bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum Geometrical Conditions for Mass Spectrometers
Authors: Geoffrion Claude
Published: February 2005

The relations between slit dimensions, beam divergence, luminosity, and resolving power of various single-focusing mass spectrometers are established. From these, the conditions for maximum luminosity for a given resolving power are derived. It is found that a third-order spectrometer operated under optimum conditions can be more luminous than one of conventional design. Data are given.
Improved Apparatus and Technique for Electromagnetic Determination of Blood Flow
Authors: Kolin Alexander
Published: February 2005

The paper describes improvements in the method of measuring blood flow by electromagnetic induction in intact blood vessels left in their normal place. ``Pick-up sleeves'' and ``occlusion cuffs'' are described which can be implanted permanently into the animal without causing irritation. A method of finding the optimum position of the blood vessel in the magnetic field and of determining the strength of the utilized magnetic field component is outlined. It is shown that calibration of individual blood vessels is unnecessary; a given apparatus is calibrated once and for all by one single flow measurement in vitro. The design of the compensator is simplified. A method for compensating disturbances encountered with blood vessels which are agitated in the magnetic field is described. Various sources of electromagnetic disturbances and means of eliminating them are discussed.
A Fast Neutron Detector
Authors: Hornyak W. F.
Published: February 2005

A fast neutron detector with an efficiency of a few percent and the capability of detecting neutrons in the presence of intense gamma-ray backgrounds has been developed. The detector consists of a ZnS and Lucite molded cylinder used in conjunction with a 5819 photomultiplier tube. This detector is well suited to experiments requiring ``good geometry'' and pulse speeds of the order of 0.1 μsec.
An Experimental Radiosonde for the Investigation of the Distribution of Water Vapor in the Stratosphere
Authors: Suomi Verner E. , Barrett Earl W.
Published: February 2005

Following a short discussion of the limitations of the various types of balloon-borne radiosondes when used to gather information in the stratosphere, an analysis of the reasons for these limitations and some means for circumventing them are presented. It is shown that the choice of sensing element, or transducer, for temperature measurement is rather arbitrary so long as the element possesses a small lag coefficient and a high albedo. For pressure measurement it is shown that a nonlinear transducer, such as the hypsometer, with a sensitivity which increases at low pressure, is essential. For humidity measurement, only the condensation (dew point) technique is capable of giving meaningful data at great heights. The balance of the paper describes in detail a complete sounding instrument consisting of a hypsometer, a fine-wire thermo junction, and a fully automatic electronic dew-point hygrometer, together with the necessary amplifier, radio telemetering equipment, and internal calibration standard. The telemetering system is of special interest due to the relatively great accuracy obtainable with a very simple arrangement of components, utililizing only a modified Diamond-Hinman radiosonde. The instrument described in this paper has been flown to altitudes of over 30 km, using ``Skyhook'' plastic balloons; these flights yielded the first detailed pictures ever obtained of the moisture distribution in the stratosphere.
A Frequency Eliminating Transconductance Bridge
Authors: Michels Walter C. , Barbera Richard C.
Published: February 2005

A simple transconductance bridge circuit, which eliminates completely a single frequency component and which suppresses in part a band of controllable width, is described. The circuit requires no reference voltages. A number of circuit variants, adaptable to special applications, are given and the applications of the device to ripple elimination and to band elimination amplifiers are discussed.
A Transmission-Line Pulse Inverter
Authors: Rochelle Robert W.
Published: February 2005

The polarity of fast rise-time pulses can be inverted with a minimum of distortion by means of a transmission-line network. The features in the design of a typical pulse inverter for obtaining push-pull cathode-ray-tube deflection voltages from single-ended signals are presented. The normalized design graphs are a considerable aid in the calculation of pulse-inverter characteristics.
Constant Pressure Apparatus for Studying Reaction Rates
Authors: Davis Wallace , Rosen Fred D.
Published: February 2005

An automatic constant pressure system has been designed and constructed on the basis of fluid displacement in a sylphon bellows system. Booth-Cromer pressure transmitters, operated in conjunction with appropriate self-balancing relays, have been used to maintain constancy of pressure. The apparatus has been tested at 25 and 60°C with air or fluorine as the confined gas at total pressures of ⅓ to ½ atmosphere and for periods as long as 30 days. Reaction or evacuation rates of 1 to 16,000 cc atmos per day gave pressures that have been found to remain constant within about 1 percent.
Sodium Pump for Purification of Inert Atmospheres
Authors: Bromley LeRoy A. , Edwards Russell K. , McKisson Raleigh L.
Published: February 2005

A liquid sodium pump and contacting tray are described and recommended for the removal of oxidizing gases from inert atmosphere working chambers. The inert gas is circulated over streams of molten sodium on the contacting tray. With this apparatus it is easy to obtain an atmosphere whose reactivity is less than the best vacuum in which comparable manipulations may be accomplished.
A Device for Computing Correlation Functions
Authors: Hastings A. E. , Meade J. E.
Published: February 2005

An analog device, using magnetic recording on tape, has been constructed for computing cross- and auto-correlation functions. Auto-correlation functions and their transforms, the power spectra, are obtained for several types of functions.
A Rotating-Shutter Time-of-Flight Spectrometer for the Slow-Neutron Resonance Region
Authors: Selove W.
Published: February 2005

A high speed rotating-shutter spectrometer has been built for making slow-neutron measurements in the resonance region, using a neutron ``pile'' as a source. One of the principal advantages of the new apparatus is that comparatively small samples are required—typically less than one gram. The design and operation of the apparatus are described.
A Uniform Solenoidal Magnetic Field Nuclear Spectrometer
Authors: Schmidt F. H.
Published: February 2005

The mechanical and electrical features of a ring image type spectrometer are described. The baffle system may be rolled out of the vacuum chamber for ease of adjustment. The predicted momentum resolution vs percent transmission has been verified; e.g., 0.4 percent resolution at 2 percent transmission. A close doublet in the internal conversion spectrum following beta-decay of Cs134 has been observed. The lines differ in momentum by 0.6 percent.
A Planimetric Method of Harmonic Analysis
Authors: Daniels Fred B.
Published: February 2005

A method of harmonic analysis is described which requires only a planimeter and a set of ruled grids. An approximate value of a sine or cosine coefficient is obtained from a single tracing of the plotted function and the accuracy may be improved by means of correction terms obtained from higher order harmonics. The error resulting from the neglect of the correction terms is less than in the Fischer-Hinnan method.
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.
Use of the Flying-Spot Scanner to Study Photosensitive Surfaces
Authors: Pantchechnikoff J. I. , Lasof S. , Kurshan J. , Moore A. R.
Published: February 2005

A flying-spot tube was used to scan a large-area germanium photocell with a minute light spot. The output of the cell was amplified by a wide-band amplifier which controlled the intensity of a kinescope driven in synchronism with the flying-spot scanner. The display on the kinescope is a map of the photosensitivity at the surface of the photocell. A similar technique was also used to measure the frequency response of the photocell.
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.
Fast Neutron Counting with Hydrogenous Liquid Phosphors
Authors: Keepin G. R. , Lovberg R. H.
Published: February 2005

A series of controlled experiments has been undertaken to study the dependence of neutron counting efficiency on the type of liquid phosphor and on the geometry and light collection efficiency of the liquid container. Five hydrogenous scintillating liquids have been compared in various container geometries. From differential lead absorption measurements using a calibrated polonium-beryllium neutron source, neutron counting efficiencies from 5.4±2 percent to 17.9±6 percent have been obtained.
Automatic Recording of the Pressure-Area, Pressure-Time, and Area-Time Characteristics of Monomolecular Films
Authors: Anderson P. A. , Evett A. A.
Published: February 2005

A null-deflection film balance which retains the sensitivity and range of the manually operated Langmuir-Adam balance but which is capable of following rate processes continuously is described. It provides automatic plotting of (1) film pressure as a function of molecular area during continuous compression or expansion, (2) film pressure as a function of time at constant film area, and (3) film area as a function of time at constant film pressure. The design utilizes commercially available components. Recording is done with a pen-and-ink recorder of standard type, and the curves are visible in their entirety during an experiment. The coordinates are adjustable to make the chart direct reading in F(A), F(t), or A(t) to any convenient scale or degree of scale expansion. Continuous use for 18 months has shown the instrument to be consistently reliable and convenient.
Alternating-Gradient Magnetic Spectrometer
Authors: Martin Hugh J. , Kraus Alfred A.
Published: February 2005

An alternating-gradient magnetic spectrometer has been constructed. The spectrometer consists of two magnetic lenses that deflect the analyzed particles through a total angle of 30°. It is able to analyze protons with energies up to 6 Mev and has a solid angle of 0.012 sterad and a momentum resolution R=p/dp=77 for 0.5-mm exit slit. The distance between the source and image positions is 85 cm.
Instrumentation for High-Field Conductance Measurements
Authors: Kotter F. R.
Published: February 2005

Improvements have been made in the differential pulse transformer bridge which increase its inherent precision by approximately an order of magnitude and extend its range to measurements with electrolytes of twenty times the concentration previously feasible. A circuit is described which permits study of the errors introduced by polarization and self-heating when electrolytic conductivity measurements are carried out with rectangular voltage pulses. Also described is an equipment for four-terminal resistance measurements with single-voltage pulses, which allows high-field conductance measurements free from errors caused by contact resistance, self-heating, and space-charge accumulation; it has been applied to semiconductors.
Wide-Band High-Pressure Dielectric Cell
Authors: Vallauri M. G. , Forsbergh P. W.
Published: February 2005

A quartz and metal seal capable of holding compressed gases at 1500 atmospheres forms the tapered, coaxial transition leading from a standing-wave detector or from a bridge, into a coaxial condenser. The continuity of characteristic impedance through the seal is sufficiently good to allow accurate measurement of dielectric constant and loss in compressed gases and liquids from low frequencies to 3000 megacycles (λ0=10 cm) in a single cell. The performance is illustrated with isotherms of the dielectric constant of N2O through the critical point. Organic sealing materials are not used. The unit promises to be satisfactory for a wider temperature range than is reported here.
Spinning Rotor Pressure Gauge
Authors: Beams J. W. , Spitzer D. M. , Wade J. P.
Published: February 2005

A magnetically suspended rotor pressure gauge is described for measuring pressures below 10−4 torr. The data are in good agreement with those obtained with a calibrated Alpert ionization gauge over the range 10−4 to 5×10−8 torr. When the gas in the vacuum system was frozen out with liquid helium, the rotor gauge recorded a residual pressure of about 5×10−10 torr. A brief discussion is given of a number of effects which unless eliminated may introduce errors into the measurements at the lowest pressures.
Precision Continuous Current Integrator
Authors: Mobley R. C.
Published: February 2005

An all-electronic precision current integrator for use with a charged particle accelerator has been developed which eliminates the substantial deadtime normally associated with multicycle current integrators utilizing relays as their basic switching elements. Integration is accomplished in the conventional fashion of charging a precision condenser with the current to be integrated, electronically noting the completion of a predetermined voltage excursion and then returning the condenser to its initial charge state for repetition of the cycle. A unique feature of this integrator is the return of the integrating condenser to its initial charge state through the transfer of a precise amount of negative charge to the condenser by an all-electronic charge transfer circuit. Integration continues during the charge transfer with no interruption and with no effect on the precision of integration. An electronic counter circuit interrupts the integration at the end of a preset number of cycles and gates off any associated equipment. Current range is approximately 1–500 μa. Accuracy at low currents is limited primarily by a total circuit leakage current of the order of 1.5×10−9 amp. At higher currents, electrometer and other circuit instabilities limit accuracy to slightly better than 0.01%.
Digital-Computer Analysis of Data from Bubble Chambers : Kinematic Analysis of Complete Events
Authors: Rosenfeld Arthur H. , Snyder James N.
Published: February 2005

A digital computer program called KICK (K-meson Interaction Coplanarization and Kinematics), which carries out the analysis of complete bubble chamber events, is described. The program inputs data from a single-track analysis program which has used raw track measurements to perform the spatial reconstruction of tracks and has fitted appropriate curves to them. KICK consists of a set of general processing or analysis routines, each of which is capable of carrying out one of the unique processing steps to which a given event may have to be subjected for proper analysis, for example, ``Input Event,'' ``Fit Vertex,'' ``Transform Variables Along Track,'' ``Output Results,'' etc. Also included is a set of event-type control subroutines each of which, calling upon the proper sequence of these general processing routines, is able to carry out the desired analysis of a particular type of event. This program is in use on IBM 704/9's at many laboratories.
Extended Range Extensometer for Determining Elongation of Elastomers
Authors: Penther C. J. , Husing W. H.
Published: February 2005

An extensometer is described which, with an X-Y recorder, draws stress-strain curves for specimen extensions up to 33 in. It is designed so that the specimen contributes negligible energy to the follow-up mechanism. Finger-like sensors lightly contact the specimen at the bench marks. They are carried on ball bearing bushed carriages which are independently advanced by endless cables driven by reversible servo motors to keep the sensors on their starting positions on the specimen. Each motor also drives ten-turn potentiometers which are connected in parallel to a power source available in the tensile tester. The differential voltage thus developed between the potentiometer contacts is proportional to the sensor spacing. It is balanced by an opposing voltage from a follow-up potentiometer associated with the recorder chart drive so that the slightest movement of the sensors results in a proportional chart movement. The tensile tester load cell deflects the pen to trace a stress-strain curve. Reference point spacings are automatically set at ½, 1, or 2 in. (or other) as selected. Installation is easily made, and the entire extensometer can be removed or replaced without tools.
Temperature Variations in d Values and Expansion Coefficient Recorded by the X-Ray Diffractometer
Authors: Shimura Y.
Published: February 2005

New automatic recording methods are described. One is the recording of the angular shift of a specific diffraction peak in a continuous line. The other is the recording of the angular shift of more than two diffraction peaks. The method of automatic recording of the thermal expansion coefficient is also described.
Quartz Crystal Thermometer
Authors: Wade W. H. , Slutsky L. J.
Published: February 2005

The electrical circuits and mechanical design of a thermometer which employs a Y-cut quartz crystal as the temperature sensitive element is described. A temperature resolution of a few ten-thousandths of a degree over the temperature range 77–435°K was achieved.
Laboratory Production of Hot Dense Gases
Authors: Lalos George T.
Published: February 2005

A ballistic piston compressor is described which makes possible the study of gases at simultaneously extremely high values of density and temperature, under conditions of pure thermal excitation, and in the absence of external electric or magnetic fields. Calculations are presented which demonstrate the density-temperature-pressure relations. Preliminary results are given of a current study of density and temperature effects on spectral line width, shape, and position of a diffuse series line (4603 Å) and a sharp series line (4972 Å) of Li due to collisions with He and with Ar atoms.
Liquid Metal Solution Calorimeter
Authors: Howlett B. W. , Leach J. S. Ll. , Ticknor L. B. , Bever M. B.
Published: February 2005

A liquid metal solution calorimeter and its operation are described. The method of calculation is outlined and the sources of error are analyzed. In this calorimeter, heat effects upon dissolution of samples in liquid metals are measured; heats of solution are determined directly and heats of formation, energies of ordering, and the stored energy of cold work are found by a difference method. The calorimeter operates in the temperature range 240 to 450°C; samples are added from 0 or −195°C. Highest accuracy, of the order of ±2 cal/g-atom, is attained with suitably chosen solute-solvent combinations giving very small total heat effects upon dissolution.
Ultrasonic cw Spectrometer for the Investigation of Electron Spin-Phonon Interactions in Solids
Authors: Bolef D. I. , de Klerk J. , Gosser R. B.
Published: February 2005

A cw acoustic spectrometer operating in the frequency range of 10 to 1000 Mc is described. The acoustic probe, applicable to low temperature measurements, is characterized by its mechanical resonance properties. Several of the novel features of the spectrometer are described in some detail. The apparatus, essentially the acoustic analog of an electron paramagnetic resonance microwave transmission spectrometer, has been applied to the study of electron spin-phonon interactions in solids.
Energy Anomalies Observed in Ion Beams Produced by rf Sources
Authors: Cook C. J. , Heinz O. , Lorents D. C. , Peterson J. R.
Published: February 2005

The beam characteristics of several Thonemann rf sources have been studied as a function of source parameters such as oscillator power, magnetic field, gas pressure, and extraction potential. Beam energy spreads 10 to 100 times thermal, and mean beam energies 100 to 400 eV above the extraction potential are consistently observed. The maximum beam intensity appears to be independent of mass from M=4 to M=40. A qualitative explanation of the energy effects is discussed.
Thin dE/dx Counter with Large Aperture
Authors: Weinman J. A. , Smither R. K.
Published: February 2005

The construction and operation of a thin dE/dx counter with relatively large aperture is described. The counter consists of a 4.1-mg/cm2 layer of CsI(Tl) evaporated on a nickel foil 0.00005 cm thick. The active area of the counter was 2.2 cm2. The energy spread (ΔE/E) of the dE/dx counter was 31% for 5-MeV alpha particles.
System for Low-Frequency Noise Measurements
Authors: Caringella P. C. , Eisenman W. L.
Published: February 2005

A system for measuring low-frequency noise spectra of thermal detectors is described. Its features also make it useful for other noise measuring applications. Low equivalent input noise is realized by incorporating an RCA 6CW4 Nuvistor in the system preamplifier. A constant bandpass of 0.3 cps is maintained over the entire tuning range of 1 to 50 cps by utilizing a heterodyne-type spectrum analyzer modified for this application. A typical thermistor bolometer noise spectrum is given.
Modification of a 256-Channel Scaler for Neurophysiological Time Analysis
Authors: Levick W. R.
Published: February 2005

A modification of a commercial pulse-height analyzer is described which enables it to be used in the neurophysiological field to measure the distribution of intervals in trains of nerve impulses, and to measure the probability density of occurrence of nerve impulses during the cycle of a repetitive stimulus. The application of this device represents a considerable saving of time and effort compared to conventional manual compilation. The pulse trains can be processed ``on line.'' Considerable accuracy is obtained and a wide range of trains can be analyzed. Some representative distributions are illustrated.
Probes for High Temperature Nuclear Magnetic Resonance
Authors: Hafner Stefan , Nachtrieb Norman H.
Published: February 2005

Two designs are described for single coil NMR probes and furnaces with the Varian wide line spectrometer (V-4210) to temperatures up to 1000°C. Their application to molten salt systems is outlined.
``On-Line'' Operation of a Digital Computer in Nuclear Physics Experiments
Authors: Whalen J. F. , Meadows J. W. , Larsen R. N.
Published: February 2005

The instrumentation necessary for coupling a commercial digital computer to several nuclear physics experiments in an ``on-line'' operation has been designed and constructed. Multiparameter experiments utilizing the ``on-line'' operation include fission fragment mass ratio measurements, neutron time-of-flight measurements, and the measurement of prompt ν̄ for fissionable materials.
Cesium Vapor Dispenser
Authors: Eichenbaum A. L. , Moi M. E.
Published: February 2005

A simple dispenser of cesium vapor was investigated to determine its utility as a stable and controllable source of cesium vapor for long life applications. The dispenser is basically a container filled with a mixture of cesium chromate and silicon powder. The powder reacts when it is heated to temperatures near 1000°K, and it releases a cesium vapor stream through a slit. The cesium vapor release rate was found to be stable and controllable by adjustments of the powder temperature. A constant and stable cesium flux could, therefore, be maintained over periods of many hours. At temperatures below 800°K the powder mixture is inert. This permits conventional bake-out of the device and provides a convenient source of cesium vapor in demountable vacuum systems. These dispensers have been used successfully in experimental energy converters, cesiated cathode tubes, and in demountable vacuum systems.
Gamma-Ray Detection Efficiency and Image Resolution in Sodium Iodide
Authors: Anger Hal O. , Davis Donald H.
Published: February 2005

Photoelectric, Compton, and photopeak efficiencies have been calculated at several gamma-ray energies for large flat sodium iodide crystals in which the thickness ranges from ⅛−2 in. Also, the loss of position resolution by gamma-ray scattering within the scintillator is calculated, since this is of interest in the design of gamma-ray imaging devices like the scintillation camera. An examination of the data shows the advantage of using low energy gamma rays for imaging whenever possible. They are efficiently detected by solid sodium iodide scintillators ½ in. thick, and there is little loss of resolution due to scattering of gamma rays in the scintillator. In the higher energy range, a choice must be made between a thin scintillator with its relatively good position resolution and low detection efficiency, or a thick crystal with higher detection efficiency and less satisfactory resolution.
Wideband Feedback Coherence Control for Superregenerative NQR Spectrometers
Authors: Peterson G. E. , Bridenbaugh P. M.
Published: February 2005

A description is given of a wideband feedback coherence control system for superregenerative NQR spectrometers. By making use of a servo motor to adjust the oscillator grid bias, increases in rf searching band are possible. As an example, a bandwidth of 30 Mc around a center frequency of 70 Mc has been obtained. The sensitivity of the circuit to nuclear quadrupole resonance signals is high. The spectrometer will operate unattended.
Errors in Noise Measurements due to the Finite Amplitude Range of the Measuring Instrument
Authors: Cohn Charles Erwin
Published: February 2005

Systematic errors are introduced when amplitude measurements of Gaussian random noise are made with practical instruments having finite amplitude ranges. Graphs are presented which should assist in designing experiments to minimize these errors and in correcting existing data.
Charge Analyzer for Aerosols and Sprays
Authors: Berg T. G. Owe , Fernish G. C. , Flood W. J.
Published: February 2005

A charge analyzer is described that permits the rapid and convenient charge analysis of aerosols and sprays emerging from a nozzle at a high flow velocity. The charged particles are deposited on two collector electrodes. The rate of charge deposition is measured by means of a recording voltmeter, one for each electrode. The amount of material deposited is determined by weighing on a microbalance. Measurements have been conducted with several materials at flow rates between 1.5 and 15 m/sec. Such data are presented.
System for Measuring the Dynamic Properties of Materials
Authors: Barker L. M. , Hollenbach R. E.
Published: February 2005

A system is described which facilitates a detailed study of the response of materials to shock loading under conditions of uniaxial strain. The uniaxial strain loading is produced by a flat projectile plate driven into a target plate by a gas gun. The resulting motion of the free surface of the target plate is monitored by the shorting of a resistance wire which is inclined at a slight angle to the free surface. An accurate time base relates the free surface data to the time of impact. The measured free surface motion may be used to determine the dynamic stress-strain behavior of the material.
High Frequency Properties of Peaking Strip Probes
Authors: Huber H. J. , Rogers K. C.
Published: February 2005

Measurements of the properties of peaking strip probes in rapidly oscillating magnetic fields are presented. Studies were carried out from 18 kc to 2.6 Mc with field rates of change from 8×106 to 3×1010 G/sec. A typical probe response at Ḃ=1010 G/sec is a triangular pulse of 1 V amplitude and half-amplitude pulse width of 40×10−9 sec at field reversal.
Torque Reversing Drive for Light dc Target Motor
Authors: Feltman A. V. , Cottingham J. G.
Published: February 2005

A silicon-controlled rectifier driver for Cosmotron target motors has been developed. This driver controls a motor to produce accelerating and braking torques for optimum target transport times. It features simplicity and reliability with minimum components.
Kerr Cell Measuring System for High Voltage Pulses
Authors: Wunsch D. C. , Erteza Ahmed
Published: February 2005

This paper describes a system to measure, with very high resolution, high voltage pulses. The system is based on a unique application of the electro-optic Kerr effect and measures voltage pulses with magnitudes from 3×104 to 1×105 V. This technique also could be used to measure higher voltages by changing the separation of the Kerr cell plates. The system has a linear frequency response to approximately 100 MHz. Unlike the resolution of other voltage-measuring systems, the resolution of this system increases as the voltage pulse increases towards its peak value. The peak pulse magnitude can be measured with a resolution of better than 0.1%. The system can be calibrated so that the measured value of the peak voltage should be accurate to within ±1% of the true value. This high resolution is obtained by modulation of a constant intensity light source by action of a Kerr cell. The electric field intensity resulting from the high voltage pulse causes phase differences as great as 25π radians between light components in the Kerr cell. Consequently, many light cycles are obtained during the voltage rise of the pulse. This produces extreme resolution near the peak of the pulse. Near the peak, a 2% change in voltage results in a 100% change in light intensity.
Polarity Coincidence Detector for the Measurement of Very Small Signal-to-Noise Ratios
Authors: Raether M. , Bitzer D.
Published: February 2005

A synchronous detector based on the polarity coincidence principle is described that permits the use of very long integration times. The theory of operation is discussed with special emphasis on the influence of correlations between samples and the influence of error sources. Details of the construction are presented and test results are discussed. The present instrument works in the range of 20 cps to 20 kc and is capable of measuring amplitude signal-to-noise ratios as low as 10−4. It has been in constant laboratory use for more than a year and has proven to be a very reliable tool for the synchronous measurement of small ac signals.
50—Nanosecond Printed Circuit Linear Gate Using Transistors
Authors: Barna Arpad , Marshall J. Howard
Published: February 2005

A 50-nsec linear gate with primary use in high energy physics experiments is described. The gate has a pedestal stability of 0.2% of the maximum output pulse height and a feedthrough of less than 0.2% over a pulse-height range of 100 to 1. Design considerations, construction details, and performance are discussed.
Prototype of a Portable Microcalorimeter for Measurement of Absorbed Dose
Authors: Schleiger E. R. , Goldstein N.
Published: February 2005

A prototype of a compact, portable microcalorimeter has been built which measures ionizing radiation dose rates as low as 3 rads/min measured in aluminum. The absorber and temperature sensing system are conventional but the temperature-controlled bath which usually surrounds a vacuum chamber in such microcalorimeters has been replaced by an aluminum isothermal shield bolted to the bottom surface of a copper reservoir containing liquid nitrogen. Both the shield and the reservoir are contained in a vacuum chamber. Calibration of the absorber is accomplished by observing the response of an imbedded thermistor when the calorimeter is placed in a gamma-ray field of known exposure level provided by a 200-Ci 60Co source.
Production of Low Divergence Positive Ion Beams of High Intensity
Authors: Brooks N. B. , Rose P. H. , Wittkower A. B. , Bastide R. P.
Published: February 2005

In this paper ion sources are described which take advantage of the focusing properties of a plasma boundary, thereby producing positive ion beams of very high directivity or brightness. It was found that by employing a considerable degree of space-charge neutralization beyond the accelerating-field region of the ion source, the beam formed by plasma-boundary focusing can be transported away from the source with low and constant divergence. It is also shown that the divergence of the beam could further be decreased by reducing the space-charge expansion of the ion beam in the acceleration region. The positive ions were removed from the plasma boundary in a region of high field gradient before being retarded to the required final energy as they left the ion source. By use of these three developments, low divergence, high intensity dc ion beams were obtained, and a comparison between these and earlier results is provided. Under optimum conditions, 80 mA of positive hydrogen ions at 30 keV, extracted from a 5.0-cm-diam plasma boundary, were transmitted through a 5.0-cm aperture placed 75 cm from the ion source. The beam emittance was measured to be 11×10−3 rad·cm·MeV½ with a maximum half-angle divergence of 45×10−3 rad.
Kinematic Method for Determination of Accelerator Beam Energies
Authors: Bardin B. M. , Rickey M. E.
Published: February 2005

A method for determination of accelerator beam energies using hybrid targets is described. A target consisting of a homogeneous mixture of reference nuclei having well-known excited states and projectile nuclei is used. Determination of the ``crossover'' angle at which recoil projectile particles and inelastically scattered particles from reference nuclei produce equal pulse heights is shown to provide a beam energy measurement. No special apparatus is required. The method is applicable over a wide range of energies. An alternative related measurement using other hybrid targets is discussed briefly.
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 DOUBLE-RANGE ELECTROSTATIC VOLTMETER FOR 200 KILOVOLTS
Authors: Clark Harry
Published: February 2005

The electrostatic voltmeter described in this paper consists, from an electrical standpoint, of two meters which may be used in series or in parallel. Mechanically, however, it is essentially a single meter, since it contains only one moving part. With the parallel connection voltages between 15 and 100 kv may be measured to within .1 of 1%. With the series connection and voltages between 100 and 200 kv (one-half on either side of ground, the halves fairly well balanced) the error need not exceed .1 of 1%.
THE PROPERTIES OF SPUTTERED METAL RESISTORS
Authors: Van Atta L. C.
Published: February 2005

Satisfactory high resistances have been made by sputtering platinum on soft glass rods and embedding the rods in paraffin in glass tubes for protection. These resistances are useful for measuring small currents in conjunction with an electrometer, by the resistance shunt method. When properly prepared, sputtered resistors are found to change but slowly with age (tests lasted over 15 months), thus overcoming the principal defect of sputtered metal resistors. They fulfill the following requirements excellently: no trace of polarization, a negligible temperature coefficient, and Ohm's Law is obeyed.
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.
A VACUUM SPECTROGRAPH FOR PRECISE MEASUREMENTS OF X-RAYS OF LONG WAVE LENGTH
Authors: Howe Carl E.
Published: February 2005

The spectrograph has four unique features which make it fitted for precise measurements (1) A slit system, consisting of five slits each one thousandth of an inch wide, excludes optical light and gives excellent collimation of the x-rays. (2) A universal grating support permits the plane grating to be set at any desired angle and to be removed in vacuo from the path of the x-rays without disturbing any adjustments. (3). A set of two parallel plate-holders at a fixed and known distance apart, placed at right angles to the slit system, permits accurate measurements of angles from the lines recorded on the two plates. (4) An x-ray tube with interchangeable targets is mounted on a micrometer slide permitting the focal spot to be readily lined up with the fixed slit system. The slit system, grating support and ways for the plate-holders are mounted as one unit which may be completely removed from the rest of the spectrograph for the purpose of adjustment. The apparatus is mounted on heavy concrete blocks to avoid mechanical vibrations. The spectrograph is maintained at constant temperature. Typical spectra are shown.
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.
THE MULTIPLE CRYSTAL X-RAY SPECTROGRAPH
Authors: DuMond Jesse W. M. , Kirkpatrick Harry A.
Published: February 2005

The need for improvements in scattered x-ray spectroscopic technique along the lines of increased intensity and contrast is discussed and a new instrument composed of fifty small units, each a Seeman Spectrograph in itself cooperating to form a single spectrogram, is described in detail. The technique of adjusting the instrument is also described.
THE MEASUREMENT OF CAPACITANCE AND INDUCTANCE IN TERMS OF FREQUENCY AND RESISTANCE AT RADIO FREQUENCIES
Authors: Boner C. P.
Published: February 2005

A method of measuring capacitance and inductance is described, in which the product LC is found in terms of frequency by adjusting a circuit which contains the capacitance and an inductance to resonance, the ratio L/C is found in terms of resistance by a high frequency bridge, and the value of C is finally calculated by solving the two equations for LC and L/C simultaneously. A method of eliminating the effect of condenser leads is described. The bridge equations are derived and the effects of residuals in the arms are discussed. Details are given concerning the construction of the bridge, the oscillators, and the heterodyne detector, and concerning essentials of the operating technique. Numerical results are given for a sample condenser calibration.
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 SENSITIVE METHOD FOR DETERMINING REFRACTIVE INDICES
Authors: Korff S. A. , Stewart J. Q.
Published: February 2005

A combination of Michelson interferometer and spectroscope is described which has proved useful in giving accurate values of the refractive indices of vapors, especially near absorption lines. The method involves measurements, easily made, of wave lengths of fringes seen in the spectroscope. Photographs of the fringes are given. The combination also provides an interesting method for putting along a spectrum a natural scale of frequencies, provided by these fringes.
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.
A NEW HIGH VACUUM SYSTEM
Authors: Becker J. A. , Jaycox E. K.
Published: February 2005

A new high vacuum pumping system is described in which oil* is used in a diffusion type pump, and a trap containing activated cocoanut charcoal replaces the usual liquid air trap. The system is capable of attaining a pressure of 2×10−8 mm Hg. A high degree of vacuum can be attained at least as quickly as with a mercury diffusion pump and liquid air trap. The system is especially adapted to maintaining a low pressure for several days in apparatus which cannot conveniently be sealed off from the pumps.
OPTIMUM OUTPUTS OF PHOTO-SENSITIVE DEVICES
Authors: Wilson Earl D.
Published: February 2005

The terms power sensitivity and voltage sensitivity are defined for photoelectric elements in a circuit, and a mathematical expression is derived to evaluate each of these characteristics for the three classes of light-sensitive devices. Curves are plotted for comparing the outputs with one another for various intensities of light flux.
AN AUTOMATIC CONSTANT LEVEL DEVICE FOR LIQUID AIR
Authors: Scott R. B. , Brickwedde F. G.
Published: February 2005

An apparatus is described which will automatically maintain a constant level in a bath of liquid air.