bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Conductivity of Polycrystalline Zinc below 1°K
Authors: Cotignola J. M. , De La Cruz F. , De La Cruz M. E. , Platzeck R. P.
Published: February 2005

Measurements of the thermal conductivity of samples of polycrystalline zinc of thickness 0.1 mm have been carried out between 0.12 and 0.9°K in the normal as well as in the superconducting state to investigate the usefulness of zinc as a thermal switch. The conductivity in the normal state shows a linear dependence on temperature. In the superconducting state it shows a behavior typical of electronic conductivity down to the lowest temperature measured. By applying a magnetic field between 40 and 5000 Oe, magnetoresistivity was also investigated and a strong dependence of thermal conductivity on field was found. Electrical resistivity measurements were performed in magnetic fields at liquid 4He temperatures. The resistivity was found to be independent of temperature for fields up to 9000 Oe. The effect of solder joints using Cd, Sn, In, Zn, and Wood's metal was also investigated, Cd giving the least resistance. The measurements show that zinc should be a useful thermal switch for temperatures below 0.1 and 0.2°K, though effect of a magnetic field on the normal conductivity must be carefully considered.
Ring Heat Source Probe for Rapid Determination of Thermal Conductivity of Rocks
Authors: Somerton Wilbur H. , Mossahebi Mohammad
Published: February 2005

A ring heat source probe has been developed for the rapid determination of thermal conductivity of rocks. In addition to the short period of time required to run the test (2–3 min), sample preparation is minimal, requiring only that parallel flats approximately two cm in diameter be cut or ground on opposite sides of the sample. A calibration chart can be provided with each probe so that thermal conductivity can be obtained from simple experimental data without elaborate calculation.
Vacuum Ultraviolet Source
Authors: Feldman Uri , Swartz Marvin , Cohen Leonard
Published: February 2005

A low inductance three-electrode spark source for the vacuum ultraviolet fed by a 20-kV, 13-μF capacitor is described. Its main feature is its ability to generate spectra of very high degrees of ionization. A 6-kV spark produces spectra of CV and CVI as well as FeXVI, while a 17–18-kV spark yields FeXVIII, AlXII, and AlXIII.
Simple Light Spot Scanner and Its Application on Semiconductor Nuclear Particle Detectors
Authors: Schüler Werner
Published: February 2005

An apparatus has been designed and built for scanning the surface of a semiconductor device with a light spot. The apparatus uses a modified commercial television set for the display of the photoresponse and a miniature CRT as flying spot source. Photoresponse pictures of lithium-drifted silicon radiation detectors as well as of surface barrier type detectors are shown and interpretation is attempted.
Fully-Ionized Barium Plasma Source
Authors: Rynn N. , Hinnov E. , Johnson L. C.
Published: February 2005

A device for generating a fully-ionized barium plasma column is described. It is similar to the previously described Q1 device except for the substitution of rhenium ionizing surfaces for tungsten, and barium for the alkali metals. The main motivation for the use of barium is that singly-ionized barium has its resonance lines in the visible wavelength range, and thus allows the use of spectroscopic techniques for the determination of various plasma parameters. The special problems of barium in a Q device, and the spectroscopic techniques, including range of applicability and achievable accuracy of the measurements, are discussed.
Production of Small Uniform Magnetic Fields
Authors: Lambert R. H. , Wright J. J.
Published: February 2005

A technique for compensating magnetic field gradients over small regions (300 cc sphere) is described. With five pairs of bar magnets the maximum field variation over a 10 cm distance was reduced from 2.2 mG to less than 0.08 mG.
Effects of High Energy Radiations on Noise Pulses from Photomultiplier Tubes
Authors: Jerde Roderick L. , Peterson Laurence E. , Stein Wayne
Published: February 2005

Changes in the dark current and noise pulse spectrum of photomultiplier tubes due to ionizing radiations are reported. Tubes studied were the RCA 7265 and various versions of the ``ruggedized'' RCA 6199. Measurements were made both at 25°C and −40°C under exposure to 60Co γ rays, cosmic rays, 241Am alpha particles, and 90Sr β rays. All ionizing radiations incident on the phototube face were observed to produce additional dark current, and a considerable enhancement of the pulse spectrum, particularly at pulse sizes corresponding to several cathode photoelectrons. Each cosmic ray and interacting 60Co γ ray produced one large pulse, equivalent to about 10 single photoelectrons, and about 10 smaller pulses. The 241Am and 90Sr produced less than one noise event per incident particle. In order to explain the effects, three mechanisms seem to be required. Čerenkov radiation will produce the large pulses due to relativistic cosmic rays and Compton scattered electrons by 60Co γ rays. Scintillations in the glass with an efficiency of about 10 photons/MeV produce the effects due to the nonrelativistic alpha and β particles. It is suggested that phosphorescence induced by the short wavelength Čerenkov quanta can account for the many small pulses observed. These effects significantly alter the signal-to-noise characteristics of phototubes on balloons and satellites when applied to the detection of weak light sources, or low intensity x rays in the environment of space.
Effect of ``Baseline Restoration'' on Signal-to-Noise Ratio in Pulse Amplitude Measurements
Authors: Radeka Veljko
Published: February 2005

The effect of baseline restoration on signal-to-noise ratio in pulse-amplitude measurements is determined theoretically and experimentally. It is found that the signal-to-noise ratio with baseline restoration normalized to that without restoration is ηr/η=[1+α− 2α½kx(τ)]−½, where kx(τ) is the noise correlation factor at the output of the filter (amplifier), τ is the measurement interval, and α is the attenuation of noise power due to integration by the restorer capacitance and switch resistance (α=1 for fast restorer). Methods of calculation of correlation functions are outlined. A method for measurement of correlation functions by oscilloscope is described. The results are presented for the three commonly used filters: CR-RC filter, quasi-Gaussian filter, and delay-line filter. Baseline restoration is found to degrade the signal-to-noise ratio. The amount of this degradation can be reduced to negligible proportions in filters with long memory (such as CR-RC) by a small degree of integration in the restorer. Peak-to-peak amplitude measurement of double-differentiated signals performs, in effect, baseline restoration and, in addition, improves signal-to-noise ratio compared to peak-amplitude measurement.
Cold Cathode Quadrupole Mass Spectrometer
Authors: Blum P. , Torney F. L.
Published: February 2005

A magnetron cold cathode ion source (CCIS) has been developed for ultrahigh vacuum residual gas analysis. The purpose is to eliminate the spurious spectra produced by the conventional hot filament source and to obtain greater sensitivity. A commercial quadrupole mass analyzer was used to evaluate source performance and potential. Resolution equaled that obtained with a hot filament source, giving mass invariant peak separations, with 10% valleys, of 1.0 amu below 150 amu and 0.7 amu below 50 amu. Sensitivities exceeded those obtained with a hot filament source, operated at a 3 mA emission current, by factors of 1.5 to 4.6, depending on pressure and mass. The corresponding CCIS sensitivities, at 1-amu peak separation, were 0.4 mA/Torr for mass 28 at 3×10−9 Torr and 1.2mA/Torr for mass 40 at 1×10−7 Torr. Experiments indicated a potential tenfold further sensitivity improvement if a quadrupole with a higher rf potential were used; by increasing quadrupole dimensions a still greater fraction of the source internal sensitivity, which is in the vicinity of 1 A/Torr, may be realized.
Design and Performance of a K+ Detector
Authors: Giacomelli G. , Kycia T. F. , Li K. K. , Teiger J.
Published: February 2005

The design, construction, and performance of a 320-liter cylindrical stopping K+ detector is described. The efficiency of the detector is measured to be about 70%.
Automated System for Measuring and Recording Angular Deflection
Authors: Peters Donald , Herrick C. C.
Published: February 2005

An instrument is described which is a simple, accurate, reliable, and inexpensive device for continuously measuring and recording angular position or deflection. Incorporated in a torsion-effusion apparatus it permits the visual observation of phase changes, deviations from molecular flow, and approach to equilibrium. The usual alignment problems associated with a lamp and scale are eliminated.
Cathode Ray Film Scanner
Authors: Carides T. , Cottingham J. G. , Feltman A. V. , Grossman A. S. , Leipuner L. B. , Marinuzzi J. G. , Schwender G. E.
Published: February 2005

A spark chamber film reader has been developed which uses a computer directed cathode ray spot as the scanning light source. The equipment features data processing speed of 20 000 points per second while achieving position resolution of 4 μ. Search modes and film areas covered are controlled by the computer software giving wide flexibility.
New Technique for High Magnification Calibration of an Electron Microscope
Authors: Cook Charles F.
Published: February 2005

The surface of a single crystal having etch steps of known heights can be used for magnification calibration. The etched basal surface of a hexagonal ferrite single crystal has etch steps whose heights are a precisely known function of its unit cell height. Depending upon the mixed-layer stacking arrangement of the hexagonal ferrite phase such etch steps can have heights ranging in increments from 11.6 to 300 Å. After careful selection of a characterized hexagonal ferrite single crystal, it is etched in 1:1 HCl at 90°C until etch features are visible on the basal surface. The crystal is replicated by the one step method. The angle used for shadowing (from 1:1 to 3:1) must be accurately set since any error in the shadow angle will produce a corresponding error in the magnification. The shadow cast by the etch steps on the replica as viewed in the electron microscope is then used as the standard for calibration of magnifications in excess of 10 000 times.
Simple Tunnel Diode Circuit for Accurate Zero Crossing Timing
Authors: Metz Arthur J.
Published: February 2005

A simple tunnel diode circuit capable of accurately timing the zero crossing point of bipolar pulses is described. The combination of a fast tunnel diode and a nonlinear load line results in a circuit that can detect the zero crossing of a wide range of input waveshapes. This technique has been utilized in the design of a versatile, fast zero crossing discriminator. This instrument, which is compatible with existing logic systems, exhibits time slewing of less than 200 psec for an input amplitude range of at least 1 to 70 times threshold. Direct coupling and extremely short recovery time enable the instrument to function well at rates as high as 50 MHz.
Simplified Bridge System for Measurement of Internal Friction and Fractional Variations of Young's Modulus at Kilohertz Frequencies
Authors: Saul Robert H. , Bauer Charles L.
Published: February 2005

A simplified bridge system for measurement of internal friction and fractional variations of Young's modulus at kilohertz frequencies is described. The system, composed of commercially available components, is used with a two-part composite oscillator and is capable of measuring (logarithmic) decrements ranging from 10−7 to 10−2. Fractional variations of decrement and Young's modulus can be detected to within 0.5% and 0.1 parts per million, respectively.
Automatic Sequence and Photo Control System for Simultaneous Ultracentrifugation in the Analytical Ultracentrifuge
Authors: Garrett Edward R. , Cazali Rafael
Published: February 2005

The described automatic sequence and photo control system for photographically monitoring simultaneous ultracentrifugation of four different samples is compatible with existing equipment. The system is inexpensive to install and provides complete flexibility in time intervals and sequences over wide ranges. In conjunction with a motion picture camera installation, high capacity is obtained without film handling and at enormous reduction in cost per photograph.
Phase-Locked Frequency Multiplier
Authors: Harvey I. K.
Published: February 2005

A technique for locking the output phase of a frequency multiplier to its input is described. A sampling system is utilized in which a narrow phase-stable pulse, generated at a zero crossing of the input signal, is used to sample the frequency multiplier output. By means of a feedback loop the phase angle of the input to the controlled frequency multiplier is adjusted to minimize multiplier output phase variations with respect to the sampling pulse.
Production of Submicrosecond Ion Pulses
Authors: Cheon Beonguk , Kotani Koichi , Akimune Hideo , Suita Tokuo
Published: February 2005

A hot cathode ion source has been developed to produce pulsed ion beams. The source has a canal electrode whose characteristics resemble those of the grid of a vacuum triode. The characteristics are attributed to sheath formation in the canal. The ratio of the maximum current to the minimum is about 103. A pulsed ion beam of a milliampere of submicrosecond duration has been easily obtained with a low power pulser. The rise time of the pulsed current is 0.1 μsec.
Slot Compensation in a Standing-Wave Meter at Millimeter Waves
Authors: Tischer F. J.
Published: February 2005

A method of compensation for the effects of a longitudinal slot in a rectangular waveguide section used in a standing-wave meter has been devised and investigated. The slot causes changes of the propagation constant and characteristic impedance of the guide. Compensation of these effects is necessary in the millimeter-wave region where they become excessive, since the width of the guide is small so that the width of the slot represents an appreciable fraction of the former. The compensation, which is practically frequency independent, is carried out by an extension of the side walls of the slot into the interior of the waveguide forming two internal ridges on both sides of the slot. The field distribution inside the compensated waveguide is computed by conformal mapping and the height of the compensating ridges determined from waveguide and slot dimensions. Numerical results are presented for an example.
Simple Feedback Electrostatic Voltmeter with a Transparent Probe
Authors: Nielsen Paul
Published: February 2005

A simple feedback system has been developed for application to either a field-interrupting electrostatic modulator or to a vibrating electrode modulator; this system substantially increases the stability, sensitivity, and accuracy of the electrostatic voltmeter in which it is employed. An accuracy of 0.2% and a response rate of 2000 V/sec have been achieved in this instrument, which incorporates a transparent, vibrating NESA glass electrode to facilitate sample illumination.
Enhancement of Signal-to-Noise Ratio in Hypersonic Measurements by Time Averaging
Authors: Tittmann B. R. , Bömmel H. E.
Published: February 2005

We describe the application of the well-known technique of signal averaging for the enhancement of signal-to-noise ratio to the field of ultra- and hypersonic waves. The technique often referred to as autocorrelation is useful in at least two ways: (1) as an aid in extending the range of measurements toward higher frequencies, (2) as a help in improving the precision and accuracy in attenuation data.
Solid State Microwave Spectrometer
Authors: Britt Chester O.
Published: February 2005

A silicon solid state microwave spectrometer is described. It is more stable and reliable than comparable tube type circuits, is relatively low in cost, and produces a compact instrument. It is Stark-modulated and can supply a Stark voltage of 2000 V into an external load of 1000 pF. The sweep generator employed is capable of electronic sweep durations of 0.1 to 8000 sec, using either a backward wave or reflex klystron oscillator signal source. The maximum sensitivity is limited only by the sample cell and detector noise.
Theoretical Evaluation of an Oscillating Mass Flow in the Modified Moore Variometer Configuration
Authors: Fehr Uri , Gazley Carl
Published: February 2005

The behavior of an oscillating mass flow through a series of capillary tubing ending in a large reservoir, and representing the fluid mechanics system of the modified Moore variometer used by UCLA as an infrasound detector system, is analyzed both theoretically and experimentally. A comparison of the theoretical and experimental results enables an understanding of the operation of the sensor and suggests future improvements.
Proportional Counters and Electronic Systems for Observing Cosmic X Rays
Authors: Chodil G. , Mark Hans , Rodrigues R. M. , Rowe C. , Swift C. D.
Published: February 2005

A low-energy x-ray detection system has been developed and used on two sounding rocket flights. Proportional counters, sensitive to x rays with quantum energies between 2 and 30 keV, are used in this system. The signals from these counters are modified so that they can be telemetered with an FM-FM system in such a way that the pulse amplitude is preserved. Pulse-height analysis is done at the ground station. With this simple system, it is possible to obtain spectra of cosmic x-ray sources limited only by the resolution of the detectors.
Continuous Measurement of Concentration Using a Highly Stabilized Reactance Meter
Authors: Kakimoto Akira , Ichijo Bunjiro
Published: February 2005

A method of measuring the concentration of a solution is described. In this method, electrodes are installed on the outside of the pipe or vessel and the concentration is measured indirectly through the vessel material by detecting the capacitance change between the electrodes which is caused by the variation of the liquid conductivity. The measuring circuit is stable as it has a temperature compensating circuit, which, in addition, serves to control the concentration without regard to the temperature change, using another pair of electrodes which are filled with the standard solution. Concentration changes of a solution, with electric conductivity of 0.5∼10 kΩ cm, can be measured with a sensitivity of 5 μA/1%. The output caused by a temperature change of 10 C° and the stability in a day are both less than 1 μA.
Plasma Phasography
Authors: Presby Herman M. , Finkelstein David
Published: February 2005

The phase-contrast microscope of Zernike may be scaled in size and combined with ``giant pulse'' ruby-laser illumination to make possible the observation of macroscopic moving tenuous objects, such as jets, shock waves, and plasmas. The resulting instrument, referred to as the laser phase contrast (LPC) system, has performance similar to that of an optical interferometer operated in the single-fringe mode. The operation of the LPC system is treated theoretically and conditions for optimum imaging are derived. The ``phase plate'' of Zernike is modified into a ``phase mirror'' for use with focused laser illumination. Quite different mirrors are required for the full range of interesting plasmas accessible to the LPC system. The experimental model is described. Phasograms of weak and strong shocks in air and argon down to 0.5 mm Hg pressure are shown. Rayleigh-Taylor instability behind the shock is observed. Gas jets of various refractivities are also used as test objects. Phasograms of vacuum sparks producing jets of ablated electrode material are shown. Many objects studied are invisible to schlieren photography using the same illumination and optics.
Thermal Gradient Apparatus for Use in a Glovebox
Authors: Fischer D. F. , Chasanov M. G.
Published: February 2005

A thermal gradient apparatus for use in a plutonium glovebox is described. Axial gradients of 1000 C°/cm have been maintained in oxide samples for continuous periods of time in excess of 500 hours with this furnace. The system is operable in inert atmospheres or high vacuum.
Rotational Displacement Transducer
Authors: Slater Jonathan E. , Modi Vadilal J.
Published: February 2005

The construction and calibration of a rotational displacement transducer, using light sensitive resistors and a variable slit, are described. The instrument is capable of measuring both static and dynamic angular displacements and has a continuous range of sensitivity with a resolution as low as 0.01°. The linearity of the response over a 50° linear region is within 1% of the full scale deflection of 135°. The transducer exhibits no substantial phase lag and has response well suited for low frequency oscillation studies in the range 0–50 cps. The device is light in weight and has free undamped motion due to an external air-bearing suspension system. A restriction which must be noted in applying the transducer is that because of high frequency response dropoff the instrument is suitable only for recording accurately low frequency angular displacements of quasiharmonic waveform.
High-Temperature Sample Cell for the Kratky Small-Angle X-Ray Camera
Authors: Brumberger H. , Alexandropoulos N. G.
Published: February 2005

Design of a high-temperature furnace and sample cell for measuring the small-angle x-ray scattering of liquids or solids with the Kratky camera is reported. The cell may be used to 750°C with constancy of ±0.05 C°; a crucible for charging liquid metal mixtures into the cell in situ under inert atmospheres is also described.
Coupled Resonator Model for Standing Wave Accelerator Tanks
Authors: Nagle D. E. , Knapp E. A. , Knapp B. C.
Published: February 2005

The behavior of standing wave accelerator tanks, made up of chains of resonant cavities, is investigated using a coupled resonator model. This model gives accurate predictions of the behavior of such a cavity chain, including tolerances to errors in manufacture, cavity feed distributions, and transient response. The parameters necessary in the theory, the cavity couplings, Q's, and frequencies, may easily be determined by experiment. Extension of the simple chain to a more complex chain with double periodicity and second nearest neighbor coupling is demonstrated. Advantages of operating such accelerators in the π/2 mode are shown.
Solid State Gated Integrator
Authors: Clark W. Gilbert , Kerlin A. L.
Published: February 2005

A simple, inexpensive, two-channel gated (``boxcar'') integrator circuit using solid state components is described. Features of the circuit include a wide range of usable gate widths (from 0.2 μsec to arbitrarily large), a wide range of learning times (0.05 μsec to 1 sec), a high ratio of holding to learning time (as high as 4×107 for 1% output voltage sag), linearity of about 0.3% over a range of ±8 V at the output, temperature stability of about 3.5 mV/C° at the output, and a long term drift of about 0.5 mV/h at the output.
Production of Large Electric Pulses by Explosive Magnetic Field Compression
Authors: Conger R. L. , Johnson J. H. , Long L. T. , Parks J. A.
Published: February 2005

Chemical high explosives release about 4 400 000 J of energy per kilogram of explosive during detonation. Part of this energy can be converted to magnetic field energy by using the explosive to implode a conducting cylinder which contains an initial magnetic field. An apparatus is described which transfers the magnetic field energy to a resistive load.
Torsional Pendulum for Plastic Materials under Tensile Strain
Authors: Lepie Albert H. , Adicoff Arnold
Published: February 2005

This paper describes a torsional coupled pendulum combined with a tensile tester to measure simultaneously static tensile properties and dynamic and static shear properties of viscoelastic materials at constant temperature. The thermal environment of the sample is a liquid, permitting more efficient heat transfer and control in the sample itself. Several representative data are presented on carbon black filled rubber and highly filled rubber propellant samples.
Apparatus for Making Sharp Photographic Images with X Rays
Authors: Sherwood H. F.
Published: February 2005

X rays are well suited to the making of sharp photographic images because they are scattered much less by the emulsion than is light. However, careful attention must be paid to the design of apparatus used for making sharp images with x rays if satisfactory results are to be obtained. A method of making suitable jaws from Pt-Ir alloy foil and mounting them is described.
High Intensity Nozzle Beam Source for Use in Molecular Total Cross Section Measurements
Authors: Skofronick J. G.
Published: February 2005

A nozzle source which produces beams of neutral molecules, a factor of 102 to 103 more intense than that from effusive sources, is described. Further, the velocity distribution from this source is much narrower than that from effusive sources. The properties of the source and a description of its use in total cross section measurements for the case of a He beam on a H2 scatterer are presented.
Fast Response Sensing Element for a Frost Point Hygrometer
Authors: Jury Stanley H. , Bosanquet Louis P. , Kim Young W.
Published: February 2005

Developments in the field of sensing elements for frost point hygrometers are briefly reviewed. The rod type geometry connecting a refrigerant at one end with the mirror and heater at the other is analyzed mathematically to show the response and temperature distribution limitations of this geometry. A new sensing element is then described which consists of a hemispherical silver (or copper) thermal reservoir attached to a low mass mirror, heat distributor, and resistance heater via a thin layer of Invar. The latter confines most of the thermal gradient to itself due to its low thermal conductivity and optimum design of the hemisphere and refrigerant flow path. The new sensing element was simulated on a Pace 221R analog computer as well as being subjected to transient analysis which showed that the element responded as a first order lag of time constant 1.67 seconds. Actual construction and tests with step changes of input to the heater confirmed the first order response but with a time constant of 1.3 sec which corresponds to an average full scale response of 14.5 C°/sec with a maximum of 74 C°/sec. Subsequent tracking tests revealed smooth response particularly through 0°C where the ice-water transition takes place.
Square Wave Dissociation Field Effect Apparatus
Authors: Rampton Dennis T. , Holmes Lloyd P. , Cole David L. , Jensen Ronald P. , Eyring Edward M.
Published: February 2005

A dissociation field effect relaxation method apparatus for measuring rates of very rapid chemical reactions in aqueous and nonaqueous solutions is described. Chemical relaxation times between 0.3 and approximately 5.0 μsec are measurable on an asymmetric, high voltage Wheatstone bridge, two arms of which are electrolyte cells. The relaxation in weak electrolyte conductance (second Wien or dissociation field effect) caused by a square wave high voltage pulse from a coaxial delay line is detected with an oscilloscope as a changing difference in voltage between opposite points on the bridge. The construction of the bridge and triggering device and the mechanics of balancing the bridge previous to the actual measurement are described in detail.
High Pressure, High Temperature Viscometer
Authors: Sperry L. L. , Mackenzie J. D.
Published: February 2005

An apparatus for measuring the relative viscosity of molten glass-forming oxides at elevated temperatures and pressures is described. It utilizes a concentric cylinder viscometer and electric furnace enclosed in a steel pressure bomb and is gas pressured. Four thermocouples and three heating circuits enable the temperature of the sample to be controlled to within ±0.2°. Data on the pressure dependence of viscosity of molten boron trioxide in the temperature range of 380–470°C and at pressures up to 300 bars are presented.
Accurate Method for Measuring Rotational Movement of a Carriage
Authors: Masry S. E.
Published: February 2005

An accurate method for measuring the rotational movement of a carriage about an axis parallel to the direction of its translation movement is explained. It is shown that the method can also be used in determining very accurately the tilt of a supporting system.
Apparatus for Measuring the Hall Effect of Low-Mobility Samples at High Temperatures
Authors: Lupu N. Z. , Tallan N. M. , Tannhauser D. S.
Published: February 2005

An apparatus is described for measuring the Hall effect of low mobility samples at high temperatures. The measuring method is of the double ac type. An alternating current at 510 cps, in conjunction with a low frequency magnetic field at about 2 cps, is used. The use of single or double phase sensitive detection is discussed. A temperature controller with a stability of about 2×10−2 C° at 1000°C and a sample holder assembly are described. Results of measurements on NiO samples are given, indicating a noise level equivalent to mobilities of 3×10−4 cm2/V sec.
Construction of the Guide Field for a Low Inductance Air-Core Plasma Betatron
Authors: Ferrari L. A. , Rogers K. C. , Jermakian A.
Published: February 2005

The guide field for a low inductance (55×10−9 H) air-core plasma betatron is constructed by placing flux-concentrators within the interior of a single-turn solenoid. The betatron field coil is energized by the discharge of a 75 μF, 20 kV capacitor bank. The quarter period of the field-coil capacitor bank system is 4 μsec and the peak magnetic and electric fields at the equilibrium orbit (r0=4.83 cm) are ≈3250 G and 60 V/cm, respectively. Techniques used to make accurate (±0.1%) measurements of transient magnetic field distributions are also described.
Gelatin-Free Ion-Sensitive Plates for Mass Spectrography
Authors: Honig R. E. , Woolston J. R. , Kramer D. A.
Published: February 2005

Several methods have been explored to produce gelatin-free thin-film plates of superior performance for the detection of positive ions. Of these methods, vacuum deposition of silver halides has been found to be the most flexible system and has been examined in an extended series of tests. Particle size, sensitivity, and shape of the response curve were studied as a function of various experimental parameters, such as evaporation temperature, thickness of layer, substrate temperature, ion energy, developing conditions, and others. The plates obtained by this technique have particle sizes of about 1 μ and yield sensitivities, for 20 keV ions, approaching those of Ilford Q2 plates at 50% blackening. When blackening B is plotted vs log E (E=exposure in coulombs), the slope of the resulting response curve is considerably steeper than that found for Q2 plates. The thin-film plates produced have a number of advantages over the commercially available Schumann-type plates: the background blackening of unexposed areas approaches that of clear glass and has an unusually low noise level; spectral line sharpness is greatly improved; the plates show practically no halation, have good conductivity and excellent vacuum properties; and there are no storage problems.
Response of Ion-Sensitive Plates as a Function of Ion Energy
Authors: Woolston J. R. , Honig R. E. , Botnick E. M.
Published: February 2005

To attempt a better understanding of the mechanism of ion detection with ion-sensitive plates, a study was made of sensitivity as a function of ion energy, and of blackening as a function of exposure. Various commercially available and experimental plates used in mass spectrography were investigated. A dc beam of Cs+ ions was used to expose evenly areas 0.1 by 0.25 cm on the plates, which were placed between the ion beam monitor collector and the magnetic sector entrance boundary of an AEI type MS7 double-focusing mass spectrograph. Thus, after leaving the ion source, the ions traversed only the electrostatic sector portion of the instrument. For the sensitivity study, exposures were made with ion energies ranging from 0.1 to 20 keV on Ilford Q2, Kodak SWR, Kodak-Pathé SC5, and RCA thin-film plates made by the direct evaporation of AgBr onto glass (described in a companion paper by Honig, Woolston, and Kramer). In addition, blackening as a function of exposure was determined at various energies for each ion-sensitive material. The relationship observed between sensitivity and ion energy, when plotted in double-logarithmic fashion, is not a simple linear function, as has been stated by previous investigators, but exhibits a complex behavior.
Broadband Nuclear Resonance Dispersion Detector
Authors: Blume R. J. , Edmonds D. T.
Published: February 2005

The detector is a Robinson limited oscillator with a single tuning control to which has been added an untuned ``transmitter'' coil orthogonal to the usual sample coil. Oscillation is maintained by a combination of Robinson feedback and weak mutual coupling of the two coils. The rf fields of the two coils are in time phase; the transmitter field is much the stronger. Dispersion signals were obtained in tests to 20 MHz at least as easily as were absorption signals with a conventional autodyne. The circuit is especially well suited to frequency-swept searches for narrow, easily saturable lines (since the dispersion signal does not saturate) and those requiring high H1 with unimpaired sensitivity (since the ``receiver'' sees the entire nuclear signal, but only a small fraction of the ``transmitter'' output).
Operating Parameters of dc-Excited He-Ne Gas Lasers
Authors: Field R. L.
Published: February 2005

The output power of the 6328 Å helium-neon gas laser has been investigated as a function of capillary diameter, total pressure, and He-Ne partial pressure ratio at optimum dc discharge currents. The optimum value of pTd (total pressure × capillary diameter) remains constant, and the scaling laws, power ∝ d, optimum current ∝ d are approximately satisfied for the four diameters investigated. The results suggest that optimum laser output is always achieved at the same value of electron mean energy and at a constant fractional ionization. This study permits a clearer understanding of the relationship between various helium-neon discharge parameters and the 6328 Å laser output power, and by extrapolation allows the prediction of optimum gas fill for other capillary diameters. These results should also be useful in analyzing the effect of gas cleanup on tube life.
Measurement of Torques at Low Temperatures
Authors: Metz Claire D.
Published: February 2005

A method is described for producing calibrated torques at low temperatures using the interaction between an applied magnetic field and a superconducting torus. The torque produced is proportional to the square of the applied magnetic field and can thus be varied continuously over a wide range by varying the current which produces the magnetic field. It can be used in a null method to measure any torques of interest, such as the torques produced by second sound on a Rayleigh disk or on a radiation balance. The principal advantages of this method are that a wider range of torques is available with a given assembly and that the null position is more easily obtained.
Resonance Relaxation Sounder for the Multiple Ionospheric Probe
Authors: Hugill J. , Field M. J.
Published: February 2005

Design parameter selection, block diagram, special circuit description, and calibration procedure are given for rocket instrumentation used to measure plasma resonances in the E-region.
Increasing the Accuracy of Crystal Orientation Procedures Using the Weissenberg Camera
Authors: Wang Bi-Cheng , Cordes A. W.
Published: February 2005

A one-film method for orienting single crystals using an oscillation film obtained with a Weissenberg camera is described. Highly precise orientation corrections are obtained by using the curvature of the nonzero lines, which is more sensitive to crystal orientation than the zero layer line curvature used in other methods. The equations used for the corrections are derived, rather than empirical, and a general equation for the shapes of the lines caused by a misoriented crystal is given.
Unsymmetrical Friction and Pressure Calibration in Internally-Heated Piston-Cylinder Type High-Pressure Devices
Authors: Pistorius Carl W. F. T. , Rapoport Eliezer , Clark J. B.
Published: February 2005

It is shown that the procedure of evaluating pressure losses in internally-heated piston-cylinder devices by assuming symmetrical friction is in error below ∼500°C. Previous results may be in error by as much as ∼5 kilobars at 40 kilobars and 25°C. A method of calibration is described which evaluates such unsymmetrical pressure losses.
Source of Carbon Resonance Radiation
Authors: Whittaker A. Greenville , Kintner Paul
Published: February 2005

A hollow-cathode carbon resonance lamp was constructed, and the effect of anode configuration, filler gas (helium, argon, and neon), filler-gas pressure, and lamp current on the intensity of enission lines in the region 1560 to 2000 Å was studied. The carbon resonance triplet at 1657 Å could be obtained with good intensity, as could the carbon line at 1931 Å. The spectrum also showed a number of molecular bands, one of which interfered slightly with the carbon resonance line at 1657 Å. The bands could be removed, however, by reducing the pressure of the filler gas.
Vacuum Diode Detector for Measuring High Intensity Gamma-Ray Flux
Authors: Ebert P. J. , Lauzon A. F.
Published: February 2005

An insensitive gamma-ray detector for measurement of fast rising, transient gamma-ray fluxes has been developed. Linear signals ≥5×102 A have been observed, corresponding to a 1.25 MeV dose rate of >1016 R/h. The detector can also be used in the steady state mode where signals ≤10−12 A can be measured. This current corresponds to a 60Co dose rate of ∼20 R/h. Detector design criteria, sensitivity as a function of energy, linearity, and time response are also discussed.
Quadrupole Magnet Misalignment Tolerances
Authors: Meads Philip F.
Published: February 2005

The field produced by a quadrupole magnet is antisymmetric with respect to reflection through either of two orthogonal planes whose intersection is the optical axis of the magnet. Failure to perfectly align these planes for a given quadrupole magnet with the cardinal planes of the beam system incorporating that magnet induces an error field that perturbs the beam. The effects of misalignments of a number of quadrupoles are derived by including the induced error fields in the equation of motion. The results are expressed in terms of the known linear optical properties of the beam system and are sufficient for determining the tolerances required on each constituent quadpole magnet.
Recording Method for Studying the Kinetics of Gas Producing Reactions
Authors: Wilson Abraham
Published: February 2005

An apparatus for making recorded kinetic measurements on reacting systems involving gases and solids or liquids has been constructed and tested by studying the decomposition of benzene diazonium chloride. In operation, helium is flowed through one side of a thermal conductivity detector (TCC), an equilibration tube containing solvent (if necessary), through the reactor, and back through the other side of the TCC. The measurement is made under conditions of programmed ambient temperature. The resulting recorder pen displacement is proportional to the concentration of gas in the helium stream, and, with appropriate apparatus design, to the rate of evolution of nitrogen. The skewed bell curve which results can be analyzed for the kinetic data. At each temperature (time) the pen displacement is a direct measure of the reaction velocity. The measurement has thus resulted in a transformation from a differential to an algebraic kinetics expression. The area under the curve to any temperature (time) is proportional to the total amount of gas produced. In a calibrated apparatus, one thus has a continuous analysis of the reaction. Treatment of the data to obtain an Arrhenius expression is a fairly straightforward procedure, programmable for computer solution. The example of reaction chosen is the decomposition of benzene diazonium chloride. The results are compared with literature values.
Stabilized Constant Acceleration Mössbauer Drive
Authors: Hazony Y.
Published: February 2005

A closed feedback loop for the zero velocity drift of a constant acceleration Mössbauer spectrometer has been developed. Using a transducer with a built-in limit switch and the modified logic circuitry of a multi-scaler-analyzer, the feedback loop responds to the zero velocity drift of the entire system as a whole rather than to each component independently. A long-term zero velocity stability of ±0.001 mm/sec has been obtained.
System for Continuous Recording of Critical Current Curves of Superconductors
Authors: Shaw R. W. , Laquer H. L.
Published: February 2005

A method is described which allows the direct and continuous recording of the critical current versus magnetic field curves for superconductors. The system uses an electronic integrator to control a current supply so as to produce a selected small voltage across the sample. It presents an improvement in both speed and ease of obtaining critical current curves.
Magnetic Measurements under Hydrostatic Pressure: Intensity of Magnetization and Anisotropy
Authors: Kawai N. , Sawaoka A.
Published: February 2005

A new technique was developed to make magnetic observations of weakly magnetized materials under hydrostatic pressure up to 12 kilobars in a wide temperature range from liquid helium temperature up to 200°C. We have designed a special type of nonmagnetic pressure vessel in which the materials to be measured were pressurized. For measuring magnetization, the above pressure vessel was connected to a torsion pendulum and its deflection in a magnetic field was measured. For measuring the anisotropy of ferromagnetic crystals, the vessel was connected to an air-jet supported magnetometer having an unbonded strain gauge detector and its torque moment in a uniform magnetic field was determined.
Flame Ionization-Pulse Aerosol Particle Analyzer (FIPAPA)
Authors: Crider Walter L. , Strong Arthur A.
Published: February 2005

An instrument is described that counts automatically according to size aerosol particles of certain specific chemical compositions. The technique employed depends on converting to current pulses the ions produced from airborne particles passing through the combustion zone of a flame. Because the amplitude of the current pulse resulting from an ionized particle passing through a flame is dependent on both the mass and the ionization potential of the particle, the FIPAPA can aid in submicron aerosol particle identification when used in combination with instruments employing other sensing zone types. By use of electronic pulse-height circuits, these current pulses are subsequently counted in six ranges of magnitude. The minimum size particle detectable was found to be 0.15 μ diam for KOH and 0.25 μ diam for NaCl.
AC Methods for the Determination of Photoelectron Energy Distributions
Authors: Nathan Ranga , Mee C. H. B.
Published: February 2005

The sensitivity of the Spicer-Berglund retarding-potential method for the determination of photoelectron energy distributions may be improved by an order of magnitude by a more effective cancellation of the capacitative component of the signal. A double modulation technique, in which energy distributions can be traced from saturated photocurrents of the order of 10−11 A, is also described. This method can be employed to eliminate steady thermionic or photoelectric currents many orders of magnitude greater than that under investigation.
Improved Internal Friction Apparatus
Authors: Buch J. D. , Carnahan R. D. , Brittain J. O.
Published: February 2005

The authors have developed an apparatus which will allow the measurement of internal friction with a precision of ±1.3% with data processing time a matter of seconds. The apparatus was designed for the range of 2–20 cps; however, the principle can readily be applied to a much broader frequency range.
Scanner for Short Sections of Magnetic Recording Tape
Authors: Torgersen Halvard
Published: February 2005

A device is described for the repeated mechanical scanning of a very short section of magnetic recording tape. The tape section, in a shuttle-like holder, is moved backwards and forwards in front of a play-back head. To obtain a constant speed movement, the tape holder is made to follow the contour of a cardioid curve section cut along the periphery of a rotating disk. The length of the scanning stroke is determined by the depth of the cut. A synchronizing contact is provided so that by triggering and adjusting the sweep of a cathode-ray oscilloscope a stationary display may be presented on the screen. Typical applications are described.
Iron Magnet with Superconducting Coil
Authors: Fast R. W. , Del Castillo G. , Winter W. R.
Published: February 2005

A model magnet has been constructed to study the behavior of a large superconducting coil on an iron yoke at room temperature. The coil, wound with niobium stannide ribbon, has an average diameter of 40 cm, a maximum excitation of 5×105 ampere-turns, and a stored energy of 85 kJ. The superconductor carries the same current, 120 A, on the pole and yoke as it did when removed from all iron. Nylon spacers served as compression members of low thermal conductivity to support the 18 000 kg magnetic force.
Some Techniques for Sensitive Magnetic Measurements Using Superconducting Circuits and Magnetic Shields
Authors: Deaver Bascom S. , Goree William S.
Published: February 2005

A new superconducting circuit has been used in a sensitive magnetic susceptibility apparatus to detect changes in magnetic susceptibility as small as 10−10 cgs/g in a 104 Oe field, and in a low field magnetometer with which magnetic fields as low as 5×10−7 Oe have been measured. A low field superconducting shield for testing sensitive magnetometers has been developed and used to provide stable magnetic fields of less than 10−6 Oe, maintained stably for as long as six days. The measured attenuation of externally applied axial field changes is shown to be a factor of about 31 per shield radius. The stability of the persistent field of a Nb-25% Zr superconducting solenoid, observed over an 8 h period, indicated an average drift in the persistent solenoid field of less than one part in 1010/sec. Also, the attenuation of various high field magnetic shields of Nb-25% Zr foil was measured.
Fatigue Apparatus for Extreme High Vacuum
Authors: Reed Malcolm E. , Hordon M. J.
Published: February 2005

A constant amplitude, reverse bend stress fatigue testing device is described which permits simultaneous testing of up to eight specimens at extremely low pressure levels below 10−10 Torr. The vibratory force was provided by an electromagnetic exciter with vibration frequencies in the range of 50–200 cps. Fatigue tests with 1100-H14 aluminum showed that a substantial increase in the cyclic fracture life was obtained in high vacuum as compared to the fatigue behavior in unit atmosphere of air. The fatigue life improvement increased proportionally with the cyclic stress frequency.
Measurements of Beam Divergence of Q-Switched Ruby Laser Rods
Authors: Avizonis P. V. , Doss T. T. , Heimlich R.
Published: February 2005

A method of measuring beam divergence is reported that provides simultaneous variable intensity multiple exposures of the laser output on Polaroid film, and does not require densitometer tracings of the exposures to establish the beam divergence. Using this technique, beam divergence as a function of power output of 12 ``Q-switched'' ruby rods is reported. Inference is made that the active divergence of a ruby rod is the sum of the passive beam divergence of that rod plus the divergence due to radial mode structure. Thermal distortion probably contributes very little to the beam divergence.