bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric Recorder
Authors: Anderson V. C.
Published: February 2005

A description is given of the dielectric recording technique wherein information is stored as a surface charge on a rotating dielectric coated drum. The specific application of the technique to a multiple channel recorder is shown. A general comparison between the properties of analog dielectric and magnetic drum recording is presented. The comparison shows dielectric recording to have important advantages for some applications.
High Resolution Neutron Velocity Spectrometer with Betatron Source
Authors: Yeater M. L. , Gaerttner E. R. , Baldwin G. C.
Published: February 2005

A neutron velocity spectrometer with a 100-Mev betatron as a source of neutron pulses has been in use at the Knolls Atomic Power Laboratory since 1953, for cross section measurements up to about 50 000 ev. An internal, thick uranium target is bombarded by 80-Mev electrons when the betatron orbit is rapidly contracted, giving approximately 0.1-microsecond bursts of neutrons at a 60-pps repetition rate with a peak intensity of about 7×1015 neutrons per second. Measurements of total, capture, and fission cross sections are made with high-resolution detecting equipment located at points up to 20 meters from the target. The timing, registering, and data-processing techniques are designed to achieve maximum benefit from the short burst duration.
Effects of Voltage-Divider Characteristics on Multiplier Phototube Response
Authors: Engstrom Ralph W. , Fischer Edward
Published: February 2005

Data are presented on the effect of voltage-divider circuits on the operating characteristics of multiplier phototubes. Linear, superlinear, and saturated behavior of output current vs light flux are related to divider current. Characteristics are shown for varying sensitivity by controlling interdynode voltage. Divider circuits are described, which protect the multiplier phototube from excessive current flow.
Testing Machine for Short-Time Creep and Stress-Rupture Testing at 2000 to 2500°C
Authors: Smith Morton C. , Olson D. M. , Brown Harry L.
Published: February 2005

A testing machine is described in which a specimen contained within a water-jacketed vessel is heated in vacuum or in a gas atmosphere by a tantalum-tube resistance heater, and is then subjected to static tensile loads up to 100 000 psi. This machine is now in routine use at Los Alamos Scientific Laboratory for short-time creep and stress-rupture testing of metallic and nonmetallic specimens at 2000 to 2500°C. With minor modifications, it can also be used for longer-period creep and stress-rupture studies, for ordinary tensile, compressive, or shear testing, and for operation at temperatures substantially above 2500°C or down to room temperature.
Direct Reading Minority Carrier Lifetime Measuring Apparatus
Authors: Engler A. R. , Kevane C. J.
Published: February 2005

An apparatus is described which permits the direct reading of minority carrier lifetimes greater than 10 microseconds. The decay of optically injected excess minority carriers is compared with voltage decay in an RC circuit and lifetimes are read directly from a calibrated dial. Measurements can be made quickly without critical adjustment.

An alignment chart for rapid calculation of surface recombination velocity from lifetime data is included.
6.8-Meter Grazing Incidence Vacuum Spectrograph
Authors: Brehm Richard K. , Benzie George
Published: February 2005

Technical design and construction details for a 6.8-meter grazing incidence vacuum spectrograph are discussed. The spectrograph is built into a 30-in. by 12-ft steel tube evacuated by a high-speed pumping system capable of evacuation from atmospheric pressure to 5×10−5 mm in thirty minutes. Operating at an incidence angle of 82°, a spectral range from 50 to 2000 A is covered in steps on a 30-in. plateholder. Provision is made for changing entrance slit widths quickly and easily through rotary vacuum seals. The wavelength region may be changed from outside the instrument while under vacuum. Spectra from 540 to 1800 A are shown.
Measuring Refractive Index of Plastic Films
Authors: Ellis R. Hobart
Published: February 2005

By a method of successive approximation the index of refraction of polystyrene films has been determined from two photographs of continuous spectra. It is shown that the method is valid if the dispersion is known within several percent as a starting assumption.
Automatic Microwave Transmission Measuring Equipment
Authors: Linker J. Burton , Grimm H. H.
Published: February 2005

A microwave measurement system has been built which makes possible the quick measurement and automatic recording of the phase and amplitude response of a general four-terminal network. This system was set up to measure in particular the phase and attenuation properties of samples of ferrite materials in wave guide for two opposite directions of applied dc magnetic field at both X and S bands. The system is built around a traveling wave tube used in a ``frequency offset'' application. The system has been used to make rapid measurements of phase and amplitude of a device as a function of frequency.
Theory of the Ballast Resistor
Authors: Minter Clarke C.
Published: February 2005

By plotting E/I resistance of commercial ballast tubes against voltage it can be seen that ballasting action is a typical ``growth'' phenomenon. It is concluded that the requirements for ballasting action are (1) nonuniform temperature distribution in a current-heated resistor and (2) a high-temperature coefficient of resistance that increases with temperature.
Apparatus for Studying Convection under the Simultaneous Action of a Magnetic Field and Rotation
Authors: Nakagawa Yoshinari
Published: February 2005

An apparatus for the study of the instability of a layer of mercury heated from below and subjected to the simultaneous action of a magnetic field and rotation is described. The equipment is designed to examine the mode of convection and the dependence of the critical Rayleigh number (=αgβcd4/κν, where g denotes the acceleration due to gravity, βc the critical adverse temperature gradient, α the depth of the layer, κ the thermometric conductivity, ν the kinematic viscosity, and α the coefficient of volume expansion) for the onset of instability on the values of nondimensional parameters Q1 (=σH2d2/π2ρν, where H is the strength of the magnetic field, σ the electrical conductivity, and ρ the density of fluid) and T1 (=4Ω2d4/π4ν2, where Ω denotes the angular velocity of rotation), the features proven to be essential in such studies.

By using a reconditioned cyclotron magnet as a part of the experimental arrangement, this apparatus covers wide ranges of parameters Q1 (from 10 to 106) and T1 (from 105 to 1010).

Typical results that can be obtained by this apparatus are discussed with a few illustrative examples.
Double Modulation System for Narrowing Electron Resonance Absorption Lines
Authors: Unterberger R. R. , De Quevedo J. L. Garcia , Stoddard A. E.
Published: February 2005

A method is presented for observing electron resonance absorption on an oscilloscope screen by using both a magnetic field modulation and a klystron frequency modulation. This is distinguished from the usual system of keeping the klystron frequency fixed and modulating the magnetic field by the fact that the apparent line width observed on the oscilloscope is narrower than that observable by a single (magnetic or frequency) modulation. An equation is derived relating the apparent line width (double modulation) to the true line width (single modulation). Reductions by a factor of 17 can be easily obtained. As a result paramagnetic absorption lines ordinarily too wide to be observed within the width of the resonant cavity containing the sample can be observed within the cavity resonance. It is believed that this double modulation system might be advantageous in oscilloscope searching for new paramagnetic absorptions.
High-Pressure Proportional Counter
Authors: Gilmer T. E. , Mace R. , Palmatier E. D.
Published: February 2005

A large-volume high-pressure proportional counter used in a study of the ionization energy losses of mu mesons is described. The details of construction for operation at approximately one hundred atmospheres pressure are given.
Apparatus for the Measurement of Small Contact Angles between Liquids and Solids
Authors: Speece A. L. , Rutkowski C. P. , Gaines G. L.
Published: February 2005

A device for the precise measurement of small (<10°) liquid-solid contact angles is described. The technique is a variation of the tilting plate method. Measurements of the contact angle of benzene on polyethylene at 25°C indicate that a precision of ±0.1° is readily attainable.
Indium Resistance Thermometer; 4 to 300°K
Authors: White G. K. , Woods S. B.
Published: February 2005

The possible advantages are discussed of a resistance thermometer made with a metallic element of low Debye characteristic temperature and very high purity, e.g., ratio of residual resistance to ice-point resistance of 10−4. Measurements on the electrical resistance of commercially available indium wire from 3 to 300°K suggest that it may be a useful thermometer as it remains temperature sensitive down to its superconducting transition at 3.41°K, because of its high purity and τ ∼100°K.
All Metal Apparatus for the Determination of the Density of Liquefied Gases
Authors: Jarry Roger L.
Published: February 2005

An all metal apparatus designed for density measurements on liquefied gases is described. The metal construction enabled its use with corrosive materials, and also allowed measurements to be made to moderate pressures. It consists of a pycnometer, temperature control device, and gas handling system. While this apparatus was particularly designed for density work it was used for vapor pressure determinations with slight modification. The design and construction is detailed and its use with liquid fluorine outlined.
Apparatus for Precise Determination of Dynamic Young's Modulus and Internal Friction at Elevated Temperatures
Authors: Fine M. E.
Published: February 2005

Apparatus for determining Young's modulus and internal friction of metals at temperatures to 800°C is described. The resonant dynamic method with electrostatic transducers is used. The frequency range is 20 to 200 kc/sec. Data for aluminum and tungsten are given.
Coherent Emission Light Source
Authors: Griffiths R. B. , Dicke R. H.
Published: February 2005

A sharp, intense emission line may be obtained by use of resonance radiation coherently scattered from a collimated beam of atoms. The coherently scattered light may be separated from the exciting radiation by placing the atomic beam in one arm of a Mach-Zehnder interferometer or by diffraction from several parallel atomic beam pencils. The latter technique has been tested experimentally by observing hyperfine structure in light coherently scattered from a beam of sodium atoms.
Absolute Flux Measurement of Anisotropic Neutron Spectra with Proton Recoil Tracks in Nuclear Emulsions
Authors: Roberts J. H.
Published: February 2005

A technique for the measurement of neutron spectra which is independent of neutron direction has been studied. The technique consists of measuring all proton tracks in a known volume of type C2 Ilford emulsion, in which shrinkage has been reduced by treating the plates with rosin. By a suitable differentiation of the proton spectrum the absolute flux of neutrons as a function of energy is determined. Rotated plates were exposed to 0.8 and 1.3 Mev neutrons. 4000 tracks were measured, and two peaks with a width ∼150 kev at half-maximum were obtained. The statistical accuracy of the neutron flux in the two peaks is about ten percent. The flux determination was checked by a fixed C2 plate in which the conventional proton recoil method was used. Good agreement was obtained.
Improved Low-Level Alpha-Scintillation Counter for Radon
Authors: Lucas Henry F.
Published: February 2005

A low counter background is obtained by use of steel for the shell and quartz for the counter window, while marked improvement in the stability is obtained by coating the window with an electrically conducting layer of tin oxide. The distribution of radon and its daughters within the counter under various conditions was determined by comparison of observed and calculated counting efficiencies. A stable counting efficiency of 5.58±0.05 cpm/μμc radon and a background counting rate of 0.08 cpm is obtained. The usefulness of this counter is augmented by adsorbing the radon on charcoal. The radon is then easily transferred to the counter with a small volume of helium and a Sigmamotor pump. This system is suitable for the analysis of samples of radon as small as 10−14 c or concentrations in air smaller than 10−16 C radon/liter.
Electron Probe X-Ray Microanalyzer
Authors: Birks L. S. , Brooks E. J.
Published: February 2005

A 1–3 micron electron probe of simplified design has been constructed for x-ray spectrochemical analysis of metallic and nonmetallic specimens. At operating conditions of 20–30 kv and less than 0.1 microampere beam current, counting rates of about 3000 counts per second are obtained from pure elements such as iron; thus compositions as low as a few tenths percent are detectable. At increased voltage and current and with a beam size of 10–20 micron, counting rates may be increased to 50 000 counts per second. Applications include analysis of inclusions in metals and minerals, mass transfer material from liquid-metal cooling systems, phase composition, and intermetallic diffusion studies.
Extended Angular Range Direct Reading Phase Meter
Authors: Bigelow S. , Wuorinen J.
Published: February 2005

Most commercial phase meters have an inherent range of 0° to 360°. These instruments usually have a switching arrangement by means of which the range of angles from 360° lagging to 360° leading is covered in a number of sub-ranges. In the development of a specialized computer, the complex plane scanner, a phase meter was required capable of measuring angles from 540° lagging to 540° leading in one continuous range without ambiguity of output. This paper describes a direct reading pulse position comparison instrument with an inherent range of from 720° lagging to 720° leading. The design is such that this range may be further extended, theoretically without limit. The accuracy of the instrument is ±1° for angles from 540° lagging to 540° leading and for input amplitudes from 0.1 to 100 v. While the phase meter described is designed for operation at a fixed frequency of 400 cps, modifications are suggested for adapting it to broad-band applications.
Large Scintillator for Observation of Cosmic Rays
Authors: Green John R.
Published: February 2005

A liquid scintillator having an area of five square meters has been developed for the observation of the extensive air showers in cosmic rays. The scintillating liquid, in the form of a disk 10 ft in diameter and 6 in. deep, is viewed by a single 14-in. Dumont type K1328 photomultiplier tube. The associated circuitry provides a gate whose length is proportional to the logarithm of the scintillator pulse height over a range in pulse height of 2000:1. The length of this gate can be either measured and recorded on a Berkeley EPUT timing meter or converted linearly to a pulse height and analyzed by a multichannel discriminator.
Extending Transducer Transient Response by Electronic Compensation for High-Speed Physical Measurements
Authors: Liu F. F. , Berwin T. W.
Published: February 2005

Systems are described which automatically and continuously correct for dynamic errors of transducers during transient and steady-state measurements. They enable high-speed measurement to be made with improved accuracy even in regions beyond a transducer's natural frequency. Transient phenomena with rise time of a fraction of a microsecond can be measured directly with a minimum of amplitude and phase distortion. High-speed electronic analog circuits form an integral part of the transducer system to obtain the wave forms of the unknown physical phenomena, and to enable quantitative determination to be made with simple static calibration procedure. Post-measurement amplitude and phase corrections are made virtually unnecessary.
Gas-Recoil Fast Neutron Spectrometer
Authors: Benenson R. E. , Shurman M. B.
Published: February 2005

A gas-recoil fast neutron spectrometer based on the collimation scheme of R. Giles has been constructed and its behavior analyzed. The principal effort has been directed to improving peak-to-valley ratio of the instrument. Electron capture has been minimized and anticoincidence end-effect counters included in the present design. A graphical analysis has been made of the collimation scheme and the results predicted by the analysis compared with experiment. Li7(p,n)Be7 and D(d,n)He3 neutron groups have been observed using, in turn, palladium-filtered hydrogen and pure propane as spectrometer fillings. Energy spreads of 10% and under with efficiencies exceeding 10−4 have been obtained with peak-to-valley ratios of 10 to 1. Neutron groups from the Be9(d,n)B10, C12(d,n)N13, O16(d,n)F17, and A40(d,n)K41 reactions have been observed.
Improved Infrared Absorption Spectra Hygrometer
Authors: Wood Rex C.
Published: February 2005

An infrared hygrometer is described which utilizes a light beam as the principal sensing element. Composed of two narrow bands of infrared radiation, this beam traverses a 12-in. path through a sample atmosphere containing the humidity concentration to be measured. Wavelength isolation is by means of germanium narrow band-pass interference filters. One band, centered near a wavelength of 2.60 μ, is subject to attenuation by water vapor, the other located near 2.45 μ is not. Thus the ratio of transmitted band energies is sensitive to the concentration of water vapor in the path. This ratio is effectively maintained at unity through use of a servo-operated glass wedge which moves to compensate for energy unbalance caused by changes in absorbing vapor. Wedge position is given electrical significance through use of an appropriate transducer, calibrated in terms of vapor density, grams per cubic meter. Included in the design is a dry-gas purge standardization system whereby periodic checks of the zero point enable compensation for drift factors. Because of the potential use of the method in airborne applications, the instrument was used in tests to determine the character of pressure effects. These showed that vapor concentration (W), total pressure (P), and partial pressure (p) of water vapor, may be related to fractional absorption (A): A=CW0.5(P+p)0.23.Conditions under which other, simpler relations may be used are discussed.
Apparatus for Measuring the Energy Spectra of Mass-Selected Particles in Coincidence with Fission
Authors: Stokes R. H. , Northrop John A. , Boyer Keith
Published: February 2005

An apparatus used to observe the energy spectrum of protons in coincidence with 14-Mev deuteron-induced fission is described. One feature is a mass identifier which operates over a range of 5 to 25 Mev and gives good separation of protons, deuterons, and tritons. Its operation depends on measuring the particle energy loss, ΔE, in a transmission counter and the residual energy, E, in a separate counter. The E and ΔE pulses are introduced into an electronic computer which in 1 μsec produces a pulse whose height is closely proportional to mass. The accuracy of mass separation is illustrated by a representative case in which less than 0.1% of the elastically scattered deuterons appear in the proton energy spectrum. In the presence of the complicating effects of cyclotron beam modulation, the chance coincidence correction to the proton-fission coincidence spectrum is made by simultaneously measuring the delayed and undelayed spectra.
Four-Sector Azimuthally Varying Field Cyclotron
Authors: Blosser H. G. , Worsham R. E. , Goodman C. D. , Livingston R. S. , Mann J. E. , Moseley H. M. , Trammel G. T. , Welton T. A.
Published: February 2005

An electron model relativistic fixed-frequency cyclotron of the azimuthally varying field type has been constructed for the purpose of testing the orbit dynamics of such a device. An iterative technique used in designing an acceptable magnetic field shape is described in some detail. A brief description of the various components of the device is given as well as an account of the beam phenomena observed in the initial period of operation. Results strongly indicate the feasibility, from an orbit dynamics standpoint, of large proton machines of this type.
Analog Approach to the Problem of Making Resolution Corrections
Authors: Aitken J. H. , Dixon W. R.
Published: February 2005

An analog method is described for computing the Gaussian integral transformation which arises in the problem of making resolution corrections. Only apparatus which is readily available has been used. The basic element is a photomultiplier which views light flashes produced on an oscilloscope screen. A multichannel kicksorter is used to analyze, sum, and record pulses. Making a resolution correction is equivalent to inverting the integral transformation. A trial-and-error procedure is outlined for doing this.
Explosive Press for Use in Impulsive Loading Studies
Authors: LaRocca Edward W. , Pearson John
Published: February 2005

Small explosively activated presses have been used as research tools in the study of the behavior of powdered materials under impulsive loads. Both single- and double-acting presses have provided positive retention of the test specimen. The double-acting press, which is of a sandwich-type construction, uses two explosive charges fired simultaneously to drive two opposed pistons together into a central steel cylinder in which the specimen material has been placed. Estimates of the pressures which can be obtained are on the order of several million pounds per square in. By modifying the working faces of the pistons, materials can be formed into specimens of various shapes by the press action. Operation of these presses and their application to the study of several materials are described.
Ion Current Stabilization for a Surface Ionization Mass Spectrometer
Authors: Kendall B. R. F.
Published: February 2005

It is shown that ion current stabilization for surface ionization mass spectrometers offers many advantages over the conventional methods of regulation which effectively stabilize the sample temperature. A technique is described which allows accurate measurement of very small relative isotopic abundances. A number of problems associated with the design of circuits for emission stabilization of surface ionization sources are considered. A successful stabilizer which maintains the ion current from such a source at a constant value by variation of the source filament temperature is described and the performance when used for the control of potassium positive ion sources is discussed. The stabilizer is capable of reducing ion current drifts, such as those due to exhaustion of the sample, by a factor of 130.
Automatic Measurement of Small Deviations in Periodic Structures
Authors: Closson H. T. , Danielson W. E. , Nielsen R. J.
Published: February 2005

Special optical, mechanical, and electronic techniques have been combined in a new instrument—the microdeviometer—in which a beam of light and two optical gratings are used to obtain a very accurate scale of distance. The location, with respect to this distance scale, of the salient periodic features in the structure being measured is established through the interception of a second light beam by the structure. Electronic circuitry automatically stores and processes the position information and feeds the processed information, in the form of deviations from the corresponding ideal structure, to a pen recorder. A measuring accuracy of ±1 μ has been consistently obtained, and measurements which formerly required nearly 2 man-days are accomplished in less than 10 min.
High-Speed Framing Disk Camera
Authors: Bagley C. H.
Published: February 2005

A high-speed framing camera designed to investigate problems requiring a time coverage of from 6 to 20 milliseconds has been developed. Sixty pictures at framing rates up to 15 000 frames a second are possible. Unique to this system are the large image size (⅝×1¼ inches or ⅜×1¼ inches, depending on the framing rate required), and the very short exposure times (0.2 microsecond). The short exposure time has made this instrument useful in a number of applications.
Fabrication Techniques for Ceramic X-Band Cavity Resonators
Authors: Thompson M. C. , Freethey Frank E. , Waters Donald M.
Published: February 2005

Techniques are described for constructing cavity resonators at X band from low-thermal expansion ceramics. A variety of mechanical arrangements is discussed. Q values as high as 14 000 and frequency-temperature coefficients as low as 1 part in 100 million per °C have been obtained using simple processes.
Differential Pressure Gauge for Use with Liquids and Corrosive Fluids
Authors: Flotow H. E. , Abraham B. M. , Carlson R. D.
Published: February 2005

A sensitive, rugged pressure gauge is described that was developed to determine the density (composition) and the viscous pressure loss in flowing streams of UO2-NaK slurries. The differential pressure sensors are two metal bellows that are rigidly connected in opposition, the net displacement of which is detected by a linear variable differential transformer. The sensitivity of the unit is 0.05 mm Hg pressure and the range is 100 mm Hg with an accuracy of ±0.4%. By simply inserting various calibrated springs in the instrument it is possible to increase or decrease the range and maintain the sensitivity at 0.05% of the range.
30-Inch Propane Bubble Chamber
Authors: Powell Wilson M. , Fowler William B. , Oswald Larry O.
Published: February 2005

A propane bubble chamber with a sensitive volume of 30½ in. by 21½ in. by 6½ in. deep operating in a magnetic field of 14 000 gauss is described. Operating parameters and some engineering details are given. The part of the chamber containing the propane is hydrostatically supported in oil through which the chamber is photographed. This permits the use of small glass windows with a large safety factor.
Phase Shift Method of Carrier Lifetime Measurements in Semiconductors
Authors: Harnik E. , Many A. , Grover N. B.
Published: February 2005

A direct reading instrument for lifetime measurements in semiconductors is described. It is based on the phase shift that exists between a sinusoidal modulation of carrier injection and the corresponding modulation of specimen conductance. Carrier injection is effected optically, a Kerr cell being used to modulate the intensity of the injecting light. The phase shift is determined by means of a compensating RC circuit which allows a direct reading of lifetime. The actual measurement is reduced to the setting of a variable resistor in such a way that an ellipse observed on the screen of a CRO degenerates into a straight line. The performance of the instrument is discussed for the case of a thin, rectangular filament illuminated on one of its large faces either homogeneously or in a narrow band.
Topographic Microscope
Authors: Saur Roger L.
Published: February 2005

Microscopic topography of matte and mirror surfaces can be measured visually. A straight-line reticle perpendicular to the plane of incidence is optically projected obliquely onto the surface. The image deviates laterally in response to vertical surface deviation. A microscope equipped with a filar eyepiece is used to measure the image deviation from a straight line. A simple formula based on the geometry of the optics is used to calculate the topographic deviation. Precision on surface grooves of 0.0005–0.005 in. deep is about ±6%. Sensitivity is around 0.00003 in. The method is absolute, quick, easy, and usable on nonflat surfaces.
Millimicrosecond Kerr Cell Camera Shutter
Authors: Zarem A. M. , Marshall F. R. , Hauser S. M.
Published: February 2005

The instrument described here is an electro-optical shutter of the Kerr cell type, and is intended for general laboratory use as a camera shutter at effective exposure times in the low millimicrosecond region. Using this shutter system, a series of photographs of exploding wires has been made at an effective exposure time of 5 mμsec. The Kerr cell has an areal aperture of 2 × 4 cm at its smaller end and an apparent angular aperture of 20°, and is hermetically sealed. The required driving voltage pulse has an amplitude of 35 kv; the synchronizing network allows the shuttering action of the Kerr cell to be synchronized with the phenomena to be studied within less than 1 mμsec. The utilization of improved switching techniques shows great promise in attaining effective exposures in the submillimicrosecond region.
Temperature Error Associated with Imbedded Thermocouples
Authors: Thomas A. R. , Schurin B. , Morris J. C.
Published: February 2005

The error in surface temperature of a thin plate in a vacuum as measured by an imbedded thermocouple is investigated experimentally and theoretically. It is found that the error is proportional to the 52 power of the absolute temperature provided the surrounding temperature is much lower than the plate temperature.
High-Speed Multiple-Spark Light Source
Authors: Wilson Merle R. , Hiemenz Richard J.
Published: February 2005

A high-speed spark light source is described which can be used in the photographic systems of shock tunnels, shock tubes, and ballistic ranges. The source provides five high-intensity flashes, each with available delays of as low as 0.1 μsec between consecutive sparks. The transmission line principle is used with barium titanate capacitors to obtain a spark discharge time of under 0.1 μsec. Five spark assemblies are mounted in line with a lens system to provide a common point where all spark flashes are brought to focus. The light source is used in conjunction with a high-speed drum camera on which is mounted the recording film.
Two-Component Capacitance-Type Displacement Detector
Authors: Rider John A. , Roever W. L.
Published: February 2005

The design, construction, and operation of a displacement detector are described. In the operation of the detector the frequency shifts of two oscillators are observed; these frequencies depend on the separation distance of two probe capacitor plates from a third ground plate that is common to both of them. The circuitry and mechanical arrangement are such that two independent outputs are obtained; one is proportional to displacement normal to a surface and the other is proportional to displacement tangential to the surface. The calibration and testing of the device are described, and results of these tests are given along with displacement observations made on waves in a concrete surface. The detector is sensitive with good signal-to-noise ratio for displacements as small as 10−2 micron and with displacement frequencies as high as 105 cps, two components simultaneously.
Registration of Phasic Changes of Blood Flow by Means of a Catheter-Type Flowmeter
Authors: Pieper Heinz P.
Published: February 2005

A differential transformer with variable coupling placed at the tip of a catheter tube and surrounded by an umbrella type device has been used for the measurement of blood velocity. The instrument was carefully tested by means of a pump producing truly sinusoidal fluid movement. It was shown that the flowmeter has a linear characteristic and a linear frequency response with pump frequencies up to 25 cps. A blood flow recording taken in the ascending aorta of a dog with unopened chest demonstrates the instrument's practical application.
Contact Resistance Measurements at Low Loads
Authors: Flom D. G.
Published: February 2005

A modification of the fine-wire loop technique for studying surface contact resistances, as developed originally by Savage and Flom, is described. The principal change is substitution of quartz fiber for platinum wire as the resilient part of the probe. The contact end of the probe consists of either platinum or gold—other metals could be used as well.

An additional improvement is the provision for gradually increasing the applied force between the probe and surface at a low, known rate. This can provide information, not only on the electrical and physical durability of the film, but also on the changing bulk characteristics of the contact junction.

Applications in which the quartz fiber probe has been used for studying silver-plated aluminum contacts, gold-plated silver contacts, and copper-Teflon films on copper are discussed.
Microcomparator Illumination System for Improved Resolution of Rayleigh Diffusiometer Diagrams
Authors: Oncley J. L. , Ludwig M. , Thompson T. E.
Published: February 2005

A microcomparator illumination system is described which permits Rayleigh diffusiometer diagrams to be measured with increased precision. Measurement is based on the use of diffraction patterns generated by the Rayleigh diagram when this diagram is illuminated with point source, divergent, monochromatic light. Under favorable conditions a two- to fivefold increase in precision of measurement may be obtained with this illumination system.
Gas Circulating Apparatus Containing a Magnetic Balance
Authors: Scala L. C. , Hickam W. M. , Langer A.
Published: February 2005

A gas circulating system is described in which a sample undergoing thermal decomposition can be weighed continuously by means of a magnetic balance having a sensitivity of the order of 0.1 mg. Changes of composition in the gases contained in the system are determined by withdrawing samples directly into a mass spectrometer for analysis. Accurate quantitative measurements of the uptake and evolution of gases during the degradation process are thus obtained, providing an insight into the reactions that occur.

This simple system should prove useful in many other fields of investigation.
Portable Magnetic Field and Gradient Meter
Authors: Thoburn W. C.
Published: February 2005

A portable instrument for measuring magnetic fields and field gradients is described. The measurements depend on comparing the alternating emf's induced in two search coils oscillated synchronously at about 3 cps through angles of less than 3°, one in the field to be measured and the other in the reference field of a permanent magnet in the instrument. A precision Helipot is used as a potentiometer, in which a measured fraction of the signal from the reference coil is balanced against the signal from the probe coil. The null is obtained through an electronic amplifier and galvanometer. Tests of the instrument indicate 0.1% precision. A field gradient can be measured with the same instrument by use of a search coil which is given translatory oscillations in the direction of the gradient.
Pressure Gauge for Corrosive Gases in the Micron and Submicron Region
Authors: Anderson J. R.
Published: February 2005

For use with corrosive gases in the range 10−2 to 10−5 mm Hg, a gauge is described in which the pressure is indicated by the rate of damping of a hinged silica fiber pendulum, the amplitude of which is measured photo-electrically. The gauge exposes only glass and silica to the gas, may be baked to 450°C, and gives an accuracy of pressure measurement of better than 5%.
Radiation Attenuation Method of Measuring Density of a Two-Phase Fluid
Authors: Petrick Michael , Swanson Bernet S.
Published: February 2005

A gamma-ray attenuation technique is presented for measuring density and phase distribution in a two-phase fluid. A comparison is made between a ``one-shot'' and traverse method. The technique was evaluated on Lucite mock-ups of simulated flow patterns encountered in two-phase flow and by a series of tests on an air-water system at atmospheric pressure.
Capillary Viscometer for High-Temperature Measurements of Polymer Solutions
Authors: Patterson Gordon D. , Rabouin Louis H.
Published: February 2005

An all-glass capillary viscometer is described which permits dissolving polymers at high temperatures, filtering, and measuring the solvent and solution efflux flow times without removal from a vapor bath. The advantages include safe handling of liquids at high temperatures without the precipitation or oxidative-degradation difficulties normally encountered in other methods of measuring polymer solution viscosities at elevated temperatures.
Mass Spectrometer Ion Source for Solid Samples
Authors: Kendall B. R. F.
Published: February 2005

A single-filament positive ion source for solid samples is described. The source is simple and compact. Heat dissipation is low. Isotopic fractionation effects are very much smaller than is the case with conventional single-filament surface ionization sources. The main ionization process occurring in the source is considered to be the surface ionization of the sample vapor on the tungsten filament. The sample vapor is maintained at a comparatively high pressure inside the source assembly. Investigations are described which indicate that other possible emission processes do not contribute any significant proportion of the emitted ion beam. Variations in the measured relative isotopic abundance ratio K39/K41 during a run to exhaustion of the sample are discussed. There is no significant ratio trend with time and the random fluctuations of the measured ratio are such that more than half of the values are within 0.2% of their mean. The mean values can be repeated with a probable error which is less than about 0.3%.
Compact Microwave Refractometer for Use in Small Aircraft
Authors: Thompson M. C. , Vetter M. J.
Published: February 2005

A microwave refractometer has been developed for use in a Type L-20 ``Beaver'' single-engine light aircraft. A two-channel recording system is used providing simultaneous profile and turbulence records with rms noise levels of approximately 0.05 and 0.01 N unit, respectively. Power requirement is 25 amperes at 28 volts dc, and installation requires one-half hour for two men. No structural modification of the aircraft is required. The results of flight tests are presented.
Dose-Rate Dependent Dosimeter for Low-Intensity Gamma-Ray Fields
Authors: O'Brien Keran , Solon Leonard R. , Lowder Wayne M.
Published: February 2005

It has been suggested that a NaI(Tl) phosphor be used to amplify densities enough to make a film dosimeter practicable for the low gamma-ray dose rates produced by background radiation. This use is complicated by the dependence of film density on dose rate as well as dose. An analysis of the process provides a correction for the doserate dependence when the dose rate is constant. The magnitude of the error involved in assuming the dose-rate constant when it is a function of time is evaluated.
Improved Measuring Apparatus for X-Ray Absorption Spectrometry
Authors: Hanson H. P. , Flynt W. E. , Dowdey J. E.
Published: February 2005

Two techniques for simplifying data taking and for eliminating the requirement of a carefully stabilized x-ray power supply in x-ray absorption spectrometry have been developed. Method I oscillates the sample in and out of the beam with a period that is small compared to drift and the usual x-ray tube instabilities. The corresponding I and I0 are channeled to two ratemeters, and by analog techniques a quantity proportional to the absorption coefficient is electronically calculated and plotted. In method II, two counters are arranged in tandem with the sample between, yielding I and I0 simultaneously. The proper apportionment of counts in both arrangements is considered.
Cyclotron Beam Intensity Measurements
Authors: Amiel Saadia , Porile Norbert T.
Published: February 2005

A Faraday cup and target assembly for the determination of cross sections for nuclear reactions induced by charged particles from a 60-in. cyclotron is described. Independent checks and calibrations on the performance of the assembly were carried out. The conditions affecting the operation of this assembly are discussed. Cross sections for two standard alpha-induced reactions are given.
Control Device for an Automatic High-Pressure Sorption Balance
Authors: Cannon Peter
Published: February 2005

A novel photoresistive cell has been developed which will sense the position of a beam of light. This cell has been used in a servo network to null the arm of an electromagnetic sorption balance. The balance was enclosed in a metal high-pressure shell and was not observable in any conventional way. Details of the construction of the cell are given.
Microscope Attachment for Accurate Microdrilling and the Removal of Analytical Samples from Small Areas
Authors: Simon A. C. , Gildner D. A.
Published: February 2005

An air-driven microdrilling apparatus is described which can use drills as small as 0.025 mm (0.001 in.) in diameter. This machine is interchangeable with the usual metallurgical microscope objective and can be adjusted to coincide with the optical axis. An area centered under the cross hair of the ocular can be accurately drilled by replacing the objective with the drilling attachment.
Use of Polystyrene as an X-Ray Absorber—The Mass Absorption Coefficient of Carbon
Authors: Batterman Boris W.
Published: February 2005

The advantages of using polystyrene as an x-ray absorber are pointed out. The measured linear absorption coefficient for both commercial rod and high-purity molded sheet was found to be 4.165±0.008 cm−1 for CuKα radiation. The mass absorption coefficient of carbon (μl/ρ) is 4.301±0.009 cm2/g. This value is compared to other published results.
Two-Beam Fixed Field Alternating Gradient Accelerator
Authors: Ohkawa Tihiro
Published: February 2005

An FFAG accelerator accommodating two beams circulating in opposite directions is proposed. Analytical expressions for the equilibrium orbits and the betatron oscillations are developed and are compared with numerical results obtained by digital computation. Typical design parameters are discussed.
Bootstrapped Differential Amplifier with Reduced Common-Mode Effects
Authors: Blume Richard J.
Published: February 2005

The appearance of a common-mode voltage at both grids of a conventional twin-triode differential amplifier produces, by cathode follower action, an equal swing of the common cathode point. The resulting change in the operating point of the tubes causes undesired shifts of both the differential gain and the balance of the amplifier. In the present work, the change of voltage at the common cathode point is entirely transferred (``bootstrapped'') to the plate supply, with the result that a common-mode voltage does not affect the operating points of the differential amplifier tubes. By this means, a common-mode rejection ratio of >104:1 is readily achieved without tube selection or adjustments. With tube selection and some adjustment, >105:1 may be obtained. A common-mode signal of ±35 v changes the differential gain of the circuit by 0.5% or less. A bootstrapped differential VTVM circuit which deflects a 1 ma 1.5K-ohm pen recorder to full scale with ∼0.2 v dc input is described in detail.
Observation of the Deflected Ion Beam Trajectory from a Cyclotron
Authors: Kimura Kiichi , Kokame Jun , Yamashita Sukeaki
Published: February 2005

A simple and convenient method has been employed to determine the trajectory of the deflected ion beam from a cyclotron. Using several mesh screens across the beam path, the location and angular divergence of the beam in various places can be obtained simultaneously by the holes made by the ion bombardment on these meshes.
Reversible Chlorine Electrode for the Measurement of Electromotive Force in Molten Salt Cells
Authors: Senderoff Seymour , Mellors G. W.
Published: February 2005

A reversible chlorine electrode which may be used in molten salts up to temperatures of at least 900°C is described. Chlorine gas is forced through a porous graphite cylinder in contact with the solution under study. The electrode was tested in the Ag|AgCl|Cl2 (graphite) cell and an exactly linear dependence of emf on temperature was found for the temperature range 530 to 920°C. Excellent agreement with earlier emf measurements at temperatures below 600°C was found and the results indicate that the calculated values based on thermal data at high temperatures are high. Emf values for the cell from 530 to 920°C are given.
Small Barium Titanate Transducer for Aerodynamic or Acoustic Pressure Measurements
Authors: Willmarth W. W.
Published: February 2005

The design, development, and calibration of a small barium titanate pressure transducer for aerodynamic or acoustic pressure measurements is described. The calibration was carried out in a shock tube. A few typical oscilloscope records of the transducer response to shock waves are shown. From the calibration, it was found that the transducer response is uniform from approximately 5 to 50 000 cps and the sensitivity of the transducer is 0.88×10−6 v/dyne/cm2.
Efficient Precision Current Regulator for Low-Voltage Magnets
Authors: Garwin Richard L.
Published: February 2005

A simple, inexpensive current regulator has been built using power transistors and a chopper amplifier to regulate magnet currents to <0.001%. Thus far, the regulator has been used to 20 amp and 40 v, and at ∼100 amp and ∼200 v. With minor modifications, it will give very much better regulation.
Interferometer Used to Study Transient Heating of Water
Authors: McLean E. A. , Scherrer V. E. , Nanney C. A. , Faneuff C. E.
Published: February 2005

This paper discusses the use of a Mach-Zehnder interferometer in a study of heat transfer in water. A derivation of the formula is given relating temperature change to fringe shift and a correction procedure is shown for end effects. Temperature distributions are determined for pulse-heated Nichrome foils in water. With the experimental conditions used in this report, a maximum temperature gradient of 280°C/cm was observed.
Capacitor Microphone as a Radiation Detector
Authors: Harbold Mary L. , Bohn J. Lloyd
Published: February 2005

Part I describes how a capacitor microphone acts as the variable capacitance to modulate the frequency in the tank circuit of an FM transmitter. When ``chopped'' light falls on the capacitor microphone, the capacitance of the microphone fluctuates at the same frequency as the ``chopping'' frequency. In Part II is given an analysis of the action. This shows that absorption of the incident electromagnetic radiation sets up a temperature gradient across the thickness of the front electrode. As a result of this, the front of the electrode, the part facing the radiation source, expands toward the source. This causes a change in the distance between the electrodes of the capacitor and thus varies the capacitance of the microphone. The instrument, which responds to a wide range of frequencies and to a very large dynamic range of intensity, is quite rugged. It has an additional advantage in being its own telemetering device.
Magnetically Operated Needle Valve
Authors: Cope J. O.
Published: February 2005

A solenoid operated needle valve is described which gives smooth and rapid control of gas flow rates over a wide range from a cut-off value of approximately 10−4 micron-liter sec−1. In conjunction with a suitable pressure transducer the valve may be used for the automatic control of pressure in vacuum systems.
Use of Operational Amplifiers in the Measurement of Transistor Parameters
Authors: Hazel William C.
Published: February 2005

The operational amplifier which serves as the basic element of modern electronic differential analyzers is utilized in the precise measurement of the low-frequency parameters of transistors. The method is based on the current-controlling and current-measuring functions which may be performed by the amplifiers.
Intracardiac Catheter Microphone
Authors: Welkowitz Walter , Traite Max
Published: February 2005

A microphone is described that can be encased in a small-bore plastic catheter. The small size permits insertion directly into the heart and the precise localization of the origin of heart sounds.

The unit uses a two-section piezoelectric ceramic, operated in a bender mode. The frequency response is flat up to 3000 cps.

The sensitivity over the flat frequency range is −124 db referred to 1 v/μbar.