bluuebunny/crossref_metadata_2025 huggingface dataset:
A High Temperature X-Ray Diffraction Camera
Authors: Edwards James W. , Speiser Rudolph , Johnston Herrick L.
Published: February 2005

A high temperature x-ray powder diffraction camera has been designed to yield patterns at temperatures in excess of 2500°K. The sample, in form of a wire, compacted rod, or contained (wherever suitable) in a thin walled quartz or ceramic tube, is heated indirectly by conduction and radiation in a thin walled molybdenum, tantalum, or platinum furnace. The furnace is heated by high frequency (0.5 megacycles) eddy currents induced by a small induction coil. The cylindrically shaped furnace and the sample are held coaxially in the induction coil and slowly revolved. The specimen temperature is maintained constant to ±0.2 percent by an especially designed temperature regulator. A water-cooled copper jacket with slots covered with metal foil to filter the diffracted x-radiation surrounds the furnace and is used to protect the x-ray film from heat and light. The temperature of the specimen is measured with a disappearing filament optical pyrometer at temperatures in excess of 1100°K and a platinum, platinum-rhodium thermocouple at lower temperatures. The camera is either operated with a high vacuum or with an inert gas atmosphere.
Ionization Flame Detectors
Authors: Calcote Hartwell F.
Published: February 2005

Two new ionization methods of detecting flames are described for use in the measurement of flame speeds. In one the loading characteristics of a high frequency oscillator are utilized by causing the flame to pass through an oscillator tank coil. The second method employs the flame conductivity by placing two ring electrodes around the exterior of a combustion tube, and applying a d.c. voltage across them through a large series resistance. The voltage pulse created by either method when the flame passes the detector is used to trigger an electronic chronoscope.

Both methods have the distinct advantage over previous methods of flame detection in that the direct measurement of flame speeds can be made without the introduction of electrodes or wires into the combustion tube. The oscillator detector has the additional advantage that the point at which the measurement is made can be varied at will.
A Simple Calorimeter for the Simultaneous Determination of Heat Loss and Heat Production in Animals
Authors: Prouty Lawrence R. , Barrett Martha J. , Hardy James D.
Published: February 2005

This paper describes a new type of gradient calorimeter which permits the rapid simultaneous measurement of respiratory metabolism and heat loss. It uses the temperature difference between the inner and outer aspect of a fixed transitional layer of air rather than adiabatic principles. (W. O. Atwater and F. G. Benedict, ``A respiration calorimeter with appliances for the direct determination of oxygen,'' Publication 42, Carnegie Institute of Washington (1905); G. Lusk, Arch. Int. Med. 15, 793 (1915); E. F. DuBois, Basal Metabolism in Health and Disease (Lea and Febiger, Philadelphia, 1936), third edition; Forester, Ferris, and Day, Am. J. Physiol. 146, 600 (1946); L. Love and H. C. Bazett, Fed. Proc. 7, 74 (1948); C. P. Yaglou, ``Thermal insulation of clothing,'' unpublished data; T. Benzinger, personal communication.) Application of gradient principles to calorimetry so simplifies heat loss determinations that they become the easiest and most accurate part of the procedure.
The Regulation of Temperature in the Application of High Frequency Induction Heating to Thermodynamic Measurements
Authors: Speiser Rudolph , Ziegler George W. , Johnston Herrick L.
Published: February 2005

An apparatus to regulate the elevated temperatures produced by high frequency induction heating is described. The regulation is achieved by varying the inductance in series with the work coil in such a way as to hold the current through the work coil constant. Except for a negligible error due to a small percentage change in frequency, the energy transferred to the work (in applications described in this paper) can be held constant.
Magnet Coils
Authors: Coonrod L. G. , Cecconi W. E. , Gedraitis C. , Harper K. R. , Lewis R. M.
Published: February 2005

Methods of winding magnet coils using copper tape as the current-carrying element are described. Difficulties with unsatisfactory arrangements are pointed out. One satisfactory system is described in detail, providing an efficient design for magnet winding to yield relatively high copper cross section while permitting the removal of heat at a high rate.
Design for a Metal Mass Spectrometer Tube
Authors: Hickam W. M.
Published: February 2005

A 90° sector type mass spectrometer tube made of Monel is described. The design is such that the electrode assemblies and analyzer section are easily removable without destroying the slit alignment. A double gasket arrangement is used for making the necessary high vacuum seals. The tube can be operated at an elevated temperature with no cold spots which is particularly desirable for degassing and for studying samples which have low vapor pressures. Operation of the analyzer section at any desired potential with respect to ground is permitted.
Rotor Balancing with an Electronic Capacitor Gauge
Authors: Warshaw H. D.
Published: February 2005

A variable air-gap capacitor is formed between an unbalanced rotating member and a stationary plate. The output of an oscillator is modulated in accordance with the variations in air gap, the modulated wave being displayed on the screen of a cathode-ray oscilloscope for continuous observation. Cyclic displacements at the periphery of the rotor of 0.0005 in. are easily detected. A contactor on the rotor shaft provides the means for locating the point of unbalance.
The Counting Volume of a Cylindrical Ionization Chamber
Authors: Blachman Nelson M.
Published: February 2005

The effect on the electric field inside a circular-cylindrical ionization chamber of the end plates is determined. The field lines terminating on the collecting wire at the ends of the guard sleeves determine the volume in which the freed electrons are collected by the wire. Formulas and a graph for determining this counting volume are exhibited. In appendices effects of the sleeves are considered, and the inverse-square integral evaluated for both cylindrical and spherical ionization chambers.
An Instrument for Rapid Determination of Crystal Orientation
Authors: Gillette R. H. , Jellinek M. H.
Published: February 2005

The rapid orientation of crystals is accomplished by the use of an apparatus employing a Geiger counter and x-ray focusing. The instrument can be used for precise orientation or to sort samples into various tolerance ranges. Applications to sapphire are discussed in detail. The instrument has also been used in connection with rutile and barium titanate orientations.
Characteristics of Halogen Counters
Authors: Liebson Sidney H.
Published: February 2005

Some characteristics of halogen counters have been obtained which enable their preparation for given operating voltages. Other factors influencing their behavior are discussed with a view toward obtaining optimum results.
A Circuit for the Study of the Operation of the Geiger-Müller Counter
Authors: Guimarães Mario Alves , Sampaio Palmyra Amazonas
Published: February 2005

The vacuum tube circuit described in this paper was designed in order to measure the effective dead-time (σ′) of a Geiger-Müller counter and, the probability (α′) of occurrence of spurious discharges within a given interval of time (ζ—σ′) after an initial discharge. The experimental results obtained permit, by means of an adequate formula [M. A. Guimarães, Thesis for Doctor's degree, to be published], the determination of (α′) and, in some cases, (σ′).
Magnetic Susceptibility Balance for Use at Liquid Helium Temperatures
Authors: McGuire T. R. , Lane C. T.
Published: February 2005

Data are presented on the design and performance of an apparatus for the measurement of magnetic susceptibilities at the temperatures attainable with liquid helium. After extensive trials, the instrument has proved itself easy and reliable in operation and especially suited to measurements on small specimens.
A Large Cloud Chamber Using Rear Illumination
Authors: Cowan E. W.
Published: February 2005

A large cloud chamber is described that makes use of rear illumination by means of a transparent piston and back plate. This system of illumination is particularly advantageous for a large cloud chamber since the increase in the amount of scattered light for small angles of scattering from droplets reduces the total light required.
A Precision Automatic Electrometer
Authors: Seaton N. T.
Published: February 2005

A triple-range portable electrometer suitable for the precision measurement of currents of the order 10−11 to 10−14 amp. is described. Current is measured in terms of the automatically registered time interval required to charge a condenser up to a certain voltage. The use of negative feedback and special operating conditions for the input FP-54 Pliotron allow current to be simply determined to within 0.1 percent. Radio-type dry batteries, which operate the instrument completely except for a timer, are contained within the amplifier and will last at least 250 hours.
Syringe Oxygen Cathode for Measurement of Oxygen Tension in Solution and in Respiratory Gases
Authors: Tobias Julian M. , Retondo Nadine
Published: February 2005

A method is described for measuring oxygen tension in Ringer solution which utilizes the principle of the polarograph, but substitutes a platinum wire cathode for the usual dropping mercury electrode. The wire cathode and a calomel anode are mounted in the piston of a hypodermic syringe into which the solution is aspirated for analysis. Sensitivity and reproducibility are evaluated. Extension of the method to the analysis of gaseous oxygen is also described.
A Precision Vacuum Gauge
Authors: Fryburg G. C. , Simons J. H.
Published: February 2005

A pressure measuring device of the general type first described by Knudsen has been constructed for obtaining precision measurements of gaseous pressures in the range from 1×10−5 to 10−3 mm of Hg. The instrument has been calibrated, with the aid of a McLeod gauge, in nitrogen, hydrogen, oxygen, methane, ethylene, normal-butane, and iso-butane. The mechanical precision of the instrument seems to be better than plus or minus 0.5 percent and the accuracy of the above calibrations is probably of the order of plus or minus 1 percent. Calibration curves for the above gases have been treated analytically and equations for the different gases have been discussed. An empirical method of calibration has been described for calibrating the instrument in condensible gases whose pressures cannot be measured in a McLeod gauge.
The Scintillation Counter. I. The Existence of Plateaus
Authors: Robinson Lawrence B. , Arnold James R.
Published: February 2005

A method has been developed whereby inorganic phosphors can be mounted on a photo-multiplier tube in thin films. The ZnS:Ag phosphor is quite satisfactory for use in conjunction with the 931A photo-tube. Plateaus have been established similar to those associated with Geiger-Müller counter tubes and the associated circuits.
The Use of Multigrid Tubes as Electrometers
Authors: Prescott J. R.
Published: February 2005

The use of several types of multigrid tubes as electrometers has been investigated. They are shown to possess a number of advantages. Details are given for the 6BE6 and 7A8. Grid currents of between 10−13 and 10−14 amp. are obtainable with mutual conductances of the order of 5 microamp./volt and an amplification factor of 300.
An Improved Synchronous Detector
Authors: Michels Walter C. , Redding Esther D.
Published: February 2005

The synchronous amplifier design of Michels and Curtis has been modified to minimize feedback and so to allow preamplification and high sensitivity. The resulting instrument has a voltage sensitivity of 2×105 mm/volt with an inductive input impedance of 2×106 ohms. The frequency selectivity is sufficiently sharp so that the band width is of the order of 0.25 c.p.s. at 800 c.p.s. Advantages and disadvantages of the synchronous detector are discussed.
Counting with Geiger Counters
Authors: Newell Homer E. , Pressly Eleanor C.
Published: February 2005

The coincidence rate of a perfectly efficient two-counter telescope is obtained in terms of the radiation intensity and the effective dimensions and separation of the counters comprising the telescope. Formulas are presented for the counting rate in a field of isotropic radiation and in a field where radiation varies with the zenith angle in accordance with a cosine squared law. By means of the formulas the counting rate may be located between an upper and a lower bound which in most practical cases differ by only a few percent. The information embodied in the formulas is also presented graphically in a form convenient for ready calculation of the ratio of coincidence rate to radiation intensity once the effective dimensions and separation of the counters are known.
Sample Scanning Mechanism for X-Ray Diffraction
Authors: Hickman J. W. , Kleinknecht A. G.
Published: February 2005

An automatic scanning mechanism is described for the study of preferred orientations in worked materials for pole figure representation. The device maintains a fixed specimen to film distance and permits tilting to 75 degrees from the normal to the beam about horizontal and vertical axes. The yoke support is constructed to clear conventional film holders so that close specimen to film distances can be obtained. The sample holder can be easily removed and adapted to suit any specimen as required. An area of 2.38 square centimeters per hour is scanned when the beam is perpendicular to the plane of the specimen.
Design of Equipment for Thermal Studies
Authors: Teitel Robert J.
Published: February 2005

A versatile metallurgical furnace for high temperature investigations of metals and alloys is described. Its uses to conduct thermal analysis and thermal treatments on beryllium-iron alloys are described in detail. In order to apply thermal analysis to these alloys, a special thermal crucible was designed and found successful.
Preparation and Use of Tritium and Deuterium Targets
Authors: Graves E. R. , Rodrigues A. A. , Goldblatt M. , Meyer D. I.
Published: February 2005

Methods are described for preparing Ta–H and Zr–H targets for economic use of tritium. Ratios of hydrogen isotope to metals of about 1.0 were obtained. The use of these targets under deuteron bombardment is discussed.
A Fast Recycling Cloud Chamber and Pulsed Magnetic Field Equipment for Use with Pulsed Accelerators
Authors: Gaerttner E. R. , Yeater M. L.
Published: February 2005

The objective of the work described here has been the development of cloud-chamber apparatus for use with new high energy pulsed accelerators, such as the present 100-Mev betatron and the 300-Mev synchrotron now being constructed by the General Electric Company. The present cloud chamber is operated at a repetition period of about 5 seconds. An ``overcompression'' step in the cloud-chamber cycle causes old tracks to be evaporated by momentary heating of the gas through compression. A pulsed magnetic field of 12-milliseconds duration is used with this cloud chamber. The field is produced by discharging capacitors through Helmholtz coils. With these short current pulses, strong fields (20,000 gauss or more) are obtainable at fast cloud-chamber recycling rates with relatively small heating of the coils.
The Dynamics of a Synchrotron with Straight Sections
Authors: Blachman Nelson M. , Courant Ernest D.
Published: February 2005

The equations describing the ``betatron'' and ``synchrotron'' oscillations of a particle being accelerated in a synchrotron having straight sections are obtained. In particular, the relative increase in the ratio of either betatron-oscillation frequency to the frequency of revolution is found to be approximately half the ratio of the total length of straight sections to the orbit circumference. The effect of magnetic fringing fields is considered. With regard to the synchrotron phase oscillation, it is found that the criterion of non-relativistic adiabatic damping is no longer that n exceed ⅔ but that it exceed ⅔ by at least ⅓ of the ratio of the total length of the straight sections to the orbit circumference.
Operational Features of a New Electron Diffraction Unit
Authors: Picard Robert G. , Smith Perry C. , Reisner John H.
Published: February 2005

A new electron diffraction unit having a three-lens optical system and a maximum effective specimen-to-plate distance of 200 cm is described. The applications of such a system to the study of long interatomic spacings is discussed. Wide variations in the area of specimen irradiated are obtainable. An explanation is given of the design considerations in such an optical system, with special reference to the functioning of the post-specimen lens as both focusing and magnifying lens. The use of the unit as a shadow microscope is explained, and the advantages are given of this instrument over other shadow microscopes with respect to increased size of image, increased size of specimen field available for observation, and greater specimen protection from damage by the concentrated electron beam.

The resolution attainable with the instrument is calculated and a ``resolution index'' is defined which makes possible intercomparisons of resolution under various operating conditions. Factors which limit accuracy, as opposed to resolution, are discussed critically and the accuracy of data obtainable with the instrument is estimated.

A number of diffraction patterns are shown to illustrate the results obtained under various operating conditions as diffraction camera and shadow microscope, and also to illustrate the techniques of charge neutralization, spot diameter measurement, and internal calibration of plates using a known specimen.
An Apparatus for Electrode Reversal in the Tiselius Electrophoresis Equipment
Authors: Tint H.
Published: February 2005

An accessory to the standard Tiselius electrophoresis apparatus is described which permits electrode reversal during operation without changing the terminal polarity of the arms of the electrophoresis cell. It thus permits maintenance of the usual silver-silver chloride electrodes in optimum condition in runs of extended duration for critical analytical and preparative electrophoresis without increasing the physical dimensions or complexity of the electrode system. It incorporates a four-position, multiple-way valve, of Plexiglas construction, which is designed to be inserted at the position of the upper section of the standard cell, replacing it as a tubular transfer point of current between the electrode vessels and the limbs of the cell proper.
Operation of Voltage-Stabilizing Elements with Current-Stabilized Supplies
Authors: Gilvarry J. J. , Rutland D. F.
Published: February 2005

The performance parameters of a voltage stabilizer consisting of a voltage-stabilizing element (such as a VR tube) connected across the output of a current-stabilized power supply are determined and a particular parameter (the range-regulation factor Q) suggested as a figure of merit. The advantages of a current-stabilized over an ordinary supply from the standpoints of voltage stabilization and suitability for variable load are emphasized. Stability criteria for the case when the stabilizing element has a negative-resistance characteristic and a graphical analysis for the case of non-linear elements are given. Application to the special case of VR tubes is made with experimental results.
Calibration of Photographic Emulsions for Low Energy Electrons
Authors: Cranberg L. , Halpern J.
Published: February 2005

Measurements are reported for the dependence on energy of photographic darkening due to electrons of energies between 4.4 and 45 kev. For Ilford B-2 plates, in the linear density exposure region, the results can be expressed by the empirical formula D/Q/A=KEx. D is the photometric density, Q/A the exposure in electrons/mm2, E the energy in electron-volts; K and x are constants with the values (0.30±0.03)×10−12 and 1.45±0.05, respectively. The relationship for two other emulsions tested is complicated by the presence of surface coatings on the emulsions. Reproducibility of results is discussed.

Results are given on density fluctuations due to granularity of Ilford and x-ray emulsions. The limit of sensitivity, using the L. and N. recording microphotometer with scanning beam 1.0 by 1.3 mm, is estimated at 450 electrons/mm2 of 40 kev energy for the x-ray emulsion and 680 electrons/mm2 for the Ilford plates. The latter is limited by photometric sensitivity.
Inductance Apparatus for Diamagnetic Measurements
Authors: Broersma S.
Published: February 2005

Two types of inductance apparatus have been applied to the measurement of the susceptibility of diamagnetic compounds. With an alternating current apparatus, an accuracy of 0.1 percent of the diamagnetic effect, Δκ=0.7·10−8, has been obtained. The time of measurement was about 8 minutes. Liquids could be easily measured; solids would give no difficulties. In an apparatus with varying coefficient of inductance, the effect of a moving substance in a magnetostatic field was investigated. To date, its precision is a factor of 10 smaller than that obtained with the first apparatus.
A New Method for Surface-Temperature Measurement
Authors: Sasaki Nobuji
Published: February 2005

The surface temperature of a body is equal to the temperature of the measuring junction of a thermocouple, if this temperature has been, by heating or by cooling, so adjusted that the meter in the couple circuit does not deflect when the measuring junction makes a brief contact with the surface being measured. The validity of this principle was confirmed experimentally by measuring a surface whose true surface temperature was known independently. The new method does not sensibly affect the surface conditions as long as the junction is very small in comparison with the object being measured and the contact is short and light. It was shown that the temperature rise due to the proximity of the measuring junction was negligible in the case of a 0.4-mm thick glass sheet or the human skin. The new method can give the correct surface temperature even when radiation comes from above or from below. Consequently the opacity of the surface layer does not matter as in the case of the radiation pyrometry.
A Simple Pressure Balance
Authors: Swenson C. A.
Published: February 2005

Precise pressure measurement in the range from 5 to 100 atmos. is quite a difficult problem. A set of high pressure mercury manometers is very unwieldy and difficult to use, while Bourdon gauges require frequent recalibration and are inherently inaccurate. The most likely solution for this problem is to use a simple piston-in-cylinder pressure balance, which, for these pressures and for accuracies of the order of 0.05 percent, can be relatively crude, and does not require excessively precise machining or care in use. A simple pressure balance was constructed for use in the pressure range from 25 to 35 atmos., and used for both pressure measurements and density change determinations. It proved perfectly satisfactory, giving pressures reproducible from day to day to about 0.01 atmos.
Background Eradication in Thick-Layered Nuclear Emulsions
Authors: Wiener Martin , Yagoda Herman
Published: February 2005

A method for eradication of accumulated background on Ilford C-2 plates, 100–200μ thick, without reducing their sensitivity to medium ionizing particles, is described. The method involves a mild oxidation of the emulsion by air saturated with water vapor at 35°C for a period of about 16 hr. The plates are then dried and are ready for experimental exposure. Analysis of grain counts shows no loss of sensitivity in proton tracks over their last 200μ range when the plates are developed with a mild hydroquinone developer. Complete eradication of background alpha-tracks and stars is secured as well as destruction of latent images of the less ionizing proton recoils instigated by external neutron bombardment. Grain density studies on proton tracks located at different depths in the emulsion indicate substantially uniform sensitivity after eradication except for the uppermost 50μ which develop with about a 10 percent reduction in mean grain density as compared with tracks deep within the recording medium.
The Choice of Suitable Gap Forms for the Study of Corona Breakdown and the Field Along the Axis of a Hemispherically Capped Cylindrical Point-to-Plane Gap
Authors: Loeb Leonard B. , Parker James H. , Dodd E. E. , English William N.
Published: February 2005

The various corona gap forms suitable for the convenient investigation of corona phenomena of both signs in the laboratory that are capable of yielding quantitative data involving the Townsend integral for the thresholds of the manifold phenomena are discussed. For laboratory study the most convenient form of gap is the hemispherically capped cylindrical point-to-plane system. Analysis of the potential fall along the axis in such gaps by means of electrolytic model studies indicates that the essential parameter is L/r, the ratio of gap length, L, from point surface to plane relative to the point radius, r. The model study potentials are, however, incapable of giving accurate values of the field strength. These fields must be obtained by computation. Laboratory studies of corona indicate the desirability of relatively large values of L/r. Practical considerations based on studies at atmospheric pressure indicate point radii r of 0.025 and 0.05 cm with a ratio L/r=160 to be those giving the greatest flexibility and most widely separated thresholds at convenient potentials. The use of such point systems to standardize data is recommended. On this basis the field along the axis for the hemispherically capped cylindrical point-to-plane gap as computed by E. E. Dodd is given and here applied to the calculation of the point-to-plane Townsend integral for pre-onset burst pulse thresholds in air as observed by H. W. Bandel. The value is compared with the values obtained by W. N. English for confocal paraboloids where the fields are accurately known. The results are satisfactorily consistent. Discrepancies in the fixing of burst pulse thresholds by various observers are discussed.
Small Probing Geiger-Müller Counters
Authors: Robinson C. V.
Published: February 2005

Experiments with argon-ethyl acetate mixture in small counters are described. Details of construction are given for two designs of brain probing counters of 3- and 2-mm diameters.
Chart Recording of Microsecond Pulse Amplitudes
Authors: Dewan J. T. , Allen K. W.
Published: February 2005

A peak voltmeter circuit is described which will record, on an Esterline-Angus chart, the amplitudes of microsecond pulses generated at random in ionization chambers or similar counters. Slow response of the recording pen prohibits the resolution of pulses less than one second apart. Provision is made for selecting pulses coincident with some triggering event as the low counting rates suitable for the circuit are most often encountered in coincidence experiments. Coincidence resolving times as low as five microseconds may be attained, and the linearity is such that input pulse amplitudes from 2 to 100 volts are reproduced on the chart to within ±1 volt.
Precision Thermostat for High Temperatures
Authors: Eubank William R.
Published: February 2005

A precision thermostat has been developed, based upon that of Roberts, for the control of high temperatures (1000°—1550°C). With the instrument described, temperatures are readily maintained constant within ±0.1°C for several hours, and within ±1.0°C for several days.

In this method of control a thyratron is used in conjunction with an a.c. bridge and high gain amplifier. The phase angle of the unbalanced bridge regulates the firing of the thyratron. The control is highly sensitive and independent of normal fluctuations in line voltage. The thermostat is convenient to operate, easy to adjust for any temperature, and reliable for periods of continuous operation from a few minutes to several days.
An Apparatus for the Study of Electrets
Authors: Freedman Larry A. , Rosenthal Louis A.
Published: February 2005

An apparatus capable of continuously measuring and recording electret strength is described. It consists of a mechanically driven condenser whose induced voltage, due to the electric field of the electret, is filtered and amplified before being applied to a recorder. Some experimental observations of the transition from heterocharge to homocharge are presented.
Transmission of Beta-Rays by Nylon and Formvar
Authors: Heller R. B. , Sturcken E. F. , Weber A. H.
Published: February 2005

The percent beta-ray transmission by thin Nylon and Formvar films (windows) was studied to obtain experimental ``absorption'' corrections to be used with G-M counters employing such thin windows. It was found that window ``absorption'' included (1) energy loss of electrons traversing the films and (2) scattering of incident electrons by the film (a geometry effect). The results are plotted in several ways to exhibit the various factors involved and to permit easy use in applying the corrections. It was found that scattering of transmitted electrons was a factor of considerable importance, whereas the energy lost in traversing the film was not very important for the range investigated. The electron energy range investigated was limited to the region in which the ``absorption'' correction was considerable for the window thicknesses used. A scintillation counter was used as the detector, and the source of monoenergetic electrons was an electron gun with electrostatic focusing.
A Pulse Generator for the Millimicrosecond Range
Authors: Garwin R. L.
Published: February 2005

A description is given of a laboratory pulse generator producing pulses with rise and decay times less than 2×10−10 sec. at a repetition rate of 120/sec. Three simultaneous outputs are available, variable in amplitude from 100 microvolts to 100 volts and accurate to a few percent.
An Electrostatic Beta-Spectrograph
Authors: Hamilton Donald R. , Gross Leonard
Published: February 2005

A beta-ray spectrograph has been constructed in which electrons move radially outward against a retarding electric field, and the current due to those electrons having more than any given energy is measured. Momentum resolution is one-third percent. The insensitivity of current collection, as compared to single particle detection, is compensated by a large tolerable source area and a large useful solid angle subtended at the source by the detector.
A Capacitance Bridge for High Frequencies
Authors: Mendousse J. S. , Goodman P. D. , Cady W. G.
Published: February 2005

A type of bridge for measurements at frequencies in the megacycle range is described, containing two fixed capacitors and a variable capacitor. The unknown impedance is connected in the fourth arm as a ``load.'' The unbalanced high frequency e.m.f. is rectified by a germanium crystal rectifier and measured as a small d.c. voltage. The bridge is ``balanced'' by varying the variable capacitance until the ratio of output d.c. to input h-f voltage is at a minimum. The impedance of the variable capacitor is then numerically equal to that of the load.

In a second and perhaps more important application, the bridge is used for examining vibrational modes and measuring the Q of piezoelectric crystals or transducers. Here the variable capacitor is set at a fixed value equal to the parallel capacitance of the crystal, and the output voltage is observed, or recorded graphically, while the frequency is slowly varied over the resonance range. Some graphical records are shown, illustrating the performance of crystals at various frequencies and under different mechanical loads.

The theory of the bridge is given, and sources of error are discussed.
A Frequency Meter for Microwave Spectroscopy
Authors: Rogers John D. , Cox Henry L. , Braunschweiger Paul G.
Published: February 2005

A frequency meter using known absorption lines as microwave frequency standards has been developed. By mixing signals of unknown microwave frequency fx, standard microwave frequency f0, and known radiofrequency signals nfc from a crystal-controlled harmonic generator, it is possible to obtain a set of ``beat'' frequencies fr which can be detected by a calibrated radio receiver. From the relation fr=±m(fx−f0)±nfcit is possible to determine values for the unknown microwave frequency fx. Tests on methanol absorption lines with ammonia lines as microwave frequency standards show that microwave frequencies can be determined to ±0.03 mc/sec. Advantages of this device over other frequency meters are discussed; the accuracy is ultimately limited by the uncertainties in the value of the standard frequency f0.
Apparatus for Concentration of He3 by Thermal Diffusion
Authors: Schuette O. F. , Zucker A. , Watson W. W.
Published: February 2005

A multistage thermal diffusion apparatus for the concentration of He3 is described. Included is a novel three-stage, all-metal column based on a G. E. Calrod heater. Concentration was carried only to a He3/He4 ratio of 0.05 percent, a factor of 3.3×103. The performance indicates the importance of having the hot wall in concentric cylinder columns made of metal of good thermal conductivity to minimize azimuthal temperature gradients which can markedly increase parasitic remixing of the gas if a metal such as stainless steel is used.
Detection of Tritiated Compounds in Paper Chromatography
Authors: Gray Irving , Ikeda Saburo , Benson Andrew A. , Kritchevsky David
Published: February 2005

A windowless tube has been developed which can be used to detect tritium activity on paper, glass, or aluminum. The tube is of glass, with a nichrome anode and a copper sulfide coated copper cathode, and utilizes a stream of helium saturated with alcohol. This device is convenient for detection of tritiated compounds in paper chromatography.
A Continuously Sensitive Cloud Chamber
Authors: Needels T. S. , Nielsen C. E.
Published: February 2005

A particularly simple cloud chamber is described that is continuously sensitive to ion tracks. The chamber operates on the principle of vapor diffusion from a hot to a cold surface. The sensitive region is a shallow horizontal layer near the cold surface. The chamber has been placed in a magnetic field and curved tracks of β-particles from a radioactive source have been photographed. Pictures of such electron tracks are shown.
A Double Thin Lens Beta-Ray Spectrometer
Authors: Van Atta C. M. , Warshaw Sydney D. , Chen Joses J. L. , Taimuty Samuel I.
Published: February 2005

The description of the performance of a double thin magnetic lens beta-ray spectrometer is given. A detailed investigation of the separate distortions introduced by chamber misalignment, internal scattering, charged source and poor resolution has been made, and the results are presented qualitatively. An alignment procedure is presented, and also the arrangement of baffles to minimize scattering.
A Precision Faraday Effect Apparatus
Authors: Steingiser Samuel , Rosenblit George J. , Custer Robert , Waring Chas. E.
Published: February 2005

As a result of the improvements made in the Faraday Effect Apparatus as described, our results indicate an attainable precision of ±0.02 percent for visual measurements. Comparing this value with those reported by other investigators, indicates that a definite increase in precision has been achieved. As soon as our method for making measurements photoelectrically is fully developed, it is expected that the precision will be still higher. This will be especially true in the shorter wave-lengths where the eye is insensitive, and also where eye fatigue in general would be eliminated.
The Design and Construction of a Stark-Modulation Microwave Spectrograph
Authors: Sharbaugh A. Harry
Published: February 2005

A detailed description of a Stark-modulation (see reference 1) microwave spectrograph which has been designed and constructed in this laboratory is given. Circuit diagrams and values of the components are given for all the custom-built equipment. The frequency range is from 17 to 28 kmc/s. Peak Stark-modulation voltages up to 1500 volts sine wave and 800 volts square wave are used. The sensitivity is better than 1×10−8 cm−1. The absorption lines are about 300 kc wide at half-power and the practical limit of resolution is between ½ and 1 mc. Frequencies may be measured to better than ±0.08 mc.
Wire Recorded Magnetic Pulse Timing Circuit
Authors: Emigh C. R.
Published: February 2005

A time delay circuit is described for timing and sequencing the operations of a cloud chamber. By magnetizing a moving section of recording wire and at a later time using the magnetized section to actuate a sensitive relay, delays from 0.01 to 0.25 second are obtained. The delay can be adjusted visually to an accuracy of 0.001 second.
A Recording Microwave Refractometer
Authors: Birnbaum George
Published: February 2005

An instrument designed to measure and record a small difference in frequency between two cavity resonators is described. A sweep frequency technique is used to generate the resonance responses of the cavities. These responses are sharpened and made to control the operating time of a trigger circuit, whose average output is metered. A sensitivity equal to 200 c.p.s. is obtained in the measurement of the frequency difference between two high Q cavities, whose resonance frequencies are equal to 9000 Mc. Applications of this instrument are discussed, especially those relating to measuring changes in dielectric constant. A simple extension of the present instrument is suggested for simultaneously recording changes in dielectric constant and loss.
A Study of Plateau Slopes in Self-Quenching Geiger-Müller Counters
Authors: Brown Sanborn C. , Maroni Claudine
Published: February 2005

A study of plateau slopes of self-quenching Geiger-Müller counters shows that no quenching vapor tested produced flat characteristics. On the assumption that the slopes were given by spurious counts arising from the gas discharge phenomena, a study was made of the controlling factors. Neither the quenching gas nor the vehicular gas positive ions were found to be significant. A study of the negative ions produced by molecular dissociation of the quenching gas at the cathode, and electron attachment in the body of the gas shows that these factors are directly correlated with the slopes of the plateau characteristics.
An Electron Tube Potentiometer Method for Use in Circuits Involving Very High Resistance
Authors: Bloom H. , Butler G. W.
Published: February 2005

The construction and use of an electron tube potentiometer designed for circuits involving high resistances to the order of 100 megohms are described.
Construction and Performance of a Multiple Gamma-Ray Counter of High Efficiency
Authors: Gráf Tibor
Published: February 2005

A multiple gamma-ray counter is described, composed of 24 counter tubes connected in parallel. The tubes have Bi-plated brass screen cathodes and are placed inside the same envelope. Relative and absolute values for the efficiency of the counter were determined experimentally in the range 0.28 to 2.62 Mev. Compared to a single brass counter of similar dimensions, the multiple counter shows for gamma-rays of, say, 0.7 Mev energy a tenfold increase in efficiency. Its starting voltage is 5–600 volts lower.

The ``effective resolving time'' of the multiple counter appears to be 3 to 4 μseconds.

The counting rate curve seems to follow the inverse-square law down to the shortest counter-source distances. The solid angle subtended by the multiple counter for sources, placed in its middle, is nearly 4π.
A Low Frequency Sinusoidal Voltage Source
Authors: Rosenthal Louis A.
Published: February 2005

The low frequency range of an audio oscillator can be extended to d.c. by means of a heterodyning circuit using power line frequencies as a reference. The voltage wave forms are essentially sinusoidal and can be used for certain novel tests. A theoretical discussion of the beating phenomenon is included with particular applications and observed results.
Decade Pulse Counter for Geiger-Müller Tubes
Authors: Åström Björn
Published: February 2005

A pulse counter of decade type, which does not require any components with narrow tolerances, has been designed. A direct reading system for the total count has been used, which eliminates all calculations. Several instruments of the type described here have been put to daily use for more than half a year without any failure.
A Null-Coil Pendulum Magnetometer
Authors: Domenicali C. A.
Published: February 2005

A null-method magnetometer is described for the measurement of magnetization of small single crystals of polycrystalline specimens of ferromagnetic materials. It may also be used for measurements on para- and diamagnetic materials. The specimen is placed in an inhomogeneous magnetic field inside a ``null-coil'' of known geometry, and the current through the coil is adjusted so as to reduce the net magnetic moment of coil and specimen to zero. This coil is rigidly attached to the lower end of a sensitive pendulum and the null-position of the pendulum is observed with the aid of a projection-microscope. This method eliminates the necessity of measuring the force on the specimen and the gradient of the magnetic field. The conditions are discussed under which the absolute error may be reduced to arbitrarily small values. The secondary field arising from the current in the null-coil is, in general, negligible; however, a simple method is described for its elimination.
Design of Logarithmic Voltage Dividers
Authors: Hunt F. V. , Sledge O. D.
Published: February 2005

Suitably shaped electrodes attached to a thin sheet of isotropic conducting material, such as one of the newly developed conducting plastics, can make available a specified distribution of potential at a contact sliding along an edge of the sheet. Electrode contours are evaluated for the assumption of a logarithmic potential distribution along the straight-line edge of a voltage-divider strip cut out of the conducting sheet. The ratio of the total length for contact travel to the maximum width of the strip controls the attenuation rate. For a specified attenuation rate (db/in.), the three non-straight edges of the divider strip can be scribed or punched by repeated use of a single curved template or die. Alternative electrode configurations for attachment to rectangular strips of material offer simplification of construction at some sacrifice of linearity of the logarithmic scale.
Pentode Counting or Control Ring
Authors: Moore Benjamin L.
Published: February 2005

The 6AS6 pentode has been used in a very stable counting or control ring whose input is essentially independent of amplitude and wave shape. Values of supply voltages and circuit parameters are not critical. Control voltages corresponding to one or more stable states of the ring may be obtained very easily.
Low Temperature X-Ray Diffraction Apparatus
Authors: Clifton Donald F.
Published: February 2005

When studying transformations at sub-zero temperatures it is often convenient to be able to carry out treatments such as cold-working and annealing and to transfer the specimen, at temperature, to the x-ray diffraction camera. Several cameras have been designed, primarily for the x-ray spectrometer, in which this is easily done. For constant temperature work a flask, having a nozzle which allows cold liquid to flow over the specimen, is used. The holder is such that the specimen can be put in, in correct alignment, while in a cold bath. Two types of cameras giving variable temperatures are described. One, using cold gas blown over the specimen for cooling, permits putting the specimen in place under liquid nitrogen and keeping it at this temperature while it is aligned in the spectrometer. Rapid changes and accurate control in the range up to nearly room temperature are possible. A more versatile camera with a working range from 77°K to over 375°K uses liquid nitrogen as a coolant. Temperature control is by balancing the heat conduction along a tube with a heater near the specimen. This camera allows inserting the specimen at any chosen temperature in the working range but does not allow as rapid temperature changes in the cold gas camera.
Pulse Type Regulated High Voltage Supply for G-M Tubes
Authors: Watts Richard J.
Published: February 2005

A pulse type 1000-v variable high voltage supply is described. This supply utilizes a 6BG6 tube to interrupt the current through a standard inductance. Rectification is by means of a CK1013 cold-cathode rectifier which eliminates a well-insulated filament transformer. The output is shunt regulated by means of a 2C53 tube. An advantage of these supplies is the small size 5×5×6 in. and the economy in cost. Standard parts are used throughout. Ripple at 1000 v is 80 mv. Regulation curves are given.
Thermistors. Part I. Static Characteristics
Authors: Smith Otto J. M.
Published: February 2005

The fundamental thermistor equations are presented as functions only of electrical quantities and constants, and independent of temperature measurements. The universal curves allow one to predict the static characteristics of thermistors as circuit elements. The two most significant characteristics are the power coefficient of resistance, and the negative incremental resistance. These can be computed, or read from the universal curves, if the resistance and four parametric constants are known. These five values can be determined from six convenient measurements: the resistance and change of resistance with current at very low current, at the maximum voltage point, and at maximum current.
Thermistors. Dynamic Characteristics. Part II
Authors: Smith Otto J. M.
Published: February 2005

The thermistor sinusoidal and transient response characteristics are presented, as a function of the dissipation constant and incremental resistance. Equations are given for time constant, critical frequency, equivalent inductance, and Q. The construction of a low frequency oscillator is discussed, as well as possible non-linear filter applications.
Stainless Steel Micro-Needle Electrodes Made by Electrolytic Pointing
Authors: Grundfest Harry , Sengstaken Robert W. , Oettinger Walter H. , Gurry R. W.
Published: February 2005

Micro-needle electrodes of any desired taper and sharpness for insertion into living tissue can be made quickly by electrolytic etching. For stainless steel wire the electrolyte is a mixture of sulfuric and ortho-phosphoric acids. The wire to be pointed is made the anode of a circuit initially carrying about 0.03 amp. Gross shaping of the needle is done by repeatedly immersing the wire and withdrawing it slowly from the bath. Fine shaping of the point is carried out with reduced current. The electrodes are finished by insulating all but the fine tip with a baking enamel. The process described is adaptable to making a batch of micro-needles at one time.
Automatic Isodose Recorder with Scintillation Counter as Gamma-Ray Detector
Authors: Hine G. J. , Berman M. , Elkind M. M.
Published: February 2005

This paper describes an instrument for investigating the radiation field of any type of gamma-ray source. A small calcium tungstate crystal together with a light-conducting quartz rod and a 1P21 photo-multiplier tube is used as gamma-ray detector. The lines of constant radiation intensity in a selected plane (isodose curves) are recorded automatically with a good accuracy in a short period of time.