bluuebunny/crossref_metadata_2025 huggingface dataset:
An Interferometric Micro-Electrophoresis Apparatus
Authors: Lotmar W.
Published: February 2005

A micro-electrophoresis apparatus based on interferometry is described. The interferometer consists of a modified Jamin arrangement, using only one plate while the other is replaced by a reflecting cell at right angles to the beam, thereby doubling the sensitivity. A cell filling requires 0.4 ml of solution. No thermostat is provided. Details of the optical and electrical equipment are given. The apparatus may also be used for diffusion experiments.
Apparatus for Vacuum X-Ray Fluorescence Analysis of Light Elements
Authors: Birks L. S.
Published: February 2005

Air absorption in the conventional x-ray fluorescence analysis equipment limits detection to elements heavier than calcium. To avoid absorption of the longer-wavelength x-rays from lighter elements, a vacuum system, or one filled with H2 or He, is required. A vacuum apparatus has been developed for the analysis of elements from magnesium to titanium. It contains the x-ray tube for exciting fluorescence; a specimen holder for six specimens; a collimator to limit the fluorescent radiation to a parallel beam; and a single-crystal, Geiger counter spectrometer to analyze the radiation. A pressurized, double-film, nitrocellulose window is used for the Geiger counter because the usual mica windows are opaque to radiation from elements lighter than sulfur. For calcium Kα, the increase in intensity resulting from evacuating the chamber is 100-fold, with far greater increases for the lighter elements. Alkali halides and gypsum were tested as analyzing crystals. An application of the equipment to the measurement of sulphur in oil indicates that 0.5 percent sulfur can be detected with ±0.03 percent accuracy in 5 to 10 minutes.
An Electron Microscope Photometer
Authors: Hamm F. A.
Published: February 2005

The main purpose of this paper is to describe an apparatus for measuring the intensity of the focused electron beam as it passes through the final viewing chamber of the RCA electron microscope Model EMU. A portion of the electron rays serving to form the final image is collected by a metal probe; these electrons are passed to ground through a high resistor. The voltage developed across this dropping resistor is measured; it represents the intensity of the focused electron beam. Uses as an exposure meter in micrography and for metering the current density incident on the specimen are described.
Low Evaporation Rate Storage Vessel for Liquid Helium
Authors: Sydoriak Stephen G. , Sommers H. S.
Published: February 2005

Expressions are derived for the heat flux q0 and temperature gradient dT/dh in a Pyrex cylinder (a) in vacuo and (b) in the atmosphere of cold vapor issuing from a liquid helium container. In the temperature range 20<T<300 we find for case (a) that q0 α T1.8 and dT/dh α T−0.8, while in case (b) q0 α̇ T and dT/dh is nearly constant.

Design details and operating procedures are given for a 12-liter liquid helium storage vessel intended to complement our Collins helium liquefier. It can be filled in one day's operation of the liquefier, and ten days later is still half full.
Temperature Regulation in Induction Heating
Authors: Henschen Homer E. , Edwards James W. , Johnston Herrick L.
Published: February 2005

This paper describes an improvement in the design of a temperature regulator for induction heating that was the subject of a previous report from this laboratory. The improved design eliminates the optical lever by use of vacuum tube amplifiers. The result is to improve sensitivity and eliminate the large time constant of the galvanometer used in the earlier circuit. In experiments on vapor pressure of iron and cobalt at 1200°—1500°K, the new regulator held temperatures of the iron or cobalt samples constant to within about 0.1 percent of the absolute temperature.
Circuits and Tubes for Ultra-Sensitive Electrometers
Authors: O'Meara F. E.
Published: February 2005

The design of an improved electrometer circuit, which will compensate for voltage fluctuations and random emission changes, is described. The selection of suitable electrometer tubes is discussed.
Magnetostrictive Vibration of Prolate Spheroids. Preliminary Measurements
Authors: Kouvelites J. S. , McKeehan L. W.
Published: February 2005

Small but accurately shaped prolate spheroids of ferromagnetic substances, almost uniformly magnetized by direct current in a large coaxial solenoid, are subjected to alternating axial applied magnetic fields produced by high frequency current in a smaller coaxial solenoid. Measurements of the impedance of this high frequency coil with a specially designed Maxwell bridge, give, as the driving frequency is varied through the frequency of mechanical resonance in the fundamental mode of longitudinal vibration of the center-supported spheroid, precise data for analyzing the distribution of electromagnetic driving forces and of magnetic, electrical, and mechanical losses by a theory to be given elsewhere. Since the spheroid dimensions are about 10 millimeters for length and one millimeter for diameter, the resonant frequencies of interest are near 300 kilocycles per second. Optical measurements of vibration amplitude, possible in principle, have not yet been effectuated.
The Design of Cyclotron Oscillators
Authors: Backus John
Published: February 2005

The procedure used to design the 60-in. cyclotron oscillator at Berkeley is described. The procedure consists in assuming the cyclotron and associated circuits to be oscillating on one of normal modes of vibration of the electrical circuit and adjusting the circuit so that the proper voltages to drive the oscillator tube are obtained. The procedure is illustrated by numerical examples taken from the original design data.
Reverse Separation in Fractionation Pumps
Authors: Hickman K.
Published: February 2005

Measurements by Trevoy and the writer, to be published shortly elsewhere, have shown that the relative volatilities of mixtures of liquids increase surprisingly at low rates of distillations. A consequence is that organic liquids release volatiles into high vacuum apparatus more readily than would be deduced from measurements made at usual pressures of, say, 1–100 microns. The composition of condensate in an oil-filled diffusion pump is found to be a function of position in the pump, the lightest constituents straying preferentially to the high vacuum end. As an example, Octoil contaminated with less than 1 percent of butyl phthalate in the last boiler of a 3-stage pump was found to pass vapor through the high vacuum entrance as though the boiler had contained 27 percent butyl phthalate.

To epitomize the situation, a vapor pump is a specialized form of still with two exits. The intention of the designer, expressed in the geometry of the pump, is to force the lighter molecules to one exit but molecular perversity causes them to wander to the other. The effect is probably unimportant except where the highest vacuums are required, though it does point to the desirability of thorough prepurification of pump oils; the task of fractionation, before and during use, is harder than we had supposed.
A New Type of Electromagnet. Part I. Operation at 20-kw Level
Authors: Bitter Francis , Reed F. Everett
Published: February 2005

An improved iron core magnet for general laboratory use, weighing two tons, has been designed and several units have been constructed. The design incorporates the desirable features of a number of earlier magnets and is engineered to give the optimum utility with minimum space and weight and with minimum attention by the operating personnel. A summary of test performance at 20 kw is given below. Operation at higher power levels will be described in Part II. 11−in. diameter poles      5−in. gap10 kilogauss      2−in. gap17 kilogauss.534−in. diameter poles      2−in. gap23 kilogauss      1−in. gap30 kilogauss.1−in. diameter poles      1−in. gap32 kilogauss      12−in. gap37 kilogauss      14−in. gap42 kilogauss.
On the Sharpening of Microtome Knives for Ultra-Thin Sectioning
Authors: Hillier James
Published: February 2005

Conventional methods of sharpening involve extensive grinding which is primarily for the removal of large nicks but which serves the additional purpose of fitting the knife to the sharpening means. Since large nicks rarely occur in ultra-thin microtomy, the grinding would become unnecessary if the fitting of the knife to the sharpening means could be made permanent. A permanently attached short sharpening back is described which makes this possible. Using the finest abrasives and polishing powders and prepared glass plates as the sharpening surfaces, it is possible to resharpen a knife in less than ten minutes. The method is described in detail.
Nuclear Multiple Plate Camera
Authors: Allred J. C. , Rosen L. , Tallmadge F. K. , Williams J. H.
Published: February 2005

A nuclear multiple plate camera has been devised which permits observations to be made on scattering and reaction processes resulting from the bombardment of gas targets with a charged particle beam. Sixty-nine photographic plates are held in a rigid geometry which allows simultaneous measurements of interaction differential cross sections at 2.5° intervals from 10° to 170° in the laboratory system. Because of the precision with which the camera is machined, relative cross-section measurements can be made essentially within the statistical error of the number of particle tracks counted at each angle. As a check of the apparatus, measurements were made on the p—p and p—He4 elastic scattering processes. The results are in excellent agreement with previously reported counter data.
Double Focusing with Wedge-Shaped Magnetic Fields
Authors: Camac Morton
Published: February 2005

Geometric focusing in two directions for charged particles of a single energy is produced with a wedge-shaped magnetic field. The uniform field in the gap focuses in the plane of the pole faces, while the fringe fields focus perpendicular to the pole faces. With a single wedge the energy dispersion is too large for the weak electron intensities available with our source; i.e., for are asonable size slit at the collector only a narrow energy width and, thus, a small number of electrons is accepted. With the use of two wedge-shaped fields the energy dispersion can take a wide range of values, even zero in the first order. General formulas for either one or two magnet systems are derived for the focusing conditions, the energy dispersion, the second-order beam spread, and the effect of source width. These formulas are then applied to two special cases from which practically all design requirements can be obtained. Finally, a design is recommended for which the following requirements are fulfilled : five percent energy spread in an inch collector slit, large angular collection, and the same size source and collector slits.
Continuous Recording of Circulatory Hemoglobin
Authors: Guyton Arthur C. , Gillespie William M. , Armstrong George G.
Published: February 2005

An electronic method for continuously recording hemoglobin concentration in the blood of experimental animals is described, and the theory, calibration, accuracy, and uses of the apparatus are discussed. The principal value of the apparatus lies in the study of very rapid changes in hemoglobin concentration such as that which occurs following injection of fluid into the blood stream. As little as one-half cc of saline injected into the vein of an average dog will cause a quantitatively measurable change in the hemoglobin concentration.
An Exposure Meter for the Electron Microscope
Authors: Frei E. H. , Hirshfeld F. L.
Published: February 2005

A simple exposure meter has been developed which measures directly the beam current reaching the fluorescent viewing screen of the electron microscope. By its use, the characteristic curve of a Kodak lantern slide plate has been plotted at constant intensity of electron beam. The value of beam intensity given by the exposure meter is confirmed by direct counts of electron tracks in the developed emulsion.
A Magnetically Compensated Vapor Density Balance
Authors: Johnson E. W. , Nash L. K.
Published: February 2005

A magnetically compensated buoyancy balance is described. This instrument provides precise and continuous indications of gas and vapor densities falling in the range of 0 to 4 g/l. Measurements can be made at temperatures that are freely variable up to 220°C; mildly corrosive vapors can be handled; and the data are automatically corrected for adsorption effects. The long term reproducibility of the readings is 0.001 g/l.

Magnetic compensation is attained by adjusting the current in an external electromagnet until this magnet's interaction with a small permanent magnet sealed in the balance beam restores the beam to a standard null position. The virtually linear relationship between this ``restoring'' current and the ambient vapor density is established by calibration with a standard substance. High constancy of calibration has been achieved through the use of a special beam suspension which, though extremely friction free, is unaffected by repeated and relatively severe mechanical and thermal shocks.
Two Calorimeters for Industrial Measurements
Authors: Werner A. C.
Published: February 2005

Two calorimeters for the determination of the heat capacity of solid materials and heats of fusion are described. Typical data for potassium nitrate and for a solution of nicotinic acid in sulfuric acid are presented.
A Cloud-Ionization Chamber for the Study of Cosmic-Ray Nuclear Interactions
Authors: Lewis H. W. , Brown W. W. , Seevers D. O. , Hones E. W.
Published: February 2005

A combination cloud chamber and ionization chamber in which the gas (argon at 51 lb in.−2 saturated with iso-amyl alcohol) is common to both chambers is described. The ion chamber, a 3¾in. diameter brass cylinder 8 in. in length open at both ends and having a 116−in. central wire, is mounted coaxially with the cloud chamber, which has a useful rectangular volume 10 in.×10 in.×8 in. A burst occurring in the ion chamber generates a pulse which is used to trigger the expansion mechanism. Rapid reduction of the cylinder voltage from −1800 volts to ground, after electron collection is over, prohibits any appreciable motion of positive ions and thus permits observation of the tracks of the burst producing particles. In preliminary tests at sea level, cosmic ray bursts from cascade showers and from stars occurring in the wall (up to 10 prongs) and in the gas (up to 5 prongs) of the ion chamber have been observed.
A New Deflection Type Densitometer
Authors: Kirchgessner W. G.
Published: February 2005

This report discusses the design and performance of the Bausch and Lomb 33–84–91 densitometer. Fundamental requirements of design are stated and construction is described on the basis of these requirements. Performance data of the instrument are discussed in detail and records are given to demonstrate its fidelity of reproduction.
Scattering Losses in the Synchrotron
Authors: Greenberg J. Mayo , Berlin T. H.
Published: February 2005

Scattering losses in various electron and proton synchrotrons by residual gas molecules are obtained for a variety of conditions. Evaluation is made of the effects of (1) injection energy of the particles, (2) the spread of the injected beam, (3) the pressure of the residual gas, (4) the rate at which energy is supplied to the beam particles, and (5) the aperture of the accelerator. It is shown that multiple scattering is the really important factor and that losses due to single scattering are of relative importance only when the total effect of single and multiple scattering is rather small.

Scattering losses are tabulated and estimates made of the residual gas pressures in synchrotrons which will not produce prohibitively large losses.
The Proton Deuteron rf System for the Berkeley Synchrocyclotron
Authors: MacKenzie K. R.
Published: February 2005

An rf system is described which allows the acceleration of either 190-Mev deuterons or 350-Mev protons in the Berkeley 184-inch cyclotron. The dee is connected to a large cross-section line, which is in turn connected, through a rotating condenser, to a short section of grounded line of approximately the same cross section. At the upper frequency limit of 23.2 megacycles the dee and dee stem oscillate as a half wave line, while the grounded line, which is about one-quarter wave long, oscillates in the opposite phase. At the low frequency limit of 9.5 megacycles, the whole system looks like a quarter wave line. The oscillator which feeds the system is described.
Negative Ions and Charge Neutralization in the Cyclotron
Authors: Lofgren E. J.
Published: February 2005

Evidence is given for the presence of negative hydrogen ions in the synchrocyclotron. They are lost by charge neutralization before they reach an energy of about 3 Mev. Protons have been made to circulate in the cyclotron without acceleration after they have reached an energy of 5 to 22 Mev and are found to be lost with a half-life of ⅓ to 2 seconds.
Electrostatic Direct-Current Transformer of 300 Kilovolts
Authors: Malpica José Mireles
Published: February 2005

An electrostatic transformer of direct current which permits the continuous transfer of electrical charges from a primary circuit to a secondary circuit by means of a rotating dielectric is described. The primary circuit consists of a pair of metallic brushes connected to a source of high voltage, the moving dielectric being placed between them. A similar pair of brushes, placed at a convenient distance away, constitutes the secondary terminals. The continuous transfer of charges permits the passage of a steady current from the secondary brushes. In the one-to-one ratio electrostatic transformer the secondary voltage is slightly less than the primary voltage owing to losses, but since the primary circuit and secondary circuits are separated by insulating material, it is possible to place several disks on a shaft and to connect the primary brushes in parallel and the secondary brushes in series, obtaining in this way a step-up transformer. The elementary theory is developed and experimental results are shown.
A Null-Reading Absolute Manometer
Authors: Alpert D. , Matland C. G. , McCoubrey A. O.
Published: February 2005

A manometer has been developed for the pressure measurement of very pure gases or condensable vapors. It can be outgassed at high temperatures, is rugged in construction, and has a maximum error of 10−2 mm Hg.
A Timing Control for Small Spot Welders
Authors: Nichols M. H.
Published: February 2005

Of the several circuits for timing control of small spot welders which have recently appeared in the literature, the one which seems to the author to be most practical does not include circuit parameters or components. A certain amount of effort is required, therefore, in selecting parameters and components. It is the purpose of this article to provide this information.
Growth and Manipulation of Barium Oxide Crystals
Authors: Sproull R. L. , Dash W. C. , Tyler W. W. , Moore A. R.
Published: February 2005

A method is described for growing crystals of BaO from the vapor. Seeds of BaO crystals or ``pseudoseeds'' of MgO crystals are placed in an enclosure of BaO in a vacuum furnace and heated at 1400°C. Single BaO crystals as large as 1×10×10 mm have been grown by this method. Since BaO decomposes very rapidly in the ordinary atmosphere, special techniques for manipulating the crystals are described. These techniques are useful in experiments on the optical, electrical, and electronic properties of BaO.
Design of a Cyclotron Magnet. I. Pole Design Using a Half-Magnet
Authors: Foss M. , Fox J. G. , Sutton R. B. , Creutz E. C.
Published: February 2005

In order to measure the effects of gross changes in the design of the pole and yoke for a large synchrocyclotron cheaply and conveniently, a model half-magnet having a two-inch diameter pole was constructed. From data on the fields produced by poles of various lengths using a fixed amount of copper in the coil, the pole length for which the cost of power and magnet steel was a minimum could be determined. Measurements of the efficiencies of poles of various shapes indicated that it would be possible to design a shimmed pole to have an efficiency of 70 to 75 percent at a field of 20,000 gauss. Finally data on over-all magnet efficiency as a function of the ratio of the cross-sectional areas of the yoke and pole permitted calculation of the ratio for which the cost of steel, copper, and power would be a minimum.
The Design of Thin-Windowed Geiger-Müller Counters
Authors: Purbrick R. L. , Cherry Lawrence T. , Carpenter James F.
Published: February 2005

The optimum length of an end-window counter for the measurement of weak C14 activities is found to be about 1 cm.
An Enriched Homogeneous Nuclear Reactor
Authors:   Los Alamos Scientific Laboratory of the University of California, Los Alamos, New Mexico
Published: February 2005

A discussion is given of the design considerations, operational procedures, safety devices, and performance of a small homogeneous reactor using enriched uranium in a water solution and beryllium oxide and graphite for the neutron reflector. A high power and a low power phase of this reactor are described.
Measurement of the Electron Density in Ionized Gases by Microwave Techniques
Authors: Biondi Manfred A.
Published: February 2005

Methods are described in which microwave techniques are used to measure the electron density during the period following a discharge. By measuring the detuning of a resonant cavity containing electrons, it is possible to measure electron densities between 1010 and 106 electrons/cc in gases whose pressure may be varied over a wide range. Design criteria are given to permit proper operation of the method under the conditions encountered in a given experiment.
A Comprehensive Counting System for Nuclear Physics Research Part IV. Introduction to Pulse Amplitude Analyzers
Authors: Moody N. F. , Battell W. J. , Howell W. D. , Taplin R. H.
Published: February 2005

In scientific research, pulse amplitude or temporal distribution is often the analog of the phenomenon under investigation. Particularly is this true in nuclear studies, where pulse amplitude can be made proportional to energy and classification on an amplitude basis yields the energy spectrum. The present paper gives an outline of pulse amplitude analyzing equipment and indicates that for pulse widths of one microsecond and larger, as distinct from those in the millimicrosecond region, the thermionic diode leaves little to be desired as a voltage discriminating element.
The Lorentz Factor for the Buerger Precession Method
Authors: Waser Jürg
Published: February 2005

The Lorentz factor for the Buerger precession method is derived. It turns out that the angular velocity of the motion of the reciprocal lattice through the sphere of reflection is not uniform as hitherto accepted. The Lorentz factor thus depends explicitly on all three cylindrical coordinates ξ, ζ, τ of the reciprocal lattice point under consideration and not on only as ξ and ζ.
Calorimetric Determination of the Energy Flux of 22.5-Mev X-Rays
Authors: Laughlin J. S. , Beattie J. W.
Published: February 2005

A sensitive method of calorimetrically measuring the energy flux of an x-ray beam is described. Thermistors are employed as the temperature-sensitive elements and are embedded in the irradiated material in a calorimeter. Details and results of the application of this technique to a betatron x-ray beam are described. This method can be applied to x-ray beams of other energies and does not require high intensities.
Continuous Purification of Hydrogen in a Large Electron-Pulse Chamber
Authors: English W. N.
Published: February 2005

A hot uranium purifier for hydrogen (or deuterium) has been constructed which will remove relatively large amounts of negative ion forming impurities such as O2, Cl2, H2O, thus permitting electron pulse collection without any elaborate outgassing procedure. The method has been tested at 6 atmospheres hydrogen pressure by observing the pulse distribution from a Pu239 α-source in the chamber and plotting the ``most-probable-pulse-amplitude'' against purifying time. A ``purifying time constant'' of about two days was obtained.
Analysis of High Energy Proton Spectra by Means of a Stack of Photographic Plates
Authors: Walker Darcy
Published: February 2005

Stacks of photographic plates have been used to analyze the continuous spectrum of high energy protons emitted by a carbon target bombarded with γ-rays from an electron synchrotron. The planes of successive plates in a stack lay at 30° to a line through plate and target centers, and the plates were interleaved with aluminum absorbers. The numbers of proton tracks per square cm in the emulsions of successive plates yield an integral spectrum of the protons. Protons with energies up to more than 120 Mev were present when the synchrotron was operated at 195 Mev. The effects of multiple scattering of the protons in the stacks are discussed, and it is shown how the tracks of protons originating from the target can be distinguished clearly from a background of randomly oriented tracks.
Rapid and Sensitive Spectrophotometry. III. A Double Beam Apparatus
Authors: Chance Britton
Published: February 2005

An apparatus for accurately timing the sequence of spectroscopic events in turbid suspensions of the cytochrome oxidase system has been developed. This apparatus measures simultaneously small optical density changes occurring at two wavelengths in the visible region with a small spectral interval in spite of the large scattering of light by the heart muscle suspensions. The cross talk between the two channels corresponds to an optical density change of less than 5×10−4. Transients arising from the modulation and demodulation processes cause no difficulty. The error of optical measurements caused by the noise level in the photocurrent is 2×10−4 for a rise time (10–90 percent) of 1 sec. Some typical experimental results are included.
A Magnetic Float Method for Determining the Densities of Solutions
Authors: MacInnes D. A. , Dayhoff Margaret O. , Ray B. Roger
Published: February 2005

A method for determining the densities of liquids is described in which a float containing a magnet is utilized. The conditions under which the submerged float would remain poised are found by adding weights and by observing the effect of currents through a solenoid. The method may be adapted to the measurement of the densities of solutions at a series of increasing concentrations by forming the solutions directly in the vessel containing the float.
A Scintillation Counter for the Relative Determination of X-Ray Intensities in Radiological Work
Authors: Ter-Pogossian Michel , Ittner William B.
Published: February 2005

An instrument is described for determining accurately the intensity of an x-radiation by direct reading. This instrument consists in a small potassium iodide crystal which fluoresces under the action of high energy photons. The light thus emitted is ``piped'' by means of a Lucite rod to a photomultiplier tube. The current generated in the tube is measured by a microammeter.

A series of tests on the energy dependence of this detector are reported. It is concluded that the instrument described is suitable for the determination of isodose charts.
Diffusion Cloud Chambers
Authors: Nielsen Carl E. , Needels Theodore S. , Weddle Orville H.
Published: February 2005

Three forms of diffusion cloud chamber are described. Diagrams indicate their construction, and their operation is discussed. The direction of diffusion may be upward or downward. Various alcohols and water-alcohol mixtures may be used. A stable diffusion cloud chamber giving tracks of the quality shown in the typical photographs is simple to construct and operate. The sensitive volume, while necessarily in the form of a horizontal region shallower than the chamber itself, can be made to include most of the chamber volume.
A Transient Method for Measurement of Dielectric Polarization
Authors: Davidson D. W. , Auty R. P. , Cole R. H.
Published: February 2005

A transient method is described which measures the equivalent of the polarization following application of a step voltage by recording the changing current resulting from a linearly rising potential across a dielectric cell. The circuits described permit recording over intervals from 10−3 sec to several seconds and are intended for use with cells employing guard electrodes. Examples of results on dielectric relaxation in solids are given and limitations of the method discussed.
A Combined Current Indicator and Integrator
Authors: Higinbotham W. A. , Rankowitz S.
Published: February 2005

An instrument is described which combines a current integrating circuit and a dc amplifier to provide a continuous indication of the current being integrated. The instrument is stable, easy to calibrate, and covers a range of input currents from 0.01 to 500 microamperes full scale.
A Recording Torsion Pendulum for the Measurement of the Dynamic Mechanical Properties of Plastics and Rubbers
Authors: Nielsen Lawrence E.
Published: February 2005

A recording instrument for measuring the dynamic shear modulus and mechanical damping of plastic and rubber-like materials using the principle of the torsion pendulum has been constructed. The mechanical oscillations are converted into electrical potentials for recording by a torque measuring device which is actuated by a differential transformer. The apparatus is capable of measuring the modulus and damping of materials over an extremely wide range.
Plain and Beaded Wire Geiger Counters for X-Rays
Authors: Parratt L. G. , Hempstead C. F. , Jossem E. L.
Published: February 2005

The calibrations of typical self-quenching plain and beaded wire Geiger counters are studied for measurements of x-ray relative intensities over a range of 1 to 105 counts per second. For plain wire counters, correction for ``lost counts'' in terms of resolving time is found to be unreliable except at rates less than about 100 counts per second. The basic difficulty lies in a large and inconstant ratio of spurious to valid counts. This ratio depends upon counting rate, changes in counting rate, tube age, overvoltage, and spread of discharge. Beaded wire counters are studied as an improved type of counter for incident-ionizing events whose primary ionization does not extend along a large fraction of the length of the anode wire. For beaded wire counters, it is believed that corrections reliable to about 2 percent can be made to the observed counting rate over a rate range of about one to a thousand counts per second if the rate is not abruptly changed at rates above about 100 counts per second.
Multiple Mode Operation of Servomechanisms
Authors: McDonald Donald
Published: February 2005

The dynamic operation of servomechanisms should be represented by several equations of motion rather than by a single equation of motion as is commonly done. Usually, the additional modes of operation described by the additional equations of motion represent operation of the servomechanisms under torque or velocity saturation where the performance of the servomechanism is limited. If a servomechanism has these multiple modes of operation, its over-all performance can be improved by designing the controller to take maximum advantage of the characteristics of the system for each of its modes of operation. Such a design will result in improved performance with a possible reduction in over-all weight.
Improved Overload Response of the A-1 Amplifier
Authors: Magee F. I. , Bell P. R. , Jordan W. H.
Published: February 2005

It is frequently desirable to use a linear amplifier to study signals having a wide range of amplitudes. Modifications have been made to the A-1 amplifier which permit it to be used with signals up to 300 times the normal overload value.
A Flexible Pulse Amplifier with Good Overload Properties
Authors: Chase R. L. , Higinbotham W. A.
Published: February 2005

A general purpose linear pulse amplifier with good stability, short rise time, and good overload characteristics is described. The basic circuit consists of two long-tailed pairs in a negative feedback loop containing a small amount of positive feedback inside the loop.
A High Vacuum Recording Spectrograph for the Study of Radiation from Solids in the 100–800A Range
Authors: Piore E. R. , Harvey G. G. , Gyorgy E. M. , Kingston R. H.
Published: February 2005

The two-meter grazing-incidence vacuum spectrograph used by O'Bryan and Skinner for the study of the emission bands of solids has been rebuilt to operate with improved sensitivity and speed. The major modification is the replacement of the photographic plate by a Be–Cu photomultiplier which is designed to traverse the Rowland circle, giving a continuous record of photon-counting rate as a function of a wavelength. With the photomultiplier it is possible to take as many separate curves as desired, subject to x-ray target condition, without opening the spectrograph, which is normally evacuated to better than 10−5 mm Hg. In addition, the sensitivity is increased about a thousandfold; i.e., with a photographic plate, the target current and voltage needed are 10–100 ma and about 3000 v for a one- to three-hour exposure. Using the photomultiplier, however, these values may be reduced to 2–3 ma and 300–500 volts, respectively, and the complete emission band may be recorded in five minutes. The results for aluminum are in excellent agreement with the results of previous authors.
Combined Current Integrator and Sensitive Microammeter
Authors: Enge H. A.
Published: February 2005

A simple current integrator has been designed for use in connection with electrostatic accelerators. It is capable of integrating currents higher than 10−8 ampere. A compensation resistor in the input circuit of the integrator is at the same time utilized as a shunt resistor for an electronic microammeter with full-scale readings, 1, 2, and 10 μa.
An Apparatus for the Simultaneous Determination of Absorption Isotherms and Magnetic Susceptibility
Authors: Milligan W. O. , Whitehurst Harry B.
Published: February 2005

An apparatus is described for the simultaneous determination of adsorption isotherms and magnetic susceptibility. A fused silica spring with a sensitivity of 3 mm/mg is used to determine adsorption gravimetrically in the manner of McBain and Bakr. An electromagnet is incorporated in the apparatus to allow the determination of the magnetic susceptibility of the sample and the adsorbed vapor by the Faraday method. The apparent change in weight caused by the inhomogeneous magnetic field is 11.46×103 times the sample weight for a substance of unit magnetic susceptibility (cgs units). The same spring is used for the measurement of adsorption and magnetic susceptibility, and both measurements are made on the same sample.
Double Focusing of Charged Particles with a Wedge-Shaped, Non-Uniform Magnetic Field
Authors: Sternheimer R. M.
Published: February 2005

The pole faces of a wedge-shaped magnet can be shaped so as to reduce the image distance for simultaneous horizontal and vertical focusing, and thereby increase the intensity at the image. The field inside the magnet is assumed to behave as r−n, where r is the distance from the center of curvature of the normal path and n is a constant parameter. Equations are obtained for the image distance for double focusing, and the results of calculations for several representative cases are shown. It is shown that by appropriate choice of the non-uniform field, the image distance can be appreciably reduced in all cases of interest.
A Broad-Band, Coaxial Stark Cell for Microwave Spectroscopy
Authors: Rueger L. J. , Nuckolls R. G.
Published: February 2005

A coaxial-type Stark cell was designed as a conveniently small-sized apparatus for operation at all microwave frequencies between 3400 and 900 Mc (and lower) without changing either the sample under investigation or the size of the absorption cell. The Stark voltage is applied between the inner and outer conductors of the coaxial line and is separated from the rf signal at each end of the cell by sections of wave guide. The use of this cell has permitted the extension of microwave absorption measurements in gases to a new and extremely low range of frequencies. It was used to discover and investigate the full series of ND3 absorption lines in this new range.
A Radiofrequency Ion Source
Authors: Swann C. P. , Swingle J. F.
Published: February 2005

An rf ion source with transverse magnetic field giving 50 μa of resolved protons with a gas flow of less than 1 cc per hour and with a power input of 150 w is described. The effect of magnetic field upon power requirements is discussed.

With increased gas flow resolved currents in excess of 100 μa of protons have been obtained.
Pair Measurement of Gamma-Rays with a Lens Spectrometer
Authors: Alburger David E.
Published: February 2005

A conventional lens spectrometer has been adapted to the measurement of high energy gamma-rays by detecting positron-electron pairs in coincidence. The source and converter are centered on the optic axis and the baffle system selects pairs of nearly equal energy. The detection method consists of dividing the focal circle of confusion in half and observing coincidences between particles entering these two regions. Statistically the components strike different areas in half the cases. The detectors are semicircular anthracene crystals connected by light pipes to 1P21 photomultiplier tubes. Pulses from these are fed through amplifiers to a coincidence circuit of 7×10−8 sec resolving time. The method has been tested by observing ``pair peaks'' due to the 2.76- and 2.62-Mev gamma-rays of Na24 and ThC″, respectively. The Po–Be reaction gamma-ray has been measured at 7.5 percent resolution and found to have an energy of 4.47±0.04 Mev. Using a proton beam from the Brookhaven electrostatic accelerator gamma-rays of 6.19±0.08 Mev and 7.13±0.12 Mev occurring in the F19(p,α)O16 reaction have been observed with this apparatus. The results on both Po–Be and the fluorine reaction are in agreement with previous measurements by other methods.
A Critical Evaluation of the Norelco High Angle X-Ray Spectrometer for Elastic Strain Measurements
Authors: Maloof S. R. , Erard H. R.
Published: February 2005

The theory of measuring elastic strains in metals with an x-ray spectrometer is discussed and comparison is made with the x-ray back-reflection film method. It is shown that the accuracy attained in the determination of the surface biaxial stress sum from measurements on sharp diffraction lines with the spectrometer is equally as good as, or better than, that attained with the usual film techniques. An example is given of the determination of the biaxial stress sum with the spectrometer in a steel hardened to Rockwell C55. It was not possible to make the same determination photographically.

The effect of elastic anisotropy on x-ray stress determinations is briefly discussed. It is shown that the error in the determination of the stress sum due to an improper choice of elastic constants is less than that due to the normal experimental errors. An example is given of an x-ray determination of Poisson's ratio in different crystallographic directions in a FS8742 steel.
Recording and Indicating Instruments for Temperature Measurements Down to 10°K Using Copper-Constantan Thermocouples
Authors: Larson E. Victor , Mayer Robert
Published: February 2005

This paper briefly discusses the modifications and additions to a standard instrument involved in the solution of the problems encountered in the indication and recording of temperatures as low as 10°K with CC thermocouples as the primary elements.
Synchrocyclotron for 450-Mev Protons
Authors: Anderson Herbert L. , Marshall John , Kornblith Lester , Schwarcz Leroy , Miller Richard
Published: February 2005

A 170-inch synchrocyclotron recently completed at the Institute for Nuclear Studies, The University of Chicago, is described. It is capable of accelerating protons to an energy of 450 Mev, deuterons to an energy of 256 Mev, and alpha-particles to an energy of 512 Mev. The magnet poles are especially contoured to give a field of 18,600 gauss in the center decreasing to 17,600 gauss at radius 76 inches. The radiofrequency is modulated by means of a rotating condenser in a three-quarter wave resonant line oscillator. A circulating beam of about one microampere of 450-Mev protons is normally obtained. This beam falling on an internal beryllium target produces about 4×1010 π-mesons per second. Some of these π-mesons emerge from the cyclotron, pass through channels in a heavy shield and are available in well-collimated beams, well-defined in energy. The present beams range in energy from 66 Mev to 230 Mev for π− mesons and from 66 to 145 Mev for π+ mesons. In the external 122-Mev π− beam there are 1000π− mesons per square centimeter per second available over an area of about 50 square centimeters at 20 feet from the target. The energy spread is about ±4 Mev.
A Large Capacity, All-Glass Dispersion Oxygenator and Pump
Authors: Clark Leland C. , Hooven Frederick , Gollan Frank
Published: February 2005

A large capacity all-Pyrex dispersion oxygenator and pump is described which is capable of substituting temporarily for the function of the heart and lungs. Blood is oxygenated by tiny bubbles of oxygen dispersed in the blood. These bubbles are coalesced on a polymethylsiloaxane surface and eliminated in a bubble trap which also serves as the pumping chamber. Pumping is accomplished by an alternating suction and pressure controlled by two electrodes, suspended in the chamber, which actuate two solenoid valves. The apparatus causes no significant damage to the red blood cells. The apparatus is portable, easily cleaned and sterilized, and inexpensive. Oxygenation, carbon dioxide elimination, temperature, pulsation rate and pressure, flow, and mean pressure can be controlled for various physiological studies. The blood volume of the apparatus is constant except for the stroke volume and in this respect resembles the normal heart.
A Wide-Band Electrometer Amplifier
Authors: Pelchowitch I. , van Zelst J. J. Zaalberg
Published: February 2005

It is shown that by appropriate feed-back methods it is possible to construct a wide-band electrometer amplifier with a stable flat-response characteristic. By analysis the signal-to-noise ratio has been found to be most favorable in the case where the mean frequency of the amplifier is low. Some practical values of the circuit are given.
Magnetron Harmonics at Millimeter Wavelengths
Authors: Klein J. A. , Loubser J. H. N. , Nethercot A. H. , Townes C. H.
Published: February 2005

Under certain operating conditions, magnetrons emit harmonics of their fundamental frequency of oscillation. With the use of the generating, filtering, and detecting equipment described here, harmonics as high as the tenth (1.25-mm wavelength) have been obtained from K-band tubes and the third (1.1 mm) from a 3.3-mm tube. The peak power at these shortest wavelengths is estimated as a few hundred microwatts, which is adequate for a variety of physical measurements. Data are given on the harmonic spectra of various tubes and tube types.
A New Method of Converting Platinum Resistance Values to Degrees Centigrade
Authors: Werner Frank D. , Frazer Alson C.
Published: February 2005

Values of temperature in degrees C are conveniently derived from values of resistance of a platinum resistance thermometer by means of a table of temperature vs resistance. Since each thermometer has its own fundamental constants, it becomes laborious to prepare separate tables for different thermometers. This labor may be avoided by the method outlined. The method is to interpolate from a single ``standard'' table, applying corrections which have been worked out in a reasonably compact form to use the constants of each particular thermometer. A standard table and its correction table are given and were calculated by a rapid method which is outlined. A graph is the most convenient form for the corrections to this standard table. The procedure for making these corrections is discussed. In addition a graphical means of conversion is discussed, which is accurate to 0.01°C and is very convenient and rapid where this accuracy is adequate.
Application of the W.B.K. Method to the Dynamics of Linear Accelerator
Authors: Hoyaux Max
Published: February 2005

The dynamics of ``small motions'' in a linear accelerator is studied in as general conditions as possible. It is concluded that heavy particles cannot be accelerated up to the Bev range by any practical combination of Tm and/or Te traveling and/or stationary waves. Several methods are however possible for electrons.

In the case of heavy particles, charges or currents must be introduced inside the beam. Two methods seem promising, (a) the Berkeley device (foils or grids) in which the beam expands as the power (1/8) of energy, and (b) a coaxial structure with dc bias (≃100 kv) in which the beam radius remains approximately constant.

The focusing by means of a dc current parallel to that of the beam is not practical.
Molecular Weight Determinations by Effusiometry
Authors: Zemany Paul D.
Published: February 2005

An effusiometer using a thermistor as a pressure gauge is described. Molecular weights can be determined with it with an average error of ±2 percent. Only a few hundredths of a cubic centimeter of gas at N.T.P. is required as a sample, and may be recovered.
A Proportional Counter for Neutron Flux Measurements in the Energy Range 0.1 to 1 Mev
Authors: Skyrme T. H. R. , Tunnicliffe P. R. , Ward A. G.
Published: February 2005

A proportional counter, filled with hydrogen or methane, has been developed for the measurement of monoenergetic neutron fluxes in the energy range 0.1 to 1.0 Mev. The pulse distributions obtained from the recoil protons are in good agreement with the calculated distributions allowing for end and wall effects over this energy range for appropriate fillings. Flux measurements can be made with certainty to better than 5 percent. Calculations of wall and end effects have been repeated using the latest range energy relation for protons.
A Semi-Automatic Graphical Computer with Use in Spectroscopy
Authors: Weissler G. L. , Einarsson A. W. , McClelland J. D.
Published: February 2005

A device is described which is capable of transforming semi-automatically a microphotometer density versus wavelength trace into an intensity trace. In the same manner, the logarithms or antilogarithms of a variable can be graphically computed. In addition, this machine can take the differences of two curves and plot the results either directly or logarithmically or antilogarithmically, or in a way appropriate to any specific problem. It is possible to evaluate, for instance, in successive steps all the quantities in Beer's law of absorption, I = I0 exp(—kx), as a function of wavelength. A detailed example is presented to illustrate its operation.
The Low Temperature Characteristics of Carbon-Composition Thermometers
Authors: Clement J. R. , Quinnell E. H.
Published: February 2005

The low temperature characteristics of some commercially manufactured carbon-composition thermometers are discussed. A semiempirical equation relating resistance and temperature and having three adjustable constants is given. Temperatures calculated by this equation are within ±0.5 percent of the measured temperatures from 2° to 20° Kelvin. Temperature values are reproducible within about ±0.1 percent from run to run, making possible the interpolation of temperatures from 4° to 10° Kelvin on the basis of calibrations in liquid helium and hydrogen only. Thermometric sensitivity is such that by measuring resistance to one part in 5000 it is possible to detect temperature changes smaller than 0.01° at 20° and smaller than 0.0001° at 2° Kelvin. The variation of resistance with measuring current can be interpreted as Joule heating of the resistor by the measuring current. Magnetic field sensitivity is small, the change in resistance with field being proportional to H2. Equations are given which permit an estimate of the resistance-temperature curve of a resistor on the basis of its room temperature resistance.