bluuebunny/crossref_metadata_2025 huggingface dataset:
A Neutron Detection System for Use with Pulsed Accelerators
Authors: Halpern J. , Mann A. K. , Nathans R.
Published: February 2005

Description is given of a neutron detection system which utilizes the time necessary for slow neutrons to diffuse in a moderating medium for turning on a counter between pulses of an accelerator. The apparatus has a detection efficiency of 0.5 percent over a wide range of neutron energies. The arrangement of apparatus, circuitry details, and performance characteristics are described.
A Servomechanism for the Elimination of Time Lag
Authors: Garwin Richard L.
Published: February 2005

A servomechanism is developed to eliminate the time constant caused by thermal capacity and resistance in the measurement of power to a cyclotron target by thermocouple measurements. An analysis by the Laplace transform method shows that the observed reduction of the time constant from 300 seconds to 12 seconds is to be expected from the components of the system.
An Instrument for the Study of Double Refraction of Flow at Low and Intermediate Velocity Gradients
Authors: Edsall John T. , Rich Alexander , Goldstein Martin
Published: February 2005

A compact concentric cylinder apparatus, for the study of double refraction of flow at low and intermediate velocity gradients, is described in detail. Since the outer cylinder is the rotor, relatively large gradients can be attained before turbulent flow sets in, even when the gap between the cylinders is as large as 0.2 cm. The light source is a zirconium concentrated arc lamp, used in conjunction with an interference filter. Sheets of selected Polaroid are used for polarizer and analyzer; the field of view of the flowing liquid is large, so that at least three of the four arms of the cross of isocline are simultaneously visible. The polarizer remains in a fixed orientation. For measurements of extinction angle, the analyzer remains fixed also, the angle being read by turning a reticle attached to a graduated scale. Birefringence is determined by a modified type of Senarmont compensator.
Precision Measurements with a Cathode-Ray Oscilloscope
Authors: Robinson George , Van Allen Roland
Published: February 2005

Point-by-point measurement of the deflection factors for several cathode-ray tubes in common use has indicated the need for calibration in applications where measurements are to be made with errors less than 5 percent. Calibration techniques and a calibrating instrument have been developed for obtaining accuracies of 1 percent or better.
Ultrasonic Method of Tire Inspection
Authors: Morris W. E. , Stambaugh R. B. , Gehman S. D.
Published: February 2005

The principles of a method are discussed for detecting internal defects in pneumatic tires, such as ply separations, by the attenuation of transmitted ultrasonic waves. Equipment for carrying out tire inspections by this method is described. It includes provisions for inspecting a large range of tire sizes, scanning the tread region from shoulder to shoulder and is suitable for operation by inspection personnel. A useful form for recording the results of a tire inspection is described. One of the principal applications for this method of inspection is the examination of tires to determine their suitability for recapping.
A Direct Current Microampere Integrator
Authors: Schweiger Royal N.
Published: February 2005

A current integrator with a current range of 0–10/1000 microamperes consisting of a feedback stabilized current amplifier whose output is fed to the current coil of a modified Thompson watthour meter is described. Inasmuch as the no-load speed of this meter is directly proportional to the current supplied, the desired integrated result is obtained by the use of a revolution counter operating at nearly zero torque. The net accuracy achieved is about one percent of full scale.
Apparatus for Controlled Atmosphere Research
Authors: Thomas George R. , Lichtin Norman N.
Published: February 2005

The handling of atmosphere sensitive substances usually requires a special technique for each case. These techniques many times involve difficultly constructed and specific apparatus which will be used only once. It is the purpose of this paper to present a controlled atmosphere laboratory which will give a general solution to such problems.
Recording of Microwave Paramagnetic Resonance Spectra
Authors: Weidner R. T. , Whitmer C. A.
Published: February 2005

The method provides a means of recording paramagnetic resonance spectra on the chart of a recording potentiometer. The recorder trace presents the microwave power reflected from a resonant cavity containing the paramagnetic salt as a function of magnet current. A modulation scheme automatically eliminates the influence of changes in the real part of the susceptibility. With a frequency of 9375 mc/sec, traces linear in magnetic field have been recorded over of a range of 6000 oersteds; also, individual lines as narrow as one oersted have been recorded with an accuracy which permits a detailed line-shape analysis. Typical recorder traces are shown.
Small Angle X-Ray Scattering Technique
Authors: Yudowitch K. L.
Published: February 2005

I. Introduction: Theory for particle size measurement by (A) peak analysis and (B) slope analysis of small angle x-ray scattering.

II. Design: (A) The basis for balance between intensity and resolution is discussed. Factors are weighed in considering the selection of (B) camera geometry, (C) suitable wavelength, (D) method of monochromatization, and (E) recording of intensity distribution.

III. Experimental: (A) A high resolution small angle scattering camera is described. Examples of its operation are given in particle size determinations of (B) Dow latex by peak analysis and (C) colloidal gold by slope analysis.

IV. Summary.
Low Powered Induction Heater for Laboratory Use
Authors: Shipp R. L.
Published: February 2005

Certain laboratory processes require low-powered radiofrequency heating with fine, continuous control. A lightweight low-powered induction heater which is capable of delivering about 20 watts of power into a load 12 feet from the heater with fair efficiency was developed to meet this need.
General Theory of Current Stabilizers
Authors: Gilvarry J. J. , Rutland D. F.
Published: February 2005

The general theory of the linear four-terminal current stabilizer is developed by specifying an arbitrary stabilizer by four parameters which completely determine its performance. By means of an equivalent circuit, the corresponding parameters for a stabilizer associated with a load are evaluated. The performance of the stabilizer associated with a load and power supply is specified by corresponding over-all parameters which are evaluated in terms of parameters of the stabilizer itself and the load and supply resistances by the same method. The effect on stabilizer currents of variations of the load resistance is evaluated by means of an over-all equivalent circuit. Two special cases of the general current stabilizer are discussed: One can be specified by only three explicit parameters and is important in practice; the other is the passive current stabilizer. Confirmatory experimental results are presented.
Apparatus for Imposing and Measuring Rapid Pressure Changes in Gases
Authors: Coffin K. P. , Bauer S. H.
Published: February 2005

A simple apparatus is described in which rapid volume changes can be imposed on a small reaction vessel by means of a bellows and cam arrangement. Thus pressure increments of the order of 10 mm Hg can be induced in about 2 milliseconds. The pressure changes during the expansion or compression, and the subsequent adjustment to equilibrium in case the vessel is filled with a dissociating gas is followed by a Massa Sound pick-up (piezoelectric unit). The sensitivity of the apparatus is such that a Δp=6.7 mm gives an inch deflection on the oscilloscope. Limitations of the present design, and possible improvements for increased stability and sensitivity are discussed.
An Instrument for the Rapid Determination of Ionization Efficiency Curves Using the Mass Spectrometer
Authors: Hercus G. R. , Morrison J. D.
Published: February 2005

An instrument is described which carries out automatically the measurement of ionization efficiency curves using the mass spectrometer. It operates by applying a scanning signal to the ion-accelerating voltage, whilst the ionizing-electron voltage is reduced by a motor-driven potentiometer, and a voltage measuring unit prints voltage calibration marks on the mass spectrometer record. The time taken for a complete measurement is of the order of a few minutes.
A Computer for Correlation Functions
Authors: Brooks F. E. , Smith H. W.
Published: February 2005

Correlation functions of data, such as fading radio signals or temperature and humidity fluctuations of the atmosphere, offer a powerful tool for analysis. By conventional methods, computation of these functions is long and tedious. This paper describes a computer which was constructed for this purpose. The data to be studied are transcribed onto magnetic tapes. These tapes are then run through a computer which computes the auto- or cross-correlation functions and plots the resulting function through a recording meter. An example of the application of this computer to the study of the turbulence of the atmosphere is shown.
On the Preparation of Stilbene Crystals
Authors: Leininger R. F.
Published: February 2005

A method of preparing large stilbene crystals suitable for use in scintillation counters is presented.
Charts for the Interpretation of Rotation and Weissenberg Photographs
Authors: Donnay Gabrielle , Donnay J. D. H.
Published: February 2005

Two charts are presented. The first one gives, from a rotation photograph, the direct lattice translation of the rotation axis. From a zero-layer undistored Weissenberg photograph, the second chart gives the reciprocal lattice translations perpendicular to the rotation axis. The nomographs are constructed for the standard camera radius (R = 180/2π mm), but they can be used with any wavelength.
An Airborne Microwave Refractometer
Authors: Crain C. M. , Deam A. P.
Published: February 2005

A device for measuring directly tropospheric index of refraction fluctuations and profiles is described. The change in resonant frequency of a cavity resonator exposed to atmospheric air is recorded continuously —thus giving a continuous recording of atmospheric index of refraction relative to an arbitrary reference. The method used for sampling the air and the measured errors involved are described. A typical segment of recorded data is shown.
Determination of Air Velocity by Ion Transit-Time Measurements
Authors: Cooley William C. , Stever H. Guyford
Published: February 2005

A method is described for measuring the velocity of an air stream by producing positive ions at one point in the flow and measuring the time required for the ions to be carried to an induction-type detector located a known distance (0.5 to 2.0 inches) downstream. Positive ions are produced intermittently near the tip of a positive corona point by burst discharges which are initiated by stray ions in the air stream or by irradiating the air in the neighborhood of the positive corona point with polonium alpha-particles. The ion transit-time is measured by observing the induced pulses from the detector on a cathode-ray oscillograph sweep which is triggered by the burst discharges of the corona point. The accuracy of velocity measurement using a measuring length of one inch with a free-stream air velocity of 1730 feet per second (based on pressure and temperature measurements) was better than two percent. It is shown that the direction of streamlines in a supersonic flow can be determined approximately by aligning the corona point and the induction detector probe to give the maximum amplitude of induced pulses. It is believed that this method may be applied to map velocity fields in supersonic wind tunnel experiments.
Measurement of Neutron Flux with Lithium Borate Loaded Emulsions
Authors: Kaplan Nathan , Yagoda Herman
Published: February 2005

Methods for the incorporation of lithium borate in nonelectron sensitive nuclear emulsions have been investigated from the viewpoint of emulsion stability and high B10 and Li6 pick-up for use in the estimation of low neutron flux. Ilford C-2 plates loaded by absorption from 10 percent lithium borate solution buffered with lithium carbonate and containing 3 percent by volume of glycerine or diethylene glycol pick-up an equilibrium concentration of 34 mg per cc of boron and 12 mg per cc of lithium ions, respectively. Isothermal absorption curves indicate that the borate and lithium ions migrate into the gelatin—AgBr mixture at different rates. Higher concentrations of B- and Li- nuclei in the emulsion can be introduced by the method of evaporation loading.

Methods for evaluating the boron and lithium concentration in the emulsion are described. Quantitative recording of tracks from the B10(n,α)Li7 and the Li6(n,α)H3 reactions can be maintained for periods of about 3 months; which provides a convenient means of estimating low slow-neutron flux for purposes of health monitoring, or investigations of spontaneous fission processes, and for the evaluation of the cosmic radiation neutron background. The flux at sea level arising from cosmic radiation is of the order of 230 slow neutrons per cm2 per day, (ranging from 160 to 300 with change of exposure conditions). At an elevation of 3500 m, the flux shows a 10-fold increase.
Universal Specimen Mount for Pole Figure Determination Using the Schulz-Decker Technique
Authors: Williams D. N. , Eppelsheimer D. S.
Published: February 2005

A specimen mount is developed for use in the determination of pole figures using the Schulz-Decker Geiger counter technique. This specimen mount consists of five simply made parts. By suitable combination of these five parts the necessary rotation axes for both the transmission and reflection x-ray specimens are obtained. The application of the specimen mount is discussed and sample pole figures of cold-rolled titanium and alpha-brass determined.
The Measurement of Respiratory Air Temperature
Authors: Webb Paul
Published: February 2005

To reduce error in measuring rapidly fluctuating air temperatures within a body cavity, a small, shielded thermojunction was devised. Experimental evaluation demonstrated that it read changing air temperatures to ±0.1°C with a 50 percent response time of 0.2 second at air flows exceeding 2 liters/minute. The technique of making the small junction and the recording apparatus is described.
The Herschel Effect and Selective Erasing of Nuclear Emulsions
Authors: Goldstein Allen M. , Sherman Charles H.
Published: February 2005

The Herschel effect has been used as a means of obtaining selective erasing of nuclear emulsions. Radiation which produces background fog is often unavoidably present in an experimental arrangement designed for the registration of the tracks of heavy ionizing particles. It has been possible to erase background darkening which would have completely obscured tracks without erasing any of the tracks, thus extending useful exposure periods. The possibility of selective erasing by use of the Herschel effect is presented in terms of the Gurney and Mott theory of latent image formation. Background darkening on Eastman Kodak NTA emulsion was produced by visible light, x-rays, γ of Co60, and β of Sr90–Y90; the 5.3-Mev α-particles of Po210 were used to obtain the individual tracks. By use of an infrared exposure the permissible background exposures were increased by factors of 3–7, without destroying any of the tracks. Other information regarding the Herschel effect has also been obtained.
A Radiofrequency-Coupled Input Stage for Biological Amplifiers
Authors: Haapanen Lars
Published: February 2005

A description is given of an ungrounded input circuit consisting of a miniature radiofrequency transmitter, the carrier of which is modulated by the signal under investigation. After being transmitted to a receiver the carrier is demodulated, filtered, and the resulting signal used as the input to the standard amplifier. This method results in achievement of a high discrimination against interfering potentials without need to select closely matched components. An especially valuable feature is the elimination of the baseline shifts which often mask the recorded potentials when using a strong stimulus and recording with the differential amplifier.
Methods of Obtaining Amplitude-Frequency Spectra
Authors: Hastings A. E.
Published: February 2005

A method of obtaining the amplitude-frequency spectrum of a complex time function of short duration by repetition of the function is discussed. Three practical devices based on this method are described.
A Hydrogen Liquefier Using Neon as an Intermediate
Authors: Hood Charles B. , Grilly E. R.
Published: February 2005

A hydrogen liquefier is described in which the hydrogen is condensed at 6.6 atmospheres by means of liquid neon produced in a Joule-Thomson liquefier. This cascade liquefier produced and consumed 17 liters/hour of liquid neon and produced 27.5 liters/hour of liquid hydrogen, representing an increase of 6 to 20 percent over direct Joule-Thomson liquefaction of hydrogen. Means are described whereby further increase in yield and ease of operation could be achieved. Owing to some mechanical difficulties, the elimination of which would mean major construction changes, the system was abandoned in favor of the original Joule-Thomson method.
A Precision Differential Manometer
Authors: Maslach G. J.
Published: February 2005

The requirements imposed by investigations of flow and heat transfer characteristics of low density gases have been met by developing a precision manometer for measuring pressures in the range from approximately 0.05 mm Hg to 20 mm Hg. The instrument makes use of optical elements to allow the observer to view a clear magnified image of the meniscus. Precision lead screws and gearing control the movement of the optical viewing systems, and together with a mechanical differential indicate the differential height on a counter directly in thousandths of an inch. The instrument employing a low vapor pressure oil can be operated and read rapidly, and the reproducibility of its readings by different observers is half its least count, or 0.001 mm Hg.
A Multiple-Cavity Linear Electron Accelerator
Authors: Miller Bernard L.
Published: February 2005

A linear accelerator comprising 5 cylindrical cavities operating in the TM010 mode on the divided power of a 10-cm magnetron (nominally 1 megawatt) has produced electron beams up to 1.4 Mev. The first cavity is a phase buncher; the remaining ones, accelerators. Power is fed to the cavities through series tee connections to a master wave guide which is loaded with dielectric rods for adjusting the relative phases. The fields are of the order of 100 kilovolts per cm.

The maximum output has been 0.25 microampere average, 5 percent of the injected current. The accelerated electrons consist of a high energy bunch containing 50 percent of the total output current, with the remainder of the electrons spread over the lower energies. The energy of the bunched component can be varied widely by changing the magnetron voltage and by operating with fewer cavities.

This accelerator has proven a reliable research tool in a study of secondary electron emission of solids as a function of primary electron voltage over the range of 18 kilovolts to 1.4 Mev.
The Phoswich—A Multiple Phosphor
Authors: Wilkinson D. H.
Published: February 2005

The combination of fast and slow phosphors with a single photomultiplier has coincidence and anticoincidence properties. The fast phosphor gives a sharp spike on the leading edge of the pulse due to the slow phosphor if a charged particle traverses both phosphors. This makes possible the construction of highly directional phosphors, phosphors responding only to neutral radiations, and phosphors free of wall effects. The transparency of sodium iodide (thallium) and stilbene to each other's radiations is demonstrated; these phosphors form a possible, though not ideal, pair.
The 6BN6 Gated-Beam Tube as a Fast Coincidence Circuit
Authors: Fischer Joachim , Marshall John
Published: February 2005

The performance of the 6BN6 gated-beam tube as a fast coincidence circuit for short positive pulses is investigated experimentally. Design considerations are discussed and curves of performance are shown. Resolving times better than 3×10−10 second have been observed with pulses from a mercury-switch pulser. The circuit is simple and reliable in operation. It has been applied to coincidence measurement of pulses from photomultipliers.
A Tracer Method for the Thickness Measurement of Thin Bi Films
Authors: Antal John J. , Weber A. H.
Published: February 2005

The use of radioactive Bi210 as a tracer in thin Bi films prepared by evaporation in a vacuum has resulted in a simple and direct method for the measurement of film thickness in the range 1–300A. The radioactivity of a standard, prepared by evaporating a weighable amount of active Bi on a piece of glass, is compared to that of a specimen of unknown thickness. For films 200A or less in thickness, the ratio of counting rates of the ``unknown'' and standard yields the mass of Bi on the unknown which, together with the film area (measured with a planimeter) and the density of Bi, yields the average Bi film thickness. Two levels of activity occurring in the standards were assigned after an electron diffraction study to a difference in structure of the Bi films. The method is accurate for extremely thin films (probable error is less than 4 percent if counting statistics are carried to a probable error of 3 percent), simple procedures and calculations are used, calibration is continuous, and the specimen is not altered in any way.
Instrument for Measuring Dynamic Viscosities and Rigidities
Authors: Markovitz H. , Yavorsky P. M. , Harper R. C. , Zapas L. J. , DeWitt T. W.
Published: February 2005

An instrument is described for measuring the dynamic rheological properties of viscoelastic liquids and solids. The design of this instrument is based on that of Goldberg and Sandvik, but differs from theirs in that it is not limited to use at a point of resonance. Examples are given of results obtained by its use on a Newtonian liquid, a viscoelastic liquid, and a viscoelastic solid. A derivation of the equation governing the instrument when used for solids is given in an appendix.
A Magnetic Potential Divider
Authors: Hinman George , Crane Frank
Published: February 2005

A type of magnetic potential divider for shaping the magnetic field near a pole edge is discussed. This method of terminating a pole has been applied to a β-ray spectroscope magnet recently constructed at Carnegie Institute of Technology. The maximum usable radius has been increased by about fifteen percent over the value without it. The method is applicable to many low field magnets.
A Remark on the Space-Charge Sheath of the Geiger Counter
Authors: Wilkinson D. H.
Published: February 2005

The popular notion of the Geiger counter space-charge sheath as a thin expanding shell is shown to require modification. Owing to the considerable charge transported in the sheath it grows in thickness as it crosses to the cathode and may occupy more than half the total volume of the counter. The attendant wide straggle in arrival time of the positive ions at the cathode may explain, to some degree, the time distribution of spurious counts.
Measurement of Transient Surface Temperatures
Authors: Huggins Robert A. , Roll I. Bob , Udin Harry
Published: February 2005

This paper deals with the design, construction, and operation of apparatus to produce, measure, and record transient surface temperature cycles of the type produced at and near a typical steel spot weld.
Construction and Calibration of a Fast Neutron Scintillation Spectrometer
Authors: Guernsey G. L. , Mott G. R. , Nelson B. K. , Roberts A.
Published: February 2005

A quadrupole coincidence scintillation counter telescope has been constructed for neutron studies with the University of Rochester 130-inch synchrocyclotron. A calibration of pulse height vs proton energy has been obtained for the fourth crystal of the telescope. The response of this crystal to monoenergetic protons has been found to be in fair agreement with calculations for the distribution of energy loss for protons, made using the method developed by K. R. Symon. The instrument covers the range from about 50 to 240 Mev in recoil proton energy.
A Gauge for Indicating Pressure Transients in a Combustion Chamber
Authors: Warshaw Howard D.
Published: February 2005

A gauge that is linearly responsive to pressure changes in the order of 400 psi per microsecond with a useful range of 0–16000 psi is described. The gauge is designed for mounting in the wall of a combustion chamber and is small enough for use in the barrel of a caliber 0.50 weapon. A bonded wire strain gauge in a conventional ballast circuit converts the pressure function into an electrical signal that is displayed on the screen of a cathode-ray oscilloscope. This equipment has been used extensively to measure gun muzzle pressures.
Total Absorption Čerenkov Counter
Authors: Jones W. B. , Kratz H. R. , Rouvina J.
Published: February 2005

A Čerenkov counter is described for detecting and measuring the energy of x-rays in the 50- to 300-Mev range. The incident x-ray produces a photon-electron shower in a cylinder of carbon tetrachloride, and the Čerenkov radiation emitted by the electrons in the shower is a measure of the x-ray energy. The cylinder of carbon tetrachloride is 12 in. diam by 36 in. long. The Čerenkov radiation is measured with seven 5-in. photomultiplier tubes mounted at one end of the cylinder. The pulse distribution from the counter has a σ/x̄ which varies from 0.146 at 217 Mev to 0.216 at 47 Mev. The energy response of the counter is linear up to 217 Mev, the highest energy at which measurements have been made.
Recording Oxygen Concentration and Rate of Exchange
Authors: Brackett F. S. , Daniel J. H. , Crickard R. G.
Published: February 2005

A recorder for oxygen concentration and rate of exchange is described. A polarographic square wave method is adapted to servo-pen-recording. Cam-driven microswitches provide the square potential pattern and also the programed timing on which the rate evaluation is based. A three-second time resolution in rate reveals transient details unobserved in concentration recording.
Study of Injecting and Extracting Contacts on Germanium Single Crystals
Authors: Lin L. Y.
Published: February 2005

It is well known that the density of minority carriers in a germanium crystal can be altered near a rectifying contact. The purpose of this paper is to describe a procedure for preparing reproducible and dependable injecting and extracting contact, in order to obtain a good exponential decay or rise curve of minority carriers for determining their lifetimes by the Many bridge method. It is found that the rectifying and ohmic contacts to a single crystal must be considered together.
Cylinder Radiation and Activation
Authors: Masket A. V. H. , Macklin R. L. , Schmitt H. W.
Published: February 2005

In the calculation of the interaction of radiation from a point source with a body (or conversely, the intensity of radiation from an emitting body at a point in space), a somewhat complex exponential integral must be evaluated. If the interaction in the body is small, however, the integral may be approximated by I=∫V dv/R2, where V is the volume of the body and R is the distance from the point to the volume element dv in the body. This integral is discussed and applied to the case of a cylindrical body. Extensive tables (>12 000 entries) and formulas have been prepared which will enable the reader to determine the value of this integral for a cylinder of any size and any point in space. A discussion of non-negligible absorption and multiple interactions is also included.
Solid Angle Contour Integrals, Series, and Tables
Authors: Masket A. Victor
Published: February 2005

The solid angle subtended at a point by any object is determined by the closed contour which outlines the ``visible'' boundary of the object from the point. By transformation of the double integral Ω=∫ ∫ sinθdθd[open phi] into a single integral over θ or [open phi] with limits determined by the contour and choice of axes, the solid angle may be simply represented in the important cases discussed as a contour integral. The integration has been carried out on the high-speed digital computer ORACLE at Oak Ridge National Laboratory. Solid angle tables have been prepared for the case of the circular disk and the entire finite right circular cylinder in terms of cylindrical coordinates. Each table contains in excess of 12 000 entries to six significant figures.
Tunnel Diode Hydrostatic Pressure Transducer
Authors: Sikorski M. E. , Andreatch P.
Published: February 2005

A very sensitive hydrostatic pressure transducer was made using a silicon tunnel diode. The transducer consists, essentially, of a tunnel diode shunted by a resistor which satisfies the stability conditions for operation in the amplifier mode. The advantages of the tunnel diode transducers are (1) small size, (2) sensitivity, and (3) versatility. Since the p-n junction region is normally 1 mil in diameter or less, miniaturization is possible. Pressure sensitivities as high as 2 mv/v/psi were observed over a 60-psi pressure range. Expressed in terms of gauge factor, the above sensitivity is equal to about 30 000. Such high sensitivities, within narrow pressure ranges, were achieved at pressures up to 20 000 psi. The pressure range as well as the pressure sensitivity in a chosen pressure interval can be varied very simply by adjusting the values of the shunt resistor and the current through the diode-resistor combination. Even higher gauge factors can be obtained with other semiconductor materials.
Feasibility of Accelerating Polarized Protons with the Argonne ZGS
Authors: Cohen David
Published: February 2005

A computing program was developed for simultaneously tracing trajectories and classical, relativistic spin precessions around the zero gradient synchrotron (ZGS). Depolarizing resonances, previously predicted, were found and their properties were computed; there were 36 significant resonances, 12 of which were serious. A method is proposed for avoiding these 12 resonances by using two or four pulsed quadrupole magnets around the ZGS ring. These would rapidly shift νz, the vertical betatron oscillation frequency, at appropriate energies during the acceleration cycle. With this method, a proton beam, injected into the ZGS with P=1, would have P>0.7 at the end of the acceleration cycle.
Beam Loading of a Radio-Frequency Cavity
Authors: Neil V. Kelvin
Published: February 2005

The interaction of a beam of charged particles in an accelerator with the radio-frequency cavity that provides the accelerating electric field has been investigated previously for the condition that the characteristic frequency of the cavity exactly coincides with a harmonic of the beam circulation frequency. In the present work an equivalent circuit is used to extend the self-consistent analysis to situations where this condition is not satisfied. It is shown that by proper tuning (appropriate choice of cavity inductance) it is possible to minimize the power consumed in the external driving circuit by bringing the cavity-wall currents into phase with the external generator. The power delivered to the beam and the cavity walls is not affected by the tuning. A high-Q cavity is advantageous if the system is properly tuned. A numerical example is given which indicates that the necessary change in the eigen-frequency is of the order of 1%, and that the resulting reduction in power requirements may be quite significant.
Automatic Optical Thickness Gauge for Thin Film Measurements
Authors: Murray Thomas P.
Published: February 2005

An automatic ellipsometer for measurement of the thickness of thin films in the monomolecular range is described. The instrument is capable of pushbutton operation by untrained personnel, and has been in use in an industrial laboratory for about two years.
Microprobe for Measuring Magnetic Fields
Authors: Roshon D. D.
Published: February 2005

The Hall effect has been widely utilized to measure magnetic fields. The relatively simple geometry of a Hall element suggested the use of such a device on a microscale as a probe to examine magnetic fields of small structures. Hall probes are described which were constructed with a sensitive area about 10×10 μ. Fields of less than 0.01 gauss were found to be measurable using evaporated bismuth films. Probe fabrication techniques are described, and the factors affecting probe performance are discussed. A number of instrumentation systems, which have proven suitable for measuring small dc magnetic fields and high frequency ac fields, are presented. High accuracy (1%) of field measurement is readily attained.
Microsize Magnetic Field Probes with Axial Symmetry
Authors: Shiffman Carl A.
Published: February 2005

Magnetic field probes occupying less than 10−8 cc and having axially symmetric response have been developed for use at liquid nitrogen temperatures and below. The probes are made by drawing a microscopic boule of bismuth from the melt, using a wire which ultimately serves as a pair of leads at one end. A second wire is fused to the other end by ohmic heating.
Lorentz Polarization Absorption Corrections in the X-Ray Precession Method
Authors: Burbank R. D. , Knox Kerro
Published: February 2005

The effect of absorption in the x-ray precession method cannot be separated from the Lorentz factor except for special cases. Consequently, a combined Lorentz polarization absorption correction 1/(LPA) is required. The angular coordinates of the camera motion which are needed to discuss absorption are defined and then expressed in terms of reciprocal lattice coordinates. It is shown that all precession reflections fall into five classes in their dependence on these angular variables. Using this classification, the degree of anisotropy in the intensity distribution of reflections from cylindrical specimens is estimated. A procedure for automatic computation of 1/(LP) has been expanded to compute 1/(LPA) for cylindrical specimens.
Liquid Hydrogen Bubble Chamber for Low Energy Nuclear Physics
Authors: Flynn E. R. , Bendt P. J.
Published: February 2005

The bubble chamber contains 3.2 liters of liquid hydrogen, and has two vertical and two horizontal windows 4 in. in diameter, which are used for 90° stereophotography. The energy and scattering angle of recoil protons from 5–38 Mev can be measured. As a neutron spectrometer, the chamber has an efficiency of 8×10−3 recoil protons in the zero to 30° forward cone per incident neutron, at 22.5 Mev. The peak of the energy distribution has a full width at half maximum of 1.3 Mev, and the background is about 4%. With the present track reading microscope, the average scanning rate is 2000 tracks per man-week. A full description of the apparatus and track-measuring equipment is given.
Bakeable Absolute Pressure Gauge for the Millimeter of Mercury Range
Authors: Condell W. J. , Mandelberg H. I. , Beahn T. J. , Muehe C. E.
Published: February 2005

A bakeable absolute pressure gauge which uses the compression of a gas in a precision bore glass tube by a piston of known weight is described. The measurement of the compression is accomplished by means of an electronic timing circuit. Equations are given for the design of the gauge and its accuracy under various operating conditions. Comparison is made between pressures measured by the gauge and pressures measured by liquid manometers.
Low Inductance Low Pressure Spark Gap Switch
Authors: Cormack G. D. , Barnard A. J.
Published: February 2005

A low pressure spark gap switch suitable for use as a main switch and as a ``crowbar'' switch on a capacitor bank is described. The switch has been operated over a voltage range of 0.5 to 25 kV, at energies up to 4 kJ and currents up to 500 kA. Under normal operating conditions the triggering time is 40 nsec and the jitter approximately 10 nsec. The inductance of the main switch is 4 mμH and the inductance of the crowbar switch is about 1 mμH.
Electron Resonance Magnetometer for Alternating Magnetic Fields
Authors: Spokas O. E. , Danos M.
Published: February 2005

Alternating magnetic fields in the range of 2800 to 4300 G are measured in terms of the frequency of the free-electron spin resonance in 1:1-diphenyl-2-picryl hydrazyl. The probe is constructed entirely of dielectric materials. An accuracy of 0.1% in the field determination was obtained.
Roller X-Ray Spectrometer
Authors: Salem Sema'an I. , Peake Neil G.
Published: February 2005

A spectrometer that utilizes rollers rather than gears to perform the appropriate angular changes of its components has been designed and put into operation. The precision ground rollers proved to be effective in reducing any backlash in the drive mechanism without introducing any noticeable skidding. A set of screws provides a simple and rapid way of securing the diffraction crystal in its proper place for continuous alignment.
High Temperature Drop Calorimeter
Authors: Levinson Leonard S.
Published: February 2005

A high temperature drop calorimeter to measure heat contents between 1000 and 2500°C was made. A graphite tube furnace and an adiabatic shielded receiver block are described. The receiver block was electrically calibrated and the calibration compared with the heat content of α-aluminum oxide.
Multichannel, Multicolor Oscilloscope
Authors: Hersh S. H.
Published: February 2005

A practical, dual-channel, multicolor oscilloscope has resulted from NRL research on transparent cathodoluminescent screens. A transparent multicolor screen is used with a conventional cathode-ray tube in an NRL modified commercial dual-channel oscilloscope. An inherent advantage of this oscilloscope over the conventional one is the apparent ease of monitoring two or more channels simultaneously without the possibility of error. Another advantage is that it maintains sharp distinct patterns under adverse light conditions.
Automatic Frequency Control System for a Microwave Linear Electron Accelerator
Authors: Karzmark C. J.
Published: February 2005

In the operation of microwave electron linear accelerators, adjustment of the frequency-determining element of the power source is frequently required to optimize performance. These adjustments are necessitated by thermal-mechanical changes of the accelerator structure proper as well as independent changes of the oscillator frequency. An automatic frequency control system has been designed to maximize the x-ray output for an S-band accelerator used in radiation therapy. Frequency modulation of the oscillator produces a phase sensitive amplitude modulation component in the x-ray output. This information is used with a suitable detector and servo system to effect frequency corrections.
Orbitron Ionization Gauge
Authors: Mourad W. G. , Pauly T. , Herb R. G.
Published: February 2005

An ion gauge with high ionization efficiency and low input power is described. In this gauge, called the orbitron, electrons are injected by a small tungsten filament into the electrostatic field between two concentric cylinders, with energies and angular momenta such that a relatively long mean free path is achieved. Only 4 μA electron current is needed to produce the same ion current obtained from 8 mA emission in a conventional Bayard-Alpert gauge. X-ray and photocurrents are held to low values by locating the ion collector remotely from the main source of light and x rays. The ion current is linear with pressure below 1×10−5 Torr and has been tested down to 5×10−11 Torr. The lower pressure limit has not yet been determined.
Vibration Method for the Elastic Constants of Small Plates
Authors: Bopp Charles D.
Published: February 2005

A method is described in which a clamped mode of vibration is used in order that the driving force may exceed the weight of the specimen. A supported cantilever plate is vibrated in flexural and torsional modes by driving the support. An approximate solution of the vibration equation is used to calculate the elastic constants from the resonant frequencies. The solution is expressed in terms of the ratio of the resonant frequency of the unknown specimen to that of a standard of the same length and width, to reduce the precision required in specification of the support location. This method was applied in a radiation effects study to measure the Young's moduli of small ceramic plates within 3–5%. The accuracy was limited in this instance by the dimensional tolerances of the specimens.
Gamma-Ray Pair Spectrometry from 20–650 MeV
Authors: Mead Gilbert D. , Cence Robert J. , Lind Don L.
Published: February 2005

Two pair spectrometers have been developed to measure gamma-ray spectra over a range from 20 to 650 MeV with good resolution. One is a conventional 180° spectrometer to measure the lower energies; the other, for high energies, utilizes a circular geometry. An expression for the absolute efficiency is given in terms of the geometry, magnetic field, and pair-production cross section. The effects of geometry, electron scattering, and radiation straggling on the efficiency and resolution function are considered. All these factors are then used to provide the proper normalization for the experimental spectra over the range of energies measured. The counting data are stored in a magnetic-core device, then read out on punched cards. A computer program analyzes the data and makes all the necessary corrections and subtractions. These spectrometers have been used in experiments with neutral pions at cyclotron energies.
High Pressure Polymorphic Transitions Studied by Audio- and Radio-Frequency Techniques
Authors: Giardini A. A. , Poindexter Edward H. , Samara G. A.
Published: February 2005

Volume and resistivity changes associated with polymorphic transitions in solids under pressure have been studied by an ac inductive method. A small coil is wound over a core of the sample, and the electrical impedance of the coil determined as a function of pressure to 65 kbar. The coil method was demonstrated in three electrically different operating regions: large skin depth, small skin depth, and an intermediate case. With large skin depth, the inductance of the coil reflects the volume of the sample core. With small skin depth, the reactance and resistance of the coil represent a mixture of volume and resistivity information, but the data may be easily analyzed to yield resistivity alone. In the intermediate case, volume and resistivity are separately displayed by the inductance and resistance, respectively. The coil method offers the advantage that volumetric transitions may be studied remotely, with no moving mechanical indicators. The sensitivity to volume change was demonstrated to be at least 0.1%.
Zone-Melting Apparatus for Alkali Metal Cyanides and Alkali Metal Halides
Authors: Neubert Theodore J. , Susman Sherman
Published: February 2005

A zone-melting apparatus is described that can be largely assembled from commercially available components. Details of a technique are given for zone refining alkali metal cyanides and halides in reinforced, flexible metal boats.
Thermal Stability Apparatus for Liquid Propellants
Authors: Stiefel L. , Grossmann E. D.
Published: February 2005

A thermal stability test apparatus for liquid propellants is described which consists of a closed chamber that can be maintained at fixed elevated temperatures. The sample can be rapidly pumped directly into the chamber by means of a remotely operated, syringe-type pump. A check valve, incorporated into the pump, sealed off the bomb after the liquid was injected. Time from injection to ignition can be recorded. The method offers the advantage that no container or capsule intervenes between the heating medium and the sample, and there are no temperature lags due to the intermediate wall.
Device for the Precise Measurement of Small Temperature Changes
Authors: La Force Richard Conley , Ravitz S. Frederick , Kendall Weston B.
Published: February 2005

A device capable of measuring temperature with a precision corresponding to a standard deviation of about 14 microdegrees at room temperature has been designed and constructed. The device employs a thermistor as the temperature-sensing element in an ac bridge. The bridge imbalance, after being amplified, is detected by two phase-sensitive detectors phase-shifted 90° with respect to each other to insure that both the resistive and reactive components of the bridge elements are balanced.
Fast-Acting Superconducting Power Switches
Authors: Ameen D. L. , Wiederhold P. R.
Published: February 2005

Superconducting switches operating on the basis of superconducting-to-normal transitions are considered as a means of initiating high power pulsed discharges from inductive energy storage systems. An analysis of transition times, power losses, and design techniques is presented. Thermally and magnetically activated switches, consisting of long, noninductively wound 0.005-in. Nb-25% Zr wires, with normal resistances in the kilohm region, have been tested. A linear representation of the reappearance of resistance during a superconducting-to-normal transition yielded values up to 105 Ω/sec. A mathematical analysis, which is in good agreement with experimental results, is given. Factors influencing the rate of increase of resistance are reviewed.
Rotating Mirror Vibration
Authors: Winkler Max A.
Published: February 2005

An experimental arrangement is given for measuring the relative amplitude of vibration at any given speed for rotating mirrors. A code is introduced which predicts the frequencies at which resonance occurs for any uniform stepped shaft with a maximum of ten steps. This code is applied specifically to rotating mirrors. Results are then given for a number of rotating mirrors used in various cameras at the Los Alamos Scientific Laboratory.
Ballista or Ball-Throwing Device for Momentum and Density Measurements in a Rotating Plasma
Authors: Bannenberg J. G. , Insinger F. G.
Published: February 2005

A ball-throwing apparatus has been built to be used as an instrument for measuring the local momentum and density of a plasma in a rotating plasma device. Reasons are given for the choice of this technique and the critical design parameters are discussed. The necessary timing equipment and calculation method are given. The time of flight of a launched ball is known with an accuracy of ±0.15%.
Time Resolution of Streak Cameras Equipped with Rotating Mirrors of Beryllium
Authors: Landré J. K.
Published: February 2005

After a brief discussion of the limiting factors in streak record information, a test method is described with which the influence of mirror distortion and air turbulence on the time resolution can be studied. Results for 1×2 in. beryllium and steel rotating mirrors are given. The time resolution of a streak camera equipped with a beryllium mirror is found to be a few nanoseconds when the instrument is used as a chronometer; velocity measurements can be carried out with over-all accuracies of a few tenths of a percent.
Accurate Wideband Multiplier—Square-Law Detector
Authors: Frater R. H.
Published: February 2005

A multiplier—square-law detector is described which has fewer limitations than existing types. It is shown that the gain of an emitter coupled amplifier (longtail pair) is proportional to quiescent current. This property makes it possible to obtain accurate wideband multiplication. Test results are given for a unit designed for radio astronomy application which, when used as a square-law detector, has an input dynamic range of over 40 dB. It is noncritical in adjustment and operates at frequencies up to 50 Mc. A single thermistor is used to maintain gain within 2% from 10 to 50°C.