bluuebunny/crossref_metadata_2025 huggingface dataset:
Coincidence Experiments for Noise Reduction in Scintillation Counting
Authors: Kallmann Hartmut , Accardo Carl A.
Published: February 2005

A method is described which permits discrimination between noise pulses and pulses of small light flashes. The arrangement consists of three multipliers facing the three faces of one and the same crystal. One multiplier acts on the ``Y'' axis, another on the X axis and the third one on the Z (intensity) axis of an oscilloscope. Light flashes induce pulses in all multipliers simultaneously, whereas noise-pulses occur at random and produce triple-coincidence pulses only very rarely. Triple coincidences are easily recorded with the scope. Pictures are presented illustrating the operation of the arrangement. The original noise being of the order of three thousand per second was dropped to one noise pulse in three seconds.
A Large Dempster-Type Double-Focusing Mass Spectrograph
Authors: Duckworth Henry E.
Published: February 2005

A description is given of a large Dempster-type double-focusing mass spectrograph. The dispersion of the instrument is 2.3 mm for one percent mass difference. The theoretical resolution for a 0.001-in. principal slit is 7000 and has been experimentally realized. The performance of the instrument is illustrated by a mass spectrum showing doublets formed by singly-charged Cu and Zn and triply-charged Pt.
An Investigation of the Possible Use of the Glow Discharge as a Means for Measuring Air Flow Characteristics
Authors: Werner F. D.
Published: February 2005

The glow discharge in air at atmospheric pressure from a point of fine platinum wire has been experimentally investigated in its sensitivity to variations of pressure, velocity, temperature, and humidity, as well as such variables of the instrument as needle point characteristics, location and shape of the other electrode, and magnitude of the discharge current. It has been concluded that the glow current is markedly pressure sensitive, has low velocity sensitivity, is only slightly humidity sensitive, and is negligibly sensitive to ordinary temperature variations. The device offers a significant improvement over conventional pressure measuring instruments by the small size of its sensitive portion (of the order of 0.001-inch diameter wire and 0.002-inch glow diameter) and in its response to high frequency variations (more than 106 c.p.s. has been demonstrated experimentally). It suffers from high background noise in the present arrangement. A workable instrument is not presently described, but rather, some promising possibilities are shown to exist. The successful application to measurement of instantaneous pressures in very high frequency sound has been made, however; and the instrument will be reported as soon as possible.
A Small Milligaussmeter
Authors: Adams G. D. , Dressel R. W. , Towsley F. E.
Published: February 2005

Means are described for measuring magnetostatic fields from the order of one milligauss to 100 gauss. The operation consists of measuring the second harmonic content of the exciting current for a ferromagnetic strip which is normally excited to partial saturation. The second harmonic component appears when the strip is biased by an external magnetic field and the amount is directly proportional to this field over the bulk of the useful range. Methods of use are described.
A High Speed Synchroscope
Authors: Kelley G. G.
Published: February 2005

Described is an instrument for observing or photographing fast voltage transients. It consists of a sweep generator with sweep speeds ranging from 30 cm per microsecond to 0.05 cm per microsecond, a vertical deflection amplifier having a rise time of 0.005 microseconds and a preamplifier which, when used with the deflection amplifier, produces an over-all rise time of 0.0063 microseconds with a gain of about 1,000. These units are used in conjunction with a type 5XP cathode-ray tube using 20 kilovolts accelerating voltage.
Design Study for a Three-Bev Proton Accelerator
Authors: Livingston M. S. , Blewett J. P. , Green G. K. , Haworth L. J.
Published: February 2005

A design study is presented for a proton synchrotron (to be called a ``Cosmotron'') to accelerate protons to energies of the order of three billion volts. Protons are injected from a four-million volt Van de Graaff machine. They are deflected electrostatically into a racetrack orbit including four quadrants of thirty-foot radius of curvature, and four straight sections ten feet long. The energy gain per revolution supplied by the radiofrequency system will be about 1000 ev. Acceleration will continue to 1.0 seconds to a final energy of about three Bev. Construction of this machine is now in progress.
Technical Apparatus for Determining Thermal Conductivity of Steels up to 500°C
Authors: Horák Z. , Krupka F.
Published: February 2005

An apparatus for determining the thermal conductivity of metals based upon the comparison of flux of heat in a conductor in the usual form of a bar consisting of three parts of different materials has been developed. This method enables one to measure the temperature gradients by only one differential thermocouple sliding in an axial boring of the bar. In this way usually difficult measurements of thermal conductivity can be carried out very easily with sufficient accuracy for industrial purposes.
Polarimeter for the Study of Low Frequency Radio Echoes
Authors: Benner A. H. , Nearhoof H. J.
Published: February 2005

An instrument is described which allows the determination of the ellipticity, angle of tilt, and sense of rotation of low frequency radio waves returned from the ionosphere.
The Design of Neutron Counters Using Multiple Detecting Layers
Authors: Lowde R. D.
Published: February 2005

A discussion is given of ion chambers in which a series of electrodes carry layers of solid detecting material. Counters of this type require low operating voltages, and can easily be miniaturized. Formulas are given for the correct layer thicknesses and for the neutron counting efficiency. The equations are applied to boron 10, and it is shown that there is a permissible tolerance of about 50 percent on the thickness of a boron layer, and a very considerable tolerance on the assumed values of the disintegration product ranges. Curves are given relating the optimum boron layer thicknesses and the efficiency to the number of layers. A miniature instrument is described having a sensitive volume of 0.4 cm3. It operates at a thermal neutron efficiency of 24 percent with a collecting voltage of 70.
A System for the Collection and Purification of Radon by Remote Control
Authors: Shiflett Chester H. , Steidlitz Mark E. , Davis Wallace
Published: February 2005

A plant for the collection and purification of radon has been constructed. In order to reduce the gamma-radiation level, the plant was designed to be operated entirely by remote control except for the final sealing of the radon capsule. This plant compares favorably with other collection systems both with regard to the time required for a collection and to the yield of radon obtained.
Synchrotron-Oscillation Resonance
Authors: Blachman Nelson M.
Published: February 2005

The frequency of phase oscillation in a synchrotron is so low as to make possible resonances with harmonics of the power-supply frequency. The interaction may take place through ripple in the magnetic field or in the frequency or amplitude of the accelerating voltage, the first two interacting very strongly and the third moderately. Thus, a small ripple in the magnet power supply output, though it produces only an extremely small ripple in the magnetic field because of the magnet's inductance, may tend to cause large phase oscillations. The detuning effect of the fall in phase oscillation on frequency with increasing amplitude limits the resulting amplitude, however, and may even reduce the amplitudes of initially large phase oscillations. The ripple in the accelerating field is unlikely to be sufficient at a resonant frequency to cause trouble. In addition to ripple, there will be noise which, particularly through modulation of the frequency of the accelerating field, may result in time in considerable phase oscillations because the noise contains a wide range of frequencies, one of which is always in resonance throughout the acceleration cycle.
A Continuous Flow Respirometer Utilizing the Oxygen Cathode
Authors: Carlson Francis D. , Brink F. , Bronk D. W.
Published: February 2005

The method of construction and operating conditions are given for a respirometer suitable for determining steady-state rates of oxygen uptake by peripheral nerve. The polarographic method is used to measure the change in oxygen concentration occurring when a solution of known oxygen concentration flows at a constant, predetermined rate over a tissue sample which removes oxygen from the stream. From a knowledge of the concentration change and volume-flow rate the rate of oxygen uptake by the tissue is readily determined. Electrodes for stimulating the nerve sample and for recording the action potential are provided. By virtue of the flow system the respirometer maintains constant environmental conditions. The system is linear with respect to changes in the steady-state rate of oxygen consumption, and the sensitivity is such that, for a 10-mg sample of nerve, changes in the rate of oxygen uptake of 0.1 micromoles/g hr., (2 cu. mm/g hr.) are readily detected.
Gas Flow through the Mass Spectrometer Viscous Leak
Authors: Halsted R. E. , Nier Alfred O.
Published: February 2005

An approximate expression for the flow of a binary gas mixture through a mass spectrometer ``viscous'' leak has been derived and compared with experimental data. The factors important in the design and use of the leak are determined from this result.
Beta-Ray Spectroscopes
Authors: Persico E. , Geoffrion C.
Published: February 2005

This paper is a review of the various types of beta-ray spectrographs and spectrometers. The principal theoretical results as to the resolving power and luminosity attainable under various conditions are briefly related. Finally the construction and performance data of a number of instruments described in the literature are collected, and compared by means of a graphical representation.
An Orbit-Bender to Assist Injection into Betatrons
Authors: Davis Leverett
Published: February 2005

It is suggested that the fraction of the beam in a betatron or synchrotron that is lost by striking the injector might be decreased by a suitable transient bending of the steady-state orbit during injection.
A Semi-Automatic Device for Analyzing Events in Nuclear Emulsions
Authors: Blau Marietta , Rudin Robert , Lindenbaum Seymour
Published: February 2005

An apparatus is described the basic element of which is a microscope with a motor-driven stage. The operator controls the direction and speed of motion by a steering wheel and an accelerator pedal and drives the track to be analyzed through a target. Range, grain density, and geometrical orientation of tracks, etc., are automatically recorded on charts. Methods of measurements and results are discussed.
Continuously Sensitive Diffusion Cloud Chambers
Authors: Cowan E. W.
Published: February 2005

The following types of continuously sensitive diffusion cloud chamber have been built and successfully operated: a chamber designed to be photographed through the top for use with a particle accelerator; a chamber designed to be photographed from the side for cosmic-ray studies; and a very simple chamber for demonstration purposes. The construction and best operating conditions are described.
An Electronic Recording Analytical Balance
Authors: Lohmann Idas W.
Published: February 2005

An electronic recording analytical balance is described which is free of mechanical connections with the balance beam, direct reading, sensitive, and rapid. All mechanical and electrical contactors have been eliminated from the instrument proper, using electronic means as a substitute for mechanical. A relay and two cam-operated microswitches are, however, used in the range extender. The construction is simple, being made up, for the most part, of available standard commercial units. For work requiring a continuous record of changes in weight with respect to time, the instrument should prove to be most valuable.
Velocity-Acceleration Response from a Seismic Pick-Up via Controlled Damping
Authors: Jeffries Robert J.
Published: February 2005

The basic theory of the seismic pick-up is developed and interpreted to show that it is theoretically possible to make a simple seismic system directly amplitude-sensitive to velocity as well as acceleration and/or displacement. This is accomplished by appropriate control of the damping.
Variation of Grain Density with Temperature of Exposure in Nuclear Emulsions
Authors: Dollmann Elsie M.
Published: February 2005

Ilford C-2 unloaded and C-2 boron loaded plates, subjected to temperature changes varying from −66°C to +66°C, were bombarded with 10-Mev neutrons. The recoil protons showed that the temperature change had caused an increase in grain density which varied as much as ⅓ from −66°C to +25°C. Although the C-2 boron loaded plates showed a greater initial grain density than the unloaded plates, the ⅓ increase was preserved.
Vortex Thermometer for Measuring True Air Temperatures and True Air Speeds in Flight
Authors: Vonnegut Bernard
Published: February 2005

The aerodynamic heating experienced by thermometers exposed from airplanes can be very nearly eliminated over a wide range of operating conditions by mounting the thermometer in the center of an air vortex created by a simple housing. This method has been found to simplify air temperature measurements over the operating range of a B-17 airplane. The instrument has promise for measuring temperatures in clouds.

True air speeds can be measured by the difference between the temperature of the vortex thermometer and a thermometer exposed in the usual manner. Designs and flight data are presented for several vortex thermometers and a simple true air speed indicator.
A Wide—Band Audio Phasemeter
Authors: Ragazzini John R. , Zadeh Lotfi A.
Published: February 2005

The problem of measuring the phase angle between two sinusoidal voltages is an important one in laboratory procedure. Phasemeters which can make this measurement accurately over a substantial frequency range have heretofore been bulky and relatively stationary. This paper describes a circuit which results in a phasemeter which is accurate to about 30 minutes, has a dial adjustment which is independent of frequency, operates over a range of from 20 c.p.s. to 100 kc and is relatively small and inexpensive. The principle used is to match the phase shift between the unknown voltages with a calibrated phase shift in the meter channel. This phase equalization is observed on a standard oscillograph which is used only as a comparison instrument. The oscillograph amplifier phase shifts are balanced out with an uncalibrated phase shifter cascaded in the meter channel and do not affect the measurement.
Analog Computers for Servo Problems
Authors: McDonald Donald
Published: February 2005

The exact equations are derived for operational amplifiers used in analog computers. These exact equations are replaced by simpler equations based upon certain approximations. These approximations are discussed and it is shown, when applied to servo mechanism problems, the operational amplifiers may be designed with greater ease and less complexity than those to be used for more general problems.
An Automatically Synchronized Electronic Switch
Authors: Budlong W. A. , Lutz Bruce C.
Published: February 2005

An electronic switch has been developed which eliminates the difficulties with frequency adjustments usually encountered in existing electronic switches. This is done by developing a switching square wave synchronized by either input signal. Therefore this switch is very much easier to use as the control settings are not critical.
An Electronic Circuit Which Extracts Antilogarithms Directly
Authors: Snowden F. Curtis , Page Harold T.
Published: February 2005

It has long been established that variable-μ tubes of types such as the 6SK7 were capable of outputs which were proportional to the logarithm of the input over a specified range of bias voltages. The use of inverted triodes, and related circuits, is also widely known. It was decided to combine these two older techniques in the hope of developing a new one. Accordingly, a 6SK7 was hooked up as an inverted triode, i.e., the plate was used as the controlling element, and the control grid was employed as the output element; the results obtained with this arrangement were then plotted and investigated. As reported herein, a circuit capable of extracting antilogarithms over a fairly extended range of input voltages was developed.
On Adapting a Powder X-Ray Diffraction Camera for Reflection Patterns
Authors: Parsons Jonathan
Published: February 2005

A method is described by which a commercial x-ray diffraction powder camera, designed to take rod or tubular mounts, may be easily adapted to accommodate small, flat mounts. Provision is made to change the customary continuous rotation to that of 10° rotary oscillation. A diffraction pattern of the core of a large renal calculus is shown as being illustrative of the patterns obtained from this modified camera.
High Resolution Recording with Soot
Authors: Eldredge K. R.
Published: February 2005

The treatment of a soot coating with a hydrocarbon solvent compacts the coat so that fine lines may be drawn in it with little force. The line resolution available is somewhat better than that of ordinary photographic films. Enlargements up to fifty times the size of the original record may be usefully employed.
Focusing Properties of a Generalized Magnetic Spectrometer
Authors: Judd David L.
Published: February 2005

The first-order focusing properties of a magnetic spectrograph similar to that of Siegbahn and Svartholm, but differing in that both source and collector lie outside the field, are investigated. The parameters of the analogous thick lens optical system are derived. General expressions for image distance, astigmatism, magnification, solid angle, dispersion, and resolution of lines with a spread in momentum are obtained. Factors affecting the compromise between intensity and resolution are discussed. The possibility of increasing resolution without loss of intensity by introducing some astigmatism is considered. Second-order effects have not been included since they are thought to be of the same order as corrections for the fringing field. The first approximation proved adequate for the design of an instrument in which satisfactory focusing was obtained by simple empirical adjustments.
On the Use of Photographic Plate Detectors in Neutron Experiments
Authors: Allred J. C. , Phillips A. N. , Rosen L. , Tallmadge F. K.
Published: February 2005

A technique is discussed for utilizing photographic plate detectors in an evacuated camera, containing an appropriate radiator, to make precise determinations of the range distributions of the disintegration products of slow neutron reactions. The same technique is applied to the problem of measuring neutron energies by making range measurements on the forward recoil protons projected by fast neutrons from a thin polyethylene radiator. As an indication of the accuracy attainable with photographic plates when used in this manner, determinations have been carried out for the Q values of the Li6(n, α)H3 reaction and the B10(n, α)Li7 reaction.
Time Lags in Geiger Counters
Authors: Laufer Arthur R.
Published: February 2005

Light from a spark was used to produce a primary ionizing event in a Geiger counter by means of the photoelectric effect. The time lag between this event and the detection of the pulse on the counter wire was studied as a function of counter filling, pressure, and overvoltage. The measured lags, ranging from tenths of microseconds to many microseconds, were used to calculate electron mobilities, sheath spread velocities, and electron attachment coefficients. The lags appear to be the result of the transit time required by the initial electrons to move from their point of origin to the high field region, and the time required by the sheath to spread laterally along the wire and to move radially outward far enough to produce an electrical pulse which can be detected.
The Electric Field in a Geiger Counter
Authors: Laufer Arthur R.
Published: February 2005

The mechanism of the reduction and recovery of the electric field in a Geiger counter is discussed, and the role of the series resistance is analyzed. The contribution of the collection of the electrons to the total pulse size is shown to be negligible.
Laboratory Modifications in the RCA Model EMC Electron Microscope
Authors: Ellis S. G.
Published: February 2005

The anode opening was reduced to reduce thermal expansion in the specimen stage. The asymmetry of the objective lens was compensated. Working at the lowest possible angular aperture of illumination and focusing critically (by using a carefully settled fluorescent screen and a high magnification viewer) a resolving power of approximately 50 A.U. was demonstrated on suitable specimens.
Direct Reading Phasemeter
Authors: O'Neill L. H. , West J. L.
Published: February 2005

This paper describes a simple and accurate method for the measurement of the phase difference between two sinusoidal voltages and an instrument for making the measurement. It is shown that measurement accuracy sufficient for most ordinary purposes can be obtained through the use of very simple circuitry, and that measurement errors can be made arbitrarily small by resorting to more complex circuitry. The instrument is compact and convenient in use.
A Method for Increasing the Safe Power Input of X-Ray Tubes
Authors: Berman Arthur I.
Published: February 2005

A method for cooling x-ray tubes was devised, based on the principle of relative motion between the target and focal spot. The electron beam is deflected by a rotating magnetic field so that the focal spot moves in a circle upon the target face. Simultaneously, the tube itself is gyrated (without rotation about its axis) so that any point on the target describes an equal circle. The two rotations are equal in frequency but phased 180 degrees from each other. Thus the focal spot remains stationary in laboratory space. The advantages are (1) it is adaptable to most x-ray tubes with target face perpendicular to the tube axis, and target diameter twice that of the longest focal spot dimension, without any modification of tube design; (2) it combines the benefits of a rotating target, water-cooled target, and line focus without the need for rotating joints or vacuum connections. Tubes, operating continuously for hours at a time at a gyrating frequency of 6 r.p.s. have been cooled successfully by this method without observable shifting of the focal spot in laboratory space.
RaDEF Standard Sources for Beta-Disintegration Rate Determinations
Authors: Novey Theodore B.
Published: February 2005

The preparation and use of calibrated RaDEF equilibrium sources for absolute beta-counting is described. The sources are essentially weightless and are mounted on a thin backing to reduce self-absorption and back-scattering correction problems. Calibration was done by determination of the alpha-disintegration rate of RaF in a parallel plate alpha-ionization chamber. No secondary standards are required and the sources can be recalibrated at any time.

As an example of the application of such standards, details of the calibration of a P32 solution distributed by the Bureau of Standards for intercalibration in February 1949 are given. The final result is 88.8 mrd/ml at 8 A.M. C.D.T. March 1, 1949. The precision of the measurement is 0.3 percent. The accuracy is estimated to be 1–2 percent.
Electron Component in Geiger Discharge
Authors: Kelley G. G. , Jordan W. H. , Bell P. R.
Published: February 2005

Observation of the wave form of current during a Geiger discharge indicates the presence of a component due to electron collection ammounting to as much as 50 percent of the total energy involved in the discharge. It appears, therefore, that the initial ion sheath can have a mean radius of the order of 10 to 15 times the radius of the center wire. Apparatus is described, wave forms are shown and the method used to evaluate electron component and mean radius of ion sheath is indicated. Results for two tubes with different quenching vapors are tabulated.
Volumetric Plastic Micro Respirometer
Authors: Scholander P. F.
Published: February 2005

A simple plastic micro respirometer is described based on a direct reading volumetric principle. The respiration chamber with CO2 absorber is balanced against a compensating chamber through a manometer drilled in Lucite. As oxygen is used it is replaced from a syringe so as to maintain balance with the compensating chamber. The oxygen consumed is read directly on the syringe. Two sizes have been made covering a range of oxygen consumption from 10 mm3 to 10 cc per hour.
Design and Operation of Liquid Nitrogen-Cooled Solenoid Magnets
Authors: Fritz James J. , Johnston Herrick L.
Published: February 2005

This paper describes the design and construction of compact iron-free solenoid magnets cooled by immersion in liquid nitrogen. Construction details and performance data are given for two such magnets, which produce a magnetic field of 4000 gauss with a power expenditure of 2.7 to 3.3 kw. Heat transfer coefficients between copper wire and boiling liquid nitrogen have been measured for temperature differences between the wire and the liquid of 2 to 11°K.
X-Ray Determination of Slip Planes and Slip Directions
Authors: Turner R. W. , Wu T. L. , Smoluchowski R.
Published: February 2005

An application of x-rays for determination of active slip systems based on a comparison of distortion of Laue spots is described.
A New Mechanical Autocorrelator
Authors: Seiwell H. R.
Published: February 2005

A relatively simple and inexpensive machine for mechanical computation of the autocorrelation function is described. The original design resulted from a collaboration with Dr. George P. Wadsworth of the Massachusetts Institute of Technology.

The theoretical definition of the autocorrelation function is given. This is followed by an outline of the hand computational procedure as applied in this laboratory to observational (ocean wave) data of finite scope. The machine computation is next compared with the hand process.
The Design of a Simple Microflowmeter for Biological Perfusion Experiments
Authors: Burton Alan C. , Nichol James T.
Published: February 2005

Various types of flowmeters are discussed with reference to their use at very small flows. The differential pressure type, using rubber membranes, appears most suitable. The steps are outlined in the design of an instrument sensitive to flows as low as 0.01 ml/min. yet with a response time less than 10 sec. In this instrument a completely differential linkage between two membranes is accomplished by the use of an incompressible fluid. The theory of the response is developed. This gives a prediction of the speed of response from the sensitivity and the diameter of the membrane used.
A Vacuum Furnace for Use in the Temperature Range 1000–2000°C
Authors: Tomlinson J. W. , Bockris J. O'M.
Published: February 2005

A laboratory vacuum furnace with a glass envelope has been developed, using as a heater a cylindrical grid of tungsten wire enclosed by radiation shields.

The furnace is suitable for physicochemical measurements in the range 1000–2000°C.
A Multiple Kerr-Cell Camera
Authors: Zarem A. M. , Marshall F. R.
Published: February 2005

The need for new ultra-high speed photographic techniques in studies of brief transient phenomena has led to the development of a multiple Kerr-cell camera designed to take a sequence of three photographs at submicrosecond exposure times. This camera uses shutters of the electro-optical type utilizing the Kerr effect in nitrobenzene. Pulsing networks for the Kerr cells and synchronizing networks for the entire system are described. The system has shown itself to be capable of high shutter speed, high sequence rate, and very good stability of timing. With this camera, studies of electrical discharages at effective exposure times of 0.04 microsecond and framing rates corresponding to 40,000,000 frames per second have routinely been made. It is felt that cameras of this type are valuable research tools that will help open the way for further important studies.
The Measurement of the Magnetic Field in a Nuclear Spectrometer
Authors: Langer L. M. , Scott F. R.
Published: February 2005

An arrangement is described which gives a continuous measurement of the relative magnetic field strength in a nuclear spectrometer with an accuracy of about 0.1 percent. The method consists of balancing the a.c. voltage picked up by a coil rotating in the field of the spectrometer against that picked up in a standard Helmholtz field.
Tests of Flowing Junction Diffusion Cells with Interference Methods
Authors: Longsworth L. G.
Published: February 2005

The construction and manipulation of two diffusion cells, one of glass and the other of stainless steel, are described. In both cells the initially sharp boundary is formed by allowing solution and solvent to flow together into a narrow horizontal exit slit in the side wall of the diffusion channel. These cells have been tested by diffusion measurements with the aid of the Gouy interference method. Moreover, in the case of the metal cell which is provided with a reference channel in close proximity to that in which diffusion occurs, an interference method that gives the refractive index directly as a function of the height has also been studied.
The Velocity of Propagation of the Discharge in Geiger-Müller Counters
Authors: Saltzmann H. , Montgomery C. G.
Published: February 2005

The velocity of propagation of the discharge in a Geiger-Müller counter has been measured in a counter with a divided cathode by the method of delayed coincidences. The parameters varied were the counter potential and the percentage of ethyl alcohol mixed with argon. The results are compared with Wilkinson's theory. Good agreement is obtained except for high velocities where the theory predicts values much too low.
A Recording Torque Magnetometer
Authors: Miller D. S.
Published: February 2005

This instrument produces, automatically, a curve of torque versus angle of orientation for a thin iron or steel disk in a strong magnetic field. A resistance strain gauge converts the torque acting on the disk specimen to a small d.c. voltage, which is recorded on a ``strip-chart'' recording potentiometer. The specimen is rotated in synchronism with the translation of the chart paper, both being driven by synchronous motors. A torque curve is completed in six minutes.
Observations on Some Properties of Ultra-High Frequency Gas Discharges
Authors: Robinson Charles F.
Published: February 2005

A series of experiments designed to yield information on the mechanisms of ultra-high frequency discharges which influence the operation of ion sources employing such discharges is described. The main conclusions are that such discharges exhibit a high negative space charge due principally to secondary emission from the walls of the discharge chamber and that ion production is inhibited by the space-charge trap so formed, that under certain conditions extremely intense electron beams may be obtained from a resonant cavity containing a gas discharge, and that fairly large ion currents may be obtained by the interaction of the emergent gas and the emergent electron beam in the exit orifice of the cavity.
Duration of Scintillations from Organic Phosphors
Authors: Elliot J. O. , Liebson S. H. , Myers R. D. , Ravilious C. F.
Published: February 2005

Measurements have been made on the time of decay of scintillations from organic phosphors irradiated with gamma-rays. Interference between the output pulse from a photo-multiplier and its reflection from a shorted line is used to determine the time constants.
The Measurement of Rates of Flow of Gases by Wet Test Meters
Authors: Burwell Robert L. , Metlay Max , Pfohl Frank W.
Published: February 2005

Rates of flow of gases may be measured to an accuracy of better than 0.1 percent with properly modified and operated wet test meters. The period of a single rotation is measured by an electric stop clock. The instrument is not an absolute one but must be calibrated by a meter prover. A suitable prover is described. Within rather wide limits the calibration is independent of flow rate. The instrument may be used for direct measurement or for calibrating other types of flow meters.
A Recording Polarimeter
Authors: Levy Gabor B. , Schwed Philip , Fergus David
Published: February 2005

A recording polarimeter has been constructed. The principle of operation is essentially the replacement of an operator in conventional visual polarimetry by a photoelectric servo system. A photo-multiplier tube is used which, in conjunction with a mechanical chopping system, delivers an alternating current signal proportional to the unbalance. The latter is filtered and amplified and actuates a servo mechanism. The precision of the system is ±0.005° for static balance and the speed about 0.5° per minute. Hence the arrangement compares favorably with ordinary visual operation. The construction of the instrument is discussed briefly and its performance is illustrated by examples.
Ring Focus in a Thin Magnetic-Lens Beta-Ray Spectrometer
Authors: Keller Joseph M. , Koenigsberg Ernest , Paskin Arthur
Published: February 2005

The paths of electrons in a thin magnetic-lens type of spectrometer are described by a non-linear differential equation. The equation was numerically integrated to obtain a set of electron trajectories originating from a point source on the axis of the instrument. Trajectories for off-axis sources were approximated. On the basis of these trajectories, the location and some properties of ring focus were studied. Theoretically calculated line shapes are compared for axial and ring focus. For reasonable values of resolution, the transmission of the spectrometer would be roughly doubled by performing the momentum discrimination by a ring focus baffle instead of by a small counter on the axis.
Vacuum Tests of Rubber, Lead, and Teflon Gaskets and Vinyl Acetate Joints
Authors: Cloud Robert W. , Philp Sanborn F.
Published: February 2005

Rubber, Teflon, and vinyl acetate sealed systems are compared, by an approximately quantitative method, with a lead gasket sealed system which is shown to give off negligible gas at room temperature. Rubber is shown to evolve relatively large amounts of gas with an apparent vapor pressure above a micron at room temperature and about 0.1 micron at liquid air temperature. Continuous pumping for several days produces no improvement, nor does the use of metal-to-metal joints. Vinyl acetate joints are shown to improve with pumping over a period of several days, reaching a condition exhibiting an ``apparent vapor pressure'' of 5×10−7 mm of mercury, or less, at room temperature. Heating to 45°C raises the apparent vapor pressure to the 10−5 mm range, and heating to 100° raises the apparent vapor pressure to the micron range. If this behavior is caused by the vapor pressure of the vinyl acetate itself, continued baking in vacuum will, of course, produce no improvement.
The Design of a Magnetic Focusing Coincidence Spectrometer
Authors: Fowler C. M. , Shreffler R. G.
Published: February 2005

Design and operating features are described for a semi-circular magnetic focusing coincidence spectrometer. The primary function of the spectrometer is that of determining whether or not two different radiations from a radioactive sample are in the same branch of the nuclear decay scheme. Although the instrument is designed primarily for studies between conversion electron groups, it is also suitable for studies between conversion groups and beta-spectra.

A feature of the instrument is its extraordinarily good coincidence resolving power. Applications of the spectrometer to two activities are briefly discussed, and an explanation of the high resolving power is given.
Electronic Pile Simulator
Authors: Bell P. R. , Straus H. A.
Published: February 2005

A device has been made that follows the same set of kinetic equations as a chain-reacting pile. The voltage output varies as a function of time as the neutron flux would vary in a pile. A potentiometer varies the effective multiplication factor and can be considered as a control rod. Five delayed neutron periods are simulated. A high precision electronic integrator is used, and the instrument is capable of an accuracy much better than one percent.
Fabrication of a High Power Resonant Wave-Guide Window
Authors: Edwards E. V. , Garoff K.
Published: February 2005

The inability of present wave-guide pre-TR and TR tube windows to withstand high transmitter power necessitates improved window design if 3000-megacycle radar systems are to continue using the conventional band pass TR protective device. The fabrication of a glass window with a loaded Q of four is described and operational tests at high line power are discussed. This construction permits the TR tube parts to be brazed in a hydrogen furnace and a more rigorous pumping schedule to be followed. A flow chart of the window processing operations and pictures of the window and pre-TR tube are included.
A Microtome Specimen Holder Advanced by Thermal Expansion
Authors: Eden M. , Pratt A. W. , Kahler H.
Published: February 2005

A microtome specimen holder which advances the specimen by thermal expansion is described. The holder was heated by an electrical current, the value of which could be regulated to give any desired rate of heating and expansion. A quantitative comparison was made between the heating and expansion rates of the Newman, Borysko and Swerdlow CO2 precooled instrument and the electrically heated instrument. It was found that the electrically heated specimen holder fulfilled the requirements of flexibility, reproducibility, sensitivity and linearity.
Electron Energy Studies with the Anthracene Scintillation Counter
Authors: Hopkins J. I.
Published: February 2005

Using a β-ray lens spectrometer to supply electrons of a given energy, a study of the response of the anthracene scintillation counter to monoenergetic electrons has been made. It has been found that pulse height varies linearly with energy from 125 to 3200 kev but below 125 kev the pulse height varies less rapidly with energy. The differential counting rate distribution for given energy settings of the lens spectrometer were found to follow a Gaussian distribution and that on the average 3.3 kev is required to produce one effective photo-electron at the cathode. When Morton's correction for dynode losses is applied, it is found to require 2.5 kev for the production of one photo-electron at the cathode or that 400 electrons enter the multiplier per Mev of incident electron energy. This is in agreement with the 420 electrons per Mev obtained by direct measurement. Assuming a 10 percent photoelectric efficiency at the photo-sensitive surface, it appears that the efficiency of anthracene for the conversion of incident electron energy into photon energy is of the order of one to two percent.
An Electromagnetic Flowmeter for Transient Flow Studies
Authors: Arnold James S.
Published: February 2005

An adaptation of the electromagnetic flowmeter has been made for the observation of transients in liquid flows. The device responds to flow transients of 0.001-sec duration, and is not affected by ambient pressure changes or the velocity profile of the liquid in the conduit. The effects of fluid resistivity on the instrument are noted.
Two-Directional Focusing of Charged Particles with a Sector-Shaped, Uniform Magnetic Field
Authors: Cross William G.
Published: February 2005

For a sector-shaped, uniform magnetic field with source and detector outside the field, the non-uniform fringing fields can be employed to give simultaneous focusing of charged particles in two perpendicular directions. Equations for determining the position of the doubly-focused image are developed and graphs are given for some representative arrangements. This double focusing can be combined with the methods recently developed for second-order focusing, to increase further the useful solid angle of a uniform-field mass or momentum analyzer. Fringing-field focusing can also be used in concentrating to a point a parallel beam of finite cross section.
A Tunable Shunt Selector-Rejector for Audio Amplifiers
Authors: Villard Oswald G.
Published: February 2005

A means for adding, without circuit modification or wiring changes, continuously tunable band-pass or band-reject selectivity to existing audio amplifiers is described. This takes the form of an external electronic circuit connected to the amplifier by means of a wire attached to the plate pin of one tube, and a common ac ground connection.

The arrangement is useful in laboratory and experimental work for temporarily rejecting or amplifying a particular frequency.
Alpha-Particle Spectrograph
Authors: Reynolds F. L.
Published: February 2005

An alpha-particle spectrometer, using a 60° sector magnet capable of focusing alpha-particles of energies up to 14 Mev, is described. Description of the instrument, sample technique, focusing properties, and current supplies are discussed. Transmission is about 0.01 percent of the total solid angle of the sample and with a resolution of 8 kev.
A Magnetic Orientation Device
Authors: Golian Serge E. , Reilly Edward G.
Published: February 2005

A light weight, low current drain system for the geomagnetic orientation of experimental equipment during a high altitude balloon flight is here described. The system is specifically designed to keep nuclear emulsions oriented to within ±5 degrees of a chosen geomagnetic heading. The error detector consists of a high impedance ac bridge, two of whose arms are electrolytic resistance paths in ethyl alcohol. Deviation of a compass needle, immersed in the electrolyte, from a chosen ``on-course'' line unbalances the bridge. A correcting motor is started when the off course deviation unbalances the bridge to a sufficient predetermined extent. Direction of motor rotation is determined by the sense of the error. Quiescent power drain is 1.4 watts. Motor operation increases this drain by 4 watts. Flight analysis of orientation is made possible by an integrating camera. Some control characteristics are given.
A Sweep-Type Differential and Integral Discriminator
Authors: Fairstein Edward
Published: February 2005

A circuit is described which can be used for obtaining the pulse-height distributions from scintillation counters, proportional counters, parallel-plate counters, and other voltage pulse sources. Differential or integral curves can be plotted automatically (J. H. Parsons, ``A sweep type alpha energy analyser,'' Report No. MonC-416, Oak Ridge, Tennessee (1947); J. H. Parsons, Proc. Inst. Radio Engrs. 37, 564 (1949)) by the attachment of an electronic recorder, or can be obtained manually with the use of the built-in rate meter or an external scaler. The counting rate loss is approximately one percent per 100,000 counts per minute. The over-all drift in pulse-height setting, slit-width, and counting rate zero is less than one percent per 24 hours. It will operate from any positive output amplifier whose rise time is 0.1 microsecond or greater, and whose output is limited to 100 volts.
A Pressure Counterbalancing Apparatus for the Measurement of the Electrical Conductivity of Aqueous Solutions above Their Critical Temperatures
Authors: Fogo J. K. , Copeland C. S. , Benson S. W.
Published: February 2005

The apparatus described is used in the measurement of the electrical conductivity of vapor phase systems at temperatures to 400°C and pressures to 4500 psi. A small, lightly constructed, platinum-iridium conductivity cell is enclosed in a larger, heated, steel pressure vessel. The pressure developed in the conductivity cell on heating is counterbalanced by admitting nitrogen into the pressure vessel. The direction and magnitude of the pressure differential between the vapor in the cell and the surrounding nitrogen is indicated by a meter circuit which measures the potential drop of a radiofrequency current across a variable condenser which is operated by an aneroid diaphragm on the cell. Admission and release of nitrogen is controlled manually. Measurements of the cell resistance are made by conventional ac bridge methods and are not described.
A Photographic Pyrometer
Authors: Male Donald W.
Published: February 2005

A photographic pyrometer is described that indicates apparent surface temperatures by photographing hot surfaces and correlating the variable density of the photographic negative with the apparent surface temperature. The need for critically controlled photographic and development technique is eliminated by incorporating into every photograph the images of standard targets whose apparent surface temperatures are independently determined with an optical pyrometer. The apparent temperatures of all areas of the photographed region can be determined simultaneously and instantaneously.
A Sensitive Differential Manometer
Authors: Los J. M. , Morrison J. A.
Published: February 2005

A sensitive differential mercury manometer is described. Mercury surfaces in two arms of the manometer form plates of condensers connected to two nearly identical oscillator circuits. A change in pressure produces a change in the beat frequency of the oscillators which is measured by comparison on an oscilloscope with the output of an audiosignal generator. For 0<Δp<0.02 cm an accuracy of 0.1 to 0.2 micron of mercury is obtained. For Δp between 0.02 cm and the maximum measurable with the manometer (approximately 0.25 cm) the accuracy appears to be 0.1 percent or better.
The Use of Film in X-Ray Diffraction Studies
Authors: VanHorn M. H.
Published: February 2005

Because of the weakness of diffracted beams, it is necessary to work in the low gradient ``toe'' portion of the characteristic (D-logE) curve. The curve shape in this region is the same for all types of x-ray film commonly used, even when development is greatly prolonged.

The shape of the entire characteristic curve is insensitive to radiation quality, but the relative speeds of different films change considerably in the range of wavelengths of interest to diffractionists.

For photographic photometry, the linear density-exposure range can be extended by proper selection of the processing conditions.
Multiple Scattering Corrections for Collimating Slits
Authors: Courant E. D.
Published: February 2005

When a beam of charged particles passes through a collimating aperture, the transmitted beam contains some particles which have traversed some of the material of the diaphragm. The corrections to the effective size of the aperture are estimated. They are found to be very small for protons of energies of the order of 20 Mev but appreciable at higher energies.
Magnetization Hysteresis Loop Tracer for Long Specimens of Extremely Small Cross Section
Authors: Crittenden E. C. , Hudimac A. A. , Strough R. I.
Published: February 2005

An instrument for measurement of the low frequency magnetic properties of thin layers is described. The difference signal from two opposed pick-up coils, one of which contains the sample, is amplified, integrated, and amplified again to cause the vertical deflection of a cathode-ray oscillograph to be proportional to the intensity of magnetization of the specimen. A signal is applied to the horizontal deflecting plates of the oscillograph to cause it to represent the applied magnetizing field in the region of the pick-up coils. A large reduction in low frequency noise in the difference signal preamplifier is accomplished by use of a circuit similar to electrometer tube circuits. Noise introduced through integration of sharp peaked signals is reduced by use of first and third harmonic components in the magnetizing field current. A signal equal to noise is produced by a flux change of 75×10−6 maxwell.