unit (the same unit used in dc milli-volt recorders), a dc regulated power supply, and a number of resistors. The trajectories are found by ``steering'' the tricycle across the simulator. The trajectory plotter and the method of space charge simulation were checked experimentally and were found to have good accuracy.
Active-Metal Soldering of Crystalline Quartz
Authors: Knoll M. E.
Published: February 2005

Very strong hermetic seals can be made to quartz crystals using a hydride of titanium or zirconium and a solder composed of copper-bearing lead or indium.
Use of an Ion Pump as a Leak Detector
Authors: Young J. R.
Published: February 2005

A cold cathode gas discharge ion pump has been used as a leak detector and found to operate satisfactorily. Argon, helium, oxygen, and hydrogen have been used effectively as probe gases with argon usually giving the greatest response. Leaks from 10−3 to 10−8 std cc/sec could be located in a few minutes and leaks as small as 10−10 std cc/sec or 10−7 μliter/sec could be detected.
Rapid Beam Ejector for the Cosmotron
Authors: Rahm David C.
Published: February 2005

The theory and operation of a device that makes the beam in the Cosmotron come onto a target in about 5 μsec instead of the usual 3 msec are described. The magnetic field in a two-turn coil, pulsed with a condenser bank, deflects the internal beam enough to throw the beam onto a target during the rise time of the perturbing field. The system has an inductance of 2 μh and a capacitance of 11 μf, giving a ringing frequency of 34 kc, a peak current of 47 000 amp at 20 kv and a peak field of 1100 gauss. The ejector can also be used to put only a small fraction of the beam onto a target, permitting the rest of the beam to continue on the normal accelerating cycle.
Study of the Vibrating Reed in the Production of Small Droplets and Solid Particles of Uniform Size
Authors: Wolf W. R.
Published: February 2005

The production of uniformly sized droplets of pure liquids, solutions, suspensions, and of solid particles in the size range of 4 to 200 μ in diameter employing the vibrating reed is described. Salient features of the various devices are discussed where particular attention is devoted to the stability in size uniformity of the droplets or particles produced and their mechanism of formation. The methods described have found application in a variety of fundamental investigations, such as droplet evaporation and plant growth regulator studies, but their inherent low capacity makes them less suited for large-volume aerosols or sprays as are encountered, for example, in spray drying.
Theory of Coincidence in Coulter Particle Counters
Authors: Wales M. , Wilson J. N.
Published: February 2005

Theoretical relations are developed for the effect of coincidence (simultaneous arrival of two or more particles in the sensing zone) on the observed particle count in a Coulter counter, a device for counting particles in liquid suspensions. Two limiting cases are treated: (a) two or more particles are seen as a particle whose volume is the total particle volume present, (b) two or more particles are seen as the largest particle present. The theory was tested experimentally with a ``monodisperse'' polystyrene latex. It is shown that absolute particle volumes may be obtained from the ratio of solids content to number of counts under certain conditions. Case (b) coincidence predominates. The apparent breadth of the particle-size distribution curves in the ``monodisperse'' latex was greater than expected.
Solid-State Detectors for High Resolution Nuclear Spectroscopy
Authors: Parkinson W. C. , Bilaniuk O. M.
Published: February 2005

Use of an array of solid-state detectors in conjunction with a magnetic analyzer as a replacement for nuclear emulsions in nuclear spectroscopy is described. Arrays of both Au-Ge and gold-doped silicon have been used. The arrays consist of twenty detectors each and cover two inches along the image plane of the magnetic spectrograph. Particles of the same magnetic rigidity, but different mass, are easily identified as their energies are in the ratio Z2/m. The silicon detectors, which operate essentially as parallel plate ionization chambers, suffer the disadvantage of becoming polarized. The use of such arrays reduces by a factor of the order of twenty the time required to extract precision data from a nuclear reaction.
Scintillation Detector of 4-m2 Area and Transistorized Amplifier with Logarithmic Response
Authors: Suga Koichi , Clark George , Escobar Ismael
Published: February 2005

A scintillation detector with an area of 4 m2 and a transistorized amplifier with a logarithmic height-to-time converter are described. The detector employs tapered sheets of plastic scintillator and a single 16-in. photomultiplier mounted in a pyramidal can, coated inside with a commercial 90% reflecting white paint. The response is uniform to within 5% over the entire sensitive surface. A traversal by one relativistic charged particle (energy loss ∼10 Mev) generates approximately 20 photoelectrons in the photomultiplier. The amplifier and converter yield a rectangular pulse whose duration is accurately proportional to the logarithm of the input pulse amplitude over a range of four decades. The gain is constant to 1 db from 10 to 45°C, and the equivalent noise input is 200 μv.
Electromagnetic Bearing
Authors: Sixsmith H.
Published: February 2005

A shaft is supported by means of a laminated rotor which is magnetically suspended inside a four pole laminated stator. The diameter of the rotor is 1¾ in. and the radial clearance is 0.002 in. The position of the shaft is sensed with the aid of four quadrant electrodes which surround the shaft with a small radial clearance. Each electrode provides part of the tuning capacity of an rf tuned circuit which is tuned to one side of its resonance peak with respect to an rf generator. The rf signal is detected and amplified to provide the control current in the corresponding winding on the stator. The bearing was found to run smoothly up to 23 000 rpm. With further development, a reliable and useful bearing should result. The use of electromagnetic bearings would appear to be justified in special applications where conventional bearings cannot be employed. They would appear to be useful at cryogenic temperatures, in vacuums, and in applications where contamination with lubricants must be avoided. Since there is no wear the life should be indefinite.