bluuebunny/crossref_metadata_2025 huggingface dataset:
An Analytical Balance for Recording Rapid Changes in Weight
Authors: Mauer Floyd A.
Published: February 2005

An analytical balance has been modified by adding a solenoid and magnet so that changes in weight can be balanced electrically. The operation is made automatic by reflecting a beam of light from the balance beam into a dual phototube in a bridge circuit and amplifying the output of the bridge to provide current in the solenoid. Recording the voltage drop across a resistor in series with the solenoid gives a linear weight scale which can be made to read directly in milligrams. An electronic damping circuit enables the balance to follow very rapid changes in weight without oscillating and with an accuracy better than 0.5 percent of full scale for ranges of 100 mg and over.
Dynamic Heart-Body Simulator
Authors: Frank Ernest
Published: February 2005

A high-speed electronic analog computer is described which is a useful research tool in the analysis of body-surface voltages produced by a fixed-position, variable-moment heart dipole. The simulator is capable of generating a wide variety of electric signals resembling presently-accepted estimates of heart-vector functions, forming body-surface voltages from these signals using empirically determined coefficients, and manipulating these voltages so as to produce quantities of the type commonly dealt with in electrocardiography. The basic theory underlying the simulator is summarized, and a description of its components is presented. Typical uses are given for the case of studies using a heart dipole immersed in a homogeneous model of the human torso. The advantages and flexibility of this device are discussed along with its possible future application in the analysis of human heart signals.
Collimated X-Ray Beam for Study of Distortion in Cloud Chambers
Authors: Carter R. S. , Street J. C.
Published: February 2005

A narrow, well-collimated beam of soft x-rays has been used for the purpose of measuring distortion in cloud chambers. The path of the x-ray beam in the cloud chamber is made visible by the ionization of the short-range photoelectrons. The main advantage of this method is that it can be used in the presence of a magnetic field. A limitation of the method is the finite width of the track. In argon it was not difficult to get a track 0.06 cm wide, allowing measurement to 0.004 cm. The appearance of the beam in both a diffusion and an expansion chamber is described. In addition to its use in measuring distortion, its applications to measuring rates of droplet growth and length of cloud chamber sensitive times are discussed.
Determination of Transient Flame Temperatures
Authors: Bauserman George W. , Prien Charles H. , Zandstra Thomas
Published: February 2005

A description is given of an instrument to determine the temperatures of rapidly varying flames. This instrument uses a photoelectric modification of the line-reversal method, wherein the light beam from a temperature-variable incandescent source is split into two monochromatic beams by means of mirrors and filters to impinge upon 931A multiplier phototubes. The phototube signals are sent to a mu-bridge null detector, whose output is fed to an oscilloscope for photography of results. The instrument can detect 25°K temperature differences between about 1540° and 3100°K and three millisecond time differences. Typical time-temperature results are given, along with the analytical procedures used.
An Improved Mass Spectrometer Ion Source
Authors: Schaeffer Oliver A.
Published: February 2005

Modifications of an electron impact ion source for a 60° mass spectrometer are described. The changes consist of (1) an almost completely enclosed ionization region which greatly reduces the contribution of ions from thermal decomposition products on the filament and reduces the contribution of background peaks and (2) a built-in aligned and stronger magnetic field which eliminates source magnet adjustment, collimates the electron beam better and permits the use of a higher repeller voltage thereby increasing the collection efficiency for ions with initial kinetic energy. The performance of the source is described.
Angle-Energy Distribution of Radiation from High-Energy Electron Accelerators
Authors: Warner R. M. , Shrader E. F.
Published: February 2005

An energy-analyzing detector of the pair-spectrometer type has been used to observe the angular distribution of bremsstrahlung produced by 17-Mev monokinetic electrons in molybdenum betatron targets. Distributions were measured for gamma-ray energies of 7, 11, and 15 Mev, for each of three targets whose thicknesses were approximately 2, 5, and 21 mils. Reproducible variations of spectrum with angle were found, the variations becoming more pronounced with increasing target thickness. The experimental distributions are compared here with the theoretical distributions of Schiff and Lawson, the former being significantly narrower. Axial relative spectra are also presented.
The ``Mechanical Particle,'' an Analog Computing Machine
Authors: Rankin Bayard
Published: February 2005

A machine is described which solves the equations of motion for a charged particle in a two-dimensional magnetic field. Its accuracy is not limited by the steepness or the asymmetry of the field. Guided by remote control, the mechanism moves continuously over a contour map just as a particle would move through the field itself. The operator matches position, or local field value, with a parameter of the steering control, or curvature of the trajectory. He is able to interpolate continuously between lines of constant field value, thus speeding the process of solution and increasing the accuracy. In five minutes a 40-inch orbit can be drawn over which the field values vary through 23 000 gauss. Five minutes are required for introducing initial conditions, including momentum. For regions in which the field is more than half maximum, the orbits of the mechanical particle and the electromagnetic particle coincide in their radii of curvature to within 0.5 percent. Accuracy is less for low field values. The performance characteristics have been determined from a working instrument which is fully described. An alternative computer design to the one already in use is also discussed.
Adaptation of a Geiger-Counter X-Ray Diffractometer for High-Temperature Investigations
Authors: Chiotti P.
Published: February 2005

The construction of a specimen holder and furnace for use as an auxilary piece of equipment with a North American Phillips Company high angle goniometer is described. The apparatus can be used for obtaining x-ray diffraction patterns at temperatures up to 1600°C, and at pressures in the range of 2×10−6 to 3×10−5 mm of mercury.
New Goniometers for Single-Crystal Neutron Diffraction Studies
Authors: Pepinsky R. , Frazer B. C. , McKeown M. L.
Published: February 2005

A new type of goniometer has been designed and constructed for neutron diffraction analyses, and particularly for single-crystal studies. The neutron detecting system employs a scintillation crystal and photomultiplier, or a miniature high-pressure BF3 counter; and the detector and diffracting crystal are located within a cylindrical shielded region, in such a manner that the moving parts are entirely free of heavy shielding elements. When a miniaturized BF3 counter is used, no shielding except B4C in plastic immediately surrounding the counter is required. Rotations are accomplished by servo-controlled motors, with selsyn indicators coupled to an external servo system. This servo control is designed to permit future introduction of automatic crystal and detector setting. The system is small and inexpensive, and has the particular advantage of readily permitting three-dimensional diffraction measurements.
Automatic Pole Figure Recorder
Authors: Geisler A. H.
Published: February 2005

A device has been developed for the direct recording in stereographic projections of pole figure data as they are supplied from a Geiger counter x-ray diffraction apparatus. The specimen is rotated systematically in a suitable goniometer about two axes in synchronism with movements of the chart and printer on the recorder. When the diffracted intensity attains any one of seven preset levels, the printer impresses a point of corresponding color on the chart. The point is printed at the location that has the stereographic co-ordinates of the pole of the diffracting volume. After all possible orientations of the specimen have been explored, an array of colored points will have been obtained on the chart. When contour lines are sketched through points of like color, the usual pole figure with iso-intensity lines is obtained.
An Extensometer for Polymeric Materials
Authors: Dietz A. G. H. , McGarry F. J.
Published: February 2005

A simple, potentiometer-type tensile strain indicator for testing polymers is described in detail. Presenting information which lends itself to automatic recording, the extensometer will detect true, or logarithmic, strains from 0.01 to 200 percent, at rates from 0.10 to 1000 percent per minute. In conjunction with other apparatus it can also be used to control the strain rate of the test. Direct calibration under test conditions removes the necessity for temperature compensation. Variables in the design permit considerable flexibility in the desired performance characteristics of the instrument.
A High-Temperature Microwave Spectrometer
Authors: Stitch M. L. , Honig A. , Townes C. H.
Published: February 2005

A spectrometer for measurement of microwave absorption by gases at temperatures as high as 1000°C is described. Microwaves pass through a 5-ft nickel absorption cell. Absorption lines are modulated by Stark effect to give sensitive detection. The spectrometer has been used to study spectral lines of some alkali halides and several other high boiling point diatomic molecules between 300°C and 775°C.
A Curve Analyzer and General Purpose Graphical Computer
Authors: French C. S. , Towner George H. , Bellis Donald R. , Cook Richard M. , Fair William R. , Holt Walter W.
Published: February 2005

A graphical computer based upon five automatic curve followers, two integrators, nine adding amplifiers, and a pen recorder was built for the transformation and combination of curves and for a simple analog computer to plot curves from equations. Heavily inked curves on 14-in. × 17-in. moving tables are tracked by photoelectric followers which continuously set potentiometers so that their output voltage is proportional to the curve height. The tables are positioned by voltages so that they may be made to move at a constant rate or may be individually controlled by some variable voltage. The follower output voltages may be transformed in various ways or combined algebraically with each other and used directly or indirectly through amplifiers to drive a recorder, a table, or an integrator. By this means curves may be changed in scale (linearly or nonlinearly) on either axis. Curves may be added, subtracted, multiplied, divided, or otherwise combined or operated upon in accordance with simple equations, and the result plotted in about a minute with an accuracy under favorable conditions of about ±0.02 in. Complex curves can be analyzed by fitting with algebraic combinations of simpler curves. The apparatus may be used to fit integral or differential equations to experimental data by trial adjustment of the constants. A low ac voltage increasing linearly with time represents the independent variable; the form of the equation is determined by the way in which the various units are connected and the values of constants are set by potentiometers.
Apparatus for Microwave Spectroscopy
Authors: Strandberg M. W. P. , Johnson H. R. , Eshbach J. R.
Published: February 2005

Design considerations are presented for a video microwave spectrograph using Stark modulation and a crystal or bolometer detector. Crystal and source noise is explicitly included in the treatment. A detailed description of some of the equipment in use in our laboratory is given. Some of the advantages and dis-advantages of other systems are mentioned.
Improved Needle Thermocouple for Subcutaneous and Intramuscular Temperature Measurements in Animals and Man
Authors: Krog John
Published: February 2005

A method is described for the construction of thermocouples inside of a No. 25 hypodermic needle yet still strong enough to withstand hard use in the field. Utilization of the couples in subcutaneous temperature measurements in man and animals outdoors for approximately three years has demonstrated satisfactory operation under weather conditions varying from rain to arctic temperatures of −50°C.
Ceramic Probe Microphones
Authors: Ackerman Eugene , Holak William
Published: February 2005

The construction of two types of probe microphones is described. Hollow, ceramic (barium titanate) cylinders, 116th inch long and 116th−inch o.d., are used for the sensitive elements. The more complex probe type A-S (Allen-Spencer) is contrasted with the simpler type H-A (Holak-Ackerman). Calibration procedures are described for each in the range 6–100 kc. The response of both types is about −140 db re 1 v/1 microbar; however the A-S type has a flatter response curve. The A-S is also less sensitive to signals striking the probe handle, but both types respond to the acoustic field at the exposed 116th−inch supporting tubing near the element. The H-A type is satisfactory for certain applications, particularly in bio-acoustics; its simplicity of construction and repair make it preferable for these applications.
A Precision Grinding Machine for Diffusion Studies
Authors: Letaw Harry , Slifkin Lawrence M. , Portnoy William M.
Published: February 2005

A precision grinding machine was constructed to permit the study of diffusion in germanium. Because one may obtain data after mean penetrations of the order of 10μ, this instrument is useful for problems involving very small diffusion coefficients and radioactive tracers of very short half-life. It has been found that diffusion in ductile metals such as silver may be investigated by use of this technique.
Device for Accurate Location of Events in Nuclear Emulsion
Authors: Orear Jay
Published: February 2005

A scale with 100 μ fine divisions and 1000 μ coarse divisions is pressed into the emulsion by rolling a fine toothed wheel across the emulsion. The position of the fine division on a 10 by 10 rectangular grid reticle (whipple disk) can be recorded to within 1 μ accuracy. This permits quick repositioning of events and strips with 1 μ accuracy independent of the accuracy of the stage motion.
A Fractionating Converter for Producing Para-Hydrogen
Authors: Giauque W. F.
Published: February 2005

A fractionating catalytic converter for the production of liquid para-hydrogen is described. The purpose of the fractionating column is to permit the use of a partial converter in the main liquefier stream at temperatures in the range of liquid nitrogen and yet avoid the possibility of back conversion of return gas from the pure para-region at lower temperatures.
A Tuned Galvanometer Amplifier
Authors: Beattie J. R. , Conn G. K. T.
Published: February 2005

An amplifier is described which is suitable for the amplification of signals from a radiation thermocouple used with a low-frequency interrupter. The system consists of a galvanometer which may be tuned by feedback over the range 1 to 3 cps, followed by a tuned electronic amplifier covering the same range of frequency. The band width of both elements may be varied. The output is presented as a rectified, smoothed deflection of the output meter. The amplification is sufficient to reveal thermal (Johnson) noise in the thermocouple circuit and is both linear in response and stable.
A Multichannel Noise Spectrum Analyzer for 10–10 000 Cycles
Authors: Nielsen E. G. , Van Der Ziel A.
Published: February 2005

A multichannel noise spectrum analyzer is described which allows the rapid measurement of flicker noise in vacuum tubes. The instrument gives either the equivalent saturated diode current or the equivalent noise resistance of the tube at 10, 30, 100, 300, 1000, 3000, and 10 000 cycles. The seven channels are read simultaneously; a whole spectrum may therefore be measured in 5 minutes. The instrument incorporates a quadratic thermistor-detector circuit with a dc voltmeter of variable time constant and wide-band filter circuits. The latter have a band width of 0.75 times the center frequency, but still give an accurate measurement of the noise at the center frequency. These large band widths reduce the time constant of the detector circuit needed for performing an accurate noise power measurement.
A Two-emf Method for the Comparison of Resistances
Authors: Hoge Harold J.
Published: February 2005

A method of comparing resistances is described in which two sources of emf, each with an associated dropping resistor, are connected in series with two resistors to be compared, in such a way that the latter are not adjacent. The circuit may then be adjusted so that the potentials at the two ends of one of these resistances are equal to the potentials at the corresponding ends of the other resistance while both carry the same current. Convenient means of detecting and adjusting to this condition are described. The circuit may be used as an alternative to either the dc or the ac bridge. The method is suitable for work of either high or low accuracy. Its chief advantage over methods now in use is that it permits the continuous observation or recording of resistance without error due to uncontrolled changes in the resistances of the connecting leads. Readings are obtained directly, without the necessity of averaging or otherwise mathematically combining the results of more than one observation. If desired, more than two resistances to be compared may be included in the circuit, provided they are alternated with an equal number of emf's and associated dropping resistors.
An ac Operated Portable Electrometer-Type Millivoltmeter
Authors: Schmitt Otto H. , Macpherson Cullen H.
Published: February 2005

A stable line-powered dc millivoltmeter is described which combines the advantages of a directly calibrated scale with the long-range accuracy of a precision potentiometer. Fractional millimicroampere current drain and a full-range scale of ±1 volt with 1-millivolt sensitivity at all settings makes the instrument unusually useful for biophysical, electrochemical, and physical measurements.
Apparatus for Studying Friction and Sliding Electrical Contacts
Authors: Flom D. G.
Published: February 2005

Apparatus for the study of friction and sliding electrical contacts is described in detail. The equipment is designed for precise atmospheric control, a feature proven to be essential in any study of sliding contact phenomena.

Examples are given of the type of results obtained with this apparatus when used in frictional studies. The kinetic friction is recorded by a sensitive strain gauge system which indicates transient effects, due to the variations in surface conditions, within a single revolution of the test cylinder under the rider.
Circuit for the Determination of Contact Potentials and Electron Temperatures from Retarding Field Characteristics
Authors: Friedman Seymour , Heynick Louis N.
Published: February 2005

A new circuit for the measurement of contact differences of potential and electron temperatures of electron tubes is presented. Its basis is the retarding field equation for plane-parallel diodes. Its use on tubes of concentric-cylindrical geometry is discussed in conjunction with the errors involved in such measurements, indicating its applicability to most tubes of interest.
Analog Computer for Nonlinear Coordinate Transformation
Authors: Fritz Norman L.
Published: February 2005

Transformations in multicomponent analysis frequently are better represented by second-degree simultaneous equations than by the usual linear equations. For problems requiring repetitive evaluation of a set of equations in which the coefficient terms do not change, an analog computer can be used to obtain the results both rapidly and accurately. A computer is described which will evaluate three second-degree equations, each of ten terms, as rapidly as an operator can set the input data on the dials, and with an accuracy better than 0.2 percent of the maximum value.
Friction Apparatus for Very Low-Speed Sliding Studies
Authors: Heymann F. , Rabinowicz E. , Rightmire B. G.
Published: February 2005

The phenomenon of stick-slip, which manifests itself in the squeaking of rubbing surfaces and is of considerable practical importance, can be advantageously studied at very low sliding speeds. An apparatus has been developed in which a flat surface is driven at speeds on the order of 10−7 to 10−4 cm/sec, the driving force being a weight. The speed is controlled by the viscous drag of a paddle in a bath of pitch. There is no appreciable elastic restraint in this drive, so that stick-slip vibration of the moving surface does not occur. A stationary rider is pressed against the moving surface by a dead weight. The friction is measured by the elastic deflection of a ring, the stiffness of which controls the tendency of the rider toward stick-slip vibration. Results are briefly described.
Liquid Hydrogen, Deuterium, and Helium Target for Use with High-Energy Machines
Authors: Whalin E. A. , Reitz R. A.
Published: February 2005

A well-localized target of hydrogen, deuterium, or helium has been developed for use with the University of Illinois 300-Mev betatron. The liquefied target gas is contained in a thin-walled brass cylinder in contact with a low-temperature reservoir. For hydrogen and deuterium targets the reservoir contains hydrogen, while for a helium target the reservoir contains helium. Target cylinders of 1.25-inch diameter with 0.0005-inch walls and 2-inch and 4-inch diameter with 0.001-inch walls have been used giving proton and meson backgrounds from the cylinder walls of less than 10 percent. A liquid nitrogen cooled radiation shield surrounds the target and reservoir. The nitrogen shield and the vacuum jacket enclosing it have thin windows allowing one to study the production of protons of energy >20 Mev and mesons of energy >7 Mev. From the 3 liter reservoir the loss rate of liquid hydrogen is 40 ml per hour and of liquid helium is 250 ml per hour.
Use of the Hot-Wire Anemometer as a Triggering and Timing Device for Wave Phenomena in a Shock Tube
Authors: Dosanjh Darshan S.
Published: February 2005

The hot-wire anemometer is principally used for turbulence investigations in both subsonic and supersonic flows. Its use has been extended to the observation of transient phenomena in shock tubes. Since its sensitivity to different phenomena varies, depending upon the operating conditions, the hot wire is quite well suited for timing very weak as well as strong travelling shock waves. A triggering and timing arrangement was developed pointing to further improvement. It was found that the hot-wire trigger is a reliable instrument under widely varying shock tube operations.
Berkeley Proton Linear Accelerator
Authors: Alvarez Luis W. , Bradner Hugh , Franck Jack V. , Gordon Hayden , Gow J. Donald , Marshall Lauriston C. , Oppenheimer Frank , Panofsky Wolfgang K. H. , Richman Chaim , Woodyard John R.
Published: February 2005

A linear accelerator is now in use which increases the energy of protons from a 4-Mev Van de Graaff injector to a final energy of 31.5 Mev. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.1×106 watts peak at 202.5 Mc. Acceleration is made possible by the introduction of 46 axial ``drift tubes'' into the cavity, which is designed so that the particles traverse the distance between the centers of successive tubes in one cycle of the rf power. The proton bunches are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high-powered oscillators fed from a pulse generator of the artificial transmission line type. Output currents are 3×10−7 ampere, average, and 60 μa, peak. The beam has a diameter of 1 cm and an angular divergence of 10−3 radian.
Proton Linear-Accelerator Injector for the Bevatron
Authors: Cork Bruce
Published: February 2005

The Bevatron requires an intense source of high-energy protons. The machine should accept monoenergetic protons for a duration of approximately 500 microseconds once every 6 seconds. To satisfy the requirements of small loss due to scattering by the gas in the accelerating chamber, a 9.9-Mev linear accelerator has been built and operated.

A 500-kilovolt Cockcroft-Walton generator is used to inject 3-ma peak proton current into the linear accelerator. Focusing grids intercept approximately half of the injected beam. Additional losses, including radial defocusing and acceptance phase angle, result in a peak accelerated beam of 225 microamperes. The energy spread of the accelerated protons has not been measured, but an upper limit is less than ±30 kev.
A Nonsaturable High-Energy Beam Monitor
Authors: Tautfest G. W. , Fechter H. R.
Published: February 2005

A monitor for high-energy beams of charged particles utilizing the phenomenon of secondary emission is described. The primary beam to be monitored passes through a set of foils alternately phased in voltage. The current produced by secondary electrons ejected by the beam passage is collected onto the one set of foils and measured. Results of tests with high-energy electrons are given. The monitor gives no indication of saturation up to peak current densities of 16 ma/cm2, and is independent of the primary beam energy in the range over which the monitor was tested (111–235 Mev).
Range of 208±4-Mev Protons in G5 Nuclear Emulsion
Authors: De Carvalho Hervasio G. , Friedman Jerome I.
Published: February 2005

A range curve of the external beam of the University of Chicago synchrocyclotron was taken in G5 stripped nuclear emulsion. The range of this beam in copper was also measured in order to determine its energy. Having a mean range of 41.1±0.1 g/cm2 of copper, the beam had an energy of 208±4 Mev according to Aron's tables. The mean range of the same beam in G5 nuclear emulsion at 47 percent relative humidity was 41.3±0.2 g/cm2 which is about 1.2 percent longer than that from Heinz's measurements and about 1.3 percent shorter than that calculated by Vigneron. At 47 percent relative humidity the average density of the emulsion was measured to be 3.85±0.01 g/cm3, in good agreement with the calculations of Wilkins.
Proportional Counting of Carbon Dioxide for Radiocarbon Dating
Authors: Brannon H. R. , Taggart M. S. , Williams M.
Published: February 2005

Determinations of naturally occurring radiocarbon have been made with proportional counters filled with carbon dioxide at pressures up to 10 atmospheres. After chemical and radiochemical purification, the sample is converted into carbon dioxide for the counter filling. Extreme purity is required of the counter filling gas to prevent electron electron attachment by impurities. Procedures are described for producing carbon dioxide of sufficient purity to provide consistent and reproducible results. A counting efficiency of 100 percent is obtained for carbon-14 betas contained in the active volume of the counter, giving a sample counting rate for the counter used of 45 cpm for contemporary material at a filling gas pressure of 10 atmospheres. With the present background of 13.5 cpm and a counting time limit of two days, dating may be extended to a maximum age limit of 42 000 years.
Electron Accelerator and High Resolution Analyzer
Authors: Blackstock A. W. , Birkhoff R. D. , Slater M.
Published: February 2005

The principle of energy measurement by stopping potential has been extended to high-energy electrons, using conventional accelerating tubes. Defocusing effects which occur during deceleration are minimized by employing a low energy cylindrical electrostatic analyzer to measure the energy remaining in the beam after deceleration has been almost complete. The width of the line profile obtained by this technique appears to be largely independent of the primary energy of the electrons, the percent resolution thus improving as the primary energy is increased. Resolution up to 20 parts per million at 100 kev is obtainable by this method.
Measurement of Electronic Susceptibilities by Means of Nuclear Resonance Absorption
Authors: Feher G. , Knight W. D.
Published: February 2005

The proton nuclear magnetic resonance is observed in two crossed capillary tubes embedded in a paramagnetic material in a constant external field. The resonance frequencies from the two capillaries depend on the respective demagnetizing factors. For Mn2O3 the two resonance lines are separated by 13.0 kc at 22.3 Mc, giving a mass susceptibility of 65×10−6 cgs, in agreement with values obtained by other methods. For a magnetic field homogeneity of about one part in 107 over the sample, the ultimate sensitivity of the method would be 10−7 to 10−8 susceptibility unit. Measurements can be made at low temperatures.
Resolution of Alpha-Particle Spectra by Ionization Pulse Analysis of Collimated Samples
Authors: Engelkemeir D. W. , Magnusson L. B.
Published: February 2005

A high-resolution ion pulse analyzer has been developed for the study of alpha-decay fine structure. Alpha-particle spectra are distorted in conventional high geometry measurements by addition of ionization from excited-state radiations of the daughter atom. Covering the sample foil with electroformed nickel mesh of a few mils thickness proved to be an effective technique for collimating the alpha particles and absorbing coincident excited-state radiations. The resolution of the instrument was tested with samples of Bi212, Th230, and Pu238. The measured intensities and particle energies are in satisfactory agreement with magnetic deflection data. Alpha peak standard deviations of 12–13 kev were obtained at a detection efficiency of 0.04 count per disintegration. The standard deviation due to amplifier noise alone amounted to 10 kev.
Instrumentation for the Continuous Measurement of Certain Ionospheric Echo Characteristics
Authors: Parkinson R. W.
Published: February 2005

A method is described for continuously measuring the polarization and other parameters of radio pulse echoes reflected from the ionosphere in very compact form. Time-varied intensity modulation is employed to resolve split echoes with respect to height of reflection.
New Time-of-Flight Mass Spectrometer
Authors: Katzenstein Henry S. , Friedland Stephen S.
Published: February 2005

A time-of-flight mass spectrometer based on principles previously described has been constructed with two major modifications to facilitate appearance potential measurements. These modifications are (1) an axial electron beam is pulsed through an ionization chamber utilizing techniques of Fox, et al., and (2) a gated ion detector is employed to allow for integration of the resolved ion current from successive cycles. The instrument has been constructed of stainless steel to allow for measurements on chemically active gases. Theoretical resolution, limited by thermal energies of the ions, appears to be well over mass 200. Preliminary experimental work has verified this up to the region of mass 100. Ionization potentials, using the difference method, have been obtained from various gases that are in agreement with the spectroscopic data to within 0.05 volts.
Automatic Isodose Recorder
Authors: Berman M. , Laughlin J. , Yonemitsu M. , Vacirca S.
Published: February 2005

An apparatus is described which compares the signals developed by two detectors. An application is the measurement and plotting of the distribution of radiation energy produced by x-ray generators. Measurement of the radiation energy is made with ionization chambers or scintillation counters as detectors, the signals of which are amplified with dc amplifiers. The noise level of the amplifiers is equivalent to a current of about 5×10−15 amperes when used with an input resistor of 1011 ohms. The ratio of the outputs of the two detectors is obtained directly, using a servo system which compares a fraction of the larger signal with the smaller one. The accuracy and reproducibility of the balancing circuit is better than 0.2 percent. The minimum detectable signal is less than 0.1 millivolt. The same servo system is also employed to control the motion in space of one of the detectors (a probe) so as to seek a position such that its signal is any preselected portion of the other detector's (monitor) signal. Thus, a path of constant energy is traversed by driving the probe perpendicularly to the direction of the x-ray beam and controlling the position parallel to the beam through the servo system. The trace of the path of the probe is simultaneously duplicated and recorded on a chart. The mechanical reproducibility of the detector position and plotting mechanism in any direction is better than one millimeter. The application of the apparatus for the automatic determination and recording of isodose contours produced in water by the absorption of x-ray beams of widely different energies is outlined.
Absolute Electrostatic Voltmeter of Hemispherical Concentric Electrodes
Authors: Malpica José Mireles
Published: February 2005

The resultant force of electrostatic attraction between two concentric hemispherical electrodes can be determined rigorously, and it is a suitable arrangement for an absolute electrostatic voltmeter.

The curved electrodes have great mechanical rigidity and constancy of form.

Stability of balance between the electrostatic and mechanical forces, elimination of the error introduced by the width of separation between the moving electrode and the guard electrode, and other unexpected advantages were obtained by their use.
Some Characteristics of Chlorine Quenched Geiger-Mueller Counters
Authors: Ward A. L. , Krumbein A. D.
Published: February 2005

Extensive studies have been made of the starting potentials and plateau characteristics of chlorine-quenched neon and argon counters with titanium and zirconium metal cathodes, using a previously described optical absorption method to measure the concentration of the halogen in the presence of the rare gases. An equation of the type first formulated by Lauterjung for the starting potentials of organic-quenched counters, has been found to hold for chlorine-quenched counters. The constants in this equation have been determined for the counter fillings and cathodes used. A nomograph has been drawn which enables the starting potentials of neon-chlorine counters to be determined for various counter dimensions, total gas pressures and percentage of chlorine. From the deviations of the experimental data from straight lines at high E/p, an estimate has been made of the behavior of α/p (α is Townsend's first coefficient), for neon and argon at higher E/p values than those which are given in the literature. The consideration of secondary Townsend processes gives a new interpretation of the Lauterjung constants. The plateau length of counters filled to a constant total pressure was found to increase linearly with an increase in chlorine concentration. Plateau slopes have been found to decrease initially with increasing chlorine concentration, then to remain constant. Normally, it has been found to be of no advantage to add argon to a neon-chlorine counter.
ZnS(Ag) Phosphor Mixtures for Neutron Scintillation Counting
Authors: Koontz P. G. , Keepin G. R. , Ashley J. E.
Published: February 2005

Various zinc sulfide phosphor mixtures for neutron scintillation counting have been compared. Selected compounds of hydrogen, lithium, boron, and fissionable elements were mixed in varying proportions with ZnS(Ag), and the corresponding neutron and gamma counting efficiencies measured as functions of energy. The low sensitivity of these mixtures to gammas (10−5−10−4 percent) and the measured short time decay constant (τ=0.04 μsec) offer distinct advantages for fast neutron counting.
X-Ray Diffractometry of Radioactive Samples
Authors: Kohler T. R. , Parrish William
Published: February 2005

Geiger counter x-ray diffractometer patterns of samples with moderate to high radioactivity give a high background, which reduces the precision of the x-ray-line intensity and profile measurements. The large amount of lead shielding required to reduce the background is not practical in modern precision goniometers and could not bring as great a reduction as can be achieved with scintillation or proportional counters using pulse-height discrimination and no shielding. This paper describes a technique using a scintillation counter which permits the measurement of x-ray patterns from strongly radioactive specimens. A scintillation counter with 0.56 in.×0.16 in.×0.017 in. thick NaI·Tl crystal, 0.005 in. Be window and DuMont 6291 photomultiplier is described, which reduced the background of an 84 mr/hr/10 cm Co60 sample from 785 c/sec, measured with a Geiger counter, to 26 c/sec and increased the sensitivity to CuKα by a factor of about 2.5 to 3.
Instrument for the Direct Measurement of Angles in the Field of View of the Naked Eye
Authors: Boerdijk A. H.
Published: February 2005

The instrument described contains an illuminated scale of which a virtual image is formed at infinity by means of a spherical mirror and a glass plate. The image of the scale is superimposed on the normal field of view of the naked eye, enabling direct measurement of angles in that field.
Low-Temperature Absorption Cell for the Cary Recording Spectrophotometer
Authors: Geiger F. E.
Published: February 2005

A metal absorption cell is described for the measurement of absorption spectra of alkali-halide crystals at low temperatures. The cell is specifically designed for the Cary automatic-recording spectrophotometer. The crystal holder of the cell can also be heated electrically to several hundred degrees centigrade for crystal bleaching experiments, or rotated out of the spectrometer beam to expose the crystal to x-rays. Design and performance data are given.
Amplifier for 5734-Tube Bristle Flowmeter
Authors: Praglin Julius , Brecher Gerhard A.
Published: February 2005

An amplifier and power supply for a stable, high-frequency, electronic, bristle flowmeter is described. The transducer element is the RCA 5734 tube. The difficulty in applying this tube to blood flow measurements is overcome by use of a 500 000 ohm load resistor instead of the 75 000 ohm value recommended by the manufacturer. The advantages of this device are commercial availability of flow-sensing element, high signal-to-noise ratio, good maintenance of the zero flow base line, response to backflow as well as forward flow, and provision for the recording of either phasic or mean flow.
Instrumentation of the Rocket-Grenade Experiment for Measuring Atmospheric Temperatures and Winds
Authors: Stroud W. G. , Terhune E. A. , Venner J. H. , Walsh J. R. , Weiland S.
Published: February 2005

The temperatures and winds in the upper atmosphere have been measured by means of the Aerobee sounding rocket. The determination of the velocity of sound between grenades ejected from the rocket and exploded at successive heights measures the temperatures. The angles of arrival of the sound waves at the ground are used to determine the winds. The experimental method is outlined and the rocket-borne and ground instrumentations are described. A summary of the rocket firings carried out is also given.
New Fluorescence Photometer
Authors: Lynch Frank J. , Baumgardner James B.
Published: February 2005

An instrument for microanalytical analysis by a fluorescence method which is sensitive, linear, and stable is described. Both an unknown and a reference sample of the same constitution are excited to fluorescence by ultraviolet light emitted in pulses by an ac powered mercury arc lamp. The resulting pulsed fluorescent light from each sample is incident on a separate vacuum phototube. The ratio of the fundamental ac components of the photoelectric currents flowing in the two phototubes is measured automatically by a servo-mechanism. In such a system, the measurement is independent of the intensity of the exciting ultraviolet light, the thermionic currents of the two phototubes, and the temperature of the fluorescent samples. A simplified optical system provides good efficiency. Either solid or liquid samples may be rapidly measured. For uranium analysis the instrument may be calibrated to read full scale for 5·10−10, 5·10−9, 5·10−8, and 5·10−7 gram of uranium. Although it is designed primarily for uranium analysis, the filters may be changed to permit measurement of other materials which can be analyzed by fluorescence methods.
Apparatus for Measuring Complete Single-Crystal X-Ray Diffraction Data by Means of a Geiger Counter Diffractometer
Authors: Furnas Thomas C. , Harker David
Published: February 2005

A device for measuring x-ray diffractions from a single crystal is described. The heart of the apparatus is an ``Eulerian Cradle,'' so named because it permits rotation of the crystal about each of the Eulerian axes. It is used for orienting single crystals in an x-ray beam, in order to bring each reciprocal lattice point into the equatorial plane for Geiger counter measurement of the intensity. It eliminates the need for raising the Geiger tube out of the equatorial plane and suggests that the reciprocal lattice be surveyed by either ``zone'' or ``cone'' schemes. These are described, and the ``cone'' scheme is shown to permit a complete hemisphere of the reciprocal lattice to be surveyed with only a single mounting of any crystal. Fine points concerning the use of the apparatus in the precise orientation of a crystal, and for the measurement of integrated intensities at single settings, are given. All angular motions are controlled by worm wheels and worms with dials for direct reading to 0.01°. Data collection is further facilitated by computing appropriate angular coordinates for reciprocal lattice points from an accurate set of lattice parameter measurements (readily obtained with the same instrument) and setting the various circles accordingly. The long spacings, characteristic of protein crystals, require both the high precision of this instrument and computed coordinates for the many thousands of reflections that must be measured.
Electrical Analog Computing Machine for Solving Linear Equations and Related Problems
Authors: Mitra Samarendra Kumar
Published: February 2005

A new iteration method of solving linear equations is described. The convergence of this method depends on a single scalar parameter which can be predetermined. A brief description of an electrical analog machine for solving linear equations with ten variables based on this iteration method is given. In addition to the solution the machine gives the largest eigenvalue of the matrix of the linear system.
Formation of Thin Films of BaTiO3 by Evaporation
Authors: Feldman Charles
Published: February 2005

Ferroelectric films of BaTiO3 approximately 1 to 2 microns thick have been formed on platinum substrates by evaporation in a vacuum and a subsequent heat treatment in air. The structure of the crystallites which make up the films is mainly perovskite with the hexagonal phase as a minor constituent. Dielectric measurements show that the Curie temperature is about 120°C. The sharpness of the Curie transition depends to a large extent on the size of the BaTiO3 crystallites. The structure of the film seems to influence the dielectric constant and the saturation and remanent polarization of the film.
Automatic-Reading Viscosimeter
Authors: Junkins J. H.
Published: February 2005

An automatic-reading capillary-type viscosimeter has been constructed for measuring the relative viscosities of gases. The measurement of the viscosity is made in terms of the time required for the pressure exerted by a charge of gas in the capillary forechamber to decrease from one fixed value to a second fixed value, while the gas flows through the capillary into a constant pressure vessel. Computation of the absolute viscosity is based on the following relationship between the time t for gas A whose viscosity n is known, and the time for gas B whose viscosity is being determined: tgas Angas A=tgas Bngas B. Pneumatic and electrical instruments are employed to (1) control the temperature of the bath in which the capillary is suspended, (2) maintain a constant pressure in the capillary exit vessel, and (3) actuate the timer which measures the interval corresponding to a given pressure drop in the capillary forechamber. The performance of these instruments is completely automatic, and primarily in this respect the apparatus described differs from manually-operated expiration-type capillary viscosimeters. Small groups of consecutive measurements (e.g., five runs on dry nitrogen at 65.0°C) yield readings which deviate from the mean value by the order of 7 parts in 10 000.
Measurement of Magnetic Field Gradients
Authors: Frazer J. F. , Hofmann J. A. , Livingston M. S. , Vash A. M.
Published: February 2005

A simple instrument for measuring magnetic field gradients with one-half percent accuracy is described, consisting of a small search coil vibrated at 100 cps by a loudspeaker. The application of this instrument to field gradient measurements on a magnet with hyperbolic pole pieces is described, together with some considerations on constant gradient shimming.
Adiabatic Calorimeter for Measuring Heats of Solution at Room Temperature
Authors: Benson G. C. , Benson G. W.
Published: February 2005

An adiabatic calorimeter suitable for measurements of heats of solution in the vicinity of room temperature is described. The calorimeter vessel is hermetically sealed and suspended in a vacuum surrounded by a water jacket. The whole assembly is capable of rotation through 180° to initiate the solution process and to stir the contents. Temperatures are measured with a multijunction copper-constantan thermocouple, temperature changes of 10−4°C being detectable. The performance of the calorimeter is illustrated by some results for sodium chloride in water at 25°C. These are in reasonable agreement with the data of other workers and appear to be more self-consistent.
Measurement of High Permittivity Dielectrics at Microwave Frequencies
Authors: Harris Frank E. , O'Konski Chester T.
Published: February 2005

Apparatus is described for measurement of the complex dielectric constant of liquids of high permittivity in the range from 1 to 10 cm wavelength. The method is chosen for sensitivity in the region of high permittivity and requires no moving parts or measurements within the sample. Transmission coefficients of samples contained between mica windows in short sections of wave guide are measured by mixing the wave transmitted through the sample with a wave of fixed amplitude and phase traveling in the opposite direction. The resulting standing wave pattern is detected with a traveling probe. Equations are given relating primary data with dielectric properties of the samples, and solutions are obtained by graphical means.
Twin Knudsen Effusion Apparatus for Small Samples of Radioactive Materials
Authors: Carniglia Stephen C. , Cunningham B. B.
Published: February 2005

A twin Knudsen apparatus for the measurement of vapor pressures is described. The apparatus has been employed in the temperature range 1140–1412°K, using approximately one milligram samples of PuF3, AmF3 and Am metal. Radiometric assay of condensed effusates yielded vapor pressure data in the range ∼5×10−7 mm to ∼2×10−3 mm that were internally consistent within a mean deviation of ±5 percent. The apparatus is particularly suitable for the determination of small differences in vapor pressure of similar substances.
Technique of Microautoradiography for Metal Specimens
Authors: Plumb Robert C.
Published: February 2005

A microautoradiographic technique which may be used with aluminum alloys is described. It is shown capable of producing a resolution of at least 9 microns with x-radiation and supplying quantitative information as to the distribution of radioactive material in a metallurgical structure.