bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Depth Gauge for Laboratory Studies of Water Waves
Authors: Sturtevant B.
Published: February 2005

The absorption of infrared light by water is used to measure depth. A collimated beam of light from an incandescent filament source is projected through the water from below, filtered, and detected by an infrared sensitive phototube. The quantitative performance of the gauge is assessed, and the effects of refraction and reflection at the the free surface are discussed. A circuit that linearizes the exponential dependence of the phototube output on depth is described. The sensitivity of the gauge and linearizing circuit is determined by calibration to be about 0.05 V/cm, and the smallest measurable wave amplitude, corresponding to unity signal-to-noise ratio, is about 0.07 mm. The accuracy for absolute depth measurement is about ½ mm.
Wide Gap Chamber of Cylindrical Geometry Operated Close to Grounded Objects
Authors: Leontic B. A.
Published: February 2005

A cylindrical spark chamber consisting of only two electrodes, the radii of which differed by a factor of more than 3, has been successfully operated while surrounded by grounded conductors, one of which was situated at a distance of only 4.5 mm from the sensitive volume of the chamber. Very thin and straight tracks were obtained which followed the particle trajectory up to large inclinations from the normals to the surface of the electrodes.
New Method of Displaying Disturbance and Wave Propagation
Authors: Štirand O. , Krejčí V. , Láska L.
Published: February 2005

The measured phenomenon modulates in intensity a horizontal line on a CRO screen. The vertical position of this line is electrically linked with the position of the detector (e.g., photomultiplier). If the phenomenon is repeated many times while the detector slowly moves, the individual lines fuse into an intensity modulated space-time diagram, similar to a TV picture. The method quickly provides accurate and full information of even very complicated and fast wave phenomena, and increases the signal-to-noise ratio by summarizing many independent measurements into a single picture. Examples of the use of the method for measurements of ionization waves in a discharge plasma are given.
Design of Charging Circuits for dc Line Type Pulsers
Authors: Ingels Neil B. , Burzio Agostino , Thompson Noël P.
Published: February 2005

Design equations are developed for three types of charging circuits commonly employed in line type pulsers. Parameters determined by these equations lead to systems which optimally utilize the power source. Both resistive and inductive charging networks are considered.
Simple Volume Measurements at High Pressures
Authors: Montgomery Peter W.
Published: February 2005

This paper describes a simple and rapid system capable of detecting volume discontinuities as small as 1% over the pressure range from 0 to 100 kbar. Measured relative volume changes Δv/v0 at transformations ranging from 1 to 10% agree with values reported by P. W. Bridgman within 20%. The use of the system in making compression (pressure-volume) measurements is also described.
Average Charge Detector for Mass Spectrometers
Authors: Dimeff John , Lieber Albert J. , Burrous Clifford N.
Published: February 2005

The results of space experiments designed to determine the intensity and energy distribution of the solar plasma have been somewhat ambiguous because of the inability to provide separate measurements for the H+ and He++ components of the plasma stream. An instrument has been designed which can provide the required separation with adequate accuracy. Performance data for the instrument presented as a function of ion beam intensity and energy indicate a repeatability of the order of 3%. Data on measurement sensitivity to experimental variables suggest that the repeatability might be significantly better than is indicated by current results.
Electrolytic Tank Analog for Magnetic Field Design
Authors: Combes Lewis S. , Gallagher Charles C. , Levine Morton A.
Published: February 2005

An electrolytic tank serves as a relatively easy and reasonably accurate method of analoging magnetic field configurations. A simplified tank has been constructed for designing a field to be used in a plasma containment device. The tank is useful in determining the parameters for the field producing coils and for mapping isogaussic surfaces that may result when a high density plasma is present in the magnetic field. In this analog tank, the current density in the electrolyte is directly proportional to the magnetic flux density and, from this relationship, equations have been derived by which flux density, magnetomotive force, total flux, inductance, and energy of the coils can be found from tank measurements. The detailed analysis of a specific magnetic field problem is given.
Method for Measurements on Circularly Polarized Ultrasound in Magneto-Acoustic Experiments
Authors: Miller Barry I. , Rehn Victor
Published: February 2005

A method is presented for the measurement of the attenuation and dispersion of circularly polarized acoustic eigen modes as a function of magnetic field. These measurements are important for the study of Doppler shifted cyclotron resonance in metals. The detection of these eigen modes is accomplished by using a split, transverse receiving transducer, the two halves of which have mutually perpendicular displacement axes. The output of one of the half-transducers is delayed one-fourth period with respect to the other, after which the two outputs are added before rectification. The resultant signal is then proportional to either the right or left circularly polarized eigenmode. The generation of eigen modes is easily accomplished for propagation along a 3-fold or higher symmetry axis. A transverse linear excitation, such as produced by an AC cut quartz transducer, excites both circularly polarized eigen modes equally. Typically the ratio of the amplitudes of the selected mode to unselected mode appearing at the receiver output is 25:1. This ratio can be increased considerably by applying systematic corrections, which are presented. Possible extension of this method to elliptically polarized eigen modes is discussed.
Ion Gauge for Vacuum Pressure Measurements below 1×10−10 Torr
Authors: Helmer J. C. , Hayward W. H.
Published: February 2005

Low pressure measurements by Bayard-Alpert gauges are limited by x-ray photoelectric currents at the ion collector, equivalent to a pressure reading of about 1×10−11 Torr. Through efforts to reduce this x-ray current, the Bayard-Alpert structure has been modified, whereby a beam of ions is extracted from the grid and bent around a corner to a remote collector. By this geometry the collector is shielded from the x-ray source at the grid, and the photoelectric current is reduced by a factor of 100, without incurring a loss in gauge sensitivity. Bending of the ion beam is accomplished by a cylindrical, electrostatic field, in which the ion trajectories are independent of e/m. 100% modulation of the ion beam intensity is achieved by turning off the bending field, thereby permitting pressure measurements as low as 1×10−14 Torr. A total pressure of 5×10−13 Torr, nitrogen equivalent, has been measured in a stainless steel vacuum system employing ion sputtering and titanium sublimation as the means of evacuation.
Dielectric Cell for Liquids of High Dielectric Constant
Authors: Vidulich G. A. , Kay Robert L.
Published: February 2005

A dielectric cell with platinum electrodes fused onto concentric glass cylinders is described. The cell is completely shielded and of the three terminal, guarded type necessary for the precise measurement of dielectric constants and conductances without the use of reference liquids. It can be cleaned readily with strong oxidizing agents, can be dried and filled with electrodes in place, and can be thermostated with relative ease. Another feature of the cell is its ease of construction and its adaptability to the rapid measurement of dipole moments and conductances in solutions of very low dielectric constant.
Superconducting Switch
Authors: Huebener R. P. , Govednik R. E.
Published: February 2005

A superconducting switch is described which has an electrical resistance of 45 Ω in the nonsuperconducting state. The dimensions of the switch are 3.5×3.5×1.5 cm.
Charge Distribution of 16O Ions Produced from Tandem Accelerator
Authors: Preikschat E. , Cramer J. G.
Published: February 2005

In an effort to obtain information about the acceleration of heavy ions in tandem accelerators, the charge state distribution of oxygen ions accelerated in the University of Washington FN tandem accelerator was measured at three terminal voltages and over a range of stripper pressures. It is found that the stripper pressure normally used is below the value required for equilibrium in the charge exchange process, but that at higher terminal voltages the average charge state of the ions can rise above the equilibrium value due to focusing effects in the accelerating tubes. This phenomenon has implications in the use of foil strippers with heavy ion beams. A useful empirical relation for the optimum stripper pressure for a given charge state is obtained.
Anaerobic Stopped Flow Apparatus
Authors: Fox J. Lawrence , Tollin Gordon
Published: February 2005

A stopped flow apparatus for studying moderate rate reactions under anaerobic conditions is presented. The apparatus is described and some of its characteristics are given.
Vibrating Coil Magnetometer for Use at Very Low Temperatures
Authors: Kaeser R. S. , Ambler E. , Schooley J. F.
Published: February 2005

A vibrating coil type magnetometer is described for measuring magnetization curves of small specimens in the magnetic cooling range of temperature. For a 3 mm diam sphere the sensitivity of magnetic moment measurements is 10−6 emu. At this sensitivity the amplitude of vibration is 0.5 mm, and at 0.3°K the extra heat influx into the sample thereby introduced is less than 10 erg/min. Examples of magnetization curves are shown.
Ultrastable Triangle and Square Wave Generator
Authors: Cohen R. L.
Published: February 2005

A triangle and square wave generator designed to excite Mössbauer velocity drives is described. The version shown runs from 1 to 25 cps, and has frequency and amplitude stability and linearity substantially better than 0.1%.
Input Circuits for Pulsed NMR
Authors: Pollak V. L. , Slater R. R.
Published: February 2005

A detailed comparative analysis of several possible input circuits for observing NMR free precession signals is given. Special attention is paid to the case of signals having short decay time constants. Here the presence of a large initial ringing transient makes it necessary to consider possible modifications in the design of the receiver system. The analysis indicates that an untuned transformer coupled input circuit is potentially superior to the traditional parallel resonant circuit in this case.
Four-Probe Device for Accurate Measurement of Temperature Dependence of Electrical Resistivity on Small, Irregularly Shaped Single Crystals With Parallel Sides
Authors: Germann R. W. , Rogers D. B.
Published: February 2005

A sample holder is described that considerably facilitates the measurement of specific resistivity on small, irregularly shaped single crystals over a large range of temperature. Utilizing the van der Pauw technique, accurate values of this electrical transport parameter have been obtained without loss of contact at temperatures as low as 4.2°K. The essential advantage of this holder is its simplicity which eliminates the necessity of specialized techniques for accurate measurements on irregular crystals as small as 1 mm.
Field Emission Ultramicrometer
Authors: Young Russell D.
Published: February 2005

A simple, contact free, ultrasensitive distance and displacement measuring instrument has been investigated. Experiments demonstrate that the instrument is capable of operating at spacings as small as a few hundred angstroms. Calculations indicate that distances of 10−3 to 10−6 cm and less can be reproduced to within about one part in 105. With suitable calibration, distance measurements in the 10−3 to 10−6 cm range can be expected to have accuracies limited only by available calibration techniques. The instrument would be most useful as a null or differential distance measuring device. It has the unusual property that resolution improves over several orders of magnitude as the null or measurement point is approached. Since the instrument contains no optical or mechanical lever systems, or delicately balanced bridges, it has inherent long term stability. Proposed applications include: (1) measurement of ball and hole diameters (contact free), (2) differential thermal expansion cell, (3) mechanical vibration sensor, (4) surface profile delineator (contact free), and (5) surface contour delineator (contact free).
Measurement of Curie Point of Ferrites Using Pressure Vessel of Piston-Cylinder Type
Authors: Kume S. , Endo S. , Koizumi M. , Okazaki C. , Hirota E.
Published: February 2005

A method using a high pressure vessel of piston-cylinder type is introduced which is capable of the measurement of the ferromagnetic Curie points of fragile materials such as a sintered ferrite under high pressures. Since a sample is fixed in silicon grease inside the vessel, it is compressed hydrostatically and is protected from breaking by the application of solid pressures. Measurements on Mn-Zn and Ni-Zn ferrites show that their Curie points rise with the increase of applied pressures, the rate being nearly +1°C/kbar in both cases.
Method for Measurement of Ionization Curves by Means of Scintillation Counters
Authors: Tisljar-Lentulis G. M.
Published: February 2005

A technique is described for measuring the Bragg ionization curve of a certain kind of particle in the presence of a disturbing beam contamination. The pulses of the undesired particles are eliminated electronically by the applied counter telescope. The ionization values are gained from the pulse height spectra which the beam produces in a NaI (Tl) scintillator. The pulse train of the multichannel analyzer used and a program written in FORTRAN II supply the data for the ionization curve. Measurements with 150 MeV protons are compared with curves in the literature.
Application of Adiabatic Compression Apparatus for Study of Thermally Induced Homogeneous Gas Phase Reactions
Authors: Henderson U. V. , Rhodes Harold A. , Barnes V. M.
Published: February 2005

Attempts have been made to study the homogeneous dissociation kinetics of N2F4 and OF2 by means of an adiabatic compression apparatus attached to the fast reaction cell of a Bendix time-of-flight mass spectrometer. It was found that, if helium is used for the reaction medium, temperatures sufficiently high for reaction to occur are not obtained, nor is the maximum temperature obtained constant for a significant period of time; i.e., the high thermal conductivity of helium does not permit an approach to adiabatic operation. A further bar to successful experimentation (assuming that the nonadiabaticity could have been overcome by using an inert medium of lower thermal conductivity) was the self-destructiveness of the light weight apparatus and the damage to the ion source of the mass spectrometer, brought about by the impact of the piston at the end of the compression stroke. The experimental data obtained in this system with helium, argon, and nitrogen are critically examined and possible theoretical limits of mechanical adiabatic compression, proposed by Vernotte, are discussed.
Kinematic Locator for Crystal Alignment
Authors: Simson Bert G. , Deslattes Richard D.
Published: February 2005

A kinematic locator with one rotational degree of freedom is described. This device allows the transfer of aligned crystals within 2″.
Design Calculations for Ionization Spectrometers: Cascade Development
Authors: Pinkau Klaus , Thompson Karl V.
Published: February 2005

The total number of electrons has been calculated as a function of depth in air, glass, and iron absorbers. The nuclear interactions have been described by the model of Cocconi, Koester, and Perkins. The results help in the design of ionization spectrometers for the measurement of the total energy of ultrahigh energy particles. In particular, a correlation is established between the maximum number of electrons and the primary energy. Also, the amount of energy lost from ionization spectrometers due to limited depth can be derived from the results presented here.
Measurement of Length Changes to 0.1 Å in Irradiated Germanium at Low Temperature
Authors: North J. C. , Buschert R. C.
Published: February 2005

The apparatus described was developed to measure length changes in germanium due to electron irradiation and subsequent isochronal annealing at low temperatures. Similar techniques would be applicable to other experiments. Length changes of the sample produced changes in spacing of a system of three-terminal capacitors. These capacitors were measured by an ac ratio bridge capable of detecting changes in capacitance of 4 parts in 107. The irradiated portion of the sample, the surrounding framework, and one plate of each of the parallel plate capacitors were all part of the same monolithic germanium single crystal. A system of six capacitors was used to eliminate extraneous effects. The sensitivity and long term stability was on the order of 0.1 Å which corresponds to 2 parts in 109 for an irradiated sample length of ½ cm.
Characteristics and Operation of Xenon Filled Linear Flashlamps
Authors: Perlman David E.
Published: February 2005

Following a discussion of flashtube impedance and its dependence upon discharge current, the relation between current magnitude, initial charge voltage, circuit constants, and lamp dimensions is derived for lamps operating in pulse forming networks of cascaded LC pisections. The resulting equation, I=0.27(d/l)23(C/L)13V43, has been experimentally verified by data from flashtubes having arc lengths ranging between 7.6 and 91.5 cm. When, as is often the case, a flashtube is operated in series with a single inductor, the current pulse is not rectangular and the assumption of constant discharge resistance used in the multisection line study is invalid. A more precise analysis has been carried out with the aid of a digital computer in which the differential equation for a series RLC circuit is solved with the nonlinear condition R=Rw+R(i). Inclusion of wiring resistance Rw permits further extension of the solution's applicability and the results are found to agree well with experiment.
Optical Reflectors for Use in Internal Sample Aqueous Čerenkov Counters
Authors: Strindehag Ove M.
Published: February 2005

Properties such as reflectance, deterioration in water, and deposition of activities are investigated for several types of optical reflectors. Reflectance values for both visible and ultraviolet light are included and the deterioration tests extend up to water temperatures of 150°C. The influence of reflector properties on detector efficiency is also studied.
Bevatron Beam Spill by Amplitude Modulation
Authors: Lothrop Fred H. G.
Published: February 2005

A more efficient method for the delivery of protons onto Bevatron targets has been devised. This method involves amplitude modulation of the rf accelerating voltage by a closed loop system that regulates the rate of loss of circulating beam, as observed on a pickup electrode. The efficiency and reliability of this new method are considerably greater than those of previous methods, and the flexibility of proton delivery control has been enhanced.
Astigmatic Magnetic Analyzer
Authors: Green A. E. S. , Berkley R. J. , Watson C. E. , Moore C. F.
Published: February 2005

A fringe field double focusing magnetic spectrograph is described which was designed to achieve a resolution of the order of 103, a solid angle of the order of 10−2, and an energy range capability from about 0.5E0 to 2.5E0, where E0 is the energy of the design point. The analyzer can be used as a spectrometer with still larger solid angle near 1.44E0. The system corresponds to a prism astigmatic-lens combination which takes a point object into line images for each energy represented. At the design point, the y image distance equals the object distance, and the z image distance is at infinity. At other energies, the z image distance has various large magnitudes. A ``bootstrap'' procedure is used to generate the entrance and exit faces with the aid of a ray tracing instrument. Approximate methods are used to allow for fringe field effects so as to shape the actual pole pieces to achieve the desired effective faces. A numerical method of optimizing the horizontal focal properties is presented. The initially observed performance of the system approximately fulfills the design objectives.
Electromagnetic Shutter Suitable for Electroretinography
Authors: Buckser Stanley
Published: February 2005

A shutter utilizing an electromagnetic drive and brake regulated by solid state circuitry is described. The shutter has opening and closing times of 0.50 and 0.70 msec, respectively, a range of controlled durations that can be varied from 2 msec to as long as desired, and a maximum repetition rate of 8 per second.
Multidirectional Peak Pressure Gauge for Strong Shock Waves
Authors: Power Dean V. , Lombard David B.
Published: February 2005

A gauge using a spherical Lucite shell as the active element has been developed to measure peak pressures in strong shock waves. The instrument is insensitive to orientation, simple in design, and relatively easy to construct. The gauge tested is useful in the ranges of 46 to 110 and 180 to 220 kbar. Theory and characteristics of operation are discussed and calibration results are presented. The gauge was designed to measure shocks from an underground nuclear explosion, but the principle has wider applications. Methods for extending the usable pressure range of the gauge by impedance mismatching techniques are discussed briefly.
Electronic Hysteresigraph Holds dB/dt Constant
Authors: Mazzetti P. , Soardo P.
Published: February 2005

An electronic instrument able to trace on a X-Y recorder all types of magnetic curves of ferromagnetic materials and having better performance than ordinary ballistic equipments is described. The main features of the instrument are (a) the ability to trace any magnetic curve keeping the induction flux derivative constant, which minimizes the errors due to eddy currents in the specimen, and (b) the extremely low drift of the integrating circuit, which allows it to trace hysteresis loops of specimens of normal dimensions in times as long as 30 min, yet maintaining the accuracy within 1%. Sensitivity, accuracy, errors due to eddy currents, and comparison with ordinary ballistic methods are discussed in detail in the text. Many experimental results are also given.
Alternating Gradient Electrostatic Accelerating Tube
Authors: Boyd D. , Kane J. V.
Published: February 2005

The processes of electron multiplication and electron loading in acceleration tubes have been investigated theoretically. These effects limit the maximum voltage at which Van de Graaff generators can operate. A new design for an accelerating tube is proposed which by virtue of its closely spaced electrodes has the advantage of ease of calculation and flexibility of boundary condition. Computer calculations were done for this tube to study electron multiplication trajectories. We have found that an axial alternating electrical field gradient can limit such avalanches by periodically trapping the electrons.
Explosive Driven Shock Tubes
Authors: Duff Russell E. , Blackwell Arlyn N.
Published: February 2005

Several different high explosive driven shock tubes have been developed as sources of short duration, supersonic, high pressure pulses which can be used to load large, massive objects with accelerations up to many thousand g's. These shock tubes are particularly appropriate for simulating strong blast effects on hardened structures. An important characteristic of these shock tubes is the use of detonation products as the primary working fluid. Therefore, this represents one of the few instances in which the ``cold flow'' of a shock tube has been used for aerodynamic testing. Extensive design calculations are presented, and experimental measurements in a number of configurations are in good agreement with the calculations. The facilities tested have produced peak dynamic pressures of 70 to 2000 bar for half-time durations from a few hundred microseconds to several milliseconds. Tube diameters have varied from 0.6 to 2 m, and the lengths have ranged between 3 and 15 m. All of the shock tubes are, at least in part, expendable. However, they can be quickly constructed to meet given flow requirements at costs quite modest when compared with those of competitive techniques for producing high accelerations of large objects.
Spatially Resolved Density Measurements of Deuterium Plasma Using Energetic D+ Beam
Authors: Hickok R. L. , Jobes F. C. , Marshall J. F.
Published: February 2005

The density distribution of cylindrically symmetric deuterium plasmas can be measured by probing the plasma with an energetic deuterium beam and observing the protons from the D(d,p)T reaction. This technique measures the absolute deuterium density with good spatial resolution and is independent of the electron and ion velocity distributions. Using this method, we determined to within 10% the density distributions of a high current deuterium arc for three different operating conditions. A comparison of these density distributions with optical intensity distributions shows that the optical intensity decreases faster with radius than the deuterium density.
Dual Purpose Nuclear Magnetic Resonance and Nuclear Quadrupole Resonance Spectrometer
Authors: Barton B. L.
Published: February 2005

A technique is described for converting a single coil, wide line NMR spectrometer into a dual purpose nuclear magnetic resonance and nuclear quadrupole resonance spectrometer. The nuclear quadrupole resonance spectrometer uses a coherent, self-detecting, self-quenching, superregenerative Colpitts oscillator. The quench frequency is varied by changing the resistance between the control grid and ground. The nuclear quadrupole resonance spectrometer described is applicable to the study of internal motions in solids, which requires information on both the change in the quadrupole resonance frequency and line width.
Flowmeter for Measurement of Low Velocities in Liquids with Weak Electrical Conductance
Authors: Magrini Ugo
Published: February 2005

The performance of a probe for measuring low velocities in weak electrolytes is reported; its sensing element, dipped into the fluid, consists of two Pt electrodes supplied with direct current. The calibration was made for two types of probes in water and dilute solutions of H2SO4 and NaCl. Data are presented concerning the reproducibility of the measurements and the sensitivity of the apparatus at different current intensities. The possibilities of using the probe to yield the kinematic properties of a liquid in motion are studied.
Fast Response Picoammeter
Authors: Presley Samuel P.
Published: February 2005

This paper describes a fast response picoammeter design incorporating a commercially available transistorized differential amplifier. The input circuit uses three transistors and one electrometer tube and has unique features. A guard signal is provided for the reduction of input cable capacitance. Problems associated with large range resistances are discussed.
Phased Rotating Crystal and Chopper for Time of Flight Neutron Spectroscopy
Authors: Harling O. K.
Published: February 2005

A slow neutron spectrometer that uses a rotating single crystal to chop and monochromate the reactor neutron beam is described. A high transmission mechanical chopper is operated in phase with the rotating crystal to eliminate undesired crystal reflections, higher order contamination, and to suppress the background of time uncorrelated neutrons. Pulsed neutron beams of high quality can be obtained from the thermal energy range to greater than 0.5 eV. Energy widths as low as 1% with burst widths around 7 μsec can be attained at 0.3 eV. Intensities are adequate for inelastic scattering studies. The spectrometer is designed primarily for downscattering measurements. Scattering measurements are conducted in a completely shielded scattering chamber with eleven scattered neutron detectors arranged at scattering angles of 15° to 165°. Time of flight techniques are used to determine the scattered neutron spectra. The design, construction, and performance characteristics are given. Some representative measurements made on zirconium hydride are presented.
Quasistatic Vapor Pressure Measurements on Reactive Systems in Inert Atmosphere Box
Authors: Fischer Albert K.
Published: February 2005

What is effectively a single tube adaptation of the quasistatic method of measuring vapor pressure has been devised. The method is suitable for use in an inert atmosphere box in studying air sensitive systems. The applicability and limits of operation of the technique are described. Precision and accuracy were checked against a known system, pure sodium.
Construction of Precision Glass Cell for Hall Coefficient Measurements of Liquids
Authors: Suchannek Rudolf G. , Minghetti Learco , Naiditch Sam
Published: February 2005

The construction of a glass cell with rectangular cross section for measuring Hall coefficients of liquids is described. The cell can be hermetically sealed and is bakeable under vacuum. Probes for the detection of the Hall voltage have been accurately aligned by alternately grinding the holes through the cell wall and measuring their misalignment. In this way, it has been possible to reduce the misalignment of the voltage probes to half a micron or less.
Directional Heat Meter for Wall Shear Stress Measurements in Turbulent Boundary Layers
Authors: Drinkuth R. H. , Pierce F. J.
Published: February 2005

The design of a uniquely simple directional sensitive heat meter for wall shear stress measurements in turbulent boundary layers is described. Good directional and stress level resolution are shown, and the suitability of the device for three dimensional flows is discussed.
Versatile Stopped Flow Temperature Jump Apparatus
Authors: Erman James E. , Hammes Gordon G.
Published: February 2005

A stopped flow temperature jump apparatus is described which permits rapid mixing of reactants and application of a temperature perturbation to the reacting system from 16 msec to several seconds or longer after mixing. The apparatus consists of a flow system with a rectangular observation chamber 1 cm in length. Electrodes are fixed above and below the observation chamber. A stopping syringe activates the time delay, switching, and triggering circuits. The triggering circuit discharges a high voltage capacitor through the solution in the observation chamber, producing a 5°K temperature jump in about 50 μsec. The response of the reacting system is monitored with absorption spectrophotometry.
Demountable High Power Source for Soft X-Ray Region
Authors: Deslattes Richard D. , Simson Bert G.
Published: February 2005

A demountable x-ray source capable of operation up to 3 kW is described. Construction is largely of stainless steel with elastomer seals. The source is of use in exciting secondary spectra and producing bremsstrahlung for absorption studies.
Technique for Measuring Megagauss Magnetic Fields Using Zeeman Effect
Authors: Garn W. B. , Caird R. S. , Thomson D. B. , Fowler C. M.
Published: February 2005

Rapidly varying magnetic fields with peak values in the range from 1 to 5 MG are measured by use of a sweeping image spectrographic method. Atomic spectral lines from an exploding wire light source situated in the experimental region are recorded as the magnetic field varies in a few microseconds from a moderate initial value of a few tens of kilogauss to the peak values. Field measurements are generally accurate to within 2–3% as determined by the consistency of measurements made from several different spectral lines. The sodium D lines and the indium I 4102 Å line have proven to be exceptionally useful for field determinations. The highest field determined to date by this method is 5.1 MG, corresponding to a measured separation of 164 Å between the centers of the shorter and longer wavelength doublets which the NaD lines assume in very high fields. The doublets, of approximately 4 Å separation, are not themselves resolved.
Use of Rotating Cryostat for Infrared Studies
Authors: Mamantov G. , Fletcher W. H. , Cristy S. S. , Edwards C. T. , Morton R. E.
Published: February 2005

A modified rotating cryostat and its use for in situ infrared studies are described. An improvement in sensitivity over present low temperature infrared cells and much shorter deposition times have been obtained.
Low Shear, High Sensitivity Electromagnetic Viscometer
Authors: Gaeta F. S.
Published: February 2005

A new type of viscometer operated by electromagnetic force is described. Two versions of such an apparatus are presented, one involving the measurement of mechanical entities only, the other based upon the measurement of ionic current density and of a magnetic field. These viscometers are both closely related to ordinary flow viscometers since the force setting the liquid into motion acts directly on the liquid itself, with no mechanical moving part interposed. The force is much less intense than gravity and is easily adjusted at will down to very small values. For this reason and because of a better design of the channel in which the liquid flows, very low values of shear stress can be obtained; thus making the apparatus described ideal for use with non-Newtonian liquids, like high polymeric solutions or suspensions of DNA. The fact that the liquid must be subjected to electrolysis is a serious drawback, which can be circumvented by resorting to relative measurements. Improvement of the apparatus is under study.
Curie-Chéneveau Magnetic Balance Employing Photocompensation
Authors: Nakagome Riku , Whitmore D. H.
Published: February 2005

The design of a balance for measurement over the range from 4.2 to 300°K of the static magnetic susceptibility of weakly magnetic substances is described. The balance is a Curie-Chéneveau type torsion balance which incorporates photocompensation to achieve a null measuring instrument. The maximum sensitivity of the balance is approximately 10−3 dyne and performance with less than 1% error is possible for magnetic susceptibility values in the range from 10−5 to 10−8 emu/g (cgs units). Some typical susceptibility data obtained with the aid of this balance are presented.
Electron Bombardment Molecular Beam Detector
Authors: Brink Gilbert O.
Published: February 2005

A molecular beam electron bombardment detector is described and operational data are presented. The detector makes use of a Paul mass filter to increase its versatility. The detector is calibrated by the use of molecular beams of neon, argon, and krypton. Respective detection efficiencies are 1 atom in 2400, 320, and 80.
Reliable Submicron Pressure Readings with Capacitance Manometer
Authors: Utterback Nyle G. , Griffith Thomas
Published: February 2005

A cold trapped McLeod gauge, a capacitance manometer, and an ion gauge have been used simultaneously to measure gas pressure in the range 10−4 to 3×10−3 Torr. Data were obtained for He, Ne, Ar, Kr, Xe, N2, O2, CH4, CO, H2, and CO2. The capacitance manometer and pressure chamber were maintained at a constant room temperature to avoid thermal transpiration corrections. Comparison of data among gases clearly showed the systematic McLeod gauge error attributed to mercury streaming to the cold trap. The capacitance manometer and McLeod gauge readings agreed within 2% at 10−3 Torr for He, while the McLeod reading was 15% low for Xe at the same pressure. The errors for the other gases were intermediate. Spurious mercury capillary wetting effects, leading to serious errors in the McLeod gauge reading, were also noted for some of the molecular gases. The capacitance manometer was clearly superior to the McLeod gauge as a universal pressure sensor, and appears capable of reliable readings accurate to a few per cent at 10−4 Torr.
Miniature Diamond Ultrahigh Pressure Cell Adapted for In-reactor Irradiation Studies
Authors: Kulcinski Gerald L. , Maynard Charles W. , Walsh Robert C.
Published: February 2005

A special Bridgman opposed diamond anvil apparatus was constructed to generate useful static pressure to 50 kbar at ambient temperatures. It was designed to function in the environment of a nuclear reactor and to occupy 65 cc. A method of bombarding materials under pressure with fission fragments is described.
Production of Fine Holes in Metals and Semiconductors
Authors: Longfellow J.
Published: February 2005

Whiskers of iron, copper, tin, and silicon were obtained and used as microelectrodes in a spark erosion process. Silicon slices, thin metal sheets, whiskers, and thin films were successfully machined. Holes with diameters as small as 1 μ were produced through thin films of tantalum.
Weak Magnetic Field Measurement Using Permalloy-Film uhf Resonance
Authors: Frank C. E.
Published: February 2005

A system is described for using uhf dipole resonance in uniaxially anisotropic permalloy films to detect and measure weak magnetic fields. The dipoles are pulled to a position at right angles to the easy axis where they approach a condition of infinite permeability. Dispersion of the anisotropy over the film causes a severe degradation of the permeability but is largely overcome by low level modulation of the field with a low frequency signal. The net movement of the dipoles in response to the weak field being tested is measured both in magnitude and direction using simple uhf dipole resonance, the detected output being phase detected in turn with the low frequency source acting as the reference. Experimental results, which closely approach the theoretically predicted results, have been obtained down to 10−9 Wb/m2 sensitivity in 1 cps bandwidth in ordinary laboratory environments and using a 35 dB noise figure receiver. Means for greatly improving both the sensitivity and bandwidth are discussed.
Megampere Pulse Transformer for Coaxial Load
Authors: Clark William H. , Myrberg John E.
Published: February 2005

A transformer is described which delivers 2 MA into a low impedance load through a coaxial output line of about 6.35 mm inner conductor diameter and 12.7 mm cavity diameter. The transformer primary is connected to a 20 μF, 50 kV capacitor bank by forty-eight flexible coaxial cables. The ringing frequency of the system with the secondary shorted is 70 kc.
Signal and Noise Characteristics of Robinson Nuclear Absorption Circuit
Authors: Howling D. H.
Published: February 2005

A previous study of the signal and noise characteristics of the Pound-Knight-Watkins (PKW) marginal oscillator circuit has been extended to the Robinson NMR circuit. It is shown that although the signal and noise characteristics of the Robinson circuit are markedly different from the PKW oscillator, the signal-to-noise ratios are similar.
Field Ionization Gauge for Molecular Beam Detection
Authors: Woods R. O. , Fenn J. B.
Published: February 2005

An ionization gauge for molecular beam work has been developed which uses a field ionization tip as an ion source. Data are given regarding signal-to-noise ratio and sensitivity. Means of reducing the rate of tip deterioration are discussed and data given showing moderate reduction in signal strength over a 1 h period. Curves are given showing that the sensitive area of the gauge is small when compared to a 0.25 mm wide molecular beam.
Optimum Current Distribution in Superconducting Coils
Authors: Williams J. E. C.
Published: February 2005

A superconducting winding, sectioned and supplied with currents corresponding to the local field conditions, gives an increased field contribution over that of a single winding. This paper derives the increased field contribution in terms of the number of sections and the characteristics of the superconducting material.
Scyllacita—Compact High Voltage Theta Pinch Machine
Authors: Kemp E. L. , Dolnick E. M. , Dike R. S. , Sawyer G. A. , Tuck J. L.
Published: February 2005

A high voltage theta pinch (Scyllacita) has been developed especially for application to experiments with explosively compressed theta pinches. The system is relatively economical, simple, and compact. Twenty-four 14 μF, 20 kV, low inductance capacitors (60 kJ) are divided into two banks. Each capacitor has a 3 element spark gap (trigatron) mounted directly on it. Twelve low inductance cables from each capacitor spark gap combination are connected to a mix header which puts the two banks of capacitors in series when the gaps fire. One-hundred low inductance cables connect the mix header to a collector plate and thus to the 8 cm diam, 24 cm long load coil. The source inductance (coil terminals shorted) is 17 nH. Both mirror coils and straight bore coils have been used. With the straight bore coil, the full period of oscillation is 11.7 μsec and the efficiency of energy transfer to the coil is 59%. In second half-cycle operation at 100 mTorr filling pressure with the banks charged to 18 kV, over 107 neutrons per discharge are produced in either mirror or straight coil.
Anticoincidence Shielded Gamma-Ray Spectrometer for Nuclear Reaction Studies
Authors: Evans Albert E. , Brown Bernard , Marion Jerry B.
Published: February 2005

A scintillation spectrometer has been built utilizing a modular liquid scintillation anticoincidence shield for a 12.7 cm diameter by 25.4 cm long NaI(Tl) detector crystal. The effectiveness of the anticoincidence shield is enhanced by storing in one-half of a multichannel analyzer memory those pulses from the NaI(Tl) crystal which are coincident with shield pulses. A fraction of this coincident spectrum is then subtracted from the anticoincident spectrum as a correction for shield inefficiency. A computer system is used for data handling. Spectral response for gamma radiation from 0.35 to 17.6 MeV has been measured.
Measuring Ferromagnetic Film Magnetostriction by Means of Low Frequency rf Probes
Authors: Penn T. C.
Published: February 2005

A method and apparatus are described which enable a sensitive, reproducible measure of the saturation magnetostriction λs of thin ferromagnetic films. The use of low frequency magnetic resonance probes simplifies the measurement of the changes in the film anisotropy field which occur due to strain in a magnetostrictive film. The applicable equations for the technique are presented with the result that λs is shown to be directly proportional to an easily measured current and inversely proportional to the deflection of the substrate center. Successful measurements have been performed on films as thin as 100 Å and as thick as 2000 Å. Conducting substrates are permissible.
Measuring Ferromagnetic Film Magnetostriction by Means of Magnetoresistance
Authors: Penn T. C. , West Forrest G.
Published: February 2005

A method and apparatus are described which provide sensitive and repeatable measurements of the saturation magnetostriction λs of thin ferromagnetic films. The use of magnetoresistance provides a simple, compact method of observing magnetoelastic effects of strain on the film magnetization process. The applicable equations for the technique are presented with the result that λs is shown to be directly proportional to an easily measured current and inversely proportional to the deflection of the center of the film substrate during bending. Measurements have been made on films ranging from 100 to 2000 Å thick.
Micron Region Pressure Standard for Uranium Hexafluoride
Authors: Pappas W. S.
Published: February 2005

A standard has been developed for calibrating uranium hexafluoride pressure gauges in the micron region. The device employs the equilibrium dissociation pressure of uranium hexafluoride furnished by the sodium fluoride complex salt at easily controlled temperatures above ambient. The pressure signal obtained is in good agreement with reported dissociation pressure measured by the transpiration method. The principles are applicable to noncorrosive gas-solid systems; for example, some oxides, carbonates, and hydrates dissociate to reversibly give a definite oxygen, carbon dioxide, or water vapor pressure at a given temperature.
Static Gas Sampling Device
Authors: Adams R. O.
Published: February 2005

A modified McLeod gauge, a mercury manometer, and gas sampling apparatus are combined into one instrument. A sample of gas may be taken under static condition at a known, measurable pressure from atmospheric to 5×10−4 Torr with this instrument.
Improved Pulsed Discharge Rate Measuring Apparatus for Ionization Discharge Studies at Low Frequencies
Authors: Bartnikas R. , Levi J. H. E.
Published: February 2005

Apparatus used in the measurement of pulsed ionization discharge rates at low frequencies is described. The apparatus is capable of resolving 8000 discharges per quadrant without integration, at a power frequency of 60 Hz, thus enabling the measurement of discharge recurrence rates in high density discharge patterns emanating from gaps having dielectric electrodes. Typical results are presented.
Low Temperature Absolute Reflection Measurements of Small Samples
Authors: Feinleib J. , Feldman B.
Published: February 2005

The design of an optical system for making absolute reflectance measurements on small crystals at liquid helium and room temperature is described. The system permits accurate masking of the samples and, with only one moving component, measures reflectivity without the use of a comparison standard.
Technique for Selected Area Replication of Surfaces
Authors: Savanick George A.
Published: February 2005

A technique for replicating optically selected areas is described. It requires no special equipment beyond an optical microscope with a vertical illuminator, and yields a replica with the area of interest placed at an easily recognizable position with respect to the electron microscope grid.
Use of Simultaneous Vaporizing of Two Substances to Obtain Thin Films
Authors: Gerber Roland
Published: February 2005

An apparatus for depositing thin layers of two substances in a given ratio is described. It consists of a servomechanism which controls the rate of vaporization of one of the substances with respect to the other. The performance of the installation is evaluated.
Apparatus for Microwave Measurement of Transport Parameters in Semiconductors
Authors: Brodwin M. E. , Parsons M. K.
Published: February 2005

The essential component of the apparatus is a semiconductor loaded E plane ``T'' waveguide junction. The scattered wave produced by the induced anisotropy is measured. The principal result is that the apparatus directly determines the complex amplitude of the off-diagonal element of the apparent susceptibiltiy. The technique can be used to measure effective mass at higher temperatures than is possible with the cyclotron resonance absorption cavity technique. It can also be employed to determine the mobility of powdered or irregular samples.
Measurement of Snoek Damping in Sheet Specimens
Authors: Stephenson E. T.
Published: February 2005

The standard Kê pendulum was modified to accommodate sheet specimens. Redesign of the specimen clamps, support rods, and inertia member made it possible to handle sheet specimens 125 mm in gauge length and 6 mm in width. Because deformation was found to distort the Snoek peak, specimens were prepared by spark machining or milling rather than by shearing. The close similarity of the background damping level and the Snoek peak height and shape for sheet and corresponding wire specimens, as well as the low amplitude dependence observed in the sheet specimens, demonstrated the acceptability of the pendulum modifications and specimen shape.
Detection of Hydrogen in Air by Means of Alkali Ion Current from Hot Palladium
Authors: Hoenig Stuart A. , Carlson Charles W. , Abramowitz Jay
Published: February 2005

A surface ionization detector for hydrogen has been developed. This device detects hydrogen in the presence of air at one atmosphere. The detector is not sensitive to other atmospheric gases, e.g., O2, N2, and CO2, and operates at H2/air levels as low as 0.1% by volume.