bluuebunny/crossref_metadata_2025 huggingface dataset:
Electric Furnace for Operation in Oxidizing, Neutral, and Reducing Atmospheres to 2400°C
Authors: Reed T. B. , Fahey R. E.
Published: February 2005

A simple resistance-heated furnace has been developed for operation at temperatures up to 2400°C in oxidizing as well as neutral or reducing atmospheres. The sample to be heated is placed in a dense zirconia tube, which is mounted inside a vertical split-tube tantalum heating element. Any desired atmosphere may be used inside the zirconia tube without damaging the heating element, which is operated in argon. The heating element, which is also protected by the zirconia tube from attack by vapors from the sample, is surrounded by tantalum heat shields in a water-cooled outer shell. A temperature of 2400°C was reached in a 2.22-cm-i.d. zirconia tube at a power level of 8 kW, and 2200°C was reached in a 3.5-cm tube using 6.5 kW.
Microwave Discharge Cavities Operating at 2450 MHz
Authors: Fehsenfeld F. C. , Evenson K. M. , Broida H. P.
Published: February 2005

Five simple microwave cavities for producing discharges in gases were tested in He and H2 at pressures from 1 μ to 1 atm. Three of the cavities are commonly used, and two have been recently designed. One of the newly designed cavities offered a considerable improvement over early models with respect to compactness, ease of attachment to the system, and efficiency.
Improved Torsion Viscometer for Polymer Studies
Authors: Forgacs R. L.
Published: February 2005

A torsion pendulum type viscometer was developed to permit determination of dynamic viscosity and dynamic modulus of solid and liquid polymers. Sample temperature is automatically controlled within less than 1°C to any temperature in the −80 to +100°C range. Forced oscillation of the pendulum at frequencies from 3×10−6 to 3 cps or higher is possible, also, freely decaying oscillation and creep testing. The viscometer is unique in that an extremely sensitive (<1″) and stable photoelectric angle detector is combined with a thermoelectric temperature control system, which dispenses with vibration-inducing moving fluids. This makes possible measurements with shear strain amplitudes as low as 10−6 to 10−7, and results in improved low frequency angular measurement accuracy, limited by the ambient level of room vibrations.
Generation and Diagnosis of Synthesized Plasma Streams
Authors: Sellen J. M. , Bernstein W. , Kemp R. F.
Published: February 2005

A contact-ionization source is described which generates a cesium ion stream characterized by a high degree of order in the ion motion. Electrons are added to form a quiescent, collisionless plasma stream. Diagnostic instruments are described for demonstrating the properties of the plasma streams. Ion densities range from 5×107 to 1×1011 ions/cm3 in the source region, at accelerating voltages from 100 V to a few thousand volts, depending on the experimental application. Conical expansion of the beam reduces the densities in downstream regions. Electron temperatures in the beams range downward from the ∼2500°K emissive wire temperature. Means are described for increasing electron temperatures to several times this value, with resultant increase in beam divergence.
Technique for Determining Spin-Lattice Relaxation Times
Authors: Candela George A. , Mundy Robert E.
Published: February 2005

Experiments were performed so that the static dc susceptibility of a paramagnetic material could be measured as a function of microwave power absorbed at electron spin resonance. The spin-lattice relaxation τ1 can be expressed by τ1=[(χ0−χp)/PaΓm]MsBdc2 where Pa is the microwave power necessary to change the field independent static susceptibility from χ0 to χp. χp is the steady state static susceptibility of the sample when it is absorbing Pa amount of microwave power. Bdc is the homogeneous dc field produced by the laboratory magnet, Ms is the weight of the sample, and Γm is a constant whose value depends solely upon the system of units used. The relaxation time is determined by directly measuring Pa, Ms, B, χ0, and χp/χ0. The apparatus, the experimental techniques, and the accuracy of the measurements are described in some detail.
Gamma-Ray Absorption Instrument for Determining Fluid Saturation of Cores
Authors: Closmann P. J. , Orr W. R.
Published: February 2005

An instrument is described for measuring fluid saturation in cores by means of gamma-ray absorption. Results of this technique are compared with those from electrical resistance measurements. Good agreement is found for gas-liquid systems under conditions of comparatively slow saturation change. For rapidly moving fronts the instrument responds quickly to the arrival of a saturation gradient, but does not give an accurate measure of saturation in the region of the front.
Drift-Free Mössbauer Spectrometer
Authors: Ruegg F. C. , Spijkerman J. J. , DeVoe J. R.
Published: February 2005

In order to eliminate drifts encountered in electromechanical Mössbauer spectrometers, a drive has been developed which is drift free with regard to velocity as well as position. The spectrometer can be driven in two modes: constant acceleration and constant velocity. The constant acceleration input signal is the analog output of the address scalers of a multichannel analyzer running as a multiscaler (time mode). The constant velocity is obtained from a photocell slit system which drives the input of the spectrometer with a rectangular wave. In both modes, the photocell system is used to eliminate all position drifts by starting each new cycle from the same position. To analyze the velocity of the spectrometer a voltage-to-frequency converter and multichannel analyzer are used.
Vacuum Evaporation of Metals by High Frequency Levitation Heating
Authors: Van Audenhove J.
Published: February 2005

The equipment for high frequency levitation evaporation is described. This technique is successfully applied to evaporation of small quantities of Al, Ag, Ti, Co, Fe, Cu, and U. A small amount of starting material is needed and at least 50% of the evaporated metal may be recovered easily.
Recording Double-Beam Vacuum uv Spectrophotometer System
Authors: Sys A. , Alemany C. , Jacobs G.
Published: February 2005

A scanning method is described to directly record absorption spectra of crystals in the region between 1200 and 2400 Å. This attachment to a Seya-Namioka monochromator can be used for measurements at very low temperatures. A part of the beam is used as a reference while the other part is passing through the crystal. The logarithm of ratio of the two intensities is recorded.
The Spectrotor, a Selective Infrared Detector of High Sensitivity
Authors: Pullan H. , Swarbrick R.
Published: February 2005

Considerable improvement in the performance of background-limited infrared detectors can be obtained over a restricted range of wavelengths by using a cooled filter to reject a large fraction of the background radiation. This principle has been applied in a portable device containing a series of narrow-band and interference filters which, on external command, can successively be brought into use. In this way exceptional detectivity can be realized over a number of separate wavelength regions. Detectivities in excess of 1011 cm/W have been obtained in the 5 to 6 μ region of the spectrum, using filters of 0.6 μ half-width together with a copper-doped germanium detecting element cooled by liquid helium contained in an internal reservoir. Sharper or longer wavelength filters would give still higher detectivity.
Boron-Loaded Neutron Detector with Very Low γ-Ray Sensitivity
Authors: Jackson H. E. , Thomas G. E.
Published: February 2005

A boron-loaded liquid scintillator is described which gives a much greater difference in the pulse shapes for γ rays and for slow neutrons than any of the liquids currently used. A detailed study of the pulse shapes indicates that the γ-ray sensitivity of a neutron detector filled with this liquid can be reduced by a factor of 500 with only a 5% decrease in the neutron sensitivity by application of pulse-shape discrimination. A survey of the pulse-shape characteristics of a number of scintillators currently used, together with the results for the new liquid, is presented, and the performance of the new detector with a simple system of pulse-shape discrimination is described.
Transverse Resistive Instabilities of Intense Coasting Beams in Particle Accelerators
Authors: Laslett L. Jackson , Neil V. Kelvin , Sessler Andrew M.
Published: February 2005

The transverse electromagnetic interaction of an intense azimuthally uniform beam of particles with itself, including the effect of a resistive vacuum tank, is investigated theoretically. It is shown that a beam of particles all having velocity ν is unstable against the development of transverse waves having a phase velocity close to (1 − v/n)ν, where v is the number of transverse free betatron oscillations occurring in one revolution and n is a positive integer greater than v. The growth rate for the instability is proportional to N/σ½, where N is the number of particles in the beam and σ is the conductivity of the surface material of the vacuum tank. Stabilizing mechanisms are examined by means of the Vlasov equation and it is shown that a spread in the quantity (n−v)ν, evaluated for particles in the unperturbed beam, will prevent the instability. A criterion for the spread required is shown, in the limit of walls of high conductivity, to depend upon the beam intensity and energy as well as upon certain geometrical properties of the accelerator, but not upon the conductivity. Numerical examples covering a range of particle accelerators are presented, and suggest that the theory is in agreement with the coherent beam behavior recently observed in a number of accelerators.
Bakeable Microwave Cavity for Measurement of Electron Loss Rates in Photoionized Nitric Oxide
Authors: Shaw T. M. , Brooks G. H. , Gunton R. C.
Published: February 2005

This paper describes the design and construction of an X-band cavity resonator equipped with a variable microwave coupling device for use in the study of electron loss processes in nitric oxide plasmas. A lithium fluoride window is provided to permit plasma production by ultraviolet irradiation down to 1100 Å. The cavity is suitable for use with ultrahigh vacuum systems and can be outgassed by baking at temperatures up to 350°C.
Subnanosecond Risetime Multikilovolt Pulse Generator
Authors: McDonald Daniel F. , Benning Carl J. , Brient S. J.
Published: February 2005

A multikilovolt nanosecond pulse generator has been developed which uses a new approach to the design of an extremely fast gas-discharge switch. The design concept is based on the statistical time lag which precedes an electrical breakdown. The generator also employs large coaxial geometry so that extremely high operating voltages may be used. A description of instrumentation required to measure the fast risetime, high voltage pulses is included along with some typical oscilloscope traces.
Vapor-Deposited Thin-Film Piezoelectric Transducers
Authors: DeKlerk J. , Kelly E. F.
Published: February 2005

A new vapor deposition technique has been developed for the production of insulating thin-film CdS and ZnS piezoelectric transducers. These high efficiency transducers have been used to generate either shear or compressional waves in dielectric materials at frequencies in the gigacycle range. The thickness, which is measured by means of a quartz crystal microbalance, is controlled to produce films which operate at their fundamental resonance. The mode of the generated waves is determined by the orientation of the driving electric field with respect to the crystal axes of the film transducer.
Microwave Spectrograph for Linewidth Measurements
Authors: Rinehart Edgar A. , Legan Robert L. , Lin Chun C.
Published: February 2005

A microwave spectrograph designed for measurements of linewidth is described. The width spectrograph consists of the same general major components as a spectrograph for frequency measurements, but differs considerably in the requirements of the components and the assembly thereof since many factors which have virtually no effect on the frequency of a spectral line could influence the width significantly. Methods are given to generate a stable and pure frequency-modulated microwave signal which has a constant power output over a frequency range of 10 Mc. Great precaution must be made in assembling the waveguide components to reduce reflection in the absorption cell. For each crystal detector one must select the optimum load resistance (generally ranging from 3 kΩ to 1 MΩ) to insure square-law response since deviation from this behavior may introduce an error as large as 4%. A discussion of the general procedure of linewidth measurements which includes modulation and length corrections is given.
Techniques for Studying Electrons During Ionization Afterglows
Authors: Van Lint V. A. J. , Parez J. , Trueblood D. , Wyatt M. E.
Published: February 2005

The ionization afterglow techniques involve the production of electron-ion pairs in a gas by a short pulse of high energy nuclear radiation, 20 to 30 MeV electrons in this case. The electron density and electron-atom collision frequency are measured by passing through the dilute plasma formed a microwave signal, whose amplitude and phase shift are measured with a microwave detector in a bridge configuration. An X-band microwave cavity and a 300 Mc cavity have also been utilized to perform measurements with higher sensitivity at lower pressures. The results from these experiments include determinations of electron attachment and electron-ion recombination co-efficients as well as momentum and energy transfer cross sections. In common with other afterglow techniques, the measurements usually refer to a thermally averaged electron energy spectrum. Some specific examples from studies of momentum and energy transfer, as well as electron-ion recombination in nitrogen, are presented.
Apparatus for Determining the Partial Equivalent Volumes of Salts in Aqueous Solutions
Authors: Duedall Iver W. , Weyl Peter K.
Published: February 2005

An apparatus for determining partial equivalent volumes of salts in aqueous solutions is described. Using a cathetometer and a specially designed dilatometer, treated with an organic silicone fluid, the change in volume of a solution due to the addition of a small increment of salt is measured directly. The partial equivalent volume is determined by extrapolating the volume increments to zero salt addition. Results of the determination of the partial equivalent volume of sodium chloride in distilled water at 0.80°C are presented. Also, preliminary results for potassium chloride, sodium chloride, potassium sulfate, and sodium sulfate in sea water are discussed.
Cosmotron Filtered Flat-Top System
Authors: Feltman A. V. , Cottingham J. G.
Published: February 2005

A method has been developed to allow the cosmotron to produce monoenergetic external beams of ¼ sec duration by maintaining the magnet current constant (flat-top) and filtering the magnet voltage.
Study of the Instability of Noble Metal Thermocouples in Vacuum
Authors: Walker B. E. , Ewing C. T. , Miller R. R.
Published: February 2005

Thermoelectric instabilities of noble metal thermocouples and individual thermoelements (platinum, rhodium, iridium, platinum-rhodium, and iridium-rhodium alloys) have been studied in vacuum in the temperature range 800 to 1600°C. These studies are an extension of previous work performed in oxidizing and neutral atmospheres. As in that work, the principal source of instability was found to be contamination of the thermoelements by impurities from ceramic protection tubes. Thermocouple errors associated with this contamination are reported and compared with the previous data.
Design and Performance of a High Momentum, High Luminosity Spectrometer for Particle Analysis
Authors: Allaby J. V. , Ritson D. M.
Published: February 2005

A 90° bend n=0 magnetic spectrometer has been constructed which uses curved field boundaries to achieve second order correction of the focal properties and to make the image plane normal to the emerging particles. The spectrometer has a 112 cm radius of curvature and a maximum momentum capability of 725 MeV/c. The window frame yoke, with sloping edge profiles to minimize edge saturation, enables the focal properties to remain invariant up to 21 kG. The solid angle acceptance is 8×10−3 sr with 0.1% resolution and the maximum momentum acceptance is ±5%.
Cryostat for Tension Testing in the Temperature Range 4 to 300°K
Authors: Behrsing G. U. , Lucas L. R.
Published: February 2005

A cryostat with a load capacity of 10 000 lb has been designed for use with standard tensile testing equipment in the temperature range 4 to 300°K. Specimens up to 12.7 cm long can be mounted easily on the grip rods through an opening in the front of the test chamber. The cryostat is used in conjunction with a 10 000 lb Instron tension testing machine containing a stress-strain recorder and strain pacer.
Offset Voltages of Langmuir Probes in the Ionosphere
Authors: Bettinger Richard T.
Published: February 2005

Bipolar Langmuir probes display a voltage offset in their volt-ampere characteristics when immersed in the ionospheric plasma. The dependence of the equilibrium potential as a function of probe scale, ambient charge density, and high energy tail in the electron energy distribution is examined. We conclude that the offset arises from geometric considerations and is strongly influenced by all of the above factors. The observed altitude dependence is qualitatively explained in terms of vehicle velocity and precessional motion.
The Δl Effect in Capillary-Reservoir Diffusion Measurements
Authors: Nanis L. , Richards S. R. , Bockris J. O'M.
Published: February 2005

A cinematographic study has been made of the nature of the hydrodynamic end error (Δl effect) associated with the capillary-reservoir technique for measuring diffusion coefficients. A correlation between the Δl effect and Reynolds number was established, and it is shown how this correlation may be used to correct capillary-reservoir diffusion measurements in which a flow of bath liquid past the capillary mouth is used to maintain the boundary conditions of the diffusion system.
Position Transducer for Use at Extreme Environmental Temperatures
Authors: Fleming Lawrence
Published: February 2005

Considerations are discussed which underlie the choice of operating principles for mechanoelectric transduction in very high temperature environments. An experimental displacement pickup is described which uses a mutual-inductance principle and functions well at 1100°C.
Diaphragm Pressure Transducer
Authors: Honeywell W. I. , Pings C. J.
Published: February 2005

A diaphragm pressure transducer has been developed for the purpose of separating a sample fluid from a hydraulic oil used in a dead weight tester. The diaphragm null position is determined by a commercially available magnetic sensing unit. The null position shifts systematically with absolute pressure, but the shift is reproducible and may be calibrated. With the output scheme utilized, the unit has a sensitivity of 0.00007 atm and a reproducibility of 0.0003 atm. The equipment has been used extensively at pressures up to 70 atm, but as designed should be operable to much higher pressures. The equipment described includes a small injector for refined pressure adjustments.
Vacuum System and Cleaving Mechanism for Photoemission Measurement of CdS Single Crystals in the Vacuum Ultraviolet
Authors: Kindig N. B. , Spicer W. E.
Published: February 2005

Apparatus and techniques are described for cleaving large (1 cm3) crystals of CdS and for making photoemission quantum yield and energy distribution measurements in the vacuum ultraviolet (hv ≤ 11.8 eV; λ ≥ 1050 Å) and at longer wavelengths. It is found that CdS cleaves only in the (101̄0) and (12̄10) planes. The cleaving and measurements are done at pressures of 10−9 Torr or less, in a metal system provided with a VacIon and a titanium sublimation pump. For measurements in the vacuum ultraviolet, the sample chamber is provided with a LiF window and a special face plate which can be attached directly to the output housing of a vacuum monochromator. Measurements have been made for hv ≤ 21.2 eV by mounting the cleaving chamber directly on the output housing of the vacuum monochromator, with no window between the sample and the vacuum monochromator. In this case the cleaving and measurements are carried out at the much higher pressure (10−4 Torr or greater) of the vacuum monochromator.
Servo-Controlled Measuring Bridge for Semiconductors of High Resistivity
Authors: Fermor J. H. , Kjekshus A.
Published: February 2005

A servo-controlled measuring bridge for resistivity and Hall effect measurements on semiconducting materials with specimen resistances of up to 1013 Ω is described.
Economical Liquid Helium Cryostat and other Cryogenic Apparatus
Authors: Whitehouse J. E. , Callcott T. A. , Naber J. A. , Raby J. S.
Published: February 2005

A liquid helium cryostat which is inexpensive and simple to build is described. Its main features originate from the use of spherical metal floats arranged concentrically to form the body of the vessel. The tailpiece used with the cryostat provides for liquid helium to circulate in the sample holder. A mechanical valve allows the flow of liquid to be interrupted so that temperatures above 4.2°K may be maintained. A typical combination of cryostat and tailpiece has a capacity for 2 liters of liquid helium and will store this charge for nearly 4 days.

A liquid nitrogen vacuum system cold trap and a liquid helium transfer tube are also described. The former also features the use of metal floats in its construction. The transfer tube has a degree of flexibility and a very small outer diameter.
New Precision Thermometric Titration Calorimeter
Authors: Christensen J. J. , Izatt R. M. , Hansen L. D.
Published: February 2005

A new solution calorimeter is described which combines the thermometric titration techniques with the precision and accuracy of conventional solution calorimetry. The calorimeter through use of a unique design has a low heat leakage, k = 1.1×10−3 min−1, and a short equilibration period, 1–3 sec. Measurements of quantities of heat as small as 4 calories with an accuracy of 0.1% are possible. The heat of ionization of water at zero ionic strength has been determined to be 13.34±0.02 kcal/mole which is in excellent agreement with the value of 13.34±0.01 kcal/mole determined by conventional solution calorimetry. The large amount of information obtained from a single run makes this type of calorimeter a valuable addition to the field of solution calorimetry.
Calculation of Spectral Distortion due to Pile-Up Effect
Authors: Gold Raymond
Published: February 2005

The effect of pile-up distortion in the pulse height spectrum of a detector has been determined in the form of an integral representation. A number of important special cases, which arise in experimental applications, are treated. The integral representations for these cases have been evaluted in regions of experimental interest. Comparisons are given between the present numerical results and other estimates of pile-up distortion.
Instability of Refractory Metal Thermocouples
Authors: Walker B. E. , Ewing C. T. , Miller R. R.
Published: February 2005

Thermoelectric instabilities of some refractory metal thermocouples have been studied in the temperature range 1000–2000°C under vacuum and neutral atmospheres. The sources of instability were found to be complex, involving contamination from ceramic protection tubes and furnace environments, preferential volatilization, and various thermal anomalies such as recrystallization and phase changes in the refractory thermoelements. Refractory thermocouples and thermoelements were studied under a variety of conditions and emf changes associated with each are reported. Recommendations are presented for the selection and application of these thermocouples to attain maximum thermoelectric stability.
Large High Field Superconducting Magnet System
Authors: Laverick C. , Lobell G.
Published: February 2005

A superconducting magnet system composed of three separate, easily removable, nested solenoids is described. The outer two solenoids are split coil systems so that particle beams can be directed through the magnet when these sections are used to provide the magnetic field for a helium bubble chamber. Magnetic fields of 67, 42, and 17 kG have been achieved in winding diameters of 17.8, 27.9, and 45.7 cm, respectively. The results indicate that the system is capable of operation at fields in excess of 70 kG. The magnet is wound from various types of superconducting cable. Some of the considerations governing the choice of cable types and magnet design are given. A description of the tests is given, and the test results are discussed.
Simplified Technique for Using the Diaphragm Type, Liquid Diffusion Cell
Authors: Holmes John T.
Published: February 2005

Better reproducibility, greater accuracy, and savings of time and reagents can be realized by omitting the usual procedure of setting up a linear concentration gradient when using a ``well stirred'' diaphragm type diffusion cell. The equation which describes the cell characteristics starting with pure solvent in the diaphragm and in one compartment and the concentrated solution in the other compartment is log[(1−λ/6)ΔCi/ΔCf] = βDt(1−λ/6).
Combustion Gas Sampling Valve
Authors: Alperstein Martin , Bradow Ronald L.
Published: February 2005

A valve suitable for extracting a sample of high temperature, high pressure gases and introducing this sample into a low pressure regime has been developed and successfully operated for two years. Slow combustion reaction studies in a normally-fired spark-ignition engine are being accomplished with the aid of this gas sampling valve located in the combustion chamber end-gas region. The valve exhibits excellent sealing, achieves choked flow conditions, and permits sampling times on the order of 1 msec. The construction, operation, and monitoring of this gas sampling valve are described.
Dependence of Scalar Potential Measurements on Electrode Geometry
Authors: Plonsey Robert
Published: February 2005

An expression is derived which relates the measured potential difference of an electrode pair to the pre-existing scalar potential field where the dependence on electrode shape is implicitly indicated.
Nanocentimeter Transducer
Authors: Zinke Otto H. , Jacovelli Paul B.
Published: February 2005

The electromagnetic transducer described here is simple and compact and capable of measuring displacements of 2.6×10−9 cm with a signal-to-null ratio of 2:1.
Efficiency of Magnetic Channels
Authors: Uccelli Fabio
Published: February 2005

A quantitative method for determining the efficiency of magnetic channels for charged particles is described. Furthermore we give useful formulas for evaluating the dispersion and the chromatic aberration of a magnetic channel in the Gauss approximation.
Stratospheric Altimeter Based on the Density Dependence of a Corona Discharge in Air
Authors: Lilienfeld Pedro
Published: February 2005

A stratospheric altimeter, for use in the range of 20 to 55 km has been designed and an operational unit has been completed. Its operation is based on the air density dependence of the current in a self-sustained corona discharge. By means of temperature compensation, a pressure dependent output is obtained to eliminate errors caused by density differences between the air in the transducer and the ambient atmosphere. The theory, operation, performance, and potential applications of the altimeter are discussed.
Interference Viewed with Angular Dispersion
Authors: Kahl G. D. , Sleator D. B.
Published: February 2005

A quantitative model is presented which predicts the location of white light fringes occurring when a diffraction grating is combined with a double-beam interferometer. In particular, the use of this grating in adjusting the interferometer for zero path difference is given. Experimental observations confirm the predictions of this analysis.
Megagauss Fields Generated in Explosive-Driven Flux Compression Devices
Authors: Herlach F. , Knoepfel H.
Published: February 2005

Chemical explosives are used to compress magnetic flux trapped within a metallic liner system. In this way, final magnetic fields from 0.5 MG in a volume of 40 cm3 to 3.7 MG in 1.5 cm3 have been produced and carefully measured. The conversion efficiency of explosive into electromagnetic energy has been as high as 10% in the most favorable cases. The different compression experiments, including Bz and Bφ configurations in various geometrical arrangements, are described in detail and their results analyzed and discussed.
Measurement of Internal Friction in the Kilocycle Frequency Range
Authors: Hinton T.
Published: February 2005

An instrument for measuring the internal friction of rod shaped specimens in the kilocycle frequency range is described. The specimens are excited into longitudinal resonance electrostatically and a frequency modulation technique is used to detect the resultant vibration. The linearity of the system is established by an absolute optical calibration technique and the accuracy of measurement is shown to be as follows. The internal friction is measured to an accuracy of ±1% up to a value of δ (logarithmic decrement) of 6×10−3, with a background damping less than 5×10−6. The dynamic strain amplitude can be measured with an accuracy of ±2% over the working range of 5×10−8 to 10−5.
Two Transformer Method for Electrodeless Conductivity Measurement
Authors: Williams R. A. , Gold E. M. , Naiditch S.
Published: February 2005

An analysis of the two transformer system is presented. It is found that there is a frequency region in which the voltage transfer is proportional to the sample conductance. A comparison is made between the measured and predicted behavior of a two transformer system. The good agreement obtained indicates that the method of analysis can be used as an aid to designing two transformer conductivity measuring systems.
Viscosity Measurements of Ionic Melts at Temperatures to 1100°C
Authors: Reeves Roger D. , Janz George J.
Published: February 2005

An extension of the theory of the oscillating crucible gives an equation in η½ which is particularly useful as an absolute method for viscosity calculation. While more complex in theory, the oscillating crucible possesses useful advantages for high temperatures, namely, the features of a small flat temperature zone, and of a completely sealed sample container. Use of a closely fitting liner in the crucible offers a further advantage in that an exchange of the melt container is possible without any changes in the experimental assembly. Results are reported for a number of ``reference'' liquids at 25°C and at 440°C (KNO3), and for CaCl2(785–970°C) and BaCl2(985–1040°C). An error analysis shows that the precision is extremely sensitive to the decrement, δm; this appears as the largest error source. An error of viscosity of ±4% is calculated.
Circuit Analog for a Multilevel System
Authors: Solomon Peter R.
Published: February 2005

A circuit is presented which may be used to solve the differential equations describing the populations of a multi-level system as it approaches thermal equilibrium. The system may consist of any number of energy levels connected by simple transitions (representing the thermal contact with a reservoir) in which one member of the total population is transferred from one level to another. The circuit is designed so that the populations and population differences in the energy level system are proportional to steady state and transient voltage differences which are easily measured. The analog has been used to analyze the spin-lattice relaxation mechanisms in a 36 level electron and nuclear spin system in which electron spin resonance measures the population differences of adjacent levels.
Application of Digital Recording to Simultaneous Collection in Mass Spectrometry
Authors: McCullough H. , Krouse H. R.
Published: February 2005

A commercial five-figure integrating voltmeter-ratiometer and digital printer have been incorporated into the measuring circuit of a conventional simultaneous ion collection mass spectrometer. The ratio of two ion currents is printed to five figures. Increased precision and ease of measurement are among the advantages realized.
Permanent Magnet Thermomagnetic Cooling Device
Authors: Cybriwsky Alex
Published: February 2005

A device using a permanent magnet for demonstrating, testing, and measuring Ettingshausen cooling is described. The magnet and the heat sink are located in a vacuum chamber which can be immersed in a suitable cooling bath for providing various fixed temperatures of the heat sink. Cooling liquid can circulate through a hole in the heat sink to increase its heat dissipation. The Ettingshausen cooling at a fixed 5 kG field was measured as a function of electric current at 77.4, 195.7, and 273.2°K and the effect of various types of thermal contacts was shown.
Measuring the Coordinates of a Number of Points in a Complex Laboratory-Scale Model
Authors: Ordway Fred
Published: February 2005

Points on the model, together with an array of marked calibration points, are measured with theodolites from two different locations. Distances between a number of pairs of calibration points are measured precisely, and estimates of the distances from the calibration points to the measuring locations are adjusted for the best fit to these precisely measured distances. After adjustment, the distances from calibration points to measuring locations are used to obtain the best estimate of the rotation matrix and translation vector relating the coordinate systems of the two theodolites. The resulting rotation-translation matrix is used with the two sets of angle measurements on each point of the model to obtain the Cartesian coordinates of the point. The Gram-Schmidt orthonormalization procedure is carried out at each step, with a digital computer.
4096 Channel Time Analyzer with Variable Channel Width
Authors: Rockwood Curtis C.
Published: February 2005

A time analyzer for neutron time-of-flight studies is described. An ``accordion'' feature permits different channel widths in adjacent time regions. Eight independent selections of channel width for each of the 16 regions of 256 channels are provided, ranging by factors of 2 from 125 nsec to 16 μsec. A channel width multiplier increases all the widths by a factor of 8, 4, 2, or 1. Deadtime is 5 μsec per event stored. Channel capacity is 262 143 counts. Readout is punched paper tape, followed by verify in a tape reader.
Simple, Continuously Indicating Helium Liquid Level Gauge for Opaque Cryostats
Authors: Lyon D. N. , Gillich J. J.
Published: February 2005

Design parameters which assure operation in liquid helium above or below the λ point are given for the simple, self-contained mechanical liquid level detector of Pope and McLaughlin. The indicating device is a commercial differential pressure gauge, which may be located wherever convenient. Small heat leak, reasonable accuracy, and good reproducibility are obtained.
Pulse Shape Discrimination System for 6LiF(ZnS) Scintillation Counters
Authors: Legler E. , Attwenger W. , May F. , Quittner G.
Published: February 2005

A pulse shape discrimination system for 6LiF(ZnS) scintillators is described and its electronic layout discussed. Test results under typical operation conditions at the location of a neutron scattering experiment in a light water research reactor are given. They show that the system is able to suppress virtually all spurious (γ and tube noise) pulses down to a rather low discrimination level. By taking a low discrimination level it is possible to exploit the potentially high efficiency of the scintillator to a much larger extent. In our particular case the over-all counting efficiency could be doubled.
Measurement of the Dielectric Properties and Thermal Expansion of Polymers from Ambient to Liquid Helium Temperatures
Authors: McCammon R. D. , Work R. N.
Published: February 2005

A three terminal combined dilatometric and dielectric cell for measuring the thermal expansion and dielectric properties of high polymers or other solids down to liquid helium temperatures is described. Some preliminary results on fused silica and poly (dl propylene oxide) are presented. The frequency range of 50 Hz to 10 kHz and the resolutions, at 1 kHz, of 1×10−6 pF in capacitance and 1×10−6 in dissipation factor are determined by the characteristics of the capacitance bridge used.
Liquid Neon-Hydrogen Bubble Chamber
Authors: Prodell A. G.
Published: February 2005

Tracks have been observed in various liquid neon-hydrogen mixtures in the 20 in. Brookhaven National Laboratory bubble chamber. A neon-hydrogen mixture was used whose radiation length is approximately equivalent to that of propane. Separation of some of the mixtures into two liquid phases was also observed.
Indirectly Heated PTC Resistor for Measuring Air Flow
Authors: Kraus Kamil
Published: February 2005

An indirectly heated PTC resistor is described which was developed for sensitive measurements of low pressures and of high air velocities. The basic circuit which has provided high sensitivity in such measurements is discussed in the last part of the paper.
Hydrogen-Oxygen Vertical Brazing Furnace
Authors: Eldredge Arnold L.
Published: February 2005

A specially designed hydrogen-oxygen vertical flame furnace was constructed for brazing together the copper pieces of the accelerator structure for Stanford's Two-Mile Linear Electron Accelerator. To date, over 60 000 braze joints have been made without a leak appearing in any joint even though the brazed section operates at less than 10–8 Torr pressure. The accelerator structure is a disk loaded waveguide and is fabricated from precision-machined, high purity copper cylinders and disks, each approximately 10 cm in diam. These components, with input and output coupler assemblies, are carefully stacked together with a shim of silver-copper brazing alloy placed between each piece. When stacking is complete, a 3 m section of the accelerator structure is ready for brazing and is secured on a mandrel for transfer to the furnace. Purging gas is fed through the mandrel to the interior of the 3 m section to prevent oxidation during brazing. Also, as the section is brazed by the split ring burner of the furnace, a special, water cooled cylinder filled with reducing gas follows the burner to protect the exterior of the section and prevent oxidation. The furnace provides excellent control of the brazing alloy fillet inside the disk loaded waveguide section and prevents the alloy from increasing the rf loss on the section's inner surface.
Rigid-Tail Helium Cryostat for X Ray Diffraction Studies of Crystallized Gases
Authors: Peterson O. G. , Simmons R. O.
Published: February 2005

A rigid-tail cryostat suitable for x ray back-reflection diffraction studies requiring temperature control within a few hundredths of a degree for extended time intervals in the range above 2.3°K is described. The specimen chamber permits the growth, visual study, thermal etching, and annealing of crystallized gases. It may also be pressurized to 20 atm for x ray studies of compressibility.
``Electric Wind'' Gas Discharge Anemometer
Authors: Nygaard Kaare J.
Published: February 2005

The pressure gradient produced by the ions in a corona discharge has been used to balance the wind-induced drag forces in a new type of gas discharge anemometer. Measurements were carried out in a 1 atm air wind tunnel at free-stream velocities of 1.5–4.5 m/sec. The instrument was operated in such a way that the effect of gravitational and electrostatic forces could be neglected. In the velocity range indicated above, the free-stream velocity was found to be proportional to the gap voltage.
Effect of Wire Cross Section on the First Pulse of an Exploding Wire
Authors: Oktay Erol
Published: February 2005

The optimum discharge in an exploding wire circuit is described. In this type of discharge, the stored energy of the capacitor discharges completely during the first pulse of the exploding wire phenomenon. It was determined from the results of experiments conducted in air at atmospheric pressure with Cu, Ag, and Pt wires that for an optimum discharge the initial voltage of the capacitor is directly proportional to the wire cross sectional area, and it is independent of the wire length. Consequently, the ratio of the stored energy of an optimum discharge to the mass of the wire is proportional to the inverse of the resistance of the wire at room temperature. The wire length was varied from 2.5 to 17.8 cm and the wire cross sectional area was varied from 4.8×10−5 to 3.2×10−3 cm2.
Method for Studying Low Energy Ion-Molecule Reactions Using Monoenergetic Ions
Authors: Ryan Keith R. , Futrell Jean H. , Miller C. Dean
Published: February 2005

An experimental technique is described for the study of ion-molecule reactions permitting the investigation of ions with kinetic energies in the range 0–3 eV which introduces negligible spread in ion energy. A 20 nsec ionizing pulse is used to produce ions in the reaction chamber to which a steady dc electric field is applied. Because of the short time interval for ionization all ions have essentially the same energy and move as a ``bunch'' under the influence of the applied field. Thus the energy of the ions at any subsequent time may be readily calculated, and the energy dependence of ion-molecular interactions may be studied. Practical considerations, determined by source dimensions, limited the maximum energy to 1.3 eV in the present study for the reaction CH4++CH4 → CH5++CH3.
Large Gas Filled Čerenkov Counter
Authors: Frankel S. , Highland V. , Sloan T. , Van Dyck O. , Wales W. , Wolfe D.
Published: February 2005

A large pressurized gas Čerenkov counter is described. The counter is designed to assist triggering on electrons in high energy counter-spark chamber experiments. The requirement of large solid angle resulted in a counter of large dimensions and heavy construction. The results of tests made on the counter are presented. The tests indicate that the counter rejects pions very well and is roughly 50% efficient to electrons in the Λ° beta-decay spectrum (0–200 MeV).
High Speed Microwave Phase Shifters Using Varactor Diodes
Authors: Gardner Andrew L. , Hawke Ronald S.
Published: February 2005

A reflection type microwave phase shifter is described which is similar to the units developed by Hardin, Downey, and Munushian. It employs the voltage-variable capacitance of varactor diodes as the adjustable element. The ``pill type'' diodes tune their associated circuit through a resonance to produce phase shifts of over 90°. With proper adjustment of the tuning—a simple procedure—the output amplitude is made essentially constant. The use of two series diodes mounted back-to-back permits higher power operation, although the unit is essentially a low power device.
Resistance Heated Crystal Puller for Operation at 2000°C
Authors: Reed T. B. , Fahey R. E.
Published: February 2005

A resistance heated crystal puller has been used to grow crystals of NbO, Ti2O3, and Al2O3, which have melting points of 1945, 2000, and 2050°C, respectively. The puller incorporates a modified version of a tantalum tube furnace described previously, which is capable of operating in oxidizing, neutral, and reducing atmospheres up to 2400°C. The seed holder is water-cooled.
ARGUS—A Simple Device for Simultaneous Measurement of Breakdown Times of Many Spark Gaps
Authors: Rostagni Giorgio
Published: February 2005

A simple device, which enables one to observe on a single oscilloscope trace the individual breakdown times of many spark gaps in parallel, is described. It employs signals from magnetic probes placed near each spark gap. For illustration the signals of typical breakdown conditions are shown and briefly discussed on the basis of some qualitative remarks on the behavior of a fast discharge capacitor bank.
Apparatus for Measurement of Magnetic Anisotropy
Authors: Fleischmann C. W. , Turner A. G.
Published: February 2005

An apparatus is described for the measurement of magnetic anisotropies of single crystals by the maximum torque method. It has an accuracy of 0.5%. The apparatus features a rugged design and provision for working in a controlled atmosphere. Two methods of calibration are discussed and experimental procedures are described. The diamagnetic anisotropy (χ1−χ2) of naphthalene is reported to be 90.6±0.05×10−6 cgs units per mole.
Machine for Uniaxial Tensile Straining in the X-Ray Diffractometer
Authors: Bartholomew E. L. , Biederman R. R.
Published: February 2005

The design and operation of a straining rig to achieve uniform tensile stress in specimens properly aligned within an x-ray diffractometer with vertical axis are presented. Experimental results are shown which indicate the suitability of the instrument for determinations of x-ray stress constants or studies of lattice strain by diffraction.
Magnetic Field Measurement in an Electromagnetic Shock Tube Using Large Area Probes
Authors: Miller Bennett
Published: February 2005

We examine the problem of measuring with a probe the magnetic field in a plasma which is moving with respect to the probe. It is shown that integration with respect to time is, in general, not proper and we develop correct expressions for the case of a current conducting plasma produced by a strong ionizing shock wave in an electromagnetically driven shock tube. Use of the correct expressions is described for large area magnetic field probes employed in a coaxial electromagnetic shock tube. The results demonstrate the need for careful interpretation of data obtained from magnetic field probes used to measure magnetic fields in moving media.
Automatic Double Probe Method of Obtaining Electron Temperatures
Authors: Hines R. H.
Published: February 2005

An instrument used for continuously determining electron temperature in an ion engine exhaust is described. The ratio of measured currents at specified regions of the double probe characteristic is computed to yield a good approximation of electron temperature for conditions in which the ion sheath buildup is small.
Ionization Gauge for Transient Gas Pressure Measurements
Authors: Valsamakis E. A.
Published: February 2005

A gauge has been developed that is particularly suited for measuring transient gas pressures (e.g., gas bursts expanding in vacuum). A commercial subminiature pentode has been used in a suitable circuit for this purpose. Calibration curves for helium, nitrogen, neon, argon, krypton, and xenon at room temperature are given in the 1 to 400 μ Hg range. The features of this gauge are its small size, short risetime, and simple construction and installation. The serious disadvantage is its short lifetime, about 3 weeks of continuous use, mainly due to filament failure.
Use of Conformal Mapping to Improve Field Uniformity of Electromagnet
Authors: Fuller F. L.
Published: February 2005

Conformal mapping is used to determine the cross section of a shim in order to improve the uniformity of the field in the air gap of a magnet. Experimental measurements on a laboratory electromagnet demonstrate the improvement in field uniformity.
MPL Acoustic Transponder
Authors: McGehee M. S. , Boegeman D. E.
Published: February 2005

A description is given of a compact, low cost expendable acoustic transponder suited for use in the deep ocean. A unique signal recognition circuit is employed that gives a very high ratio of correct answers to false replies when exposed to the wide variety of noises found in the sea. A very low battery drain permits a relatively small supply to last for a year or more, thus resulting in an instrument that can be easily handled at sea.