bluuebunny/crossref_metadata_2025 huggingface dataset:
The Properties of Some New Types of Counters
Authors: Curran S. C. , Reid J. M.
Published: February 2005

It is generally assumed that it is essential to use a cylinder of circular section as the cathode if a good counter of the point or wire type is to be made. Investigation of various geometrical forms of cathode with a wire as anode shows that counters may be made in a large variety of shapes and yet operate satisfactorily. Thus a large rectangular vessel with a wire placed symmetrically within the volume or mounted close to one wall has been found to operate as a self-quenched counter.

The use of such shapes is shown to result in improved performance in several important respects, e.g., reduced operating voltages, shorter dead-times. By the use of several wires in the same vessel, coincidence arrangements are made easily possible. This can be applied successfully to the construction of a counter which has a reduced natural counting rate but still presents a large solid angle to an external source. Various other applications are considered.
A New Radiation Meter
Authors: Kalmus Henry P. , Striker George O.
Published: February 2005

Present industrial methods of photoelectric measurement are incapable of approaching the theoretical sensitivity limit set by thermal agitation noise because of various practical limitations restricting the maximum useful gain. A new method is described for converting the d.c. space currents in photo-tubes into a.c. voltages capable of amplification to the point where only fluctuation noise limits the accuracy. This conversion consists in the magnetic deflection or suppression of space currents with the use of an alternating magnetic modulating field applied transversely across the path of photoelectrons. A practical circuit is described with which photo-currents were measured close to the threshhold of agitation noise without use of other than commercial radio components. The new method affords complete separation of the actual photo-currents from all leakage currents in the input circuit without the use of a.c. light sources or light-chopping mechanisms.
High Vacuum Valve and Seal
Authors: King L. D. P.
Published: February 2005

A simple two-way valve and a method of making a seal are described, both well adapted to large or small port openings in high vacuum work. The valve gate consists of two rigid flat surfaces on which are mounted the gaskets. The plates are normally drawn together but can be pushed in front of the ports and forced apart by the action of a cam fixed to rod. A round rubber gasket held in a special groove of one surface pushed against another flat surface produces an excellent vacuum seal. The metal-to-metal seat prevents injury to the rubber from excessive pressure or the exposure of the rubber to the vacuum system.
A Rapid Method for Preparing Powder Camera Specimens with Cellulose Acetate Capillary Tubes
Authors: Beu Karl E. , Claassen Howard H.
Published: February 2005

Several details are described in the preparation of capillary tubes for x-ray power specimens which greatly facilitate the synthesis of such tubes and their subsequent removal from the pilot wire. The over-all method employed is essentially that of Fricke et al. Wires of 22-gauge copper, after annealing in an atmosphere of helium, are cleaned and dipped into the cellulose acetate solution by means of a crank-driven rack. The rate of withdrawal determines the wall thickness. A method is given for centering the filled specimen tubes precisely in the powder camera by the use of a centering jig.
An Electronic Eyepiece for Spectroscopy of Near Infra-Red
Authors: Harvalik Zaboj V.
Published: February 2005

An electronic eyepiece for the observation of near infra-red of the spectrum is described. It can be attached to any spectroscope and consists of an image tube of the type 1-P-25 which converts an infra-red image into a visible one. The spectrum is projected by the telescope system of the spectroscope upon the mosaic face of the image tube. The infra-red radiation releases photoelectrons from the mosaic face of the image tube which are focused electron-optically upon a fluorescent screen. The image appearing on the fluorescent screen can be observed directly or magnified optically. The visible range of a spectroscope equipped with an electronic eyepiece extends the visible range to approximately 1150 mμ into the infra-red and to 300 mμ into the ultraviolet.
The Rate of Evaporation of Liquid Hydrogen Due to the Ortho-Para Hydrogen Conversion
Authors: Larsen A. H. , Simon F. E. , Swenson C. A.
Published: February 2005

The evaporation of liquid hydrogen caused by the heat of reaction of the ortho-para conversion has been measured as a function of the o-hydrogen concentration. The results are discussed, and a set of curves is given which describes all cases of practical interest. Methods of minimizing the rather serious evaporation of liquid hydrogen as the result of this effect are suggested.
Construction and Performance of a Low Voltage Arc as a Source of Positive Ions
Authors: Allison Samuel K.
Published: February 2005

A low voltage arc of the ``capillary'' type which has given reliable performance since its installation in 1940 is described. The design stresses simplicity and reliability, but no special attempt is made to attain very low consumption of gas. Operating at an arc current of 0.75 ampere and consuming 25 cc of deuterium at N.T.P. per hour, a total beam current of 1.1 milliampere is produced with a probe potential of 3500 volts. About 50 microamperes of deuterons, magnetically selected from this beam, can be focused on a target.
Self-Quenching Halogen-Filled Counters
Authors: Liebson S. H. , Friedman H.
Published: February 2005

Counters filled with small percentages of the halogens mixed with the inert gases produced self-quenching counters. The lifetimes of these counters in terms of total counts are apparently unlimited. Several mixtures exhibited thresholds below 250 volts at total pressures ordinarily used in counters. Pulse size, efficiency, and quenching characteristics are similar to those obtained with argon-alcohol Geiger-Mueller counters filled with a ten percent mixture to total pressures in excess of 10 cm Hg. The percentages of halogens required to make good counters were about the same as the optimum concentrations reported* for quenching metastable states in the rare gases.
The Mach Interferometer Applied to Studying an Axially Symmetric Supersonic Air Jet
Authors: Winckler John
Published: February 2005

The Mach interferometer has been used to study a supersonic air jet, and the method of adjustment, measurement, and evaluation of interferograms, calculation of densities, and typical results are given. A satisfactory light source embodying speed, monochromacy, and brilliance has been found. The resolution, accuracy, and sensitivity are discussed, and photographs illustrating many features of the instrument are presented. The method of analysis is not limited to air jets but is generally applicable to all axially symmetric air streams.
A Strain-Sensitive Resistance Wire Manometer
Authors: Keenan A. G. , McIntosh R. L.
Published: February 2005

A manometer employing a metal bellows and strain-sensitive resistance wire is described. By varying the diameter of the bellows and of the wire, gauges with sensitivities from 0.003 mm Hg, in the range 0–12 mm, to 0.8 mm Hg, in the range 0–200 mm, were obtained. The gauges showed hysteresis and points on their calibration curves were reproducible only to ±0.04 mm and ±0.7 mm, respectively. Experiments in which the wire alone was loaded showed that a large part of these effects was due to the particular wire used.
A Pick-Up for the Measurement of Quasi-Static Angular Acceleration
Authors: Statham L.
Published: February 2005

Design parameters for an angular accelerometer are developed. The accelerometer incorporates an electrical sensing element which may be energized by dry cell batteries and whose output may be connected directly to a recording galvanometer.
Coincidence-Counting System of High Resolution
Authors: Schultz H. L. , Beringer Robert
Published: February 2005

A coincidence counting apparatus of high resolution is described. It employs proportional counters whose amplified pulses trigger blocking-oscillators to give artificial pulses which are used in the coincidence discriminator. A continuously variable time delay is provided in one of the amplifier channels for determining the resolving time and for studying delayed coincidences. Under favorable conditions the passage of an ionizing particle through a counter can be determined to within an uncertainty of about 10−8 sec.
Impulse Determinations of Rockets by Means of Rotating Systems
Authors: Penner S. S. , Whiteman R. C.
Published: February 2005

Two simple rotating systems have been designed for the determination of the specific impulse of rocket propellants. The pin wheel consists of a bicycle wheel mounted horizontally in a steel frame. A small rocket motor containing the propellant which is to be tested is mounted on the wheel so that the thrust delivered by the rocket accelerates the speed of rotation of the wheel. A photographic record of the rotational speed is then used to calculate the impulse delivered as a function of the time. The rotating bar is operated in a manner similar to that of the pin wheel.

The rotating systems have been used for the determination of relative effective gas velocities of a number of double-base rocket powders. Impulse measurements of miniature rockets of the order of 1 pound-second were made. An investigation of the effect of expansion ratio of rocket nozzles on the reduced specific impulse showed good agreement with theoretical calculations.
A Precision High Voltage Vacuum-Tube Voltmeter
Authors: Yuan Luke C. L.
Published: February 2005

A vacuum-tube voltmeter circuit is described which is capable of measuring voltages within the range of from 0 to −5000 volts with an accuracy of 0.05 percent and a linear characteristic over the entire range. The input impedance is greater than 5×1010 ohms. The circuit was developed for the purpose of measuring accurately high voltage sources of extremely low current drain which were employed for cosmic-ray studies. It is based on a null method, using a vacuum tube having a high amplification factor as one arm of a balanced circuit and a constant current source as the other arm. The negative terminal of the measured voltage is applied to the plate of the tube, and the grid voltage is varied to maintain the same grid current which balances the current from the constant current source. Linearity results from the negligible varying space-charge effect at constant grid current, and high precision measurements are obtained by means of a special circuit for measuring the change in grid voltage. By setting the grid current equal to the value of 1/μ, where μ is the amplification factor of the tube, the meter can be made to read directly the measured voltage.
Electromagnetic Deflector for the Beam of the 184-Inch Cyclotron
Authors: Powell W. M. , Henrich L. R. , Kerns Q. A. , Sewell D. C. , Thornton R. L.
Published: February 2005

The removal of the ion beam of 190-Mev deuterons from the magnetic field of the 184-inch cyclotron is complicated by the fact that at large radii the ion increases its radius very little in one revolution. The usual type of deflector did not appear to be usable. Consequently, a pulsed electric deflector was designed that would give an additional radial oscillation to the ions which could be as much as seven centimeters. This permits deflection of the ions outward to a magnetic deflector which is outside the range of the circulating ions. The field is sufficiently reduced inside the magnetic deflector to permit the ions to leave the magnetic field of the 184-inch cyclotron. Approximately ½ percent of the circulating beam appears in the external beam.
A Field Instrument for Measuring Volume and Instantaneous Flow Rate of Inspired Air
Authors: Silverman Leslie , Plotkin Theodore , Lee George
Published: February 2005

The object of this study was the development of a portable self-contained instrument which would record the rates of inspiratory air flow through protective canisters under actual field conditions. This instrument was developed so that observations made in the laboratory could be checked under actual field conditions. Measurements of air flow on subjects in tanks or parachute troops or men moving in industrial operations cannot be obtained without a portable instrument.

The essential requirements of this instrument are that it obtain records of air flow, air volume, and respiration rate while worn by or held closely to the individual under observation. The apparatus should be rugged and independent of positional effects or a reasonable amount of rough handling. Its operation should be automatic and not require attention by the subject.
Circuit for Testing Efficiency of Geiger Counters
Authors: Hagen G. E. , Loughridge D. H.
Published: February 2005

Design and operating characteristics of an electronic device for measuring over-all efficiencies of Geiger counters are provided. The device will rapidly, and without any standard tube, yield these data as well as provide a means of checking the relative sensitivity of various sections of a counter tube.
Design Study for a Ten-Bev Magnetic Accelerator
Authors: Brobeck W. M.
Published: February 2005

A ten-billion volt proton synchrotron design using injection from Van de Graaff generators and betatron starting to reduce the required oscillator frequency range is described. Factors affecting the design of the iron core magnet, its power supply, and associated apparatus are discussed. Cost is roughly estimated as fifteen- to twenty-million dollars.

The exposition [E. M. McMillan, ``The synchrotron—a proposed high energy particle accelerator,'' Phys. Rev. 68, 143 (1945); V. Veksler, ``Concerning some new methods of acceleration of relativistic particles,'' Phys. Rev. 69, 244 (1946)] and successful test [J. R. Richardson, K. R. MacKenzie, E. J. Lofgren, and B. T. Wright, ``Frequency-modulated cyclotron,'' Phys. Rev. 69, 669 (1946)] of the synchrotron principle of magnetic particle acceleration has removed one of the limits to the energy obtainable with magnetic accelerators. Radiation loss [E. M. McMillan, ``Radiation from a group of electrons moving in a circular orbit,'' Phys. Rev. 68, 144 (1945)] varying inversely as the rest energy of the particle, is negligible for protons even at ten-billion electron volts. The maximum obtainable energy therefore appears to be limited only by engineering feasibility and available funds. In order to gain some information on these factors a preliminary design of a proton accelerator has been worked out for what is believed to be the largest machine that could be made in the near future without departing from the techniques used on machines at present in operation. Ten-billion electron volts, which is in the range of energy of some primary cosmic-ray particles and the requirements for proton pair formation, appears to be attainable within the above restriction.
An Optical Bench for Electron Optical Studies
Authors: Reisner John H. , Picard Robert G.
Published: February 2005

An evacuated chamber containing a heavy lathe bed for supporting and aligning optical parts, and means for moving the essential internal components from the exterior, is described. The construction is explained in detail. Stabilized high voltage to thirty kilovolts and stabilized low voltage supplies for energizing electromagnetic lens coils are provided. The equipment may be used to illustrate the operation of such electronic equipment as cathode-ray tubes, electron microscope and diffraction apparatus, or to study the properties of phosphors and optical components such as lenses, guns, and deflection electrodes.
An Electronic Intensity Regulator for a Hydrogen Discharge Tube
Authors: Pondrom W. L. , Robertson W. W.
Published: February 2005

An electronic intensity regulator has been developed which exercises direct control upon the intensity of the source of continuous radiation used in absorption spectrophotometry and which provides regulation at any desired intensity within the limits of the source. The Hanovia hydrogen discharge tube when used with this regulator gives an intensity that changes by less than 0.1 percent for changes of ±10 percent in the line voltage and/or ±2 percent in frequency.
Coincidence Device of 10−8−10−9 Second Resolving Power
Authors: Bay Z. , Papp G.
Published: February 2005

A coincidence device for use in nuclear experimentation is described. The radiation detectors are secondary electron multiplier tubes of high resolving power and these are connected to a variation of the Rossi-type coincidence circuit. The resolving time for coincidence appears to be of the order of 10−8 to 10−9 sec.
The Determination of the Pulse Period of Electron Multiplier Tubes
Authors: Papp G.
Published: February 2005

The pulse period of secondary electron multiplier tubes has been determined by two independent methods. The first method consisted of feeding the pulses on capacitors with variable R.C. and observing the oscilloscope screen. The second method consisted of creating artificial coincidences. Both of these methods give a pulse period of T<5×10−9 sec.
A Sensitive Mercury Manometer
Authors: Puddington I. E.
Published: February 2005

A mercury manometer, of the U tube type, in which the volume of mercury which flows between the arms when a pressure is applied can be measured precisely, is described. The arms of the U tube are made in the form of large diameter, shallow cylinders to give a large flow of mercury for a relatively small pressure change. The flow is measured by determining changes in the volume of mercury in one arm of the manometer. This is done by isolating that arm through the closure of a stopcock contained in the small bore tubing which connects the two arms, and adjusting the level of the mercury to an etch in a capillary; the volume change is then read directly from the position of the end of the mercury thread in a second capillary. The magnification of a pressure change is one-half the ratio of the cross-sectional areas of the U tube cylinder and the capillary on which the volume change is noted. Magnifications as high as 4000 have been obtained with this device.
A Microwave Secondary Frequency Standard
Authors: Unterberger Robert R. , Smith William V.
Published: February 2005

A method of obtaining accurate frequency markers every 90 megacycles from 2970 megacycles to above 40,000 megacycles is described. Interpolation between markers is possible by means of a calibrated standard communications receiver. The basic frequency of 10 megacycles is continuously checked against the primary frequency standard broadcast by WWV. This equipment may be used for measuring the frequencies of spectra observed in microwave spectroscopy or for accurately calibrating microwave wavemeters. A table of absorption lines providing reference frequencies between 23,000 and 40,000 megacycles is given.
Technique for Observing Nuclear Disintegrations and Scattering in Small Gas Volumes
Authors: Taschek R. F.
Published: February 2005

A scattering chamber of small gas volume is described and its uses as a neutron source pointed out. Data is shown for the deuteron-deuteron interaction.
Focusing Field for a 180° Type Spectrograph
Authors: Beiduk F. M. , Konopinski E. J.
Published: February 2005

A magnetic field is derived for a 180° type of spectrograph so as to meet two requirements: it is to vary only with the distance from the central axis; it must focus perfectly the electrons emerging from a point source and confined in the median plane. The transmission and resolution of an instrument using such a field is then investigated.
Orbital Stability in a Proton Synchrotron
Authors: Twiss R. Q. , Frank N. H.
Published: February 2005

The theory of the electron synchrotron has been amply covered elsewhere, but the proton synchrotron exhibits a number of distinct but important differences particularly at low energies. In the present paper the theory for this latter accelerator is developed with particular reference to the problems of injection and stability in the initial acceleration period. This theory is used to set up criteria relating the dimensions of a proton synchrotron to the conditions for stability and to the beam intensities obtainable.
A Self-Contained Recording Pressure Gauge
Authors: Brown David R. , Galloway William C. , Robertson Jack B. , Silvey Gene A.
Published: February 2005

This instrument is a self-contained time versus pressure recording device capable of measuring pressures up to 1200 pounds per square inch at frequencies from 0 to 200 cycles per second over a period of five seconds. The instrument is set in operation by the arrival of a pressure wave above a predetermined threshold, triggering a locking mechanism and permitting compressed springs to drive the record surface past an engraving stylus actuated by a pressure-sensitive diaphragm.
Improved Magnetic Focusing of Charged Particles
Authors: Kerwin Larkin
Published: February 2005

A general theory of geometric magnetic focusing of charged particles is developed. Some special cases are discussed. One proves to be the type of focusing in general use; another, equally simple, eliminates second-order aberrations.
A Geiger-Mueller Counting Unit and External Quenching Equipment for the Estimation of C14 in Carbon Dioxide
Authors: Mann W. B. , Parkinson G. B.
Published: February 2005

A counter unit and external quenching circuit for use with carbon dioxide and carbon disulfide mixtures are described. The counter unit consists of a long and short counter to eliminate end effects. The quenching circuit, which depends on the action of a multivibrator, enables the voltage across the Geiger-Mueller counter to be reduced in a controllable manner by any desired amount and for any desired time.
Circuits for Minimizing Transient Effects on Energy Measurements in Calorimetry
Authors: Hoge Harold J.
Published: February 2005

Transient effects on electrical energy measurements in calorimetry will be minimized if P, the power developed in the heater, satisfies the condition dP/dR=0, where R is the resistance in which the power is developed. It is shown that this condition is satisfied if the resistance U between the two points of the supply network to which R is connected is kept equal to R. Circuits for maintaining this condition are described.
Optical Properties of Surface Films. II
Authors: Rothen Alexandre , Hanson Marjorie
Published: February 2005

Measurements of ellipticity of light reflected from a film-coated metal surface have been made for films varying in thickness from 25 to 40,000A. It was found that the approximate formulas of Drude which express as a function of the film thickness the ratio and phase difference of the components vibrating in the plane of incidence and perpendicular to it are valid for thin films. The general formula of Drude expressing the phase shift as a function of the film thickness represents with a fair approximation the experimental results obtained with metallic slides coated with films of Ba stearate whose thickness is up to the order of the wave-length of light. Thus, for the first time, Drude's theoretical formulation has been verified experimentally. For films whose thickness is many times the wave-length of the light used, there is a progressive divergence from Drude's general formula, the cause of which can possibly be due to the birefringence of the films which has been neglected in this work.
An X-Ray Camera for Obtaining Powder Pictures at High Pressures
Authors: Lawson A. W. , Riley N. A.
Published: February 2005

Two methods are described of obtaining x-ray powder diffraction pictures of materials subjected to high hydrostatic pressures. Both techniques have been successfully employed to identify simple high pressure structures at pressures ranging up to 15,000 atmos. The essential feature common to both schemes is to encase the sample in a small beryllium bomb which serves to retain the pressure but permits the x-rays to be transmitted to the sample and diffracted to an external recording film. Sample data on cerium are given to illustrate the possibilities and limitations of this technique.
Instrumental Distortions in the Shapes of Continuous Beta-Spectra
Authors: Owen George E. , Cook C. Sharp
Published: February 2005

The positron spectrum of Cu61 and the negatron spectrum of P32 have been studied in a 5.7-cm radius of curvature magnetic spectrometer using a variety of vacuum chamber sizes and baffle designs. Conclusions are drawn from these data concerning the distortions in continuous beta-spectra caused by scattering from the finite geometry of the chamber.
A Flexible High Voltage Square Wave Generator
Authors: Hedrick Langdon C.
Published: February 2005

Presented here is the design of a high voltage square wave generator suitable for modulating the absorption cell of a microwave spectrograph. Peak to peak voltages up to 1800 have been produced at 100 kc, feeding into an 800μμf capacitive load. The lower half of the cycle is kept automatically at ground potential and the adjustment of voltage from 0 to 1800 is controlled by a single variable.
A Fractional Microsecond X-Ray Pulse Generator for Studying High Explosive Phenomena
Authors: Breidenbach H. I.
Published: February 2005

An x-ray pulse generator capable of producing short bursts of x-rays not greater than 3×10−7 seconds in duration has been constructed. These short bursts are obtained by supplying a negative 50 kv, 12.5 Joule trigger pulse to the cathode shield of a standard Westinghouse W.L. 389 flash x-ray tube. This pulse generates a pre-discharge plasma in the tube which blocks the main 100 kv, 290 Joule pulse until the cathode to anode gap impedance is lowered by ionization.

An arrangement is also described whereby 3 separate, successive radiographs of a single detonation may be taken at predetermined time intervals.
An Air Ionization Chamber for Soft X-Rays
Authors: Seemann Herman E.
Published: February 2005

An ionization chamber is described which is nearly air-equivalent from 0.5 to 2.5A, ``effective wave-length.'' It has been made adaptable for use with the electrometer and charging system of the Victoreen Minometer. Its sensitivity is of the order of 0.15 roentgen per scale division. Suggestions are made for possible improvements.
Design Curves for 180° Magnetic Spectrometers
Authors: Owen George E.
Published: February 2005

The image shapes resulting from 180° focusing of charged particles in a homogeneous magnetic field have been computed. General curves are presented in terms of three variables for variable ρ-spectrometers (as in the case of photographic detection) and in terms of four variables for constant ρ-spectrometers (as in the case of detection with a fixed counter). The variables are source and exit-slit height, source width, angular selection, and exit-slit width.

The advantages of using sources and exit-slits with a large dimension parallel to the magnetic field (i.e., height) are noted.
Apparatus for Isotope Separation by Thermal Diffusion
Authors: Watson W. W. , Onsager L. , Zucker A.
Published: February 2005

A compact, all-metal, multi-stage thermal diffusion apparatus for the separation of isotopes in quantity in non-corrosive gases at any pressure up to 175 lb/in.2 is described. For a particular gas the proper pressure may be well-enough calculated in advance as that giving maximum separation factor in the last column only. Operating with neon at 3 atmos. pressure, and using 12 meters of column consuming 4.9 kw for 260 hours, 7 liters of gas with a Ne22 content of 93.4 percent were produced.
A Secondary-Emission Electron Multiplier Tube for the Detection of High Energy Particles
Authors: Stone Robert P.
Published: February 2005

The requirements of high gain and low background current in an electron-multiplier tube for the direct detection of high energy particles are considered. The design and construction of an experimental electron-multiplier tube with a stable over-all gain of at least 108 and a background at room temperature corresponding to three or four electrons per minute released at the input is described. An 0.0008-inch thick nickel window is provided in the tube envelope to admit the high energy particles to the multiplier. The efficiency of this device is compared quantitatively with that of a Geiger tube as a detector of beta-particles. It is found that the over-all beta-particle counting efficiency of the tube is of the order of 1.3 percent, and that the efficiency of the oxidized silver magnesium target surface is 4.9 percent for a uranium source and 6.0 percent for a strontium source.
A Sensitive Magnetometer for Very Small Areas
Authors: Chapin Daryl M.
Published: February 2005

A vibrating wire system for measuring weak magnetic fields is described for use in very small spaces. Quartz crystals are used for drivers to get sufficient velocity with very small displacements. To adjust the driving voltage to correspond exactly to the natural crystal frequency, the crystal is also used to regulate the oscillator.
Growing and Processing of Single Crystals of Magnetic Metals
Authors: Walker J. G. , Williams H. J. , Bozorth R. M.
Published: February 2005

Single crystals of nickel, cobalt, and various alloys are grown by slow cooling of the melt. They are oriented by optical means and by x-rays, and ground to the desired shape using the technique described.
An Electromagnetic Blood Flow Meter
Authors: Clark John W. , Randall James E.
Published: February 2005

This report describes the design of an instrument for electrically measuring the rate of flow of blood passing through a glass cannula which has been inserted within a vessel of an anesthetized animal.
An Apparatus for the Production of Large Metallic Crystals by Solidification at High Temperatures
Authors: Gold Louis
Published: February 2005

The design and operational aspects of an apparatus suitable for large-scale production of metallic crystals is described and the various high temperature difficulties indicated.
A Large Helium Liquefier
Authors: Daunt J. G. , Johnston H. L.
Published: February 2005

A large helium liquefier is described which produces 7.5 liters of liquid helium per hour through a Joule-Thomson expansion valve when operated from a compressor giving 21 cu ft./min. flow at a pressure head of 320 lb./sq. in. The liquid helium can readily be transferred into exterior cryostats. The consumption of liquid hydrogen, used to pre-cool the helium gas, during the process of liquefaction is 1.3 liters of hydrogen per liter helium. The liquefier fits into a container 6′ long by 8″ in diameter.
New Techniques Applied to the Buerger Precession Camera for X-Ray Diffraction Studies
Authors: Evans Howard T. , Tilden S. G. , Adams Douglas P.
Published: February 2005

The usefulness of the Buerger precession method for single crystal x-ray diffraction studies is increased by the following techniques: (1) The use of a nomogram to facilitate the setting and operation of the instrument; (2) the simplification of orientation and lattice measurement techniques; and (3) the application of the Dawton photographic method to precession photographs for obtaining quantitative intensity data, together with a graphical method for determining Lorentz and polarization corrections.
Tissue Stimulators Utilizing Radiofrequency Coupling
Authors: Schmitt Otto H. , Dubbert Donald R.
Published: February 2005

Voltages of arbitrary wave forms, such as those employed for stimulating biological tissues, are normally obtained from ``grounded'' signal generators. Isolation of such signals from ground can be accomplished by utilizing radiofrequency transmission of energy. The signal generator voltage serves as the source of plate power for a midget radiofrequency oscillator which converts the signal to amplitude-modulated carrier energy. This radiofrequency energy is then transmitted across a small air gap to a receiving circuit where it is demodulated and filtered. The voltage thus recovered is a faithful reproduction of the original signal but is isolated from the input circuit as well as from ground. One model of this radiofrequency link which was developed for nerve stimulation and which has performed well in the laboratory is described in detail.
The Scintillation Counter as a Proportional Device
Authors: Hoyt Rosalie C.
Published: February 2005

The statistical distribution of fluctuations in the gain of a 1P21 photo-multiplier tube has been investigated and standard deviations of 36 percent to 48 percent have been found. The distribution in photo-multiplier output pulse heights obtained with Po alphas incident on a ZnS screen has also been investigated and standard deviations of 27 percent to 80 percent found. The importance of the contribution from the fluctuations in gain is shown to be small in this case.
A Magnetic Ion Source
Authors: Bailey Carl , Drukey D. L. , Oppenheimer F.
Published: February 2005

An ion source for particle accelerators is described. The ion source utilizes an axial magnetic field for collimation of ion and electron beams and provides an electric field-free region for ion formation. The ion source has afforded yields of 500 microamperes of resolved protons when used in conjunction with a 200-kv high voltage set. A feature of the ion source is the possibility of obtaining favorable atomic to molecular ion ratios.
A Theory of the Solenoid Beta-Ray Spectrometer
Authors: Persico E.
Published: February 2005

A theory of the magnetic lens beta-ray spectrometer utilizing the uniform field of a long solenoid is developed. First the case of a point source is considered, and it is found that the resolving power, for a given solid angle, is maximum when the emission angle α (average angle between the rays leaving the source and the axis) is 45° 37′. Then the theory is extended to the case of a disk source, and it is found that for a given intensity (product of the source area by the solid angle) there is an optimum source diameter and an optimum emission angle, ranging in practical cases between 36° and 40°. The problem of optimum conditions when the quantity of copper in the solenoid and the electric power available are limited by economical considerations is also studied, and it is found that the optimum α-value is in this case about 21°.
The Maxwell Bridge at Low Frequencies
Authors: Brown Vinton A. , Ramsay B. P.
Published: February 2005

The Maxwell bridge has been found useful for measuring inductance L and a.c. resistance Rac at periods from 0.01 sec. to 200 sec. In some applications, the inductors had solid ferromagnetic cores and inductances of several hundred henries. The effect upon the bridge circuit of induced currents in the ferromagnetic material is expressed as a first approximation in terms of the equivalent mutual inductance M. The resulting equations expressing the frequency dependence of L and Rac are in qualitative agreement with experiment. Because of harmonic frequencies generated by magnetic hysteresis, the bridge cannot be completely balanced when measuring L and Rac of ferromagnetic-cored inductors. Analysis of the precision of measurement indicates that the effect of the residual voltage at best balance is a reduction in bridge sensitivity. Factors determining the choice of bridge resistors and of balance indicator are discussed, and typical graphs of L and Rac as functions of frequency are presented.
Further Improvements in Magnetic Focusing
Authors: Kerwin Larkin , Geoffrion Claude
Published: February 2005

The general theory of magnetic focusing in a plane developed in a previous paper is extended to asymmetric cases. The general asymmetric case being developed, several particular examples are considered, including one which eliminates second-order aberrations, and requires a smaller magnet than the normal design. Methods of minimizing aberrations are discussed.
A Cloud Chamber of Light Weight for Balloon Flights
Authors: Shutt R. P. , Johnson A. L. , Thorndike A. M.
Published: February 2005

Some constructional details of cloud chambers used for balloon flights are described. Details are given on the fabrication of transparent plastic front walls and cylinders for the cloud chambers. A relatively large number of bicycle spokes is used for holding the chamber together, thus distributing material stresses, enabling one to make the aluminum parts of the cloud chamber quite light.

The back and front walls of the cloud chambers are somewhat spherically curved, resulting in considerable reduction of material thicknesses. By the same means a piece of slightly curved metal gauze is sufficient to limit the motion of the rubber diaphragm in the compressed position.

A mechanism used for adjusting expansion ratios can be removed before a balloon flight. Gas and liquid can be inserted through bicycle valves.

The cloud chambers are 12 inches in diameter, 3½ inches deep, and weigh approximately 6 pounds.
A Magnetic Field Strength Meter Using the Proton Magnetic Moment
Authors: Hopkins N. J.
Published: February 2005

A simple, portable instrument is described which employs the nuclear absorption method and the known value of the proton magnetic moment to determine magnetic field strength. No known fields and no geometrical calculations are required for calibration. The range covered by the present instrument is approximately 3000 to 19,000 gauss. No upper limit is inherent in the method. Homogeneity is required over a small cylindrical volume. Absolute accuracy of better than ±0.2 percent is obtainable, depending only on precise measurement of frequency. Higher accuracy is possible in comparing fields and in measuring field changes.
A 22-Inch Wilson Cloud Chamber in a Magnetic Field of 21,700 Gauss
Authors: Powell Wilson M.
Published: February 2005

A Wilson cloud chamber 22 inches in diameter in a magnet producing a magnetic field of 21,700 gauss at the center of the chamber is described. The magnet is pulsed in synchronism with the 184-inch Berkeley cyclotron and can be operated with a steady field of 10,000 gauss. The use of the instrument for identifying light atoms is discussed briefly.
A Counter Controllable High Pressure Cloud Chamber
Authors: Valley G. E. , Vitale J. A.
Published: February 2005

A high pressure cloud chamber is described which is so designed as to be as easily counter controlled as an ordinary cloud chamber. The instrument is fitted with a magnet capable of producing a field of approximately 10,000 gauss continuously. It is mounted in a trailer and can be readily transported to mountain sites.
Differential Counting with Reversible Decade Counting Circuits
Authors: Martens Frederick H.
Published: February 2005

Three circuits were designed and built to apply a reversible decade counting circuit to the direct measurement of the difference in the counting rate from two counter tube telescopes used in cosmic-ray research. The circuits are equally applicable to the direct measurement of the difference in the strength of two radioactive samples. An input circuit prevents two pulses from the Geiger tubes from arriving simultaneously at the first ring-of-ten. A driving circuit switches and shapes the pulses for correct bi-directional operation of the ring-of-ten. A coupling circuit permits two decade rings to be operated in cascade, giving a differential electronic scale of 100.
The Measurement of the Series-Resonant Resistance of a Quartz Crystal
Authors: Rosenthal L. A. , Peterson T. A.
Published: February 2005

Three instruments are described which will measure the equivalent resistance of commercial quartz crystals in the range of 80 kilocycles to 100 megacycles. Information on the theory and operation of these instruments is given. Some data are shown indicating the results to be expected.
A New High Sensitivity Remanent Magnetometer
Authors: Johnson Ellis A. , Murphy Thomas , Michelsen P. F.
Published: February 2005

The remanent magnetometer, sturdily constructed for use in a mobile field laboratory, is capable of measuring magnetic moments of rocks as small as 2×10−8 c.g.s. unit per cc. A sample of rock of 25- to 50-cc volume is rotated over a pick-up coil at 10 cycles per second, and the induced alternating voltage, after amplification, is measured in both intensity and phase, and the direction and intensity of magnetization determined. The apparatus is calibrated with a needle-magnet of known magnetic moment. It has been used successfully in measurements of polarization of the glacial clays of New England and sedimentary rocks of the western states.
Effect of Temperature on the Steady-State Sensitivity of Vacuum Radiation Detectors
Authors: Amdur I. , Brown N. L.
Published: February 2005

The steady-state sensitivities of two vacuum radiation thermocouples of very different design and a vacuum compensated bolometer have been measured at 298°, 205°, and 96°K, and the effect of temperature has been found to vary widely for the three detectors. The observed results have been accounted for quantitatively in terms of theoretical sensitivity relations which are based on exact heat flow theory and take into account the specific structural characteristics of the detectors. The treatment is sufficiently general to permit the prediction of steady-state sensitivities as a function of temperature for any vacuum radiation thermocouple or bolometer whose structural characteristics are known.
A Direct Reading Pulse Length Meter and Shape Analyzer
Authors: Rudin Robert
Published: February 2005

An electronic circuit is described which allows determination of the length and shape of a voltage or current pulse in the microsecond range, by measuring the pulse duration at different levels of the pulse and reading these figures directly on a meter. Comparison with other measuring methods shows good agreement of the results.
Measurement of the Spin of a Projectile in Flight
Authors: Warshaw H. D.
Published: February 2005

Projectile spin is measured by recording the voltage generated in a pick-up coil as the rotating field of a transversely magnetized projectile passes the coil.

A permanent magnet within a brass sleeve (for magnetic insulation) is inserted in a projectile of mild steel. Rotation of the projectile as it passes the pick-up coil generates a sinusoidal e.m.f. which is displayed on the screen of a cathode-ray tube and photographed for subsequent analysis.
Stress-Strain-Time Apparatus for Fiber Testing
Authors: Reichardt C. H. , Schaevitz H. , Dillon J. H.
Published: February 2005

A stress-strain apparatus for testing individual fibers is described. The apparatus employs a ring dynamometer in conjunction with a linear variable differential transformer. A constant rate of elongation apparatus is fully described and a schematic diagram of a constant rate of loading apparatus is discussed. The use of linear variable differential transformers allows simple a.c. amplifiers to be employed and thus removes many of the difficulties involved in d.c. bridge circuits. Load ranges from 50 grams to 1 gram per ten chart inches can be obtained with a sensitivity of several milligrams. By changing the size of the ring dynamometer employed, an apparatus giving the greater load ranges necessary to test yarns can be constructed.
A Cardiotachometer Based on the Plethysmogram
Authors: Suckling E. E.
Published: February 2005

An instrument is described which enables the pulse rate in humans to be continuously observed. The pulsations generated in a partially inflated blood pressure measuring cuff are converted into electrical pulses and applied to a counting rate circuit.
A High Current Ion Source
Authors: Setlow Richard B.
Published: February 2005

An ion source is described which utilizes a hot cathode as an electron source and an axial magnetic field for focusing. The electron beam is pulsed for 250 μsec. 60 times a second. Peak ion currents of 100 ma are readily obtainable. At a hydrogen pressure of 25 microns of Hg the proton content of the beam is between 30 and 40 percent. Constructional details and operating conditions are given.
Microsampling and Microanalysis of Metals
Authors: Clifton Donald F. , Smith Cyril Stanley
Published: February 2005

In studies of composition gradients in diffusion samples, or for identifying inclusions, it is often desired to obtain analytical samples from minute and exactly located positions in experimental material. This paper deals with the design and use of a microshaper using a diamond tool to take linear cuts separated by as little as 0.02 mm. A hand-driven drill can be used for sampling circular areas of diameter greater than 0.1 mm. The chips, which may weigh as little as 0.1 microgram, are picked up on an electrified quartz fiber and centrifuged into a capillary which is evacuated and sealed for annealing. A precision x-ray diffraction photograph is then obtained from the annealed chip, and the calculated lattice parameter used as an index of composition. Two examples of the use of the technique are given.
Frequency Analyzer for Bioelectric Potentials in the Sub-Audio Range
Authors: Markey Charles , Schoenfeld Robert L. , Hoefer Paul F. A.
Published: February 2005

An analyzer for sub-audio bioelectric potentials, particularly the human electroencephalogram, is described. The instrument is coupled to the output of a standard EEG amplifier and records twenty frequencies by means of individual filters each coupled to a two-inch cathode-ray oscilloscope. A 35-mm slow moving camera provides a time base while simultaneously photographing, the filter deflections, a cathode-ray trace of the unanalyzed slow wave and one-second time markers produced by a clock driven flashing light. The system employs amplitude modulation of a 1200 cycle carrier; the filters being selective to the lower sideband frequencies which are recorded as horizontal deflections of the oscilloscopes.

The present analyzer, in contrast to others, has a one-half-second time constant and is thus a low ``Q'' system responsive to activity of short duration. The frequency spectrum obtained is necessarily broad but detailed in the time domain, an aspect of physiological importance, hitherto neglected.
The Detection of Ca45, I131, P32, and Zn65 by Photographic Film
Authors: Steinberg Daniel , Solomon A. K.
Published: February 2005

The density response of photographic emulsions to the radiations of Ca45, I131, P32 and Zn65 has been determined. Characteristic curves for all four isotopes against Eastman no-screen x-ray film and Eastman type M stripping film are presented, together with certain additional studies on Eastman NTB stripping film and Eastman type K x-ray film. The relative photographic effectiveness of the isotopes examined increases in the order: Zn65, P32, I131, Ca45, C14. Applications of the data for quantitative radioautography are discussed.
A Versatile Microinjection and Micropipetting Syringe
Authors: Buck John B.
Published: February 2005

A screw-driven microinjection syringe capable of delivering volumes as small as 0.1 mm3 with statistically good reproducibility is described. It features interchangeable impellers mounted on a sliding way for simultaneous availability of coarse and fine adjustment, and a mechanical positioner permitting known and reproducible fractional revolutions of the control knob.
Design and Use of Piezoelectric Gauges for Measurement of Large Transient Pressures
Authors: Arons A. B. , Cole R. H.
Published: February 2005

This report discusses the design and use of piezoelectric gauges for the measurement of rapidly varying hydrostatic pressures of large amplitude in gaseous and liquid media. Reasons are given for the selection of tourmaline in preference to other types of crystal. Fundamental principles of design are stated, and gauge construction is described in the light of these principles. A simplified theoretical analysis of transient response characteristics is presented.
An Improved Schlieren Apparatus Employing Multiple Slit-Gratings
Authors: Mortensen Tage A.
Published: February 2005

In the schlieren apparatus described in the following, the conventional knife-edge elements are replaced by multiple slit-gratings. The main advantage gained by this design is the fact that larger-sized working fields can be achieved with an objective lens of given aperture. Also, in some cases, greater intensity of image illumination is obtained, and usually the over-all length of the system is reduced.