bluuebunny/crossref_metadata_2025 huggingface dataset:
Crushing Strength of Cemented Tungsten Carbide Pistons
Authors: Haygarth John C. , Kennedy George C.
Published: February 2005

The crushing strength of various models of cemented tungsten carbide pistons has been determined as a function of the ratio of unconstrained length to diameter (L/D). There was little effect for pistons whose ends were unsupported, but a dramatic increase in crushing strength with decreasing L/D for pistons whose ends were supplied with interference-fitted binding rings. Tests with pistons of different diameter but constant L/D suggest the absence of any effects dependent on the diameter of the pistons.
Contribution of Small Angle Nuclear Scattering to Error Formulae in Bubble Chamber Analysis
Authors: Johnson William B.
Published: February 2005

The contribution of small angle nuclear scattering to uncertainties in bubble chamber measurements is reexamined to include experiments at high momenta (above 4 GeV/c). Use is made of recent high energy elastic scattering data to estimate these uncertainties for π±, K±, p, and p̄. Finally the contribution from interference between Coulomb and nuclear scattering is evaluated for π± and p.
High-Q Fabry-Perot Resonator for Nitric Oxide Absorption Measurements at 150 GHz
Authors: French I. P. , Arnold T. E.
Published: February 2005

A tunable high-Q Fabry-Perot resonator and related instrumentation which has been used to measure the shapes of nitric oxide rotational lines is described. The cavity was used around 150 GHz, but is suitable for any frequency above 120 GHz. The transmitter klystron is phase-locked to a tunable 15 MHz crystal standard. A sawtooth sweep is applied to this standard resulting in a linear-frequency sweep of the 150 GHz signal across the cavity resonance. The shape of the cavity response is a measure of the gas absorption. A beamsplitter is used to couple energy into the resonator. It is demonstrated that such resonators are well suited for certain microwave spectroscopy experiments.
Energy-Independent Detector for Total Hydrogen Fluxes in the Range 1–10 keV for Space and Laboratory Applications
Authors: Wax R. L. , Bernstein W.
Published: February 2005

An energy-independent instrument capable of detecting total hydrogen fluxes (either H0 or H0+H+) in the energy range 1–10 keV has been developed. Low extreme ultraviolet sensitivity has been achieved by scattering of the incident particles in a thin carbon foil to a detector located in an off-axis position. Energetic electrons are removed by a magnetic field. Measurements of the ratio of the neutral to total fluxes leaving the foil, the angular distribution of the scattered particles, and the energy lost in transit of the foil are presented. The instrument has an efficiency for energetic hydrogen of 0.7%, an euv sensitivity of 2×10−3, and a geometrical factor of 0.06 cm2 sr.
Digital Pulse-Shape Analysis of Repetitive and Nonrepetitive Pulses
Authors: Marshall S. W. , Pruitt R. A.
Published: February 2005

The use of a multichannel analyzer for the analysis of waveforms is described. A gated receiver coupled to the analyzer forms a ``digital boxcar integrator'' when the analyzer is operated as a pulse height analyzer. This arrangement has been used to study the backscattering of acoustic energy from water waves generated in a wind-tunnel. The method is also applicable to the detailed study of the shape and stability of a repetitive pulse.
Sensitive 4 mm Lecher Wire Interferometer for Electron Concentration Measurements in Low-Density Plasmas
Authors: Polman J.
Published: February 2005

A 4 mm microwave interferometer has been developed for measurements on electron concentrations in low-density plasmas (ne≥1010 cm−3). The microwaves are transmitted via Lecher wires, inserted across the discharge tube, to obtain high spatial resolution (≲one wavelength). The sensitivity of the system is improved by eliminating the influence of possible variations in the klystron frequency. A microwave phase shift as low as 2π×10−3 rad can be detected in this way. Density oscillations can be scanned by means of a sampling technique. An example of applications on low-pressure arc discharges is given.
New High-Sensitivity Quartz Thermometer
Authors: Branca Francesco Paolo
Published: February 2005

A new type of temperature sensor is suggested, actuated by piezoelectricty generated by means of thermal expansion of suitable materials. A crystal of quartz, preloaded in a special frame, senses the effects of load changes due to the difference between the thermal expansion of the frame and that of the quartz itself. A fixed proportion exists between the difference of potential, measurable on the appropriate faces of the crystal, and the temperature of the sensor. The tests carried out in order to check the characteristics of the new device fully confirm this proportionality. The voltage output of the sensor has been found to be about 0.001 V/C°.
Magnetic Viscosity in Sensitive Suspensions
Authors: Pankey Titus
Published: February 2005

A previously described suspension employing permanent magnets is shown to be a sensitive device for measuring magnetic viscosity. A large increase in viscosity concomitant to the loading of the suspended mass with nonmagnetic weights suggests that some of the observed viscosity originates in the mechanism of magnetic suspension per se.
Solid State Microwave Refractometer
Authors: Vetter M. J. , Thompson M. C.
Published: February 2005

A solid state 9.4 GHz microwave refractometer has been developed using a new technique for phase measurement. Noise level in a passband of 0.3 to 30 Hz is about 0.03 N-unit rms using a 10 mW microwave source with losses of 30 dB between source and sampling cavity. It is easily adapted to measuring multiple sampling cavities simultaneously, thus allowing absolute and relative refractive indices (in various combinations) to be observed at several locations.
Use of Pure Copper as a Standard Substance for Low Temperature Calorimetry
Authors: Martin Douglas L.
Published: February 2005

Measurements in the temperature range 0.4 to 3°K have shown that the specific heat of American Smelting and Refining Co. 99.999+% pure copper in the ``as received'' condition may be higher than the specific heat of samples which have been vacuum annealed or vacuum cast from this material, possibly due to the presence of a dissolved gas. The specific heat of copper has been increased (by a percent or so) by heating in a hydrogen atmosphere. The effect of very low levels of transition metal impurities on the specific heat is discussed.
Method of Producing and Measuring Charged Single Droplets
Authors: Lindblad N. R. , Schneider J. M.
Published: February 2005

A method is discussed for producing and measuring the electric charge on single droplets pulsed out of a main stream of droplets which were produced by periodic mechanical excitation of a jet of liquid. With this method, charges on the order of 100 electrons can be measured on the single droplets.
Particle-Beam Profiling System
Authors: Gilmer Robert E. , Neu Franklin D. , Sprakfa Robert J. , Strople Joseph E.
Published: February 2005

A system using a 25.4 cm square wire spark chamber with acoustic readout and storage oscilloscope to display a particle-beam profile is described. The instrument was built for an experiment at the Stanford Linear Accelerator Center.
Measurement of Contact Resistance
Authors: Russakoff Robert , Snowball Robert F.
Published: February 2005

An instrument for measuring the long term quality of electrical connecting devices is described. The parameter which controls this property is the contact resistance. In the instrument described, the contact and bulk resistance are separated by utilizing the difference in thermal response time between a contact spot and bulk metal. The circuits, mode of operation, and applications of the instrument are discussed. Contact resistance can be measured within 5% in most electronic connectors, switches, and relays.
Simple System for Temperature Control and Cycling in the Range 4 to 300°K
Authors: Angelo P. M. , Palma M. U. , Vaiana G. S.
Published: February 2005

A feedback system for temperature measurement, control, and cycling in the range 4 to 300°K is described. The system can be easily assembled by adding a few off-the-shelf components to any standard thermometric set up used in the same temperature range. The system is easily operated to control the temperature of a chamber, e.g., the microwave cavity of a ESR spectrometer well within 10−2°K. However, due to the stability of its feedback loop, even at high gains it is capable of achieving closer control, if necessary, and it is suited for use in a variety of configurations.
Technology of Intense dc Ion Beams
Authors: Morgan O. B. , Kelley G. G. , Davis R. C.
Published: February 2005

The present status of a program directed toward the improvement of ion sources and the technology of intense dc ion beams is described. The work is in the energy range of from 20–600 keV at currents of up to 1 A. Several factors have differentiated the approach from that existing in some other areas of ion beam research. There are severe cooling problems in the ion source and in beam targets. Grids cannot be used in the electrode system, and many of the techniques which have been used to study detailed emittance shapes are very difficult to utilize because of these thermal problems. On the other hand, it is possible to accumulate electrons in these dc beams to eliminate the dispersive effect of space charge. Pulsed beams with on-times of less than a few hundred microseconds ordinarily are completely unneutralized. Ion sources are described which are especially suited to proton production and to molecular ion production at source arc currents of up to 50 A. Single gap accelerating and focusing arrangements are described. A special configuration prevents electron trapping and subsequent break-down in the combined electric and magnetic fields.
Electron Microprobe and Electron Diffraction Analysis of Surface Replica Extractions
Authors: Estill W. B. , Robertson M. M. , Conrad G. H.
Published: February 2005

Identical particle extraction, a new method for the microanalysis of contamination particles on surfaces or the identification of precipitates or particles in various matrixes, utilizes the extraction replica method and the identical area method. The principal advantage of this method is that the electron microprobe is used to obtain an elemental analysis of the identical particles from which electron diffraction patterns are obtained.
Differential Calorimetry of Thermally Induced Processes in Solution
Authors: Danforth Raymond , Krakauer Henry , Sturtevant Julian M.
Published: February 2005

An apparatus for the differential thermal analysis of small (1.7 ml) samples of solutions is described. A heat effect amounting to 50 cal per liter of solution taking place over a 30° temperature interval can be measured with a precision of 5%, and a change in heat capacity of the solution amounting to 2 cal deg−1 per liter of solution can be measured with a precision of 15%.
Instrument for Continuous Measurement of Internal Resistance of Voltaic Cells During Discharge
Authors: Clark Robert P. , Zaffery Efstratios D.
Published: February 2005

An instrument for measuring electrolyte conductance or resistance is described. This instrument is unique in that it has the following combination of features: (1) resistance values in the range 1×10−1 to 2×105 Ω can be measured with an accuracy of better than 5%; (2) resistance can be continuously recorded as a function of time; (3) the internal resistance of voltaic cells can be measured during cell discharge; and (4) no special conductivity cells are required. The present instrument is a modified ac Wheatstone bridge. The value of the unbalance signal is monitored and mathematically converted to resistance. Uses for the instrument are discussed and typical results are given.
Experimental Arrangement for Comparison of the Optical and Physical Characteristics of Particulate Smokes
Authors: Vogel D. C. , Circle R. R. , Powell R. S.
Published: February 2005

An experimental apparatus to allow generation, control, and sampling of particulate smokes has been combined with an angular scanning spectropolarimeter to allow study of the optical character of polydisperse and irregularly shaped particles. The experimental apparatus and its operation are described.
Precision Dosimetry System Suited for Low Temperature Radiation Damage Experiments
Authors: Andersen H. H. , Hanke C. C. , So/rensen H.
Published: February 2005

A calorimetric system for dosimetry on a beam of charged particles is described. The calorimeter works at liquid helium temperature. The total dose may be measured with an accuracy of 0.3%, and the dose per area with 0.4%. No theoretical corrections are needed.
Vibrotron Analog Microbarograph System
Authors: Morris F. E.
Published: February 2005

An analog microbarograph system for recording atmospheric pressure is described. Pressure sensitivity ranges and time response are selectable from simple front panel controls making the system extremely observable for experimental work. Slight modifications would make the system adaptable to pressure ranges other than the atmospheric range.
Simple Giant Pulse Ruby Laser of High Spectral Brightness
Authors: Magyar G.
Published: February 2005

A small rotating prism switched ruby giant pulse laser is reported which, with the aid of a specially designed resonant reflector and moderate cooling, delivers all its available power (∼25 MW) in a spectral width of <0.01 Å. It can be used as the oscillator of a high power amplifying system.
Time-of-Flight Electron Velocity Spectrometer
Authors: Baldwin G. C. , Friedman S. I.
Published: February 2005

A velocity selector is described which is designed for measurement of the total collision cross section of electrons in the energy region below 1 V. The system determines the distributions of times of flight of single electrons over a measured path at selected pressures of a specimen gas. The electrons are generated by repetitive illumination of a photoemitter by a spark gap, pass over a shielded drift path, enter an accelerating field, and impinge on an electron multiplier. Electronic equipment and data reduction for analysis of time-of-flight and amplitude distributions of electron counts are described; data illustrative of performance are presented, including typical transmission measurements in helium and argon which extend to 150 mV.
Novel Lithium Drift Control Method for Silicon and Germanium Radiation Detectors
Authors: Schüler W. A.
Published: February 2005

A method and an apparatus are described which allow a nondestructive indication of the progress of the drifting operation. While drifting, pulsed light is shone onto the face opposite the lithium diffused layer of the device. The photosensitivity of the detector is used to obtain a signal whose amplitude is inversely proportional to the window thickness, i.e., the thickness of the undrifted region. A charge sensitive amplifier and a peak rectifier convert the pulses into a dc signal which is used for window thickness indication.
Buoyancy Microbalance for Measuring Gas Densities
Authors: Tisinger Richard M.
Published: February 2005

A microbalance is described which uses a stainless steel beam mounted on two tungsten pivots bearing on sapphire vee jewels. A 20 g buoyed mass is located on each arm, one made of brass and the other of aluminum. A restoring torque, equal and opposite to the net buoyant torque, is applied by a beam mounted permanent magnet located within a magnetic coil. The coil current is proportional to the density of the fluid. The beam displacement is sensed by an LVDT. Balance sensitivity is 0.4 μg/cm3, and reproducibility is 0.01% for pressures up to 35 kg/cm2. The free volume of the device is 75 cm3.
Charged Particle Transmission Through Spherical Plate Electrostatic Analyzers
Authors: Paolini F. R. , Theodoridis G. C.
Published: February 2005

The transmission characteristics of spherical plate electrostatic analyzers for external sources are studied. Transmission as a function of particle point of incidence, angle of incidence, and kinetic energy, and of analyzer plate geometry (central angle and radii of curvature) and plate potentials, is determined analytically and graphically. Our method (which assumes that the ratio of plate spacing to mean radius is small) uses derived relationships between these parameters and the position of the center of the particle's trajectory, which trajectory is approximated by a circular arc. For a fine incident beam of particles, angular resolution at mean transmitted energy and energy resolution at normal incidence are independent of the point of incidence; the angular resolution is moreover a constant and the energy resolution varies linearly with the mean energy. The area of energy-angle transmission diagrams is likewise independent of point of incidence. Energy and angle response functions for diffuse beams of particles are derived semi-empirically. The energy response function (integrated over angle) has the same FWHM as the function for a fine beam incident normally. The angle response function (integrated over energy) has the same FWHM as the function for a fine beam at appropriate fixed energy. Theoretical results for fine beams are compared with experiment and agree well. A practical instrument, specifically for satellite use but suitable for the laboratory, is also described.
Charge Measurements on Insulating Particles by the Use of a Photoconducting Electrode
Authors: Kottler W. , Krupp H. , Rabenhorst H.
Published: February 2005

The average charge of insulating polymer particles has been measured as a function of particle size and tribo-electric treatment of the sample. Particle sizes were in the range 5–30 μ; the particle size distribution was determined by means of a light microscope. The charges were measured with an electrometer: the particles were supported on a photoconducting layer and the electrometer measurements were made in the dark and in the light; thus, the position of the ground plane was effectively varied, and by comparing the two sets of results the average distance of the particle charge from the photoconductor surface could be inferred. Average charges as large as 4×105 electrons per particle were measured.
Rotating Field Magnetometer for Measurement of Anisotropic Magnetic Materials
Authors: Hagedorn F. B.
Published: February 2005

A new technique is discussed for the measurement of the properties of anisotropic magnetic materials. The basis of the technique is the harmonic analysis of the signal induced in a pick-up loop when the anisotropic material is immersed in a spatially rotating magnetic field. It is shown that the harmonics which are generated are related in a simple way to the Fourier coefficients of the anisotropy energy. High sensitivity is achieved through use of a lock-in detector for the harmonic analysis. Apparatus is described in which the magnetic field rotates at 500 Hz with an amplitude up to 50 Oe. This apparatus can detect a magnetic moment of 10−7 emu and equivalent torque of 10−6 dyne·cm. Illustrative data obtained from a thin Permalloy film (moment of 5×10−3 emu) are given, in which the first three Fourier coefficients of the anisotropy energy are 817, <18, and <1.5 erg/cm3. The absolute accuracy of the first coefficient is about 2%, while the reproducibility of this measurement is better than ½%.
Elimination of Volta-Potential Noise from Plate Field Mills
Authors: Knott Karl
Published: February 2005

The Volta effect severely limits the use of conventional plate field mills in detecting weak electric fields. A modified field mill is described which eliminates the influence of the Volta noise on the measurement. This is achieved by changing the distance between the electrodes during the operation of the instrument. The direction of the field measured is indicated without additional instrumentation. After one initial calibration, the accuracy obtained with the instrument was 1 Vm−1 over a time period of months.
Extension of Sonagraph Writing Facilities Using the Storage Oscilloscope
Authors: Bagnall Frank T.
Published: February 2005

A method is outlined whereby the Sonagraph is provided with storage oscilloscope display using the Tektronix 564 oscilloscope.
Shock Tube-TOF Mass Spectrometer Apparatus with Cryosorption Pumping
Authors: Ryason P. R.
Published: February 2005

In sampling reflected shock waves directly into a time-of-flight mass spectrometer, one of the crucial problems is to remove the sampled gas from the ion source. Preliminary experiments with the mass spectrometer flight tube and shock tube axis collinear showed that more pumping speed was required to cope with the sample jet. The required pumping rate, estimated from the rate of pressure decrease on the high pressure side of the sampling orifice, was of the order of 105 liter/sec at 10−6 Torr. A cryosorption pump was built which employed a freshly evaporated molybdenum film at liquid nitrogen temperature as the pumping surface. The shock tube and flight tube axes were placed perpendicular and the sample beam passed through the ionizing electron beam into the cryosorption pump. This arrangement proved satisfactory, and results on the decomposition of CS2 were in reasonable agreement with those of other workers.
Improved Electronic Half-Shadow Method for the Measurement of Birefringence and Dichroism
Authors: Schmidt-Tiedemann K. J.
Published: February 2005

Two methods for measuring optical anisotropy are described. The first one is based on an earlier suggestion by Kent and Lawson [J. Opt. Soc. Am. 27, 117 (1937)] and allows the simultaneous independent measurement of birefringent phase shift and dichroism. The second one, which is restricted to phase shift measurements, uses essentially a rotating birefringent plate and is capable of eliminating systematic errors due to spurious rotation in the compensator and polarization dependence of the detector. Preliminary experiments carried out with interference-filtered visible light yielded a sensitivity of one minute of arc in the phase shift, and 2×10−3 in the ratio of transmittance for the two polarizations (in the vicinity of transmittance ratio 1) at a signal-to-noise ratio of the order of 10.
X-Ray Topographic Camera
Authors: Carron Gene J.
Published: February 2005

The design of a small, versatile x-ray topographic camera is described. Primarily applicable to projection topography by the Lang technique, the design also incorporates an oscillation motion as well as several unique alignment motions. Results of topographs of silicon and ruby are shown.
Circular Sweep Camera
Authors: Prescott L. E.
Published: February 2005

An optical system has been developed to record useful streak images on Polaroid film. A revolving prism sweeps the image in a circular path, thereby confining it within the boundaries of the Polaroid film format. Present applications have not required high writing speeds, a typical rate of 3000 cm/sec has been used, but much higher rates than this are possible. The continuous writing feature of the circular sweep obviates the need to synchronize the camera and event. Combined with the advantages of Polaroid film, the circular sweep camera makes a useful instrument for analyzing arcs, sparks, and other self-illuminating or highly illuminated phenomena.
High Temperature Camera for X-Ray Topography
Authors: Blech Ilan A. , Guyaux J. , Cooper G.
Published: February 2005

A high temperature x-ray camera suited for transmission topography is described. The camera is capable of continuous operation at 900°C. The camera chamber can either be evacuated or used with an inert atmosphere. The stresses in a silicon wafer due to a thin vapor decomposed silicon oxide were followed during heating and cooling, by observing a series of topographs. Clear, large area topographs are seen even at the high temperature range.
Improved Driver Chamber for Arc Driven Shock Tube
Authors: Kelley Joseph G. , Levine Morton A. , Besse Arthur L. , Tatarian Albert
Published: February 2005

Driver temperatures in excess of 25 000°K have been obtained for an arc driven shock tube by utilizing a prestressed ceramic liner. A steel jacket is shrunk onto the 99% alumina liner enabling it to withstand 3.17×108 N/m2 internal pressure. This system has dramatically reduced the contamination and cooling of the driver gas by evaporated liner products. Velocities of up to 2.1×104 m/sec have been observed for the driver gas.
Crystal Thermometer Calorimeter
Authors: Gardner James E. , Riney John S. , Wade William H.
Published: February 2005

The design and performance of a new calorimeter is discussed. Temperature measurement is by frequency or period counting of quartz crystal oscillators. As used, temperature excursions are usually 0.1 to 0.0001C°. The equivalent temperature stability is ∼10−5C°.
Tandem Isotope Separator-Mass Spectrometer for the Study of Ionic Collision Processes
Authors: Moran T. F. , Friedman L.
Published: February 2005

An isotope separator and mass spectrometer system has been assembled for the study of ionic collision processes over an energy range of 0.25 to 60 000 eV. This system consists of an isotope separator capable of delivering intense, well resolved beams of mass analyzed ions into a collision chamber which serves as the source for the analyzing mass spectrometer. This experimental arrangement provides good energy resolution of the primary ion beam and efficient collection of the products of reaction in the mass spectrometer. With the intensities available from the isotope separator, collisions of less abundant species in an ionic spectrum can be studied in detail. Absolute total cross sections for ion-neutral interchange reactions of low velocity ions are presented as well as charge transfer processes at high kinetic energies to demonstrate the applicability of this experimental arrangement in the study of atomic and molecular collisions.
Critically Damped Oscillatory Linear Induction Engine for Driving a Bubble Chamber Valve
Authors: Coyne Donald G. , Mullins Joe H.
Published: February 2005

For the purpose of driving a large, fast, bubble chamber expansion valve, an engine has been developed for the linear transport of a mass through a sinusoid motion for one-half cycle. The unique features are that moving parts are completely inductively coupled with the power source with no physical connections, and that a damper system has been devised giving a critical damping characteristic. Basic equations are given, and the computer solution for a 4.6 kg mass, 3 cm amplitude, and 33 cps frequency is described and compared to actual performance. Scaling laws are quoted.
Oil-Smoke Generator for Use at Elevated Pressures
Authors: Roschke E. J.
Published: February 2005

The control and performance of a small smoke generator for use in the 1.0 to 4.5 atm range is described and application to flow visualization is discussed. A semiautomatic control system permits the generator to adjust for changes or pulsations in the back pressure. Oil consumption is ∼3.6 g/min for a smoke output of 12 liters/min.
High Resolution Ge (Li) Spectrometer for High Input Rates
Authors: Strauss M. G. , Sherman I. S. , Brenner R. , Rudnick S. J. , Larsen R. N. , Mann H. M.
Published: February 2005

A system was developed for obtaining γ-ray spectra with high resolution at high input rates. For rates up to 100 000 γ-ray events/sec in a 3.5 cm3 (13 mm thick) Ge(Li) detector, the FWHM at 1.33 MeV is 2–3½ keV and the spectral shift is no more than 0.1%. The amplifying chain, consisting of a cooled FET preamplifier and a simple main amplifier, is pole-zero compensated throughout. The amplifier produces unipolar pulses shaped with equal integrating and differentiating time constants of 1.2 μsec. The amplifier is followed by a two-diode baseline restorer, a pileup rejector, a linear gate, and an analog to digital converter. The salient features of the system are described and performance data are presented and discussed.
Piezoelectric Pressure Transducer with Acoustic Absorbing Rod
Authors: Ragland K. W. , Cullen R. E.
Published: February 2005

A piezoelectric pressure transducer has been designed, using readily available, inexpensive materials, which is capable of measuring sidewall pressures over a wide frequency range without serious distortion of the signal due to spurious elastic waves in the sensing element. The rise time is limited primarily by the transit time across the surface of the sensing element. The response of the gauge to a Mach 3.2 shock, gaseous detonations at pressure levels of 11 and 34 atm, respectively, is presented.
Characteristics of a Low Energy Duoplasmatron Negative Ion Source
Authors: Aberth William , Peterson James R.
Published: February 2005

A duoplasmatron has been constructed specifically to produce negative ion beams of less than 5 keV energy. Design parameters are given for construction and operation of the source. Ion beam energy analyses indicate an energy full width at half maximum of less than 10 eV, and when the ion beam energy is extrapolated to zero, a full width at half maximum of 3 eV is observed. Ion beams of H−, O−, OH−, F−, CN−, and NO2− were produced at 2 keV with beam intensities between 3×10−7 and 10×10−7 A, measured behind a 0.63 cm diam aperture 140 cm downstream from the source.
Abel Integral Inverter
Authors: Sirola Richard O. , Anderson Thomas P.
Published: February 2005

A special purpose analog computer based upon an arbitrary number of zones annular approximation for Abel's integral equation has been designed and built. The computer inverts axial data to radial data economically in terms of time and effort. The resulting radial contours have been compared with both analytical and experimental (numerical inversion) contours representative of spectral intensity distributions found in axisymmetric plasmas. The computer is as accurate as the complex numerical inversion techniques and considerably more accurate than the anticipated measurements of spectral intensities.
Semiautomatic Data-Collection Systems for Mass Spectrometers
Authors: Moreland P. E. , Stevens C. M. , Walling D. B.
Published: February 2005

Two programmed digital data-collection systems have been developed and used with static-field mass spectrometers to improve the precision of isotopic analyses of solid samples and to reduce the time required for collection and reduction of data. A large high-sensitivity spectrometer using ion pulse counting detection has been equipped with a programmer and multiscaler so that up to four masses can be sequentially scanned and the resulting counts stored in different groups of the core memory. The simpler scheme of adding a programmed integrating digital voltmeter to sample the detector output of an analytical spectrometer is used where high sensitivity is not required. Both instruments use voltage switching between masses and magnetic sweeping of the mass peaks. Mass programming is done simply, but precisely and directly, by the use of operational amplifier techniques in voltage supplies.
Method for Determining Elastic Constant Changes
Authors: Brandt Ogden G. , Walker Charles T.
Published: February 2005

A method for determining the change in elastic constants as a function of some parameter such as temperature or pressure is described. The method is a modification of the pulsed radio frequency sound technique, in which the echoes are mixed with a signal from a free-ringing quartz crystal in order to extract small phase changes in the echoes. Conventional ultrasonic attenuation equipment, which ordinarily is too imprecise for such work, is utilized. The precision is shown to be about 2 parts in 105.
Polaradiometer—a New Instrument for Temperature Measurement
Authors: Murray Thomas P.
Published: February 2005

A new automatic instrument for the measurement of surface temperatures is described. The instrument examines for polarization the sum of (1) radiation emitted by the test surface and (2) radiation emitted by a blackbody and reflected from the test surface. In measurements up to 450°C on metallic surfaces with emittances of 0.05 to 0.47, the determination of equality of sample and reference temperatures was accurate within about ±2%, with no emittance corrections. Further tests are required to apportion this error among sample surface characteristics, instrument characteristics, and experimental error. Away from the null, the error signal depends on the difference of the emittances εp and εs.
Design Parameters of Iodine Vapor Ultraviolet Photon Counters
Authors: Kauppila W. E. , Ott W. R. , Fite W. L.
Published: February 2005

By varying certain design parameters of an iodine-vapor-filled uv photon counter of the Geiger-Müller type, especially adapted to detect Lyman-α photons (1216 Å), it is found that the characteristic curve of the counter can be modified. The aim of the observations reported in this paper was to adjust the design parameters in order to obtain the most satisfactory characteristic curve.
Nanosecond Time-of-Flight Studies of Electrons
Authors: Nakai M. Y. , LaBar D. A. , Harter J. A. , Birkhoff R. D.
Published: February 2005

Low-energy electron guns have been constructed in planar and coaxial geometry. When pulsed with nanosecond pulses from an avalanche transistor pulser, they emit bursts of electrons of a few nanoseconds duration having energies adjustable between 1 and 15 eV. Electrons are focused along a drift tube by a magnetic field of the order of 1 G and are collected and then amplified by a 3-stage transistorized pulse amplifier for display on a sampling oscilloscope. For microsecond drift times an energy resolution of about 0.01 eV is calculated. The depletion of 2.5-eV electrons in the time-of-arrival distribution when the pumping system was cut off from the drift tube was attributed to vibrational excitation of N2, and a cross section of 1.34×10−15 cm2 was determined. When the drift tube was re-evacuated and a jet of nitrogen gas was directed across the electron beam at right angles to it and close to the gun, the time-of-arrival distribution revealed energy losses of 0.6 or 1.0 eV which were attributed to vibrational excitation of the v=0 to v=2 or v=3 levels in nitrogen. These experiments, plus work done in other laboratories on gating grid arrangements, seem to indicate that a time-of-flight electron monochromator having energy resolution comparable to the best systems in operation at this time may be possible in the future.
Thin Aluminum Foil Spark Chamber Spectrometer
Authors: Hoang T. F. , Niemeyer G. L. , Phelan J. J. , Groves T. H.
Published: February 2005

A description of a thin aluminum foil spark chamber spectrometer is given. The magnet has two sets of slots to allow 90° stereo views for photography. A discussion is presented on its characteristics as well as its possible use for the measurement of high-energy γ rays.
Photomultiplier Gate for Stimulated-Spontaneous Light Scattering Discrimination
Authors: De Martini Francesco , Wacks Kenneth P.
Published: February 2005

A simple gating method for photomultipliers is presented. The very high cutoff efficiency of the gate, its linearity, and the absence of spurious effect are shown by measurements taken on a RCA 7265 tube by using a pulsed and a cw light source in the S-11 spectrum. This method has been found to be very useful in experiments of molecular physics where a weak spontaneous radiation to be detected is associated with a very intense pulse of stimulated radiation arising from a laser induced, coherent excitation of the medium.
High Frequency Phase Sensitive Detection Applied to Helicon Wave Studies
Authors: Hansen J. W. , Grimes C. C. , Libchaber A.
Published: February 2005

Two types of phase sensitive detection systems which have been used up to 130 Mc are described. The first utilizes a wideband amplifier and a single phase detector to provide a system which is continuously tuneable between 1 and 130 Mc. The second uses two phase detectors in quadrature to obtain the vector representation of a wave, and extends by three orders of magnitude the frequency range of previously available apparatus. Below 100 Mc, the equivalent input noise of these systems is less than 5×10−8 V rms.
Crush Strength Apparatus with a Photocell Detection Unit
Authors: Amos W. R. , Burgess E. T. , Mershad E. A.
Published: February 2005

An apparatus utilizing a photocell detection system was designed and built to measure the force required to crush a spherical particle 0.05 to 0.5 mm in diameter. The force applied to the particle causes a variation in light area on two matched photocells. The signal from the unbalance in the photocells is recorded without amplification on a millivolt recorder as the particle is crushed. Standardization is accomplished by placing known weights on the apparatus and measuring the displacement on a recorder. The apparatus can be used to measure crush strengths from 0.080 to 2500 g.
Solution Calorimeter with Peltier Cooling for Operation at Constant Temperature
Authors: Kanbour Fouad , Joncich Micheal J.
Published: February 2005

A new calorimeter has been designed for measurement of heats of solution and heats of chemical reaction. Endothermic and exothermic processes can be studied at temperatures constant at ±0.001 C° by balancing the heat removed through a Peltier device with Joule heat introduced by an electrical heater. The apparatus was tested by measuring the heats of solution of KCl and the reaction of tris (hydroxymethyl) aminomethane with aqueous hydrochloric acid.
Cell for In Situ Study of Electrode Kinetics of Strained Wires
Authors: Raicheff R. G.
Published: February 2005

A Teflon cell for in situ study of electrode kinetics of strained metal wires is described. The applicability of the cell to stress corrosion studies is illustrated by a measurement of potentiostatic anodic dissolution of iron under yielding conditions.
Plasma Density Contour Measurements Using Molecular Ion Beam Breakup
Authors: Jobes F. C. , Hickok R. L.
Published: February 2005

Density contours of a magnetically confined plasma have been determined by probing the plasma with an energetic molecular ion beam and measuring the atomic ions produced by collisional dissociation. The atomic ions are separated from the primary beam by the magnetic field. A 1.8 MeV H2+ beam was used to measure the density contours of a magnetically confined energetic arc with a spatial resolution in the plane of the measurement of 0.04 cm2 and a measurement time of 80 msec.
Automatic Recording Torsion Pendulum for Measuring Elastic Moduli
Authors: Pops Horace , Jackman Victor , Barnes W. C.
Published: February 2005

A torsion pendulum has been developed which obtains automatically a permanent record of the longitudinal and torsional resonant frequencies of polycrystalline bulk samples. Shear moduli of pure metals and alloys have been measured with this apparatus at room temperature to a reproducibility of approximately 0.1%. The maximum sensitivity was obtained when the piezoelectric pickup crystal was not attached directly to the apparatus, but was fastened to the mounting bracket.
Pressure Probes for Research in Plasma Dynamics and Detonation
Authors: Jones T. G. , Vlases G. C.
Published: February 2005

Three pressure transducers that can be used in high temperature gas dynamic studies are described and their performance discussed. It is shown that the Baganoff gauge can be usefully employed to study high temperature and pressure gaseous detonation wave phenomena, provided the gauge is constructed from glass. This modification results in greatly reduced sensitivity, but preserves the high frequency response and over-all characteristics of the original gauge. A second gauge, using the pressure bar principle, is shown to have wide application in studies of high temperature shock waves in the presence of large magnetic and electric fields, provided the pressure bar is constructed from a nonconductor having appropriate properties. The results of experiments with this gauge indicate that, even with poor acoustic matching of the gauge elements, it is possible to obtain an accurate estimate of the pressure behind a shock or blast wave with a time resolution of about 2 μsec. The third device described is designed for use where only the accurate arrival time of a pressure pulse is desired and has been used extensively at this Laboratory for plotting shock trajectories in magnetic shock tubes.
Techniques for Conducting Shock Tube Experiments with Mixtures of Ultrafine Solid Particles and Gases
Authors: Watson R. , Morsell A. L. , Hooker W. J.
Published: February 2005

Techniques have been developed for conducting shock tube experiments on mixtures of fine solid particles and gases. Particles with diameters of 1 μ and smaller are prepared by grinding in a dry atmosphere. The powdered material is injected into the shock tube test section by opening a valve connecting the evacuated shock tube with a tank containing gas into which the powder has been previously suspended by a pressurized injection. The axial distribution of powder in the shock tube has been measured both by determining the weight of powder which has settled out on small stainless steel slides placed in the shock tube and by observing the optical absorption from a long-life reaction product of the shock-heated powder-gas mixture as the mixture sweeps by an observation port. Typical operating results are presented, including particle size distribution of a solid material after grinding, powder distribution along the shock tube axis after injection, and oscilloscope records of absorption at 2536 Å by the CF2 formed from Teflon decomposition behind the incident shock wave.
Application of the Electron Microscope for Production of Pseudo-Kossel Patterns and Their Use in the Determination of Lattice Constants of a Beryllium-4.4 Wt% Copper Alloy
Authors: Witt Fred , Damiano Victor V. , London Gilbert
Published: February 2005

A simple modification to an RCA EMU3G electron microscope is described which makes it possible to obtain transmission pseudo-Kossel patterns. These were analyzed to obtain accurate lattice constants for a hexagonal beryllium-4.4 wt% copper alloy.
Sound Velocity Measurements at High Pressures
Authors: Montgomery Peter W. , Montgomery Coralie , Wald David A. , Bellin Jack L. S.
Published: February 2005

This paper describes a technique for the measurement of sound velocities to pressures of 100 kbar, utilizing ultrasonic pulse techniques in which variations in transit time together with independent measurements of sample length changes are taken into account. This arrangement permits measurements to be made through and above transformations in samples under pressure and frees the apparatus from stringent parallelism requirements applicable to other interferometry techniques. The accuracy of the velocity measurements at high pressure is 1%. Results obtained in this system on gold are in good agreement with predictions based on low pressure single crystal measurements.
Laser Determination of Projectile Position During Ballistic Experiments
Authors: Collins D. J. , Charters A. C. , Sangster D. K.
Published: February 2005

A simple laser method of measuring projectile displacement in a light gas gun is described in which some of the problems encountered in the use of microwaves to determine displacement are avoided.
Design and Operation of an Electron Diffraction Camera for the Study of Small Crystalline Regions
Authors: Cockayne D. J. H. , Goodman P. , Mills J. C. , Moodie A. F.
Published: February 2005

The construction and performance of an electron diffraction camera suitable for the examination of crystalline regions of a few hundred Ångstroms extension is described. Goniometric control of the angle of incidence is available under conditions of low contamination. Brief descriptions are given of applications to (a) problems of symmetry including the direct determination of noncentrosymmetric groups, (b) the determination of thickness to an accuracy of one unit cell, (c) the refinement of structure potentials, (d) the measurement of the angular dependence of absorption, (e) the collection of structural data from thin crystals, and (f) the study of imperfect crystals.
Simple Tester for the Rapid Determination of the Tensile Strength of Fine Filaments
Authors: Schile Richard D. , Rosica Gabriel A.
Published: February 2005

A simple apparatus is described which provides tensile strength data for fine fibers in the 5–5000 g ultimate load range. The tester features a rapid fiber mounting system, visual or strip chart readout, and a constant strain rate.
Measurement of Film Thickness Using Infrared Interference
Authors: Dumin D. J.
Published: February 2005

A technique for measuring the thickness of silicon films grown epitaxially on sapphire is described. The method is nondestructive, is performed in situ, and can be used to monitor film thickness while the film is growing. The method utilizes the infrared emission from the sapphire substrate and from the growing film. The radiation from the sapphire substrate is partially transmitted through the silicon and partially reflected in the silicon, establishing an interference pattern which can be used to determine silicon film thickness. Using a detector with peak sensitivity at 2.4 μ, silicon film thicknesses to the nearest ±0.1 μ are readily measurable. The absolute accuracy of ±0.1 μ is independent of film thicknesses. Films in the range from 0.1 to 15 μ have been measured. Increased detector sensitivity can extend the maximum measurable film thickness.
Superconducting Magnet Beta-Ray Spectrometer
Authors: Shera E. B. , Bedesem M. P. , Casper K. J.
Published: February 2005

A superconducting magnet spectrometer using lithium drifted silicon detectors has been constructed for the the measurement of electron spectra. The spectrometer has a 4π geometry for electrons and a resolution limited only by the detectors. Spectral distortions arising from electron backscattering and gamma-ray interactions are eliminated by the achromatic focusing properties of a solenoidal magnet.
High-Repetition-Rate Burst Pulser
Authors: Paxson G. Donald
Published: February 2005

This paper describes a simple and reliable thyratron circuit capable of generating high energy pulses at repetition rates of 5000/sec or higher. Design considerations and factors limiting the maximum repetition rate are discussed.
Modifications of an A-60 Spectrometer for Nuclear Relaxation Studies of Chemically-Shifted Protons
Authors: Anderson J. E. , Steele J. , Warnick A.
Published: February 2005

Circuit modifications are described which enable a Varian A-60 spectrometer to be used for relaxation studies of chemically-shifted protons. T1 and T2 values greater than 0.1 sec can be measured on the modified instrument at ambient temperature. Owing to severe convection effects in the probe assembly, relaxation measurements are made with difficulty at other temperatures. Methods of time-averaging relaxation data are also discussed.
Passive Pressure Transducer Utilizing Acoustic Emission
Authors: Dunegan H. L. , Tatro C. A.
Published: February 2005

A passive pressure transducer has been developed which utilizes the acoustic emission effect. This effect is noted when a suitable solid material is placed under increasing stress, causing permanent deformation processes to occur which are accompanied by emission of acoustic energy. These processes are irreversible, so if the stress is released and then reapplied, no acoustic energy will be emitted on the second cycle until the stress reaches its previous maximum level. The instrument described here contains a diaphragm of anodized aluminum which is first exposed to the pressure that is to be measured and then withdrawn and read by subjecting it to steadily increasing known pressure while monitoring it for acoustic emission. The pressure at which acoustic emission begins is taken as the pressure originally measured by the instrument. Pressure transducers of this type are inexpensive and require no calibration. Accuracy is within a few percent and can probably be improved. Possible applications include deep ocean depth measurements, measurements of peak acceleration, and tellatale uses for monitoring peak pressures.