bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Design of a Magnetic Focusing Coincidence Spectrometer
Authors: Fowler C. M. , Shreffler R. G. 
Published: February 2005

Design and operating features are described for a semi-circular magnetic focusing coincidence spectrometer. The primary function of the spectrometer is that of determining whether or not two different radiations from a radioactive sample are in the same branch of the nuclear decay scheme. Although the instrument is designed primarily for studies between conversion electron groups, it is also suitable for studies between conversion groups and beta-spectra.
A feature of the instrument is its extraordinarily good coincidence resolving power. Applications of the spectrometer to two activities are briefly discussed, and an explanation of the high resolving power is given.
A Tunable Shunt Selector-Rejector for Audio Amplifiers
Authors: Villard Oswald G. 
Published: February 2005

A means for adding, without circuit modification or wiring changes, continuously tunable band-pass or band-reject selectivity to existing audio amplifiers is described. This takes the form of an external electronic circuit connected to the amplifier by means of a wire attached to the plate pin of one tube, and a common ac ground connection.
The arrangement is useful in laboratory and experimental work for temporarily rejecting or amplifying a particular frequency.
The Use of Film in X-Ray Diffraction Studies
Authors: VanHorn M. H. 
Published: February 2005

Because of the weakness of diffracted beams, it is necessary to work in the low gradient ``toe'' portion of the characteristic (D-logE) curve. The curve shape in this region is the same for all types of x-ray film commonly used, even when development is greatly prolonged.
The shape of the entire characteristic curve is insensitive to radiation quality, but the relative speeds of different films change considerably in the range of wavelengths of interest to diffractionists.
For photographic photometry, the linear density-exposure range can be extended by proper selection of the processing conditions.
Low Evaporation Rate Storage Vessel for Liquid Helium
Authors: Sydoriak Stephen G. , Sommers H. S. 
Published: February 2005

Expressions are derived for the heat flux q0 and temperature gradient dT/dh in a Pyrex cylinder (a) in vacuo and (b) in the atmosphere of cold vapor issuing from a liquid helium container. In the temperature range 20&lt;T&lt;300 we find for case (a) that q0 α T1.8 and dT/dh α T−0.8, while in case (b) q0 α̇ T and dT/dh is nearly constant.
Design details and operating procedures are given for a 12-liter liquid helium storage vessel intended to complement our Collins helium liquefier. It can be filled in one day's operation of the liquefier, and ten days later is still half full.
Reverse Separation in Fractionation Pumps
Authors: Hickman K. 
Published: February 2005

Measurements by Trevoy and the writer, to be published shortly elsewhere, have shown that the relative volatilities of mixtures of liquids increase surprisingly at low rates of distillations. A consequence is that organic liquids release volatiles into high vacuum apparatus more readily than would be deduced from measurements made at usual pressures of, say, 1–100 microns. The composition of condensate in an oil-filled diffusion pump is found to be a function of position in the pump, the lightest constituents straying preferentially to the high vacuum end. As an example, Octoil contaminated with less than 1 percent of butyl phthalate in the last boiler of a 3-stage pump was found to pass vapor through the high vacuum entrance as though the boiler had contained 27 percent butyl phthalate.
To epitomize the situation, a vapor pump is a specialized form of still with two exits. The intention of the designer, expressed in the geometry of the pump, is to force the lighter molecules to one exit but molecular perversity causes them to wander to the other. The effect is probably unimportant except where the highest vacuums are required, though it does point to the desirability of thorough prepurification of pump oils; the task of fractionation, before and during use, is harder than we had supposed.
A Magnetically Compensated Vapor Density Balance
Authors: Johnson E. W. , Nash L. K. 
Published: February 2005

A magnetically compensated buoyancy balance is described. This instrument provides precise and continuous indications of gas and vapor densities falling in the range of 0 to 4 g/l. Measurements can be made at temperatures that are freely variable up to 220°C; mildly corrosive vapors can be handled; and the data are automatically corrected for adsorption effects. The long term reproducibility of the readings is 0.001 g/l.
Magnetic compensation is attained by adjusting the current in an external electromagnet until this magnet's interaction with a small permanent magnet sealed in the balance beam restores the beam to a standard null position. The virtually linear relationship between this ``restoring'' current and the ambient vapor density is established by calibration with a standard substance. High constancy of calibration has been achieved through the use of a special beam suspension which, though extremely friction free, is unaffected by repeated and relatively severe mechanical and thermal shocks.
Scattering Losses in the Synchrotron
Authors: Greenberg J. Mayo , Berlin T. H. 
Published: February 2005

Scattering losses in various electron and proton synchrotrons by residual gas molecules are obtained for a variety of conditions. Evaluation is made of the effects of (1) injection energy of the particles, (2) the spread of the injected beam, (3) the pressure of the residual gas, (4) the rate at which energy is supplied to the beam particles, and (5) the aperture of the accelerator. It is shown that multiple scattering is the really important factor and that losses due to single scattering are of relative importance only when the total effect of single and multiple scattering is rather small.
Scattering losses are tabulated and estimates made of the residual gas pressures in synchrotrons which will not produce prohibitively large losses.
A Scintillation Counter for the Relative Determination of X-Ray Intensities in Radiological Work
Authors: Ter-Pogossian Michel , Ittner William B. 
Published: February 2005

An instrument is described for determining accurately the intensity of an x-radiation by direct reading. This instrument consists in a small potassium iodide crystal which fluoresces under the action of high energy photons. The light thus emitted is ``piped'' by means of a Lucite rod to a photomultiplier tube. The current generated in the tube is measured by a microammeter.
A series of tests on the energy dependence of this detector are reported. It is concluded that the instrument described is suitable for the determination of isodose charts.
A Radiofrequency Ion Source
Authors: Swann C. P. , Swingle J. F. 
Published: February 2005

An rf ion source with transverse magnetic field giving 50 μa of resolved protons with a gas flow of less than 1 cc per hour and with a power input of 150 w is described. The effect of magnetic field upon power requirements is discussed.
With increased gas flow resolved currents in excess of 100 μa of protons have been obtained.
A Critical Evaluation of the Norelco High Angle X-Ray Spectrometer for Elastic Strain Measurements
Authors: Maloof S. R. , Erard H. R. 
Published: February 2005

The theory of measuring elastic strains in metals with an x-ray spectrometer is discussed and comparison is made with the x-ray back-reflection film method. It is shown that the accuracy attained in the determination of the surface biaxial stress sum from measurements on sharp diffraction lines with the spectrometer is equally as good as, or better than, that attained with the usual film techniques. An example is given of the determination of the biaxial stress sum with the spectrometer in a steel hardened to Rockwell C55. It was not possible to make the same determination photographically.
The effect of elastic anisotropy on x-ray stress determinations is briefly discussed. It is shown that the error in the determination of the stress sum due to an improper choice of elastic constants is less than that due to the normal experimental errors. An example is given of an x-ray determination of Poisson's ratio in different crystallographic directions in a FS8742 steel.
Application of the W.B.K. Method to the Dynamics of Linear Accelerator
Authors: Hoyaux Max 
Published: February 2005

The dynamics of ``small motions'' in a linear accelerator is studied in as general conditions as possible. It is concluded that heavy particles cannot be accelerated up to the Bev range by any practical combination of Tm and/or Te traveling and/or stationary waves. Several methods are however possible for electrons.
In the case of heavy particles, charges or currents must be introduced inside the beam. Two methods seem promising, (a) the Berkeley device (foils or grids) in which the beam expands as the power (1/8) of energy, and (b) a coaxial structure with dc bias (≃100 kv) in which the beam radius remains approximately constant.
The focusing by means of a dc current parallel to that of the beam is not practical.
A Precision Megohm Ratio Unit for High Voltage Measurements
Authors: Harris John N. 
Published: February 2005

A precision megohm ratio unit consisting of 100 resistance units wound of manganin wire is described. Stability of the order of a few parts per million is achieved through careful construction. Variations due to temperature changes are reduced by operating the resistor in a circulating oil bath maintained at a temperature of 33°C, where the temperature coefficient of the resistor is essentially zero. The resistor is capable of continuous operation at a potential of 5 kv and intermittent operation up to 25 kv.
A general method is also reviewed for setting up accurate resistance ratios by comparing two groups of resistors in appropriate series and parallel arrangements. Employing this method and using the units of the described megohm ratio unit, high ratios, consistently accurate to one part per million, have been set up.
An Automatic Surface Follower for Measuring the Rate of Evaporation of Molten Metals Undergoing Vacuum Distillation
Authors: Spendlove M. J. , St. Clair H. W. 
Published: February 2005

The automatic surface follower was developed to measure continuously the rate of evaporation of molten zinc at low pressure and to measure temperature gradients near the evaporating surface. The follower consists of a motor driven electrode that moves downward continuously until it contacts the metal surface and actuates a relay which stops the driving mechanism. Evaporation of metal lowers the surface level and breaks contact with the electrode thus causing the electrode to follow the level as evaporation proceeds. A record of the level displacement is recorded on a strip-chart potentiometer as a voltage, proportional to the movement of the electrode from which the rate of evaporation can be derived as a continuous function.
A thermocouple mounted on an auxillary carriage which can be moved independently of the electrode may also be used to explore the temperature distribution above or below the surface, while the electrode automatically establishes the location of the surface as a reference point.
GENERAL THEORY, DESIGN, AND CONSTRUCTION OF SENSITIVE VACUUM THERMOPILES (Part II) Construction of Sensitive Vacuum Thermocouples
Authors: Cartwright C. Hawley 
Published: February 2005

The vacuum thermocouples herein described had a sensitivity of about 1μV for 10−8 Cal. sec−1 falling on a receiver 0.5 mm2 in area and reached practical thermal equilibrium in 0.1 sec. The sensitivity in vacuum was usually 20 to 40 times the sensitivity in air. Very short fine wires of high thermoelectric power, bismuth alloys, were soldered to a gold leaf receiver which was blackened on one side by electroplating it with platinum black. The lightness of the gold leaf receivers made the instrument extremely rugged.
Greater sensitivity was obtained for visible radiation by using a receiver of silver leaf tarnished on one side with H2S; however, the sensitivity decreased for wave lengths longer than 1μ.
A NEW METHOD FOR RECORDING ELECTRONS
Authors: Carr Percy H. 
Published: February 2005

A brief review is given of the use of photographic plates for the recording of electrons. Photographic plates are rendered more sensitive to the action of electrons by the application of a small amount of certain oils; but whether oiled or not, photographic plates are insensitive to the action of electrons when they strike the plate with a speed of less than 25 equivalent volts. This work indicates that the sensitizing action of oil is largely due to cathodo-luminescence of the oil, and that the failure of the photographic plate to record low speed electrons is due to the high electrical resistance of the photographic emulsion.
Announcement is made of the discovery of the fact that metal surfaces are affected by electron bombardment in such a way that the bombarded regions react differently toward certain vapors than do the unbombarded regions. This effect has been observed even when the speed of the impinging electrons was only 12 equivalent volts. Experiments on silver and gold are presented in detail, and the practical use of the effect for electron recording demonstrated. Possible causes of the effect are also discussed.
When the two methods for recording electrons are compared, it is found that the photographic method has the advantage of speed and ease of reproduction; while the metal method has the advantage of reliability, freedom from charging up, and insensitivity to light. Moreover, the metal method can be used for lower speed electrons than can the photographic method.
HIGH FREQUENCY ELECTRODELESS DISCHARGE CHARACTERISTICS
Authors: Stuhlman Otto , Whitaker M. D. 
Published: February 2005

A spherical bulb containing mercury vapor at 25°C and air at various pressures was excited to luminosity when placed in a fixed helical coil carrying damped high frequency currents developing a predominant electrostatic field. Range of frequency of excitation 1800 to 555 k., of pressure 3 to 60 microns, of current 0.8 to 1.6 amperes. Visual intensity measured by a flicker photometer.
No simple relations were found to exist between visual intensity of the electrodeless discharge and air pressure, current or frequency, but consistent irregularities were observed.
The visual intensity was a maximum at a pressure of about 3 microns for all values of the exciting current but the minimum measurable intensity shifted from higher to lower pressures as the exciting current was decreased. Periodic breaks were found to exist in curves showing visual intensity as a function of exciting current. Constant current and pressure maximum values of visual intensity were found for wave lengths of 252, 358, and 490 meters, corresponding to frequencies of n, n+k, and n+2k.
ON THE THEORY OF POLYSYMMETRIC STATIC MACHINES OF THE TOEPLER-HOLTZ TYPE
Authors: Simon A. W. 
Published: February 2005

It is pointed out that the ordinary Toepler-Holtz static machine is the two-symmetric member of a whole family of poly-symmetric static machines of the same general type, in which the number of symmetries (or inductors) can be both even and odd. Historically only the even-symmetric members were built on account of the fact that the significance of the angle which the neutralizing rods make with each other was not understood. In the generalized machine the angle made by the neutralizing rods is 2π divided by the number of symmetries.
The detailed theory of the four and the five-symmetric members is developed and then generalized to higher members. It is shown that machines with an even number of symmetries are essentially direct current machines, while those with an odd number are alternators. It is shown also that the even numbered machines can also alternate if properly excited, however, that they are most efficient (as regards potential transformation) when acting as direct current machines. It is also shown that the efficiency (of potential transformation) increases with the number of symmetries, so that multiple inductor machines should be more powerful than the two inductor machines. Formulas for the period of alternation and the factor of potential transformation per revolution are deduced.
A CONSTANT FREQUENCY OSCILLATOR
Authors: Miller Carl W. , Andrews Howard L. 
Published: February 2005

The frequency of a vacuum tube oscillator depends not only upon the constants of the oscillating circuit but also upon those of the tube itself. In a tuned plate circuit, operating with minimum coupling the influence of the tube on frequency depends only on its plate resistance, and decreases as the plate resistance is increased. The steady drift in frequency usually observed is due mainly to the effect on the plate resistance of progressive changes in the filament. Due to their rugged filaments the UX852 and the screen grid UX860 have been found particularly suitable for steady oscillators.
Two methods of compensating for small changes in plate voltage and filament emission are described. A curve is included showing the effect of temperature on the frequency of the oscillator. The apparatus used for this precise study of small frequency changes is described. One of its most valuable features is an audio oscillator which is controlled by a vibrating string.
A THEORETICAL AND EXPERIMENTAL STUDY OF THE RESONANCE RADIOMETER
Authors: Hardy James Daniel 
Published: February 2005

A galvanometer system for the measurement of very small voltages, of the order of 10−11volts, is described and its application to the measurement of feeble radiations with a thermocouple discussed. It has been found that energies of the order of 1/200 of that previously detected by other devices could be measured with the Resonance Radiometer. The effect of the Brownian Movement on the system has been calculated and has been found to be about 1/200 that of the effect on the ordinary galvanometer.
An experiment is described for the measurement of the speed of action of thermocouples, and results on the splashed filament type are recorded.
MEASUREMENT OF FIBER DIAMETERS BY THE DIFFRACTION METHOD
Authors: McNicholas H. J. , Curtis H. J. 
Published: February 2005

The classification of wool fibers into standard grades is based entirely on the average diameter of the fibers. The diffraction of light by a bundle of parallel fibers was employed by Thomas Young in 1824 in a simple ingenious instrument for the rapid direct measurement of average diameter, but no thorough investigation has ever been made of the practical possibilities of this method in the routine grading of wool.
In the present paper a new construction of Young's instrument (the eriometer) is described, and a critical study is made of the accuracy and adaptibility of the instrument in the averaging of a wide range of diameters as distributed in a group of fibers. Sources of error and limitations of the method are discussed.
It is found that the eriometer average is in excellent agreement with comparable data obtained with the microscope. The method affords considerable opportunity for the further development of instruments to include additional features desirable in the study of wool or other textile fibers.
A PRECISION X-RAY SPECTROMETER AND THE WAVE LENGTH OF Mo Kα1
Authors: Compton Arthur H. 
Published: February 2005

An x-ray spectrometer was designed with the first crystal mounted on an arm supported by the frame of the spectrometer, and with the second crystal mounted on the central table of the instrument, whose position is read from a precision circle. The ionization chamber (of 28 cc capacity, filled with krypton) is on an arm whose position is read by a second precision circle. The instrument was built by the Societe Genevoise de Physique.
The first crystal was adjusted to throw the Kα1 line of molybdenum over the main axis of the spectrometer, and measurements were made with the second crystal in the (1, −1), (1, +1), (1, −4) and (1, +4) positions (Allison's notation). The reflection maxima from calcite (corrected to 18° C) occur at θ1=6°42′35.″5 and θ4=27°51′33.″0 with a probable error of 0.″25 due chiefly to errors in reading the circle. Using an apparent grating space for the first order of 3.02904A at 18° C, we get λ=707.830±.002 mA. Larsson obtained 707.831±.003 mA using Siegbahn's photographic method. Comparison of θ1 and θ4 gives for the index of refraction in calcite, 1 −μ=(2.10±.15)×10−6, as compared with Hatley's value of (2.04±.09)×10−6.
APPARATUS FOR SPECTROSCOPIC STUDIES IN THE INTERMEDIATE INFRARED REGION—20 TO 40μ
Authors: Strong John 
Published: February 2005

An infrared spectrometer is described which has the following features: (1) The entire optical path may be evacuated to about 10−4 mm of mercury pressure by the use of charcoal cooled with liquid air. (2) Exit and entrance slits are both adjusted from outside the vacuum by a single graduated head. (3) The optical system is arranged to use one mirror for telescope and collimation with the slits arranged on its optical axis. (4) The prism (or grating) is rotated by a 10-inch lever actuated by an ordinary micrometer. This lever connecting the prism table, which is in vacuum, with the micrometer which is outside, is sealed by a sylphon tube. (5) By connecting the micrometer head mechanically to a recording galvanometer the spectrometer may be made self-recording. (6) The spectrometer is constructed in such a way as to give the thermopile maximum isolation from thermal fluctuations in the room.
An absorption cell is described which has the following features: (1) The cell has small windows although it will handle a beam having a numerical aperture of ⅓. (2) The radiation path in the absorbing gas is one meter. The cell may be evacuated or it will withstand pressures of several atmospheres. (4) The cell may be heated to 300°C.
Various techniques for obtaining monochromatic bands of infrared radiation are discussed. A technique is described which makes spectroscopic measurements possible with a source whose temperature may fluctuate (such as the crater of a carbon arc).
THE WENNER POTENTIOMETER
Authors: Behr Leo 
Published: February 2005

A two-range, five-dial potentiometer is described which incorporates a decade construction suggested by Wenner. The upper range is 1.9111 volts in steps of 10 microvolts and the lower range is one tenth of this. The effect of contact resistance, thermal emf's and of errors in adjustment is considered in detail.
The limit of error for the instrument is 0.005 percent or 2 microvolts for the high range and 0.01 percent or 0.2 microvolt for the low range.