bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Suspension Balance
Authors: Beams J. W. , Hulburt C. W. , Lotz W. E. , Montague R. M.
Published: February 2005

An analytical balance is described in which the materials to be weighed are attached to a ferromagnetic body that is freely suspended by the axial magnetic field of a solenoid. The vertical position of the suspended mass is maintained by the automatic regulation of the current through the solenoid by means of an electronic servo-circuit actuated by a light beam and photomultiplier tube arrangement. The horizontal position of the supported mass is maintained by the symmetrically diverging field of the solenoid. Changes in the nonferromagnetic masses of the suspended bodies are determined by the resulting changes in the current through the solenoid necessary to keep the bodies freely suspended. Masses ranging from 105 grams to 2×10−6 gram have been suspended. The precision of the balance is limited only by the natural fluctuations in the circuit, the photomultipliers and the support system. This balance is especially useful where it is necessary to weigh materials inside of sealed chambers which contain gases, vapors or liquids, or which are evacuated. A method is described for accurately calibrating the balance.
Large Scintillators as Threshold Detectors for High-Energy Processes
Authors: Thresher J. J. , Van Zyl C. P. , Voss R. G. P. , Wilson R.
Published: February 2005

The design is described of several liquid organic scintillation counters which have been used to detect 100-Mev neutrons and gamma rays with the exclusion of lower-energy particles and quanta.

The neutron counter efficiency is a few percent and is nondirectional, properties not possessed by a more conventional counter telescope system. The gamma-ray counter has an efficiency of about 50%, with a line width of about 10%.

Particular problems arise in the use of these counters; counting rate stability is difficult to achieve; the maximum counting rate is limited by the pileup of individual pulses due to their finite width. These problems are discussed in detail and some solutions mentioned.
Simple Humidity Lag Apparatus
Authors: Hasegawa Saburo , Garfinkel Samuel B. , Wexler Arnold
Published: February 2005

A simple apparatus for producing humidity step-functions at room temperature, using saturated salt solutions to maintain constant relative humidities, is described. For an air flow of 200 lpm, the time required to change from one relative humidity to another is of the order of 30 to 50 milliseconds. This apparatus is particularly useful for establishing the lag characteristics of hygrometer elements.
Weigh-Bar Apparatus for Measuring Forces Resisting Ballistic Penetration
Authors: Krafft J. M.
Published: February 2005

A Hopkinson bar wire strain gauge technique has been developed for the measurement of projectile penetration force as a function of time. The elastic strain wave resulting from projectile impact and penetration of the bar end is measured with oscillographic equipment; this strain pattern is a direct and continuous measure of the penetration force. Comparison of impacts measured by the bar with those obtained by a previously developed precision optical chronograph have shown increased accuracy, and a simplification of test procedure and analysis with the new method.
Crystal Technique for Measuring Cyclotron Beam Energies
Authors: Delbeco Charles J. , Ramler Warren J. , Rocklin Sol R. , Yuster Philip H.
Published: February 2005

A lithium fluoride crystal when irradiated with deuterons from a cyclotron develops a yellow color; if the deuterons are stopped within the crystal, there is a sharp demarcation in color between the irradiated and unirradiated portions. It has been found that the measurement of the depth of penetration of the color into lithium fluoride can be used to determine accurately (±0.1 Mev at 20 Mev, ±0.2 Mev at 10 Mev) and rapidly the energy of deuterons in a cyclotron beam. A single exposure of a crystal to the deuteron beam allows one to determine not only the energy of the deuterons but also the angular orientation of the beam trajectories.
Čerenkov Counters with Thin Lucite Radiators
Authors: Linsley John , Horwitz Nahmin
Published: February 2005

Čerenkov counters are described which we have used successfully in measurements of the flux of primary cosmic-ray alpha particles. They consist of cylindrical Lucite radiators 2.5 cm thick viewed by end-window photomultipliers. Fast singly charged particles that pass through the effective area in directions roughly parallel to the counter axis give pulse-height distributions with 35–45 percent relative width at half-maximum for effective areas up to 60 cm2. An analysis of factors that influence the resolution of Čerenkov counters is given.
Thin Glass Windows
Authors: Hemmendinger Arthur , Roensch Arno P.
Published: February 2005

The fabrication and properties of thin glass membranes are described. Foil thicknesses are a few tenths of a micron, corresponding to energy losses for 1-Mev protons of 10–20 kev.
General Purpose X-Band Laboratory Microtron with Facilities for Electron Extraction
Authors: Kaiser H. F. , Mayes W. T.
Published: February 2005

A 3-Mev X-band microtron (electron cyclotron) particularly suited for laboratory use in nuclear and electron physics is described. About twelve electron orbits, in operating modes representing energy gains per turn up to 255 kev, may be obtained. By means of a magnetic shield probe, electrons may be extracted from any orbit for external experiments. Final orbit currents of 10−7 av amp and x-ray yields of 0.5 r/min at 10 cm are obtained. Ellipsoidally shaped sealed-off glass microtron tubes are under development.
Electronic Vacuum Dilatometer
Authors: Dooley M. E. , Atkins D. F.
Published: February 2005

A vacuum dilatometer based on the use of a linear variable differential transformer has been constructed. Expansion or contraction of the specimen moves a silica pusher-rod which, in turn, changes the position of the core of the linear transformer. The output of the transformer is directly proportional to the displacement of this core. The output is amplified, rectified, and fed into the chart-moving circuit of a function-plotting potentiometer. The transformer is supplied by a 2000 cycle per second oscillator. By varying the input voltage to the transformer, magnification of the expansion curves can be increased or decreased as desired. The instrument has been used for about a year for the detection of solid phase transformations in alloys. Several curves are reproduced to illustrate the performance of the instrument.
(n,γ) Detector for Study of Low-Energy Neutron Resonances with a Velocity Selector
Authors: Albert R. D. , Gaerttner E. R.
Published: February 2005

Development of a neutron capture gamma-ray detector for study of neutron resonances by the time-of-flight method is described. The G.E. 100-Mev betatron is used as a pulsed source of neutrons. Gamma rays are detected by a pair of large annular counters, each containing toluene-terphenyl scintillation phosphor and four 5819 photomultipliers. The counters have a 4 in. diam opening for the neutron beam, which passes first through one, then the sample radiator, then the other; all centered on a common axis. Each counter subtends about 40 percent of the total solid angle, and has a detection efficiency of about 5 percent for 1-Mev gamma radiation. The two detectors are connected in coincidence, with a resolving time of about 10−8 sec. Use of the instrument for measuring capture level densities is illustrated by a resonance curve for gold. The detector is also used for measurement of neutron transmission with thick samarium oxide as the radiator. This application is illustrated by transmission curves for manganese.
Beta-Ray Spectrometer for Coincidence Measurements
Authors: Nichols R. T. , Pohm A. V. , Talboy J. H. , Jensen E. N.
Published: February 2005

An intermediate image beta-ray spectrometer has been constructed utilizing the focusing properties of a U-shaped magnetic field distribution. The construction and performance of the instrument are discussed. A transmission of ten percent has been attained with a resolution of 5.5 percent. A scintillation spectrometer is used in conjunction with the intermediate image spectrometer for the purpose of making coincidence measurements.
Adaptation of Bergsman Microhardness Tester to American Optical Metallograph
Authors: LaRocca E. W.
Published: February 2005

The Bergsman microhardness testing machine, used in conjunction with conventional metallurgical microscopes, has been adapted for use with a turret-type metallograph with parfocalized and indexing objectives. Details of adaptors necessary to accommodate the Bergsman unit to the American Optical Research metallograph are given, including a description of the method used. The observation and measurement of microhardness values, usually a time-consuming and tedious operation, is greatly simplified since the diamond (Vickers) indentor is mounted in the turret and left in place, eliminating the necessity of replacing the penetrator with the objective lens, as is usually done with single objective metallographs. The load is applied by means of the fine focus adjustment, which raises the indentor rather than lowering the massive stage. Advantages of the combined system are its simplicity, speed, and improved accuracy, as well as the reduction in wear of moving parts.
Method for the Prompt Destruction of the Electron Beam in a Synchrotron. II
Authors: Hammer C. L. , Bureau A. J.
Published: February 2005

The analysis of the betatron oscillations of a two-sector synchrotron given in the preceding paper is generalized to apply to positions in the synchrotron other than the center of the perturbed sector. In this manner the azimuthal position of the maximum radial displacement of the electrons is found. This analysis is used to find the optimum position of the internal target with respect to the perturbing coils.
New Approach to the Measurement of the Specific Heat of Gases
Authors: Collins S. C. , Van Wylen G. J.
Published: February 2005

The variation of temperature with elevation within a body of gas in convective equilibrium in a gravitational field depends upon the specific heat. Specifically, the sum of the enthalpy and potential energy is the same for all elevations. It is only necessary, therefore, to measure the temperature at two points and the vertical distance between them to find the specific heat at the existing pressure. A calorimeter for securing an approximation to convective equilibrium is described.
Method of Measuring the Screen Potential of Cathode-Ray Tubes
Authors: Young J. R.
Published: February 2005

The Kelvin vibrating condenser method of measuring electrostatic potential has been applied to the measurement of screen potential in cathode-ray tubes. Results indicate that it will work satisfactorily in such an application, and it promises to be a useful tool in obtaining information on the charging phenomena of phosphors and insulators.
Thermal Diffusion Column for Concentrating Tritium in Tritium-Hydrogen Mixtures
Authors: Almqvist E. , Allen K. W. , Sanders J. H.
Published: February 2005

A hot wire thermal diffusion column of the type described by Clusius and Dickel has been constructed to increase the concentration of tritium in tritium-hydrogen mixtures. The column, 350 cm long and 2.86 cm in diameter, produced an equilibrium separation factor of 680 when filled to a pressure of 64 cm of mercury with hydrogen containing 3.5 percent tritium.
Determination of Small Gap Widths Used in Breakdown Studies by Capacitance Measurements
Authors: Sharbaugh Amandus H. , Fuoss Raymond M.
Published: February 2005

The mutual capacitance between hemispherical electrodes which are separated by a distance less than one-tenth of their radii is found experimentally to vary directly with the logarithm of the spacing. A mathematical derivation is presented which suggests that such a relation should hold. A particular electrode-dielectric assembly may be calibrated at large spacings where accurate mechanical measurements can be made, and then the capacitance increment corresponding to any desired smaller spacing may be obtained by a simple linear extrapolation. Electrode separations as small as 1 μ have been determined to an accuracy of less than 5 percent with this technique.
Energy Control for External Cyclotron Beams
Authors: Schrank G.
Published: February 2005

A device is described which stabilizes the mean energy of the external beam from an FM cyclotron to better than 0.1 percent. This control is achieved by inspecting the end of the range of a sample of scattered particles, and then using this information to regulate the cyclotron magnet current. It is also used as an absolute instrument to measure the mean energy to 0.3 percent at the same time.
Focusing Transmission Specimen Technique for the X-Ray Diffractometer
Authors: Lang A. R.
Published: February 2005

A multiple nonparallel receiving slit assembly enables diffraction patterns combining high intensity with good resolution to be obtained from transmission specimens using primary beam divergencies of several degrees. Analysis of line profiles from specimens set for symmetric and asymmetric transmission indicates advantages of the method for low angle diffraction and preferred orientation studies.
Integrating Mechanism for the Buerger Precession Camera
Authors: Nordman Christer E. , Patterson A. L. , Weldon Alice S. , Supper Charles E.
Published: February 2005

A Buerger precession camera has been provided with an integrating mechanism of the type designed by Wiebenga and Smits for the Weissenberg camera. The integrating motion is conveyed to the film holder directly by eccentric cams geared to the precession drive of the camera. Photographs taken with this instrument allow the recording of the integrated intensities and background for all the reflections of any row line in a single run of an automatic recording photometer.
Low-Level Thermocouple Amplifier and a Temperature Regulation System
Authors: Dauphinee T. M. , Woods S. B.
Published: February 2005

A breaker-type dc amplifier suitable for measurement of thermocouple voltages as low as 10−2 μvolt is described. Mechanically driven ``choppers'' operating at 40 cps are used to modulate the thermocouple signal and later demodulate the amplifier output. Both input and output are floating and may normally be operated connected to ungrounded circuits. Over-all voltage gain is approximately 107 while the zero error corresponds to less than 10−2-μvolt dc input within five minutes of turning on. The amplifier contains only standard components and details of a suitable chopper which can be made in the laboratory are given.

A temperature regulation circuit is described which is suitable for precision control of temperature in conjunction with a differential thermocouple. An indicated temperature match as close as 0.0002°C has been obtained with a single couple.
Electronic Double Flash Generator for Monocular and Binocular Stimulation
Authors: Ireland Fred H.
Published: February 2005

An electronic generator produces double flashes of intense white light, both flashes appearing either in the same lamp or each in a separate lamp as desired. Intervals between flashes can be varied from two to 600 milliseconds. Stimulus pairs are initiated either automatically or by manual control.
Metal Foils as Filters in the Soft X-Ray Region
Authors: Tomboulian D. H. , Bedo D. E.
Published: February 2005

The paper describes the use of thin foils of Be, Mg, and Al as filters in the 50 to 500 A spectral region. Mention is made of various procedures for the preparation of plastic backing films. Included are illustrations which show how the metallic filters may be utilized to exclude visible light, to sort out overlapping orders, and to transmit narrow bands of radiation by reducing the intensity of undesirable portions of the spectrum. For each of the metals and for a plastic material (Zapon), plots showing the linear absorption coefficient as a function of wavelength are also given. The absorption curves facilitate the choice of the appropriate filter and its thickness.
Proton Recoil Fast-Neutron Spectrometer. Part II. Experimental
Authors: Cochran R. G. , Henry K. M.
Published: February 2005

A triple-coincidence-type proton recoil spectrometer has been developed for measuring neutron spectra of reactors and artificial neutron sources. The instrument is composed of a triple-section proportional counter with suitable radiator-absorber wheels, amplifiers, electronic pulse-height selectors, and a triple-coincidence circuit. Considerable effort has been made to obtain maximum sensitivity by optimizing the radiator and absorber thicknesses and the counting times, and by minimizing the background effects. Under these conditions the energy resolution obtained approaches that obtained by photographic plates. The spectrometer was calibrated by measuring monoenergetic neutrons from the O. R. N. L. Van de Graaff generator. Typical examples of spectra measurements are included.
Measurement of Electric Fields as Applied to Glow Discharges
Authors: Warren Roger W.
Published: February 2005

Using a combination of well-known techniques, it has been possible to develop a magnetically compensating, ultra fine, high sensitivity, zero deflection electron beam probe method with automatic recording for measuring fields in glow discharges applicable to a wide variety of similar problems. Fields ranging from 1000 down to 0.2 volts per cm have been measured in one-twentieth or less the times required with previous techniques and with a gain in sensitivity by a factor of ten or better. Wall potentials can simultaneously be recorded. The method is limited to pressures below about 3 mm for 10 cm diameter glows by diffusion of the beam, but correspondingly greater pressures can be used in smaller tubes or with higher energy (say 50 kv) electron beams. The limitations imposed by the effect of the disturbing magnetic field on the discharge are indicated and examples are given of data taken in a glow discharge.
Portable Potentiometer and Thermostatted Container for Standard Cells
Authors: Spinks A. W. , Hermach F. L.
Published: February 2005

Portable inexpensive equipment for maintaining the volt in a laboratory to 0.002% with saturated standard cells is described. The equipment consists of a temperature-controlled air bath for the cells, and a thermofree potentiometer for intercomparing cells with reasonable accuracy.
Three-Hundred-Mev Nonferromagnetic Electron Synchrotron
Authors: Jones W. B. , Kratz H. R. , Lawson J. L. , Miller D. H. , Miller R. D. , Ragan G. L. , Rouvina J. , Voorhies H. G.
Published: February 2005

An electron synchrotron, capable of accelerating electrons to energies of 300 Mev, which has been in operation for some time at the Research Laboratory, General Electric Company, is described. This machine uses no iron to produce the magnetic guide field. Electrons are injected at an energy of 100 kev, accelerated to 4 Mev by betatron action, and to 300 Mev by synchrotron action. The magnetic fields for the betatron and synchrotron guide fields are produced directly by large currents flowing in coils suitably disposed near the electron orbit. The orbit diameter is 48 in. and a field of 16 000 oersteds at the orbit is produced by a current pulse with an amplitude of 26 000 amperes. The entire coil system, together with the radio-frequency resonator and injector, is located in a vacuum. The repetition frequency is 15 pulses/sec, and the x-ray beam from an internal target has an intensity of about 2×1010 equivalent quanta/min through a collimator which transmits about 60% of the total beam.
Wide-Range Logarithmic Voltmeter
Authors: Hunt F. V. , Hersh J. F.
Published: February 2005

A wide-range logarithmic response function is approximated by cascading a series of ``ramp'' functions, each representing the plate current of a triode driven toward cutoff by a diode rectifier in its grid circuit. Proper apportionment of the ac signal between the biasing diode and the triode makes the ramp symmetrical so that complementary deviations from linearity cancel when two or more ramp functions are cascaded. The wide-range voltmeter consists of a cascade of such amplifier stages driven successively to cutoff. Each stage is held at cutoff after reaching it by a diode-coupled holding bias fed forward from preceding stages. This arrangement prevents overloading of any stage and makes the range of the voltmeter approximately equal to the voltage gain of the cascade amplifier. Even without invoking compensation techniques, the response at all input levels can be made independent of frequency over a range extending from 50 cy/sec to 100 kc/sec. A simple alignment procedure is adequate to compensate normal tube variations, and a logarithmic response linear within ±1 db is readily obtained over the 80-db voltage range extending from 1 millivolt to 10 volts. The range can be changed easily, in both the number of db covered and in the input voltage for full-scale deflection, by connecting the indicating milliammeter to different numbers and combinations of ramp elements.
Measurement of Electron Energies by Deflection in a Uniform Electric Field
Authors: Harrower G. A.
Published: February 2005

The well-known principle that the deflection of electrons in a uniform electric field can serve to measure the distribution of their energies, has been investigated both theoretically and experimentally. Simple theory suggests a particular choice of parameters for an instrument intended for such measurements. Design equations are presented, dimensions of a practical device are given, and the necessary associated electric circuits are discussed. An instrument of this type employes only an electric field, is small in size, is easily constructed, and provides a linear scale of energy values. An analyzer built to this design with an over-all length of five inches was able to completely separate electrons having a difference in their energies of two percent.
Liquid Scintillation Techniques for Radiocarbon Dating
Authors: Pringle R. W. , Turchinetz W. , Funt B. L.
Published: February 2005

A study has been made of the merits of liquid scintillation methods for radiocarbon dating. The synthesis of toluene from sample carbon, and the use of this liquid in a 20 cc cell, in combination with the best available photomultiplier tube, gave results which indicate that this method can be of significance for samples of age 45 000 years, for a 48 hour counting period. A background counting rate of 3.34 cpm was obtained with ``old'' toluene and adequate shielding and pulse height discrimination, but without photomultiplier cooling or the use of coincidence-anticoincidence arrangements. This method suffers, however, from a rather elaborate chemical synthesis, so that a simpler diluent technique was studied, involving the synthesis of methanol from sample carbon. This method is suitable for routine analysis, and gave results indicating a significance to 37 000 years, the decreased accuracy of the method being the result of the somewhat lower fluorescence efficiency of the scintillating mixture. There is evidence that a routine methyl borate diluent method will give an accuracy comparable to that of the toluene method.
Experimental Investigation of Chromatic Aberration in the Electron Microscope
Authors: Katagiri Shinjiro
Published: February 2005

Experimental results on the reduction of chromatic aberration in the magnetic electron microscope are described. It is proved that the chromatic field aberration can be completely compensated by a proper combination of two lenses with adequately designed pole pieces and the voltage stabilization tolerance is greatly improved. Micrographs with a resolution of about 5 mμ can be obtained even under a voltage fluctuation as large as ΔE/E=1.10−2.
Pulsed Neutron Source
Authors: Martina E. Frank , Ashby Val J.
Published: February 2005

A pulsed neutron source is described which gives 106 neutrons in a burst which is 2×10−8 second wide. The plasma of an ion pump is used as the source of deuterium ions which are accelerated to 200 kv before striking a deuterium target, where the D(d,n)He3 reaction produces 2 to 3 Mev neutrons.
Piston-Type Strain Gauge for Measuring Pressures in Interior Ballistics Research
Authors: Dimeff J. , Carson J. A. , Charters A. C.
Published: February 2005

Various types of pressure gauges used in interior ballistics research are discussed briefly. A piston-type strain gauge suitable for measuring the time history of transient pressures with components from steady state to 50 kc and magnitudes to 2×105 psi, is described in detail.
Design of Differential X-Ray Filters for Low-Intensity Scattering Experiments
Authors: Soules Jack A. , Gordon William L. , Shaw C. H.
Published: February 2005

The conditions for the thicknesses of the foils of a Ross differential x-ray filter are examined to yield the best accuracy of monochromatic intensity measurement for a given heterogeneous beam of x-rays. The results are applied to the problem of monochromatizing the Kα radiation from a copper target x-ray tube using nickel and cobalt foils. The improvement in the differential filter as a monochromator when used with a proportional counter and single-channel pulse-height discriminator is pointed out.
Electron Bombardment Furnace Temperature Controller
Authors: Rocco W. A. , Sears G. W.
Published: February 2005

An electron bombardment furnace temperature controller is described which operates over a wide temperature range with excellent stability. The controller uses a high gain servo amplifier system to maintain constant bombardment current. The bombardment voltage is held fixed over a wide current range by a constant voltage power supply. Temperature constancy of about 0.1% at 1600–1800°C is maintained over a several hour period.
High Resolution Crystal Spectrometer for Neutrons
Authors: Sailor V. L. , Foote H. L. , Landon H. H. , Wood R. E.
Published: February 2005

A crystal spectrometer for neutron measurements has been developed which has relatively good resolution over an effective energy range from 0.08 to >20 ev. The figure of merit which has been obtained is 0.171 μsec/m with Be (123̄1) and 0.127 μsec/m with Be (224̄2) monochromator. The good resolution is made possible by a multiple channel collimator (Soller slit) of novel design. The collimator is described in detail and the resolution function for the system is derived and discussed. It is shown that the resolution of the system is essentially independent of the mosaic spread of the crystal. Experimental results are presented which illustrate the performance of the instrument.
High-Speed, Direct Recording Fabry-Perot Interferometer
Authors: Biondi Manfred A.
Published: February 2005

A direct recording Fabry-Perot interferometer is described which has a high optical speed and provides a direct tracing of spectral line shapes on a linear scale. A photomultiplier views the center spot of the interference pattern. The output of the photomultiplier goes to a vibrating-reed electrometer and then to a pen recorder. The wavelength of the light at the center of the interference pattern is made to vary with time by changing the index of refraction between the interferometer plates. This is accomplished by enclosing the plates in a gas-tight housing and admitting an inert gas such as argon or helium to the housing. By the proper choice of gas and of the rate of pressure change, one obtains the desired rate of tracing the line shape. Orders of magnitude reduction in ``exposure'' time are achieved by eliminating the use of photographic plates.
Linear Densitometer Circuit
Authors: Hariharan P. , Bhalla M. S.
Published: February 2005

A densitometer circuit is described which uses two photomultiplier tubes operated at constant anode current as a balanced range compressor, followed by a logarithmic difference amplifier. A density scale linear to ±0.01 density unit over a density range of 2.5 is obtained. The circuit is stable, requires no critical adjustments, and is unaffected by changes in the luminous output of the source.
Pulsed Photomultipliers for Fast Scintillation Counting
Authors: Singer Sidney , Neher Leland K. , Ruehle Robert A.
Published: February 2005

A pulsed 931-A photomultiplier and TW-10 traveling wave oscilloscope have been used to measure the scintillation decay times of (a) transtilbene, (b) terphenyl-in-toluene, and (c) polystyrene plastic containing one percent terphenyl, 0.03% α-NPO, and 0.01% zinc stearate. The times for 1/e decay are (a) 4±1×10−9 sec, (b) 2.2±0.3×10−9 sec, and (c) 2.2±0.3×10−9 sec. The behavior of the multiplier with large collector currents was studied, using a synchronized flash lamp. Linear currents up to 1.5 amperes and maximum currents up to 15 amperes were obtained. Currents in the ampere range can give rise to an oscillation which may limit the application of pulsed photomultipliers.
Solid-State Detector for Low-Energy Ions
Authors: Heinz O. , Gyorgy E. M. , Ohl R. S.
Published: February 2005

The electrical properties of a polished surface of high-purity silicon can be greatly modified by heavy ion bombardment. In particular, the change in the rectifying properties of silicon has been used as a detector of low energy ions striking the surface. By bombarding with He+ ions through a silver film which was evaporated directly on the silicon, we determined the thickness of Ag at which ions no longer reached the silicon surface. By this method it was found that the range of 30 kev He+ ions in Ag films is 2480±250 A. The lowest ion energy which produces an observable effect on the silicon is about 200 ev. Similar effects have been observed for hydrogen, argon, nitrogen, and oxygen ions. Other electrical properties of silicon surfaces which have possibilities as ion indicators are mentioned.
Jerkmeter for Ballistocardiography
Authors: Perls Thomas A. , Kissinger Charles W.
Published: February 2005

``Jerk'' is defined as the time derivative of acceleration. Simple methods for designing jerkmeters are briefly discussed. The present design consists of a low-frequency (20 cps) piezoelectric accelerometer, the output of which is electrically differentiated. The response of the instrument is flat within ±7% from zero-frequency to 18 cps, at 21°C, but changes in response up to 33% are introduced in the range between 10 and 18 cps at temperatures between 12°C and 32°C. A ballistocardiogram is shown, with simultaneous displacement, velocity, acceleration, and jerk records.
Regenerative Beam Extraction on the Chicago Synchrocyclotron
Authors: Crewe A. V. , Kruse U. E.
Published: February 2005

The proton beam extraction system of the 450-Mev Chicago synchrocyclotron is described. The nonlinear theory of LeCouteur has been applied and an external beam of 1011 protons per second has been obtained.
Use of Counter Tubes in X-Ray Analysis
Authors: Parrish W. , Kohler T. R.
Published: February 2005

The more important properties of end-window Geiger counters, side-window proportional counters, and NaI(Tl) scintillation counters are reviewed and their performance in the 5 to 50 kvp x-ray analysis region is compared. Proportional and scintillation counters have resolving times of the order of 0.25 μsec and virtually eliminate the nonlinearity limitation of the Geiger counter. They produce pulse amplitudes proportional to the energy of the x-ray quanta, and thus simple pulse height discrimination techniques can be used to obtain greatly improved peak-to-background ratios with little loss of intensity of the characteristic x-rays. They are as reliable and nearly as easy to use as Geiger counters. The electronic discrimination method is described and explained with some practical applications. For a given experimental arrangement, the measured intensity is determined by the quantum counting efficiency of the counter tube, and the peak-to-background ratio is determined by the spectral response of the detector-discriminator combination.
Ion Source for the Production of Multiply Charged Heavy Ions
Authors: Anderson Carl E. , Ehlers Kenneth W.
Published: February 2005

A pulsed, cold-cathode ion source has been developed to produce multiply charged ions for use in a linear accelerator. Milliampere currents of such ions as He42+, C122+, N143+, O163+, Ne203+, and smaller currents of S325+ and A406+ have been produced in focused beams.

Mass spectra of the various ionization states produced by the arc are presented. Constructional details of the source and the associated electronic equipment are given, and operating characteristics of the source and ion extraction are discussed.
Thermal Transpiration in the Mass Spectrometer Inlet System
Authors: Dietz Leonard A.
Published: February 2005

Transpiration of gas in the inlet tube between the sample reservoir and the ion source is eliminated if the thermal gradient occurs in the low-pressure region between the leak and the ion source. Since transpiration was found to be a total pressure effect, sensitivity response is not affected if gas mixtures and calibrating gases are run at the same pressure, even though transpiration is present.
Automatic Toepler Pump of Improved Design
Authors: Urry Grant , Urry W. H.
Published: February 2005

The construction and operation of a compact automatic Toepler pump of the mercury piston type which has many advantages over previous designs are described. The mercury motion is controlled by a switching relay activated by electrodes so placed that at the ultimate of its stroke the air leak to the lower mercury reservoir is closed and an oil vacuum pump is started to evacuate it, and at the bottom of the stroke the vacuum pump is stopped and the air leak opened to allow the mercury to rise in the piston chamber. Pumping action is effected by two glass valves with conically ground seats in series in the gas inlet and outlet tubes.
Xenon Flash Tube of Small Size
Authors: Edgerton Harold E. , Cathou Pierre Y.
Published: February 2005

A xenon-filled electronic flash tube with a cylindrical lighted volume of 1.2-mm diam and 6-mm length has been developed for use as a small source in optical systems, such as the schlieren and interferometer types. The lamp has been operated at 6000 flashes per second from a hydrogen-thyratron driver circuit to record the density in air flow in an interferometer. Flash duration varies from 0.3 to 3 μsec, depending upon the circuit conditions. A peak brightness of 10 million candlepower per sq cm has been achieved.
Direct Method of Measuring the Contact Injection Ratio
Authors: Curtis Orlie L. , Gossick B. R.
Published: February 2005

A direct method of measuring the injection ratio of rectifying contacts is described. With this method, the injection ratio is determined by comparing the area of a current injection pulse with the area of the resulting hole storage pulse as observed on an oscilloscope screen.
Reduced Compton Effect Scintillation Spectrometer
Authors: Roulston K. I. , Naqvi S. I. H.
Published: February 2005

To assess the effectiveness of plastic phosphors in the reduction of Compton effect in scintillation spectrometers, a spectrometer with a small NaI(Tl) crystal surrounded by a large plastic phosphor has been constructed. The output from the plastic phosphor is put in anticoincidence with the output from the NaI(Tl) crystal. A reduction of Compton contribution in the scintillation spectrum to about 35% of original value is obtained. Comparison of results with, and without, the shield enables certain spectral features to be identified. Possible applications are discussed. Transistor anticoincidence circuits are used.
Beam Extraction in the Microtron
Authors: Brannen Eric , Ferguson H. I. S.
Published: February 2005

This paper describes the utilization of a simple universal vacuum joint, as the support for a magnetic shield type of deflector in the form of a cylindrical soft iron pipe. Variable insertion of this pipe and change of direction in azimuth permit the extraction, with up to 70% efficiency, of all the microtron orbits, making available, in this case, electrons between 1 and 4 Mev energy, in steps of 0.5 Mev. Radiation intensity, or electron current, from any particular orbit, up to the limit determined by the peak for that orbit, may be set at any desired level by small changes in the insertion of the deflector.
Dual Objective Optical Micrometer for Strain Measurements
Authors: Papirno Ralph , Gilbert Arthur C. , Becker Herbert
Published: February 2005

A dual objective optical micrometer for strain measurements of up to 8% is described. In this instrument the images of two reference marks on a specimen are brought to a focus in one field on the reticle scale of a filar micrometer eyepiece. The relative displacement of the images is measured by the eyepiece and the readings are reduced to strain by the use of a calibrated magnification factor. Since only the separation distance of the images is of interest, the exact position of the images in the field is not critical. No external point of reference on the instrument mount is necessary, hence alignment problems are minimized and the instrument may be moved between readings. The described calibration procedure shows that the least count of the instrument with a 2.64-in. gauge length is 42×10−6 in./in. and measurements can be made with an accuracy of ±13×10−6 in./in.
Solution of Algebraic Equations on an Analog Computer
Authors: Cahn C. R.
Published: February 2005

A method has been found for solving an algebraic equation for a real or complex root on an analog computer (electronic differential analyzer). The computer connections are arranged so that the root locations may be shifted along the real axis of the complex plane by adjusting a ganged potentiometer. A maintained transient is indication that a root has been shifted to the imaginary axis, allowing the real and imaginary parts of the root to be read. The accuracy is reduced when a second nearby root is present; however, poor tracking in the ganged potentiometer has about the same effect as an improper setting of a coefficient of the equation.
Dual Proportional Counter for Low-Level Measurement of Alpha Activity of Biological Materials
Authors: McDaniel E. W. , Schaefer H. J. , Colehour J. K.
Published: February 2005

A device has been developed for the alpha counting of solid materials of extremely low activity. It utilizes two identical detectors of novel design inside a common gas envelope and a programming mechanism to permit the automatic alternation of samples between the counters. The detectors are rectangular, screen wall, proportional counters which operate at an average background of 3.8 counts per hour. Thin, flat samples of 141 cm2 area may be accommodated.
Broad-Range Magnetic Spectrograph
Authors: Browne C. P. , Buechner W. W.
Published: February 2005

A broad-range magnetic spectrograph for precise measurement of the energies and intensities of charged particles from nuclear reactions is described. A uniform magnetic field with a circular boundary focuses particles from a source outside the field along a hyperbolic focal surface. Particles with energies varying by as much as a factor of 2.5 may be simultaneously recorded on nuclear-track plates. Under routine operating conditions, an energy resolution of better than 1000 is obtained over the length of the focal surface. The design, construction, testing, and operation of the spectrograph are described, and plots of dispersion, magnification, aberration, and calibration are given.
High-Current Ion Injector
Authors: Lamb William A. S. , Lofgren Edward J.
Published: February 2005

An ion injector is described which is capable of continuous currents of protons or deuterons of ¾ amp at 100 kv or pulsed currents of 2 amp at a 20% duty cycle. The beam comes to a focus about 3 in. in diameter and diverges at an angle of ±5°. It is approximately 95% atomic ions.
Magnetic Shielding with Multiple Cylindrical Shells
Authors: Wadey W. G.
Published: February 2005

The increased effectiveness of multiple over single shields is shown and formulas (including a recursion formula suitable for automatic computation) are given for the computation of the shielding ratio (field outside/field inside) for any number of concentric shells of contemporary high-permeability materials in any combination. Sample designs are given for shields 2¼, 3⅛, and 5¼ in. i.d. Scaling rules and charts are given for finding other designs without calculation. Graphs are given for the penetration of the field into the open end of the shield. The alternating-field case is treated and formulas are given for finding the shielding ratio for alternating fields.
Electrolytic Tank, Design and Applications
Authors: Kennedy Phyllis A. , Kent Gordon
Published: February 2005

The theory of the electrolytic tank analog as a device for the solution of potential problems is reviewed, and some of the more important applications are discussed.

The mechanical requirements of an electrolytic tank design are stated. A description of the Harvard tank is given, indicating how these problems were met. The figure of mechanical uncertainty for the Harvard tank is estimated to be 0.01 in.

A discussion of experimental error in tank measurements covers problems of electrode and electrolyte materials a well as difficulties resulting from surface tension.

Control experiments for determining the accuracy of level and tilted tank measurements are described, and the results presented. Although high accuracy is possible in the level tank, only great care can produce results in the tilted tank which are reliable to within 3%.
High Sensitivity Mass Spectrometer for Noble Gas Analysis
Authors: Reynolds John H.
Published: February 2005

A high-sensitivity mass spectrometer for noble gas analysis is described in detail. Ultra-high vacuum techniques have been used throughout so that small rare gas samples can be closed off within the spectrometer envelope and analyzed statically. This procedure is of considerable advantage in analyzing argon and lighter rare gases. The background spectrum when the spectrometer pressure is 5×1010 mm Hg is described. Sensitivity data are presented. The detectability of the instrument for xenon atoms (any isotope) is 0.5×106 atoms; for A36, the detectability is 14×106 atoms.
Negative Pressure Isopentane Bubble Chamber
Authors: Pless Irwin A. , Plano Richard J.
Published: February 2005

A negative pressure bubble chamber utilizing isopentane for the sensitive fluid is described. The chamber is of all glass construction which gives it a comparatively long sensitive time and allows the use of 90° stereophotography with consequent advantages in the speed and accuracy of analysis. An approximate theory for negative-pressure bubble chambers is given. The construction and operation of the chamber is described.
Controlled Development for Nuclear Emulsions
Authors: Blum Jacques M.
Published: February 2005

A method consisting of separating the active phase of the development of nuclear emulsions into two or more stages is presented here. The purpose of this procedure is to obtain a reproducible degree of development of these emulsions at some prefixed level of sensitivity. The preliminary results reported indicate the feasibility of this procedure.
Turbulent Concentration Fluctuations through Electrical Conductivity Measurements
Authors: Prausnitz J. M. , Wilhelm R. H.
Published: February 2005

A description is given of an instrument for measuring turbulent concentration fluctuations in the liquid phase. A calibrated conductivity cell is used to measure the conductivity of a small volume surrounding a fixed point in a turbulent fluid. The output of the cell is fed into suitable electronic apparatus. Mean-square and mean-absolute-value concentration fluctuations are measured. The method gives promise of providing a new experimental technique for the study of turbulence. Measurements permit calculation of a scale of turbulence with a standard deviation of ±2.8%. Details of relation between concentration fluctuation measurements and turbulence parameters are provided in another paper.
Modified Adiabatic Calorimeter
Authors: Belaga M. W. , Coddington D. M. , Marcus H.
Published: February 2005

A modified adiabatic type calorimeter, capable of measuring the heat capacities of natural and synthetic organic liquids in the temperature range of 100° to 500°F, was designed, constructed, and calibrated. In this calorimeter a fixed rate of power is supplied to the sample, and a bath which surrounds the sample container is maintained at the same temperature in order to prevent heat losses from the sample. The heat capacity of an unknown material may be calculated from measurements of the time rate of temperature rise, heat input, and mass of the sample. The calorimeter was calibrated with materials of known heat capacity and the following relation between the calorimeter constant and temperature was obtained: K(T)=0.256−3.706×10−5t+6.839×10−7t2.
Simple 60-cps Hysteresis Loop Tracer for Magnetic Materials of High or Low Permeability
Authors: Howling D. H.
Published: February 2005

A simple form of 60-cps hysteresis loop tracer for materials of high and low permeability is described. By including a differential form of balance control, all 60-cps voltage present in the leads and pickup coils, prior to the insertion of a magnetic specimen into the field coils, may be completely balanced out. The sensitivity is sufficient to provide a one-inch peak to peak deflection on a Dumont 304A cathode-ray oscilloscope for a flux change of 0.1 maxwell.
Achromatic Beam Translation Systems for Linear Accelerators
Authors: Brown K. L.
Published: February 2005

The beam of electron linear accelerators has desirable geometric properties, but usually contains undesirable secondary particles and a relatively broad energy spectrum.

In order to dispose of the secondary particles and, at the same time, establish control of the width of the energy spectrum, several magnetic deflection systems have been considered for the Stanford machines. Two such systems are described here, one of which has been adopted for three of the Stanford accelerators. Both systems are capable of translating the beam without energy dispersion.
Microinhomogeneities in Magnetic Fields
Authors: Brown H. H. , Bitter F.
Published: February 2005

Small variations in the fields of magnets, caused by structures or domains in the pole faces, were investigated by moving a small coil in a circular path. It was found that for a given pole face the variations in the field were all about the same size, and decreased exponentially from the pole face. None of the materials tested as pole faces produced strikingly better fields than another.
High-Temperature Adapter for X-Ray Powder Cameras
Authors: Fridrichsons J.
Published: February 2005

A high-temperature x-ray diffraction unit for powder specimens is described, which can be attached to standard room-temperature cameras. The evacuable heater-specimen space is surrounded by a beryllium cylinder with cellophane windows and the heater, either a small, gap-divided spiral, holding the specimen capillary, or a Pt wire with coated-on specimen, can be slipped in it and rocked during exposures. Temperatures up to 1000°C can be obtained with power consumption of ca 10 w. Specimen temperatures are determined from line-shifts in the pattern of added internal standard or the pattern from the platinum heater wire.
Thyratron Circuit for Reliable Temperature Control
Authors: Frigerio Norman A.
Published: February 2005

Two temperature control thyratron relays for use with contact thermoregulators are described, posessing long life, high reliability and low control power requirements. In addition, simple phase shift circuits have been incorporated allowing continuous control of system thermal hysteresis.