bluuebunny/crossref_metadata_2025 huggingface dataset:
A Double-Channel, Direct Reading, Low Frequency Counting Rate Meter and Counting Rate Comparator
Authors: Kloepper Robert M. , Hoecker Frank E.
Published: February 2005

A two-channel, direct reading counting rate meter for measurement of low frequency (average random or uniform) pulse rates in either channel or in both channels simultaneously is described. The outputs of two degenerative vacuum-tube voltmeter integrating circuits are combined into a bridge circuit whereby the equality of pulse rates in the two channels may be determined on a null-reading galvanometer. An impulse register amplifier is provided on each channel for operation of impulse counters for monitoring and/or calibration. The five ranges provided are 0–100, 200, 500, 1000, and 5000 pulses per minute. Although primarily designed for the specific purpose of adjusting two atmospheric pressure wire plate alpha-particle detectors (W. Y. Chang and S. Rosenblum, Phys. Rev. 67, 221 (1945)) to equal average pulse rates, the circuit design may be modified to detect pulse rate ratios other than unity, pulse rate differences, and/or pulse rate ranges other than those enumerated above.
A Wide-Range Saw-Tooth Generator
Authors: Sulzer Peter G.
Published: February 2005

A new and comparatively simple saw-tooth generator is described. The circuit is capable of operating over the range from 15 cycles to 500 kilocycles with good linearity and rapid flyback.
Variable Temperature Dielectric Cell of Wide Frequency Range for Solids and Liquids
Authors: Baker Edward B.
Published: February 2005

A cell was developed with which power factor and dielectric constants of solids and liquids can be accurately and conveniently measured from −25°C to +150°C and 0 to 200 Mc. It uses 7 cc of liquid or a solid disk up to 1.5 in. in diameter and up to 150 mils thick. A rapid means of controlling temperature with a circulating oil stream is provided, with a view toward automatic recording vs. temperature at constant frequency. Thermal expansion of solids may be simultaneously recorded. Fringing errors for solids may be eliminated by using a sample of smaller diameter than the electrodes.
Construction and Calibration of a Cylindrical Electrostatic Analyzer
Authors: Allison S. K. , Frankel S. P. , Hall T. A. , Montague J. H. , Morrish A. H. , Warshaw S. D.
Published: February 2005

A cylindrical electrostatic deflector has been constructed with average radius 15 cm, spacing 0.5 cm and deflection 90°, in which the deflecting potential can be in the neighborhood of 50 kv. Thus protons up to 0.75 Mev can be focused. Movable slits have been incorporated in the design, and the geometry of the entrance and exit apertures of the deflecting channel is such that the stray field may be calculated analytically. This has been done for the case in which the deflecting plates are symmetrically charged above and below zero potential. The predictions have been compared with experiments on the focusing of electron beams by the instrument under controlled conditions. Agreement with the calculations is demonstrated within the accuracy of the experiments, which is about 0.3 percent.

Experiments with asymmetric charging of the electrodes are reported and shown to agree with a plausible extension of the theory. Further experiments investigated the effect of small displacements of the slits from the computed focal positions. A set of factors, or calibration constants, has been measured so that, given the coordinates of the centers of the entrance and exit slits, and the potentials applied to the deflecting plates, the kinetic energy of the focused ion beam, as it left its source at zero potential, can be calculated to within 0.3 percent.
A New Type of Diffusion Pump
Authors: Harrington E. L.
Published: February 2005

Certain features have been added to the standard diffusion pump which give to it certain definite advantages in both operation and control without introducing any new limitations.
Application of the Electrical Analogy in Fluid Mechanics Research
Authors: Hubbard Philip G.
Published: February 2005

The electrolytic bath and a modification thereof are presented as valuable tools in fundamental investigations of potential fluid flow. Principals and techniques are presented in full, together with some typical results which indicate the scope of the method and the accuracy obtainable. Particular emphasis is placed upon techniques which permit the high accuracy necessary in most studies.
A Stark-Effect Microwave Spectrograph of High Sensitivity
Authors: McAfee K. B. , Hughes R. H. , Wilson E. Bright
Published: February 2005

A microwave spectrograph is described in which the absorption of the gas being studied is modulated by the application of a periodic Stark-effect field so that the output of the crystal detector contains a radiofrequency component which can be amplified with a narrow-band amplifier. By using a very narrow band-width, achieved by employing phase-sensitive detection, high sensitivity is obtained. The klystron is swept mechanically over the frequency range. Details of the components are given.
Double Magnetic Lens Nuclear Spectrometer
Authors: Agnew Harold M. , Anderson Herbert L.
Published: February 2005

A large double magnetic lens spectrometer has been constructed for the study of gamma- and beta-ray spectra. The magnetic field is produced by two identical coaxial water-cooled coils, each 10.2 cm wide, 31.7 cm I.D., 73.7 cm O.D., and spaced 95.6 cm apart. The source is placed on the axis at the center of one coil and the detector is placed on the axis at the center of the other. The instrument is characterized by a large transmission with moderate resolution. Scattering is virtually absent because of the nature of the trajectories which are used, and because the large dimensions have made possible the removal of scattering material to a considerable distance from the source. The design has lent itself easily to the application of accelerating voltages at the detector admitting the detection of beta-rays down to 1 kilovolt. The maximum energy conveniently studied with the present arrangement is 2.8 Mev. Beryllium-coated Zapon films of thickness 0.01 mg/cm2 have been used to mount sources. Charge does not accumulate on these sources. Observations with a Cs137 source 4 mm in diameter have shown a transmission of 1.4 percent with a resolution of 1 percent. The appearance of the internal conversion and Auger electron lines testifies to the absence of appreciable scattering.
A Small Differential Analyzer with Ball Carriage Integrators and Selsyn Coupling
Authors: Meyerott R. E. , Breit G.
Published: February 2005

A small scale differential analyzer is described which uses ball carriage integrators instead of the usual Kelvin disk integrators, and selsyn angle transmission instead of mechanical coupling of the rotating parts. The machine is inexpensive, easily constructed and is moderately accurate.
A Slide Rule for Radiation Calculations
Authors: Makowski M. W.
Published: February 2005

A slide rule has been developed to facilitate rapid calculations based on the Planck radiation formula. Quantities such as the radiant flux density in a given wave-length region, the spectral radiant flux density at a given wave-length, or the corresponding quantities expressed in photon units, can be obtained readily for a black body over a range λT=2×102 to λT=4×106 micron degrees with an accuracy of about 1 percent. Simple extension rules can be used for larger values of λT.
Instrument for Measurement of X-Ray Diffraction Patterns
Authors: Bennett John A.
Published: February 2005

An instrument is described for measuring x-ray back reflection patterns for surface stress determinations. The chief feature of the apparatus is a curved slit in the optical system so that the beam of light which scans the diffraction ring is an arc having the same radius of curvature as the ring. This simple, inexpensive instrument has been found to be at least as precise as a microphotometer for these measurements and its use has resulted in a considerable saving of time. It is suggested that the instrument might appropriately be called a photomicrometer.
A Single Pulse Voltmeter
Authors: Rado G. T. , Johnson M. H. , Maloof M.
Published: February 2005

The voltmeter described herein is capable of measuring the average amplitude of a single pulse with a random error of 0.2 percent of full-scale deflection. The instrument consists of a gated cathode follower bridge in conjunction with a ballistic indicator. In its present form the circuit responds to the average pulse amplitude over an arbitrarily selected interval of two milliseconds; thus, it measures the actual amplitude in the special case of a flat pulse of sufficient duration. The required input is 0.8 volt for full-scale deflection. The nonlinearity is less than 1 percent of any given deflection throughout the major part of the range of the instrument.
A High Resolution Scale-of-Four
Authors: Fitch Val
Published: February 2005

A high resolution scale of four has been developed to be used in conjunction with the nuclear particle detection devices in applications where the counting rate is unusually high. Specifically, it is intended to precede the commercially available medium-resolution scaling circuits and so decrease the resolving time of the counting system. The circuit will function reliably on continuously recurring pulses separated by less than 0.1 μsec. It will resolve two pulses (occurring at a moderate repetition rate) which are spaced at 0.04 μsec. A five-volt input signal is sufficient to actuate the device.
Design of the Radiofrequency System for the 184-Inch Cyclotron
Authors: MacKenzie K. R. , Schmidt F. H. , Woodyard J. R. , Wouters L. F.
Published: February 2005

A description is given of the frequency-modulated oscillator and its associated r-f circuits, as used in the 184-inch cyclotron for accelerating deuterons to 190 million volts or alpha-particles to 380 million volts. A 9C21 water cooled tube is used in a grounded-grid circuit, which is tightly coupled to the single-dee resonant circuit so that the oscillator follows the frequency of the dee over the wide range required. During normal operation the oscillator delivers approximately 20 kw of r-f power to the dee system at an efficiency of 60 percent, giving 20 kv at the front of the dee, although the oscillator is capable of considerably more output. The frequency is swept from 12.5 mc to 9.0 mc approximately 100 times per second by a rotating condenser connected to the dee by a half-wave transmission line. Much of the history of the design, and reasons for choices made, are given, as it is felt this may be useful to others designing frequency-modulated oscillators for cyclotrons.
Developments in the Useful Circular Nomogram
Authors: Adams Douglas P. , Evans Howard T.
Published: February 2005

The particular type of alignment diagram for the function U · V = W in which the U and V scales lie on the circumference of the same circle and the W scale along a diameter is developed in detail. The forms of the diagram for which certain intervals on these scales are maximized in their spread are derived and described. Such maximized diagrams, it is found, have certain characteristic properties of symmetry. These developments are illustrated with examples.
Absorption Corrections in X-Ray Studies of Preferred Orientation
Authors: Smoluchowski R. , Turner R. W.
Published: February 2005

A general formula is derived for the evaluation of correction factors in the study of preferred orientations in flat specimens. These factors depend on orientation of the sample, angles of diffraction, thickness of specimen, etc. In practical applications a graphical presentation of the absorption correction proves to be particularly useful.
A Rapid Infra-Red Gas Analyzer
Authors: Fowler Richard C.
Published: February 2005

A brief description of an apparatus, together with a few representative curves, is presented, suitable for measuring the composition of very small amounts of any gas having at least one near infra-red absorption band or, if measured in the presence of other gases, at least one unique absorption band. With the bolometers used, 90 percent full scale response is obtained in 0.15 seconds on a 0.5 cc sample, permitting a 0.4 cm optical path and a very nearly linear response over the range usually found in physiological concentrations and anesthesia.
Design and Performance of a Multicellular Geiger Counter for Gamma-Radiation
Authors: Lind David A.
Published: February 2005

The design problems for Geiger counters which have a high gamma-radiation sensitivity are discussed. A description of a Geiger counter consisting of nine individual counters in the shape of pillboxes mounted inside a single envelope is given. The individual pillboxes are 3 inches in diameter. The anode has the shape of a four-pronged spider which is centered in the box. The nine section counter has a flat plateau of about 150 volts, and intrinsic sensitivity of 25 percent. Its lifetime is better than 107 counts.
Conversion of a Motor Generator into a Low Noise Power Amplifier
Authors: Sommers H. S. , Weiss P. R. , Halpern W.
Published: February 2005

The noise output of motor-generator sets is so large as to impair their use in precision control work. This paper describes a method for reducing this noise by incorporating a motor generator in an electronic feed-back circuit. The method is based on the use of a high frequency output channel in parallel with the generator to permit cancellation of the higher harmonics of the noise. Design, construction, and performance of an amplifier based on a ½-kw M-G set are described. The noise output of this unit is ⅕ percent of the normal noise of the generator.
An Interferometric Study of Supersonic Channel Flow
Authors: Bershader Daniel
Published: February 2005

The Zehnder-Mach interferometer has been applied to the study of supersonic flow of air expanding from a pressure tank into the atmosphere through channels of rectangular cross section. This was made possible by using plane-parallel glass plates for a pair of opposite walls of the channel. Two such channels were used, each about one centimeter in width and two centimeters in depth, one being a divergent channel (half-angle=4.0°) and the other a Laval nozzle constructed by the ``characteristics'' method for M=1.7. It was found possible to measure the density distribution with a rather small estimated probable error (two percent or less). Knowledge of the stagnation temperature and pressure made it possible also to compute pressure, temperature, and velocity. Results obtained for the potential flow agree, for the most part, within one percent with the well-known theory of isentropic channel flow. The interferometric technique has been used also as a guide in improving the Laval nozzle, giving quantitative data on the inhomogeneities resulting from small errors in construction. Further quantitative data was obtained on the degree of non-uniformity of the flow in the throat regions of both channels. The boundary layers, which reach a thickness of about ten percent of the channel width near the orifice of the Laval Nozzle, introduce further accuracy problems into the study of channel flow by interferometry. These are taken up in some detail. Some of the considerations here will also apply to the interferometric analysis of flow in larger supersonic wind tunnels whose working sections are essentially channels of rectangular cross section.
Cloud-Chamber Equipment for Study of Infrequent Cosmic-Ray Processes
Authors: Chang W. Y. , Winckler J. R.
Published: February 2005

The cloud chamber described operates if a particle passes through a vertical telescope and stops before reaching anticoincidence counters under the chamber. The chamber is surrounded by a minimum amount of material, and a large number of the anticoincidence events consist of particles stopping in foils of aluminum, iron, and lead within the chamber. The expansion valve is of the fast electromagnetic type having a thin iron diaphragm which completes a magnetic circuit when closed. Six slow expansions for clearing the chamber occur immediately after each event. The chamber is housed in an insulated room kept within ±0.1°C. The Geiger counter coincidence circuits operate time delays for controlling the expansions, flash lamps, camera, clearing field, and recorders. The electronics is suitable for the study of very infrequent events. Several pictures of meson decay and shower events are presented.
A Large Mass Spectrometer Employing Crossed Electric and Magnetic Fields
Authors: Mariner Thomas , Bleakney Walker
Published: February 2005

Because of continued general interest in this type of instrument and because of relationship with previously published work it has seemed desirable to report here the progress made, up to cessation of work in 1940, on a large crossed field mass spectrometer, the basic design features of which were directed toward a resolution of about 25,000 in order to permit its use for mass measurement. Although the instrument was necessarily diverted to less exacting applications before development was sufficiently complete to permit attainment of this high resolution, nothing in experience with the instrument indicated that the goal could not substantially have been reached.
A Novel Recording Accelerometer
Authors: Iberall Arthur S.
Published: February 2005

The novel features of a small recording accelerometer of slow chart speed are described. Principally, these are its compactness—the recorder, less power supply, fits into a panel type aircraft instrument case—and the use of spark recording to obtain a visible record on a paper chart. Components selected to achieve compactness are a timing type synchronous motor to drive the chart; a 35 mm film cartridge to store the chart, and a model airplane spark coil to provide a high voltage repetitive spark. A simple preliminary chemical treatment for ordinary paper was developed to obtain an intensified trace on the record chart. Small or panel type recorders of other physical quantities can be similarly built, applying the main features of this design.
A Mass Spectrometer for Continuous Gas Analysis
Authors: Hunter Jack A. , Stacy Ralph W. , Hitchcock Fred A.
Published: February 2005

An instrument for recording continuously the relative abundance of gases in a three component mixture is described. High accuracy of analysis has been sacrificed in favor of high speed response since the instrument was designed primarily for use in the investigation of respiratory problems. An instantaneous change in gas composition will appear on the record with a lag of less than 0.2 second and will require approximately 0.1 second to settle on this new value.
Photomicrography of Tracks in Nuclear Research Emulsions
Authors: Morrison Adair , Morton Fred
Published: February 2005

A simple projection system and film holder for taking photomicrographs of particle tracks in photographic emulsions of the type used for nuclear research is described. With this film holder a series of exposures covering a considerable length of the track image is obtained on a single film as adjacent segments of track are brought successively into sharp focus and recorded.
A Methane Flow Beta-Proportional Counter
Authors: Bernstein William , Ballentine Robert
Published: February 2005

A methane flow beta-proportional counter has been designed to detect the high and low energy solid beta-emitters used in tracer experiments. At present, both C14 and P32 are being counted. The use of a sintered-glass Gooch crucible, both as a filter and sample holder, greatly simplifies the analytical technique involved in such experiments. The instrument is stable and the results are reproducible over long time periods.
Experiments in the Possibility of Increasing the Efficiency of Gamma-Counters
Authors: Slätis Hilding
Published: February 2005

The efficiency of G-M tubes for recording γ-quanta is increased by insertion of concentric ring systems of metal between the wire and the cylinder. When the ring systems get suitable voltages, good plateaus and resolving times are obtained. The efficiency of a counter, which had 3 ring systems with 24 rings in each system, was 2.5 times that of a conventional counter of the same size. This means an increase of 6 times in γ—γ-coincidence measurements. The efficiency of an improved tube (see note added in proof) is 3.2 times that of a conventional counter.
An Improved Low Angle X-Ray Diffraction Camera
Authors: Wright Barbara A. , Cole Peter A.
Published: February 2005

A description is given of a low angle x-ray diffraction camera which incorporates both high resolution and facility in adjustment and alignment of components. A diffraction pattern of the low angle pattern of collagen photographed with this instrument is compared with a similar pattern photographed with commercially available equipment.
Instrumentation for Nuclear Studies with Externally Focused Deuteron Beam from Ten-Mev Cyclotron
Authors: Curtis B. R. , Fowler J. L. , Rosen L.
Published: February 2005

A beam of ten-Mev deuterons of about ½ μa has been focused on an area ¼ in. in diameter at the center of a 2-ft. diameter reaction chamber 15-ft. away from the cyclotron. In the center of the reaction chamber a gas target is supported with side ports so constructed that nuclear reaction products from the gas can be counted by a proportional counter mounted at the periphery of the chamber. The counter can be rotated through a Wilson seal to make any angle with the beam in the horizontal plane. At the exit of the reaction chamber a Faraday cup is supported. This can be removed to allow the beam to pass between the poles of an analyzing magnet for energy measurements. Tests with charged particle detectors such as a proportional counter or photographic plates show the background to be sufficiently low to allow good resolution of the products from the d-d reactions. Using the d-d reaction as a neutron source, background neutrons above 12 Mev are only about ten percent. However, the background neutrons above one Mev amount to about 25 times the neutrons from the d-d reactions.
A New Method of Measuring the Stopping Power of Several Materials for Alpha-Particles
Authors: Hammer F. Emmett , Hoecker Frank E.
Published: February 2005

The application of an atmospheric pressure alpha-particle detector to the measurement of the relative stopping power of thin films of absorbing material for alpha-particles was investigated. The air-equivalent of absorbing films was measured directly by balancing the counting rates of two detectors in air, and again when an absorbing film is inserted between one of the detectors and its source. Measurements of the air-equivalent and relative stopping powers of films of mica, polystyrene, and aluminum are given. The relative stopping powers determined agree well with previous values. The errors of the method are discussed and an attempt is made to specify the magnitude of the probable error in the result.
Modified String Flowmeter for Measuring Breath Velocity
Authors: Specht H. , Brubach H. F.
Published: February 2005

An instrument is described which measures instantaneous breath velocities without incurring high flow resistances. It records reciprocating flows, such as those of the full breath cycle, within the limits of normal breath velocities with high frequency resolution and yields accurate and reproducible measurements when suitably calibrated. The system described incorporates an automatic control over a valve system insuring directed flow of the respired gases through a closed breathing circuit, permitting measurement of breath velocities at simulated high altitudes. The advantages, disadvantages, and idiosyncracies of this type of instrument as used in physiological measurement are discussed.
The Ten-Channel Electrostatic Pulse Analyzer
Authors: Watkins Dean A.
Published: February 2005

A ten-channel pulse height discriminator using a beam deflection tube is described. The instrument provides one-volt channels and has a high degree of stability. Essential circuits are given so that the analyzer may be readily duplicated. Performance and limitations are discussed.
A New Technique for the Determination of Heats of Sublimation of Slightly Volatile Substances
Authors: Simpson O. C. , Thorn R. J.
Published: February 2005

A technique is described which enables one to measure relative vapor pressures by measuring the rate of change of transmissivity of thin deposits as they are formed by condensation from the vapor. From the temperature dependence of this rate the heat of sublimation of slightly volatile substances can be determined. In the case of graphite, deposits of the order of 0.1 μg per cm2 can be detected.
Amplitude Bridge for Detection of Nuclear Resonance
Authors: Thomas H. A. , Huntoon R. D.
Published: February 2005

A circuit for detecting nuclear resonance absorption is described that, unlike the rf bridge, is simple to construct and adjust and very insensitive to microphonics. The voltages in two branches of an rf network, one of which contains the coil and sample, are rectified by diode detectors and the audio outputs combined in such a way that noise modulation from the rf generator is balanced out but the desired signal is not. Experimental performance is discussed and typical signal-to-noise ratios are given.
A Scintillation Counter for Laboratory Counting of Alpha-Particles
Authors: Graves J. D. , Dyson J. P.
Published: February 2005

A simple, reliable, wide range alpha-counter has been developed which is suitable for the routine counting accompanying radiochemical laboratory analysis. This instrument utilizes the alpha-scintillation process in conjunction with a photomultiplier tube and a commercial Geiger tube power supply, amplifier, and scaler. Desirable features include low cost, ease of construction, ruggedness, and long life. Tests performed on the completed counter assembly indicated the following operating characteristics: a counting efficiency of 100 percent for 4–5 Mev alpha-particles; a resolving time limited by the electronic circuits (photomultiplier pulses have a rise time of about 0.5 microsecond); a counting rate unaffected by variations in temperature, humidity, or pressure; a background below 10 counts per hour. The chief undesirable feature is the small field of view for high sensitivity. Samples to be counted must be small, about ¼ in.×½ in. maximum, and must be confined to a known region on the sample holder.
A Transistor Trigger Circuit
Authors: Reich Herbert J. , Ungvary Robert L.
Published: February 2005

Analysis of the characteristic curves of transistors shows that the negative resistance necessary to the functioning of a trigger circuit exists in the base circuit of a transistor. A trigger circuit may therefore be formed by inserting a resistance of proper magnitude in series with the base. Such a circuit has the advantages over vacuum-tube circuits of much shorter triggering time, simplicity, small size, absence of filament power supply, and low operating voltage. The rise and fall times of the output voltage are less than 0.1 microsecond and the circuit is stable from zero triggering frequency up to the maximum frequency used. Although the circuit has been tested only up to 1 Mc, an upper limit of at least 10 Mc is probable. An output voltage of 5 or 6 volts may be readily obtained. Like other types of trigger circuit, the transistor circuit may be converted into a relaxation oscillator or a pulse generator.
Optimum Conditions for a 180° Beta-Ray Spectrometer
Authors: Geoffrion Claude
Published: February 2005

The relations existing between source dimensions, beam divergence, luminosity, and resolving power of a 180° homogeneous field spectrometer are established. From these the conditions for maximum luminosity for a given resolving power are derived. By increasing the source height and slightly decreasing the width, the luminosity may be increased without affecting the resolving power.
A Microwave Secondary Electron Multiplier
Authors: Greenblatt M. H.
Published: February 2005

The construction and operation of a dynamic electron multiplier, of the type sometimes called a multipactor, is described. Briefly, the multipactor consists of two parallel secondary emissive plates having an alternating voltage across them. The magnitude of the voltage is adjusted so that the transit time across the gap for electrons starting with zero velocity from one of the plates when the field is passing through zero shall be just one-half the period of the a.c. voltage. In this way, electrons and their secondary descendents can be made to bounce back and forth between the plates and multiplication takes place. The necessary phase relationships between the electrons and the field are discussed.

The multipactor described here uses 10 cm microwave power to get the a.c. voltage. It has been used as a gamma-ray detector in which case the cavity is ``broken down'' by the multiplication of a Compton electron ejected from the cavity wall by a gamma-ray. This breakdown gives rise to a microwave pulse several millivolts high at a crystal rectifier. The efficiency of this process is about 1.5×10−5 count/gamma-ray. The rise time of the pulse is calculated to be about 5×10−10 sec. and is measured to be less than 10−7 sec. The deadtime is presumed to be about 5 microseconds.
The Theoretical Background of the Multiple Pressure Tube Anemometer
Authors: Goudy Paul R. , Colvin Henry F.
Published: February 2005

A recent investigation has resulted in the development of a multiple pressure tube anemometer, which measures both wind speed and direction without moving parts exposed to the wind.

From the expression for the air flow past a quadric surface, it is shown that, by the use of one system of suitably spaced impact holes, it is possible to measure the rectangular components of wind velocity in one quadrant. Another arrangement of holes is presented that takes advantage of the breakdown in flow pattern past 90° to measure wind components in all quadrants without ambiguity.

The components of wind velocity so measured are combined in an electromechanical system which provides indications of speed and direction.

Finally, the experimental instrument embodying these principles is evaluated and performance data taken from it are presented.
A Tachometer
Authors: Benfield A. E.
Published: February 2005

The theory and operation of a simple tachometer are described, in which a direct electrical e.m.f. is generated by attaching a magnet to the rotating member. It is shown how the position and orientation of the magnet affect the magnitude of the generated e.m.f., and suggestions are made for further increasing the e.m.f. generated per rate of revolution.
Wet Bulb Temperatures without a Wick
Authors: Jehn Kenneth H.
Published: February 2005

It is desired to determine the feasibility of measuring wet bulb temperatures without a wick. The sensing element is a thermistor bead of small mass and rapid response, which, when dipped into distilled water, retains water in sufficient quantity to register a wet bulb temperature when exposed to the air. The experimental apparatus and procedures are described in detail, and the data presented. It is concluded that wickless wet bulb measurements are feasible, with an accuracy of the order of ±0.1°C.
Electrolytic Thermistors
Authors: Gutmann F. , Simmons L. M.
Published: February 2005

A thermistor for use with alternating current and having a half-temperature at 300°K of 7.2°C is easily constructed by immersing platinum electrodes in a viscous solution of waterglass. It is three times as sensitive as commercial thermistors, withstands a.c. potentials of more than 240 volts, and its cold resistance and sensitivity are easily controlled. Other electrolytic solutions have been tested, but these, although withstanding high a.c. potentials, are less sensitive.
A Versatile Pneumatic Instrument Based on Critical Flow
Authors: Wildhack W. A.
Published: February 2005

Gas flows through two restrictions in series, the second one or both being a nozzle operating with sonic throat velocity so that discharge is independent of the downstream pressure. For fixed restrictions, the ratio of entrance pressures at the two restrictions depends on their relative sizes and the ratio of entrance temperatures. After calibration, the pressure ratio may be used to measure temperature with a sensitivity of 1°C or better over a range of 2000°C. With the same arrangement, the temperature being constant, the intermediate pressure is a direct measure of mass flow. A sensitivity of better than 0.1 percent is possible in this measurement. For given temperatures, the device can be used as a ``pressure divider,'' with the intermediate pressure controlled by adjusting the restrictions, or as a pneumatic micrometer. Gas analysis is accomplished by removing one component of the gas flow between nozzles. A vacuum pump is used, if necessary, to ensure critical discharge through one or both nozzles; divergent cones on nozzles may be used to minimize pressure drop.
Note on the Detection of Coincidences and Short Time Intervals
Authors: Hofstadter Robert , McIntyre John A.
Published: February 2005

A flexible method of detecting coincidences and short time intervals has been devised in which a photo-multiplier tube views the screen of a cathode-ray tube. By using one pulse as initiator of a sweep and the other in vertical presentation, coincidences can be observed in a fixed portion of the screen while the remainder of the screen is masked off. In present use the method is limited only by the pulses available (5×10−8 sec.). The method appears to be capable of extension to time intervals of the order of 9×10−10 second or smaller.
A Diaphragm Cell for Thermal Diffusion Measurements
Authors: Huse E. S. , Trevoy D. J. , Drickamer H. G.
Published: February 2005

A diaphragm cell for thermal diffusion using a fritted glass disk like those used for ordinary diffusion is described. The results obtained are consistent with those obtained for other cells, and the operation of this cell is simpler and shorter than for most other methods.
Design and Construction of Universal Function Generating Potentiometers
Authors: Korn Granino A.
Published: February 2005

The design and construction of a new type of function generating potentiometer, whose output voltage may be made proportional to a wide variety of functions of the shaft rotation, is described. Voltages corresponding to the desired function values are set up at will at the taps of a linear potentiometer, which then interpolates linearly between these values. The new device combines remarkable flexibility with relatively low cost.
A Magnetic Analyzer for Charged-Particles from Nuclear Reactions
Authors: Snyder C. W. , Rubin S. , Fowler W. A. , Lauritsen C. C.
Published: February 2005

A double-focusing magnetic spectrometer for detecting and analyzing charged particles from nuclear reactions is described. The magnetic field, varying as r−½ near an average radius of 10.5 in., extends over a semicircle yielding object and anastigmatic image positions some distance outside of the region of strong field. The acceptance solid angle is Ω=0.0061 sterad. and the momentum resolution with an 8-mm slit at the detector is R=128. The ultimate resolution determined by spherical aberration and some residual astigmatism is about 1000. Applications to the study of the energy and yield of nuclear reaction products are discussed.
Magnetic Tape Recorder for Very Low Frequency Phenomena
Authors: Green Paul E.
Published: February 2005

An apparatus is described for the recording of electrical signals of frequencies below 100 cycles per second on magnetic tape for subsequent playback. A system of wide deviation frequency modulation of an audio frequency carrier has been employed to eliminate the difficulties normally encountered in the direct recording of low frequency and d.c. signals.
A Method for Measuring the Thermal Conductivity of Small Samples of Poorly Conducting Materials such as Optical Crystals
Authors: Ballard Stanley S. , McCarthy Kathryn A. , Davis William C.
Published: February 2005

Thermal conductivities of from 2 to 500×10−4 c.g.s. units are measured by comparing the flow of heat through a given sample with that through a standard material. On the basis of repeat runs and checks with literature values, an accuracy of about five percent is estimated for this method. The dimensions of the apparatus limit the face size of both the unknown and standard samples to a maximum of 10 millimeters square; thicknesses of 2 to 10 millimeters are suitable. Values at average temperatures between 30°C and 75°C are reported for nine materials:—sodium chloride, potassium chloride, potassium bromide, calcium fluoride, lithium fluoride (both air-grown and vacuum-grown), silver chloride, thallium bromide-iodide, thallium bromide-chloride, and fused silica.
A Note on the Geometry of Geiger Counter Telescopes
Authors: Newell Homer E. , Pressly Eleanor C.
Published: February 2005

The contribution of a portion of the solid angle of a two-counter telescope to the total coincidence rate is studied for both isotropic and cosine squared law radiation fields. Formulas and graphs are presented for estimating the percentage of counts due to radiation from directions near the telescope axis. The average path length traversed by particles passing through the telescope is touched upon briefly.
Transmission Line Reflection Doubling Amplifier
Authors: Marshall John
Published: February 2005

A pulse amplifier has been constructed using voltage doubling by reflection at the open end of a transmission line. Cathode followers are used to couple the output of one line into the input of the next. An amplifier using in each stage the four triode units of two 6J6's in parallel driving 16 feet of 100-ohm line has theoretically a voltage gain of 1.32 per stage. With appropriate grid series compensation the gain can be made constant, theoretically, to 100 megacycles. Experimentally the gain is 1.3 per stage with a rise time less than 6×10−9 sec. Below 50 volts, distortion is not serious for pulses shorter than twice the transmission time of the line. Pulses up to 150 volts can be handled by the amplifier.
An Improved Electrical Network for Determining the Eigenvalues and Eigenvectors of a Real Symmetric Matrix
Authors: Many Abraham
Published: February 2005

An electrical computor for determining the eigenvalues and eigenvectors of real symmetric matrices up to the tenth order is described. It is an enlarged and an improved form of a computor described in a previous paper. The time required for solution is considerably reduced, and the accuracy is ten times higher. The solution of a matrix of the tenth order takes four hours, as compared to a hundred hours by computational methods. The accuracy of the eigenvalues is about 0.01 percent of the difference between the greatest and smallest eigenvalues, and the accuracy of each eigenvector is better than one percent of its greatest component.
Distributed Coincidence Circuit
Authors: Wiegand Clyde
Published: February 2005

A coincidence circuit using the traveling wave principle as applied to distributed amplification is described. The resolving time is about 10−8 sec. when the device is used in connection with scintillation detectors.
A Rapid Method for Calculating and Using Platinum Thermohm Tables
Authors: Buerschaper R. A.
Published: February 2005

A method is described whereby resistance-temperature tables can be calculated in a few hours using punched cards. The method is much simpler and quicker to use than the ``platinum temperature'' tables. An example is given for reducing resistance measurements to temperature and a method for checking bridge and thermohm drift with respect to the tables is proposed.
Positive Displacement Pump for Corrosive Fluids
Authors: Glenn E. E. , Hackerman Norman
Published: February 2005

A positive displacement-type pump in which there are no metal parts exposed to the fluids has been built and tested. Gases, liquids, or mixtures of both can be pumped without any corrosive effects on the pump.
A Frequency Modulation Pressure Recording System
Authors: Hett J. H. , King R. W.
Published: February 2005

A simple frequency-modulated pressure gauge employing a variable capacity pick-up element has been devised to measure the oscillating pressures of burning gases. It has been used to measure pressures in pulse jet engines ranging from −5 to +60 p.s.i. gauge, under conditions where the gas temperatures ranged from approximately 300°K to 2450°K and the gauge mount vibrated with an amplitude of approximately 0.125 inch. The fundamental frequencies of temperature variation, pressure variation and mechanical vibration were 40 cycles and 220 cycles per second. Under these conditions the pressure response is essentially linear from 0 to 5500 cycles per second.
Gas Phase Counting of Low Energy Beta-Emitters
Authors: Bernstein W. , Ballentine R.
Published: February 2005

A proportional counter has been designed to detect soft beta-emitters in the gas phase. Data is presented to illustrate the applicability of the counters to the detection of C14, S35, and H3. Various partial pressures of C14O2 have been investigated to determine the effects on the counter properties. Corrections have been made for the counter ends and the memory effects are described. An energy spectrum is presented for H3 to determine the low energy limit of the instrument.
Measurement of Fast Neutron Energies by Observation of Li6(n, α)H3 in Photographic Emulsions
Authors: Keepin George R. , Roberts James H.
Published: February 2005

A new technique of neutron energy measurement not requiring neutron collimation is described. The method employs the nuclear reaction Li6(n, α)H3 (Q=4.64 Mev) observed within photographic emulsions impregnated with enriched Li6. Results on monoenergetic neutrons indicate a resolution of at least ±0.1 Mev in the region studied (from thermal energies up to 1.3 Mev). To extend the method to measurement of continuous neutron spectra, both the excitation function and the angular distribution of the Li6 disintegration process should be known. However, for immediate practical application, the method may be calibrated with a well-known spectrum. The Li6 technique is particularly well suited to energy measurements on neutrons within a material medium where perturbations introduced by the detector must be minimized and where collimation is clearly impossible.
Integrator for Small Beam Currents
Authors: Hall T. A. , Warshaw S. D. , Dorsey J.
Published: February 2005

A simple circuit is described which integrates approximately beam currents of 10−14 amp. or larger. It consists of a d.c. amplifier, which converts the current into a voltage signal, and a voltage integrator circuit. Integration is approximate primarily because of slow circuit response to fluctuations; under usual conditions of high voltage accelerator work, one can expect integration accuracy of about one to five percent.
Magnetic Suspension for Small Rotors
Authors: Beams J. W.
Published: February 2005

A magnetic suspension for small rotors has been developed which employs scattered light to regulate the vertical height of the rotor. Upon entering a horizontal beam of light the rotor scatters or reflects light into a photo-electron multiplier cell. This cell actuates an electronic circuit which in turn regulates the current through the supporting solenoid in such a way as to maintain the ferromagnetic rotor at the desired vertical position. Rotors with diameters down to 0.004″ have been stably supported. A 164′′ rotor was spun to an estimated speed of 800,000 r.p.s. which gave a centrifugal field in excess of one-half billion times gravity. Besides providing a support for rotors, the apparatus may be used as an analytical balance for weighing materials inside a vacuum chamber. It detects changes in mass of from 10−8 to 10−9 gram. Other uses also are indicated.
A Ratio-Recording Double Beam Infra-Red Spectrophotometer Using Phase Discrimination and a Single Detector
Authors: Savitzky Abraham , Halford Ralph S.
Published: February 2005

A simple modification is described for converting a Perkin-Elmer Infra-Red Spectrophotometer to double beam operation for direct recording of percent transmission versus wave-length. A phase discrimination system is used, requiring no changes in the optical system, and no sacrifice of versatility or ease of prism interchange. A complete spectrum over the rocksalt region may be obtained in 25 minutes with good resolution, and with no attention from an operator. Samples as small as 1×6 mm can be studied. The system is readily adaptable to other spectrophotometers, including those in the visual and ultraviolet range, the only limitation being sufficiently rapid response by the detector.
The Scintillation Counter as a Low Resolution Gamma-Ray Spectrometer
Authors: Pringle Robert W. , Roulston Kenneth I. , Taylor Harry W.
Published: February 2005

A scintillation gamma-ray spectrometer has been developed, which is of particular use for the study of isotopes of low specific activity and in which the energies of the gamma-rays are identified from the pulse height distributions of the recoil electrons produced in an activated NaI crystal. The Compton distributions are easily recognized, and a study of the gamma-radiation of Co60 and I131 shows a proportionality to exist between the total light output per scintillation and the energy of the corresponding secondary beta-ray particle. The noise level of the RCA 5819 photo-multiplier, as used in this test, corresponded to an energy on the pulse height scale of less than 20 kev. A brief description is given of a new type of differential pulse height analyzer which has been developed for work of this type.
A Radiofrequency Spectrograph and Simple Magnetic-Field Meter
Authors: Pound R. V. , Knight W. D.
Published: February 2005

A simple oscillating circuit with a special feed-back circuit is employed as a tool for the search for and detailed analysis of nuclear paramagnetic absorption lines. The sensitivity approaches the optimum for a given noise band width and particularly useful is the ease of conducting slow, continuous changes of frequency while recording the output data. Spectra having several components at scattered frequencies are thus displayed. Line shapes are unambiguously recorded because of the absence of sensitivity to dispersion. Using protons in water, or solutions containing Li7, the device can be used as a versatile and extremely precise meter for measuring magnetic field strengths in the range from about 100 to 25,000 oersteds with a minimum of auxiliary equipment.
An Analog Computer
Authors: Bayly J. G.
Published: February 2005

An integrator has been constructed which is capable of computing the yield of nuclear reactions produced by radiation of intensity that varies arbitrarily with time. By combining the appropriate number of such machines the yield resulting from a series of consecutive reactions may be found.

While the emphasis in this paper is on applications involving the yield of radioactive isotopes produced by a pile or other source of radiation, the instrument may be used to calculate temperatures in thermodynamic problems, voltages and currents in electrical networks, and so on, wherever the quantity (x) to be determined is governed by the differential equation dx/dt=−λx+f(t),f(t) being a given function of the time, and λ a known constant.
Photographic Methods of Measuring Slow Neutron Intensities
Authors: Blau M. , Ruderman I. W. , Czechowski J.
Published: February 2005

The relative slow neutron sensitivities of β-sensitive emulsions, x-ray film-indium foil combinations, and boron-loaded plates were investigated. Since the detection efficiency depends upon the neutron energy, experiments were made with epithermal, thermal, and cold neutrons. β-sensitive emulsions and x-ray-indium combinations are about equally useful for the detection of epithermal neutrons. B10 loaded plates, which are best for the detection of thermal and cold neutrons, have the following advantages: very low neutron intensities can be measured by microscopic counting of α-tracks, neutrons can be counted in the presence of β-and γ-radiation, the number of α-tracks is essentially independent of the development conditions, and a wide range of neutron intensities can be measured with a single plate.