bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydraulic Ram Design for Modern High Pressure Devices
Authors: Hall H. Tracy
Published: February 2005

Equations are developed for designing hydraulic rams of maximum thrust for a given external cylinder diameter. For push type rams, the optimum ratio of outside to inside wall diameter w is 1.554, and the maximum fluid pressure P to be used is 0.4142 times the allowable hoop stress ft in the cylinder. For pull type rams in which the allowable tensile stress fb in the pull bar (cylinder rod) and the allowable hoop stress ft in the cylinder wall are equal, w=1.414 and P=0.333 ft. When these allowable stresses are not equal, more complicated relationships exist and are discussed in the text.
Optimized Pulsed NMR Single Coil Circuit Design
Authors: Gray K. W. , Hardy W. N. , Noble J. D.
Published: February 2005

A single coil pulsed NMR sample circuit is described which allows optimization in the transmitting and the receiving modes. In the transmitting mode the circuit is matched to the transmitter output impedance, 50 Ω, and in the receiving mode it is matched to the optimum input impedance of the preamplifier.
Gas Density Stabilizer for Flow Proportional Counters
Authors: Deslattes Richard D. , Simson Bert G. , LaVilla Robert E.
Published: February 2005

A controller for gas density (pycnostat) is described with particular view to gain stabilization in flow proportional counters. The device is capable of operation at small flow rates and at pressures both above and below atmospheric. Constructional details and performance measurements are reported.
Motion Picture Projection of Multiple Spark Camera Film
Authors: Kent J. Christopher
Published: February 2005

A method is described for motion picture projection of multiple spark camera film records. Motion picture projection of these nonstandard film records can enhance their usefulness by aiding visualization of the photographed event. Such projection can be accomplished by using the objective lens group of the multiple spark camera (or a duplicate lens group) as a projection lens group. The addition of a viewing screen, an illumination source, and an appropriate shuttering device enables the film to be projected as a motion picture sequence.
X-Ray Spectrometer Attachment for Elmiskop I Electron Microscope
Authors: Fuchs E.
Published: February 2005

With the aid of an x-ray spectrometer attachment for the electron microscope (Elmiskop I), it is possible to perform quantitative analyses of the chemical elements in a specimen. The spectrometer attachment is based on the semifocusing method. It is equipped with six analyzing crystals and two counters which may be exchanged during operation. It is possible to analyze for all elements with an atomic number greater than 11. The minimum mass detectable is 10−14 g.
Characteristics of Grid Controlled Ionization Gauge in Nitrogen
Authors: Weinman J. A.
Published: February 2005

The operating characteristics of a grid controlled ionization gauge in nitrogen at pressures between 2×10−3 and 4 Torr are presented. Positive ions were produced by a primary electron current, space charge limited by a control grid. The positive ion current was thus independent of filament temperature over a moderate range of filament heating currents. Elastic scattering reduced the ionization path of the electrons at pressures greater than 0.03 Torr. A secondary discharge established by suitably chosen electric fields compensated for the reduced ionization efficiency of the gauge above this pressure. The gauge thus yielded a positive ion current which increased monotonically from 1.7×10−9 to 4.3×10−7 A with increasing pressure throughout the investigated range of pressure.
New Zone Refining Techniques for Chemical Compounds
Authors: Pfann W. G. , Miller C. E. , Hunt J. D.
Published: February 2005

Improved apparatus has been developed for the zone refining of organic and inorganic compounds. A new heating technique utilizes natural convection in the liquid and slow rotation of a horizontal charge tube to achieve unusually short zone lengths in tubes of modest diameter. A new cooling technique utilizes direct contact of liquid coolant with the charge tube to achieve short interzone spacing and flat liquid-solid interfaces. Either or both techniques are useful for metals and semiconductors as well, and for other operations such as zone leveling, normal freezing, and the growth of single crystals.
Apparatus for Seismic Modelling Optically
Authors: Thomson Ker C.
Published: February 2005

Apparatus for the photoelastic study of propagating stress waves by a repetitive stroboscopic technique has been developed in a form suitable for seismic modelling. Using a 30 cps repetition rate the transient waves propagate forward or backward or are ``locked'' in position on the viewing screen at the control of the operator. An impact device capable of very brief contact time (1 msec) and high source strains (⅓ cm penetration) produces a very brief but intense mechanical transient. This impacter, coupled with the large size of the models used (46 cm square), permits wave propagation to be studied over a significant length of travel path, suitable for certain seismic propagation problems. Isochromatics and isoclinics of propagating waves are shown.
Instrument for Measurement of Hydrogen Atom Population
Authors: Shombert D. J. , Low M. J. D. , Argano E. S.
Published: February 2005

A transistorized Wheatstone bridge suitable for precise current or resistance measurements is described. The bridge is inexpensive, compact, and versatile, and was used for measuring hydrogen atom populations by the recombination wire probe method.
Inverse Magnetic Field Readout for Superconducting Magnet Sweeps
Authors: Sullivan Paul F.
Published: February 2005

A circuit is described for driving the abscissa of an X-Y recorder as the inverse of the magnetic field (H−1) of a superconducting solenoid. The output is independent of the sweep rate for any sweep within the range of the instrument and the error in the resultant plot is less than 0.5% of full scale for any 10 kG sweep of the magnet.
Improved Spin Wave Instability Threshold Plotter
Authors: Purnhagen Tom G.
Published: February 2005

An improved system for plotting spin wave instability threshold data is described. The system combines analog and digital techniques and eliminates many of the drawbacks of a method previously described by the author [Rev. Sci. Instr. 35, 558 (1964)].
Distortion of Pulse Height Spectra by Pile-Up Effect
Authors: Williamson J. H.
Published: February 2005

A method is developed to compute the distortion of pulse height distributions by the pile-up effect for arbitrary spectra and pulse shapes. The distorted spectra can be processed by an iterative method to reproduce the original distribution. Results are given for pulses shaped by resistors and capacitors or by short circuited delay lines. The best pulse shaping network is a simple modification of the double delay line clipping amplifier.
Superconducting Bearing
Authors: Daniels B. , Matthews P. W.
Published: February 2005

A superconducting bearing is described which depends for its operation on the conservation of the fluxoid in a closed loop of superconductor. In operation this bearing is identical with the well-known Beams magnetic suspension, except that the function of the servomechanism is performed automatically by the superconducting loop. The observed load characteristic of the present bearing is compared with theoretical predictions, and a practical rotor is described.
Modified Diaphragm Pressure Gauge for Corrosive Gases
Authors: Sheft Irving
Published: February 2005

The Booth-Cromer diaphragm gauge has been modified to use a linear variable differential transformer to detect the position of the diaphragm. The sensitivity of the unit is 0.01 mm Hg. The ruggedness and simplicity of the original gauge are retained.
Electron Microscope Camera with Fiber Optic Output
Authors: Burroughs E. G. , Kennedy A. J.
Published: February 2005

The design and performance of an electron microscope camera with fiber optic output is described. A line resolution of 30–35 line pairs per millimeter was obtained on the negative of the Polaroid type 55 P/N film. The general features described may be helpful in developing an adaptation for other instruments.
Techniques for Using Liquid Helium in Very Low Temperature Apparatus
Authors: Vilches O. E. , Wheatley J. C.
Published: February 2005

A discussion of what is known experimentally about the thermal contact problem at very low temperatures is given. Liquid 4He is a particularly promising contact agent. Methods of using liquid 4He, thermometry using cerium magnesium nitrate, and solutions to the filling and isolation problems using an open capillary are discussed. The techniques are applied to an apparatus suitable for heat capacity measurements to below 0.02°K and to an apparatus for measurement of superconductive properties at temperatures substantially below 0.01°K. The performance of the apparatus for heat capacity and superconductivity measurements is discussed.
Contour Plotting System with High Speed Symbol Head
Authors: Skuce D. R.
Published: February 2005

An instrument for producing contour diagrams using a conventional X-Y plotter is described. It consists of a specially designed pulsed current plotting head controlled by gating circuits which use commercial analog and digital modules. The X-Y plotter scans the head over electrosensitive paper and symbols consisting of dot patterns are plotted with no mechanical delay. The gating circuits may be adjusted to any desired set of contour intervals.
Linearizer for Constant Temperature Hot Wire Anemometer
Authors: Champagne Francis H. , Lundberg John L.
Published: February 2005

Experiments to determine the heat transfer from hot wires with length-to-diameter ratios on the order of 102, which are commonly used in hot wire anemometry, were performed. The Reynolds numbers used were less than 10, the overheat ratio was kept at 0.80, and the fluid was air. The results indicate that the exponent n in the relationship Eb2 = A+BUn, where Eb is the bridge voltage and U the fluid velocity, was equal to 0.45 for wires operated at constant temperature. A linearization circuit which provides an accurate means of recovering the velocity from the above relationship for values of n of 0.45 and 0.50 is described. The main component of the circuit is a temperature compensated, ten segment silicon diode function generator manufactured by Philbrick Researches, Inc. The frequency response of the linearizer is from dc to 36 kc or from dc to 180 kc depending on the operational amplifiers used in the circuit.
30 keV Ion Bombardment Apparatus for Study of Interaction of Light Ions with Surfaces
Authors: McCracken G. M. , Maple J. H. C. , Watson H. H. H.
Published: February 2005

An ultrahigh vacuum system is described which was designed to study particles emitted from surfaces under bombardment by hydrogen ions. Stress has been laid on obtaining pressures ∼10−9 Torr in the presence of the ion beam. The beam is mass analyzed and its energy is variable from 5 to 30 keV. A maximum current of 300 μA over 0.1 cm2 is obtainable at the target, so that a beam/neutral gas bombardment ratio of better than 1000/1 can be achieved. A target mounting turntable is described which allows up to six targets to be bombarded in turn. A quadrupole mass filter is incorporated in the target chamber as a residual gas analyzer and as a means of identifying gas species resulting from the bombardment of surfaces.
Four Point Sheet Resistivity Techniques
Authors: Zrudsky Donald R. , Bush Harry D. , Fassett John R.
Published: February 2005

A technique of averaging two resistivity measurements, each made using a different pair of current probes of a square array on an infinite sheet, has been developed. It is shown in theory and practice that when one probe is common to each of the two measurements, an average eliminates all first order errors due to misalignment of the array. An electronic averaging circuit which provides a continuous single meter measurement of sheet resistivity is presented. Data taken with 1.27 mm infinite sheet probe assembly are shown to have a repeatability of ±0.33% (3σ) on a 145 Ω per square sample. This particular system has a useful range of 0.1 to 10 000 Ω per square. The circuity developed for the infinite sheet method is also shown to be applicable to the bounded sheet method (Van der Pauw technique). A novel infinite sheet probe assembly design is illustrated.
Quenching Furnace for Elevated Temperature Tensile Test
Authors: Holley William G. , Talbot Thomas F.
Published: February 2005

A method of quenching a specimen subjected to a tensile stress at elevated temperatures has been developed. Tensile tests with stress, time, and temperature as variables are possible. The cooling rate of specimens in the 600°C range can be controlled from ¼ to 25°C/sec.
Simple Procedure for Measurement of Hg Vapor Pressure of Amalgams
Authors: Margolis Joseph M.
Published: February 2005

A simple, relatively accurate method for determining the Hg vapor pressure of amalgams at elevated temperatures is described. The transmission of 2537 Å radiation through an evacuated quartz optical cell containing the amalgam is compared with that of a similar cell containing only Hg, using a spectroradiometer. After plotting log transmission vs 1/T °K for each of the cells, the Hg vapor pressure of the amalgam is found by determining the temperature at which the Hg cell shows the same transmission as the amalgam, and reference to a table of Hg vapor pressure vs temperature.
Detonation Calorimeter and Results Obtained with Pentaerythritol Tetranitrate (PETN)
Authors: Ornellas Donald L. , Carpenter John H. , Gunn Stuart R.
Published: February 2005

A bomb calorimeter for measuring the heat of detonation of 25 g charges of high explosive is described. A complete calorimetric measurement can be made in 1 h with a precision of 0.3%. Calorimetric measurements and analysis for PETN are described. The data are interpreted with the aid of thermodynamic and hydrodynamic computer calculations. For unconfined or lightly confined charges, the released energy is largely retained in the products which are shocked considerably off the Chapman-Jouguet isentrope by reflections from the bomb wall. For heavily confined charges, the energy is largely converted to kinetic and internal energy of the confining case, and the essentially unshocked products expand along the Chapman-Jouguet isentrope. The products of detonation are found to freeze out at 1500 to 1800°K. The heat of detonation of PETN at 298°K is 1490±6 cal/g, H2O(l).
Factors Affecting Resolution of Lead Scintillator Sandwich Shower Counters
Authors: Walker J. K. , Knasel T. M.
Published: February 2005

Recent results by Crawford and Messel on the development of showers in lead by the Monte Carlo method are used to estimate the energy resolution of total energy absorption scintillation shower counters. It is probable that slight improvements in energy resolution over existing counters can be obtained by using 15 radiation lengths in the direction of the incident particle and sampling the shower after every 110 radiation length.
Constant Current Source for Instrument Calibration
Authors: Santoro R. T. , Gillespie F. E. , Aebersold P. M.
Published: February 2005

Two current sources which give a constant current over a wide range of applied voltage have been built for use in calibrating electrometers having input resistors in the 10+10 to 10+12 Ω range. The sources consist of sealed parallel plate ionization chambers having one electrode coated with 241Am. Calibrations using the rate of charge method spaced over a period of 1 year define the respective current output of the sources as (6.943±0.003)×10−11 and (4.263±0.004)×10−12 A.
Micaceous Biotite as Efficient Brewster Angle Polarizer for Vacuum Ultraviolet
Authors: Robin M. B. , Kuebler N. A. , Pao Yoh-Han
Published: February 2005

A naturally occurring, iron rich silicate mineral commonly known as biotite has been found to perform very well as a Brewster angle reflection polarizer in the region 1100 Å to nearly 6000 Å. This observed behavior is somewhat anomalous since it is well-known that nonabsorbing dielectric surfaces which polarize well in Brewster angle reflection have low reflectivity whereas the light reflected from highly reflecting surfaces has a low polarization. In contrast to this, we have found biotite to have a rather high reflectivity with strong polarization of the reflected light. The characteristics of this polarizer are reported in this paper and the apparent anomaly is resolved in terms of an optical anisotropy hitherto disregarded in this context.
Double Resonance Modulated Microwave Spectrometer
Authors: Woods R. C. , Ronn A. M. , Wilson E. Bright
Published: February 2005

A practical non-Stark modulated double resonance microwave spectrometer has been constructed and tested in which frequency modulation is applied to one (strong) microwave source, the power from which passes through the sample gas but is prevented from reaching the crystal by filters. The second source does reach the crystal but is unmodulated. The modulation is therefore transmitted to the crystal and tuned amplifier exclusively via the phenomenon of double quantum absorption. The only transitions observed were those which occur as active pairs involving a common energy level, the two frequencies being near the two source frequencies. This provides extremely specific spectra for identification in complex situations, and is a convenient way of searching for linked transitions which are useful for assignment purposes. Because no Stark electrode is needed, it is easier to construct special absorption cells such as coiled guides, high temperature cells, free space paths, etc.
Measurement of Low Light Intensities by Synchronous Single Photon Counting
Authors: Arecchi F. T. , Gatti E. , Sona A.
Published: February 2005

Single photon counting technique is used for measuring continuous light fluxes of very low intensity suitably modulated. Demodulation and integration processes usually made in conventional synchronous detectors on analog signals are here performed with drift free digital operations. The main advantage of this procedure is the possibility of improving the signal-to-noise ratio by very long integration times which are not limited by drifts of the electronics following the detector. An analysis of the noise filtering properties of the device is given. Raman light angular distributions obtained by this technique are reported as an example and noise characteristics of the device are measured and compared with the results of the theoretical analysis.
Stereoscopic Viewer for Measuring Positions and Angles in Three Dimensions
Authors: Cowan E. W.
Published: February 2005

An optical device is described that is used for the measurement of the positions and angular coordinates of lines viewed in stereoscopic photographs, such as the photographs of particle tracks in a cloud chamber or bubble chamber. In addition to the absolute angular coordinates of a line in three dimensional space, the viewer furnishes the relative angular coordinates of a second intersecting line and the three rectangular coordinates of the point of intersection. All coordinates are read directly on linear scales. Applications include the measurement of scattering angles, the angles of secondary particles in an interaction or decay with respect to each other and the primary particle, and the angle of traversal of a particle through an absorber.
Precision Technique for Measuring Asymmetric Distortions in Optical Lenses
Authors: Hohenstein Jack
Published: February 2005

Apparatus and techniques were developed for accurately measuring asymmetric distortion in camera lenses. Great care was taken in fabricating the camera, which was made cylindrical so that the lens could be rotated. The experimental setup included a collimating telescope, the cylindrical camera containing the lens to be tested, and the test pattern. By rotation of the cylindrical camera, the same portion of the test pattern could be used for checking asymmetric distortion in different sectors of the lens. The distortion was recorded on film plates, which were then measured with a linear micrometer. Results were obtained to an accuracy of 1 part in 105. Causes for distortion were investigated but not quantitatively.
Improved Precision Ice Calorimeter
Authors: Opdycke Jack , Gay Charles , Schmidt Hartland H.
Published: February 2005

An improved Bunsen ice calorimeter has been constructed and calibrated for use in measuring critical region heat capacities. A novel method for continuously monitoring the weight of the mercury displaced by using a flexible capillary between the calorimeter and an analytical balance makes possible greater precision, easier operation, and wider applicability of the ice calorimetric method. An improvement in the method of thermostating the calorimeter allows higher precision over long period heat measurements. The measured electrical calibration factor of 270.45±0.03 J/g Hg agrees satisfactorily with previous very careful calibrations and the observed precision of ±0.011 J/g Hg is easily attainable during electrical calibrations. Relatively simple improvements in other aspects of the calorimeter are suggested for increasing both the precision and accuracy significantly.
Apparatus for Electron Irradiation Studies at Low Temperatures
Authors: Chaplin R. L.
Published: February 2005

To pursue accurate quantitative studies of radiation effects in crystals, it is necessary to adopt precise experimental techniques for controlling the bombarding electrons and for cooling specimens to very low temperatures. With regards to the irradiating electron beam, measurements have been made to determine some of the factors which influence the electron flux density over the irradiated area, and a description is given of a system which insures precise alignment of the beam with respect to the specimens. A sample holder is described which provides good thermal contact and good electrical isolation between specimen and specimen holder at low temperatures. The method used for regulating the temperature of the sample holder depends upon adjusting the rate and the amount of helium vapor flow through the holder and data that indicate how these two adjustments govern the resultant temperature are presented.
Electron Densitometer for Irradiation Studies in Electron Microscope
Authors: Sciacca T. P. , Eubanks A. G.
Published: February 2005

A probe assembly is described which permits the use of an electron microscope to irradiate materials with low energy (50–150 keV) electrons. The electron beam current produced by the microscope can be monitored quickly and accurately with this unit so that the irradiation rate can be closely controlled. Although developed for use in the Hitachi HU-11 electron microscope, the device can, with but minor modifications, be utilized in other microscopes as well.
Sensitive Low Level Transistorized NMR Spectrometer Employing Frequency Modulation
Authors: Blankenburg Fred J. , Knispel Roy R. , Schmidt V. Hugo
Published: February 2005

A transistorized NMR spectrometer has been developed which affords sensitivity comparable to that of the best vacuum tube spectrometers. This spectrometer has operated with sample coil voltages below 10 mV peak-to-peak. Frequency modulation is used to facilitate modulation at frequencies high enough to minimize effects of transistor 1/f noise.
Alternating Current Losses and Magnetic Field Aberrations Associated with Use of High Field Superconducting Wire in Adiabatic Demagnetization Apparatus
Authors: Anderson A. C. , Roach W. R. , Sarwinski R. E.
Published: February 2005

Experiments were conducted to determine ac losses, principally near 105 cps, in coils and leads fabricated from high field superconducting wires. The samples were placed in an environment similar to what might be experienced in actual use in a low temperature experiment utilizing adiabatic demagnetization. The measurements showed that losses associated with the use of high field superconducting wire could be less than for electrical grade copper wire. Further experiments were then carried out to determine what aberrations of magnetic fields would be caused by the presence of high field superconducting material.
Cranz-Schardin Multisource Spark Camera Systems
Authors: Garg Sabodh K. , Siekmann Julius
Published: February 2005

A multisource spark camera of the Cranz-Schardin type is described. Various applications, limitations, and alternatives are discussed.
Nuclear Magnetic Resonance Probe for Calibrating Superconducting Solenoids
Authors: Rupp L. W.
Published: February 2005

A cesium metal NMR probe, which can be used directly with a Varian fluxmeter at liquid helium temperatures, has been developed. Such a device is generally useful in accurately calibrating magnetic fields to better than 1 G in the range 7600 to 60 000 G typical of currently available superconducting solenoids.
Polymer Degradation Dosimeter of Polyisobutylene in Heptane
Authors: Carriker A. Wendell
Published: February 2005

A radiation dosimeter that utilizes a polymer solution is described. The viscosity of the solution is an inverse function of dose, and the dose range for a given range of viscosity can be adjusted by changing the concentration and molecular weight of the polymer solute. Several small vibrating transducers for measuring the change of viscosity were investigated. Since polyisobutylene in heptane is a non-Newtonian solution low frequency transducers were most effective.
Construction of Presses for High Pressure Research
Authors: Gordon R. B. , Mike L. F. , Vaišnys J. R.
Published: February 2005

Large press frames such as are often required in high pressure research apparatus can be constructed from thin plates provided that frictional forces are used to distribute the load uniformly on all the plates. A method of achieving this distribution of load is described. The resulting structure is strong and rigid, cannot fail by fracture, and can be made without the use of heavy machine tools.
Versatile High Temperature Furnace
Authors: Wagner Paul
Published: February 2005

Past experiences in making a variety of thermal and physical measurements at high temperatures have resulted in a general furnace design which has proved to be quite successful for a variety of measurements. The operating range of the furnace described covers the temperature interval 750–2900°C. General design principles and details of construction for one of the furnaces are discussed. Several modifications of the furnace and some examples of the types of measurements which have been made are described.
Beryllium Pressure Bar Having Submicrosecond Risetime
Authors: Jones Ieuan R.
Published: February 2005

A pressure bar gauge was constructed from beryllium. The active element is a PZT polarized ferroelectric disk. The gauge was subjected to step pressure loading; the time taken for the output signal to increase from 10 to 90% of its final steady value is 0.54 μsec which is substantially faster than any other previously reported for a bar gauge.
Isothermal Drop Calorimeter for Alpha Active, Pyrophoric Materials
Authors: Savage Howard
Published: February 2005

A copper block drop calorimeter to measure the heat content of intensely alpha active materials has been constructed. The furnace, calorimeter, and aluminum isothermal jacket are contained within an inert atmosphere glovebox. This permits the use of unencapsulated materials without exposing personnel to an alpha contamination hazard. The inert atmosphere also permits measurements to be made on materials which are pyrophoric in air. The apparatus is equipped with a suppressed range recorder to monitor continuously the resistance thermometer signal with a resolution of ±0.4 cal/μV. Electrical calibration of the calorimeter yielded a precision of ±0.08% in the thermometer and recording system. The heat content of a sample of Calorimetry Conference sapphire obtained from the National Bureau of Standards was measured, and the results deviated from the Bureau's reported data a maximum of 1.0% at 1008°K. The useful range of the apparatus extends from 306 to about 1450°K.
Laser Used for Mass Analysis
Authors: Fenner N. C. , Daly N. R.
Published: February 2005

The focused beam from a `giant pulse' laser has been used to vaporize and ionize thin samples of solid material and so provide the ion source of a time of flight mass spectrometer. Ions produced in this way have an energy spread of 0–500 V and this has necessitated employing an energy filter to obtain a resolution of about 30. Samples of 10−9 g from metal foils have been successfully analyzed and have shown comparable ionization efficiencies for a large number of metals. When this technique was applied to the analysis of crystals of organic compounds only atomic ions were observed and although the ionization efficiency of the metal atoms is again comparable, the efficiency of the other components depends critically on the power of the laser beam.
Apparatus and Techniques for Retention and X-Ray Examination of Metastable High Pressure Phases at 4.2°K
Authors: McDonald T. R. R. , Barberich G. S. , Cunicella V. T. , Gregory E.
Published: February 2005

Apparatus and techniques are described for retaining high pressure phases in a metastable state at atmospheric pressure and 4.2°K, and for examining them by x-ray diffraction at this temperature. The apparatus consists of a press capable of exerting a pressure of about 50 kbar on small quantities of sample material, and a cryostat which permits x-ray diffraction photographs to be taken of a specimen transferred from the press and immersed in liquid helium. Diffraction data are presented for the halite modification (NaCl type) of AgI retained at 4.2°K and atmospheric pressure, and mention is made of the retention of a metastable high pressure phase of gallium.
Apparatus for Determining Creep Behavior Under Conditions of Ultrahigh Vacuum
Authors: Buckman R. W. , Hetherington J. S.
Published: February 2005

A system for determining the creep behavior of refractory metals at temperatures up to 1900°C and at environmental test pressures of less than 1×10−8 Torr are described. Results are presented which show that contamination of a tantalum alloy test specimen is inhibited when tested at 1370°C and 1×10−8 Torr.
Considerations Affecting Design of Atomic and Molecular Beam Resonance Apparatus Employing Two-Pole State Selectors
Authors: McColm Douglas
Published: February 2005

Optimum design criteria for atomic and molecular beam apparatus are discussed, and signal strengths under a number of conditions are calculated. Signal strength and signal-to-noise ratios are shown graphically as functions of the design parameters.
Response of Silicon Fission Detectors to Channeled 127I and 40Ar Ions
Authors: Moak C. D. , Dabbs J. W. T. , Walker W. W.
Published: February 2005

When very heavy ions were directed along the crystalline channels of Si fission detectors, a three-fold improvement in energy resolution was obtained for particles remaining in the channels. For such channeled particles the usual pulse height defect was reduced by more than a factor of 10. The results seem to fit certain theoretical explanations of detector nonlinearities found in the literature, in which the nonlinearities are ascribed to the predominance of atomic collision processes near the end of the range.
Nanosecond Time Resolution in Fission Fragment X-Ray Lifetime Experiments Using Thin Plastic and NaI (Tl) Scintillation Detectors
Authors: Bridwell L. , Wyman M. E.
Published: February 2005

Apparatus for the half-life measurements of x rays from fission fragments is described. The fission fragment detector was an ultrathin plastic scintillator and the x-ray detector was a 1 mm NaI (Tl) crystal. Both detectors were mounted on fast (56 AVP) photomultipliers. The details of the design of the plastic scintillator are given and curves showing the double humped fission fragment kinetic energy spectrum are illustrated. A systematic study of the x-ray energy detection characteristics of the NaI (Tl) on a 56 AVP is given. The pulse heights were determined to be linear with x-ray energy and the spectra were shown to follow Poisson's statistics. The number of photoelectrons produced at the photocathode was determined to be 3.2 per kiloelectron volt. The time measuring device was a conventional time to amplitude converter using pulse overlap methods. The prompt response of this converter could be predicted from the results gained in the energy detector study. Both the width and the apparent half-life were consistent with the assumption that the time to amplitude converter was triggered on a single photoelectron.
Absolute Power Measurement at 1.2 mm Wavelength
Authors: Senitzky B. , Liebe H.
Published: February 2005

A new technique for the measurement of electromagnetic power at millimeter wavelengths is described. A gas filled waveguide is used to measure the absorption of an electric dipole rotational line. From a study of the change in the absorption as a function of power, the degree of saturation of the gas is measured. The experimental results are then compared to a collision broadened absorption theory including linear waveguide losses to determine the input power required for the measured saturation. The technique can be used to measure powers as low as 10−6W.
Low Temperature Liquid Helium Level Indicator
Authors: Canter K. F. , Roellig L. O.
Published: February 2005

A low temperature liquid helium level indicator which is capable of detecting the liquid helium level in an opaque Dewar in the temperature range of below 1°K to above 4.2°K is described. A high current electronic switch has been designed so that only one calibration of the instrument is necessary for the entire temperature range.
Scanning Electron Beam Profile Monitor
Authors: Reagan Daryl
Published: February 2005

A scanning beam profile monitor is described that was developed for use along the Stanford 3 km linear accelerator. The maximum beam loss due to scattering caused by this monitor can be made to be a small fraction of that which would be caused by a Čerenkov radiator or scintillating screen.
Transistorized Liquid Helium Temperature Regulator
Authors: Lindsay J. D. G.
Published: February 2005

A transistorized temperature regulator that is capable of controlling the temperature of a liquid helium bath to better than ±10 μ°K for periods of 20 to 30 min is described. The circuit employs a carbon resistor as the temperature sensing element and achieves its temperature control by varying the current supplied to a 200 Ω heater located in the liquid helium bath. Both a null meter and a heater current meter are incorporated in the design so that regulator performance can be continuously monitored.
Automatic Plotting of Conductance and Capacitance of Metal-Insulator-Semiconductor Diodes or Any Two Terminal Complex Admittance
Authors: Shewchun J. , Waxman A.
Published: February 2005

A very important feature of present day semiconductor device technology is the measurement of the complex impedance or admittance characteristics of two-terminal diodes or three-terminal transistors. An electronic technique has been developed to automatically and continuously display the incremental conductance and capacitance of any two terminal nonlinear admittance as a function of applied dc bias over a frequency range 10 cps to 100 kc. The method employs phase sensitive detection to separate the in-phase and quadrature components of the signal generated by a diode under test. Phase angle settings can be made to better than 0.1°. The system can measure over at least five orders of magnitude in admittance, and conductances as low as 0.001 μmho can be detected. The detection sensitivity of the apparatus is 0.0032 μV in a signal-to-noise ratio of 6.5×10−3. The performance of the system is described in terms of actual experimental data that have been obtained on various metal-insulator-semiconductor diodes.
Permittivity Measurements Using Spherical Sample Microwave Scattering Technique
Authors: Keller William C.
Published: February 2005

This paper describes a free space method for measuring the permittivity at X band and higher frequencies over a wide temperature range. Measurements are limited to values of ε′>6 and 10−3<tanδ<0.2. ε′ can be determined to 1 or 2% over a significant range; however, for tanδ the range and accuracy are limited. X band measurements are presented for ZrO2 at room temperature and Al2O3 at room temperature, 1100°C, and 1450°C. Elevated temperature measurements can be performed without heating the microwave components. This method is suitable for use in the millimeter wavelength region. Curves for use in evaluating ε′ and tanδ have been previously recorded by the author [``Values for Scattering by Dielectric Spheres in the Region of the First Resonance,'' NRL Report 6365 (30 December 1965)].
Image Orthicon Slit Spectrograph
Authors: Anderson J. E.
Published: February 2005

A sensitive image orthicon slit spectrograph has been developed for the investigation of aurora and night air glow, particularly with respect to their time changing characteristics. The equipment design meets the following specifications: sensitivity, 20 photoelectrons produce a detectable signal; dynamic range, 200:1; resolution, 5–30 Å; spectrum coverage, 3800 to 8200 Å; and typical exposure required on a just visible aurora, 1 sec, on night air glow, 10 sec.
Identification of Flame Ions by TOF Mass Spectrometry
Authors: King I. R. , Scheurich J. T.
Published: February 2005

A technique is described which permits extraction of ions from a flame burning at atmospheric pressure, and identification of these ions by a time-of-flight mass spectrometer. The sampling system (consisting of a differentially pumped inlet system for rapidly reducing the pressure, a series of ion lenses for collimating the incoming beam, and a grid system for decelerating and bunching the ions as they enter the mass spectrometer) is described in detail, and performace data for the system are presented.
Air Bath Thermostat for Use with Absorption Spectrophotometer
Authors: Gould John H.
Published: February 2005

An automatically controlled absorption cell thermostat with a useful range of from −150 to +60°C is described and has been successfully used with a commercial spectrophotometer (Cary 14). This apparatus accepts ordinary cylindrical absorption cells to 5 cm in length.
Coil Systems for Measuring Conductivity and Velocity of Plasma Streams
Authors: Rossow Vernon J. , Posch Rudolph E.
Published: February 2005

A theoretical and experimental study is made of a device that measures the conductivity and velocity of plasma streams. The instrument consists of a primary coil and several secondary coils. Alternating current through the primary coil produces an oscillating magnetic field in the shape of a dipole. Positions of the secondary coils relative to the primary are such that they respond to distortions of the applied magnetic field of the primary that are brought about by the presence and motion of an electrically conducting fluid. These signals on the secondaries vary linearly with the conductivity and with the product of conductivity times velocity. Various possible coil arrangements and the results of tests conducted with a simple three coil configuration in an electric arc jet are presented. Details of the probe tested, its calibration, and its theoretical basis are described. Results obtained with the three coil system are in good agreement with theory.
Electron Monochromator Design
Authors: Kuyatt C. E. , Simpson J. Arol
Published: February 2005

A study has been made of all the known factors which limit the performance of high resolution (0.07 to 0.01 eV FWHM) monochromators. These limiting factors have been incorporated into design equations for the optimum (maximum current output) monochromator. The conclusions are tested by performance measurements on a prototype instrument. The results require the introduction into the design equation of a new limiting factor, an anomalous energy spread in dense electron beams, which is empirically determined.
Molecular-Beam Sources for Vapor Deposition on field Emitter Substrates
Authors: Gretz R. D.
Published: February 2005

Molecular beam vapor sources suitable for use in high vacuum (10−10 Torr or less) and for deposition of a known flux of vapor in the field electron emission microscope (FEM) are described. The field emitter itself is used as a substrate. Because of the sensitivity of the FEM to contaminants, a vapor source design must be used that will permit (1) establishment and maintenance of a clean FEM pattern during deposition, (2) minimization of metallic mass in the system, (3) reproducible achievement of the required vacuum, (4) flexibility in operation of sources as regards outgassing, loading, and controlling flux, and (5) quantitative determination of the impinging flux. The construction, calibration, and use of four vapor sources are discussed. The methods used to outgas these sources and to load them with an evaporant under high vacuum are given. Movement within the vacuum system to effect loading or transfer operations of the evaporant or source is accomplished by using externally actuated rod magnets. Nucleation of silver on tungsten is given as an example to illustrate the difference in FEM patterns obtained in deposition of silver from vapor with a ``clean'' source and a ``dirty'' source.
System for Fast Temperature Changes and High Temperature Stability
Authors: Boschi Luis A. , Pampillo Carlos A.
Published: February 2005

An apparatus was designed and constructed to attain fast changes in temperature during creep tests. The sample is heated by hot air. A typical SCR electronic circuit of low cost but high reliability was used as temperature controller. It controls 100% of the supplied power, which can reach 4.5 kW. Temperature changes of 15°C were obtained in about 40 sec while the temperature stability was kept within 1°C. The temperature controller was also used in ordinary furnaces with very good results.
Extremely Small and Simple Pulse Generator for Injection Lasers
Authors: Koechner Walter
Published: February 2005

A pulse generator is described for pulsing high power injection lasers at room temperature. The outstanding features of this pulser are the small size, cheapness, and simplicity, combined with the capability of switching several thousand amperes. However, the pulse repetition rate is limited to about 500 pulses/sec. The pulser may be used in optical systems where higher repetition rates are not necessary. Although this pulser was developed for pulsing injection lasers, it can also be used for all applications in need of high power pulses combined with the small size of the pulse generator.
7.7 m Bent Crystal Spectrometer at the 184 Inch Cyclotron
Authors: Crowe Kenneth M. , Shafer Robert E.
Published: February 2005

We describe the design, operation, and calibration of a 7.7 m DuMond geometry bent crystal spectrometer, constructed at the 184 in. Cyclotron for the study of mesonic x rays. The application of crystal diffraction techniques to mesonic x-ray measurements is briefly discussed.
Electrical Resistance of Manganin Coil to 7 kbar and 200°C
Authors: Wang Chi-yuen
Published: February 2005

The electrical resistance of a manganin coil was measured at various temperatures and pressures in the ranges of 20 to 200°C and 0 to 7 kbar. Three useful results were obtained from this study. (1) At elevated temperatures, the resistance of the manganin coil is reproducible with rising and falling pressures. (2) At elevated temperatures, the resistance-pressure curves remain linear. (3) The pressure coefficient changes only slightly with temperature. The present study indicates that the manganin coil may be used as a pressure indicator at elevated temperatures, provided that a convenient correction due to the shift of the resistance at different temperatures is made.
Light Probe for Measurement of Turbulent Concentration Fluctuations
Authors: Nye James O. , Brodkey Robert S.
Published: February 2005

A modified design of a light probe with improved signal-to-noise ratio and reduced sample volume is described and compared to that previously discussed by J. Lee and R. S. Brodkey [Rev. Sci. Instr. 34, 1086 (1963)].
X-Ray Diffraction and Optical Observations on Crystalline Solids up to 300 kbar
Authors: Bassett William A. , Takahashi Taro , Stook Philip W.
Published: February 2005

Diamond anvils driven by a simple piston and screw device have been used to subject solid samples to pressures up to 300 kbar at ambient room temperature. Samples can be examined optically and by x-ray diffraction while under pressure. Pressure is measured by means of the lattice parameter of sodium chloride mixed with the sample. Reflectivity and volume data on iron, as well as crystallographic data on PbS, PbSe, and PbTe, are presented.
Lightweight 50 kG Superconducting Magnet System for Optical Research Instrumentation
Authors: Hawkins S. R. , Harshman J. H.
Published: February 2005

Since the discovery of high field superconductors, it has been possible to generate high magnetic fields with lightweight, compact superconducting solenoids. In most cases, these magnets are operated in conventional liquid helium Dewars which are heavy and unwieldy and usually offer only vertical access to the magnetic field, which makes them very inconvenient for many uses, such as with optical research instrumentation. A system is described in which the magnet and cryostat are integrated into a single light weight package which weighs only 13.6 kg and provides horizontal access to magnetic fields in excess of 50 kG with working bores of 3.80 cm at temperatures near 4.2°K and 2.54 cm at room temperature for periods up to 12 h between fillings. Due to its over-all configuration, the magnetic field is highly accessible and allows spectroscopic measurements to be made conveniently at 50 kG. Also, the system can be easily transported while it is filled with liquid helium.
Use of Crystal Diffraction with Ge Diode Detector for High Resolution Gamma-Ray Spectroscopy
Authors: Smither R. K. , Namenson A. I.
Published: February 2005

The Argonne 7.7 m bent crystal gamma-ray spectrometer is combined with a lithium drifted Ge diode detector to perform high resolution gamma-ray spectroscopy on complicated neutron capture gamma-ray spectra. The system combines the energy precision of the bent crystal spectrometer with the high resolution of the Ge diode. The system is most useful in the 1–3 MeV energy range where both the precision and energy resolution obtained by the combined system frequently are from 3 to 10 times those of either the bent crystal or the Ge diode used individually. A 50-fold improvement in the signal-to-background ratio is obtained through the use of the combined system. The use of the system is illustrated by 113Cd(n,γ)114Cd spectra. The Argonne system is compared with other possible crystal diffraction arrangements and with coincidence and anticoincidence techniques for improving the quality of the (n,γ) measurements. The application of the Argonne system to the comparison of (n,γ) transisions with gamma transitions following radioactive decay is discussed. New values for the strong gamma transition associated with the decay of 137Cs and 60Co are quoted along with a more precise value (1294.35±0.30 keV) for the gamma ray associated with the decay of 41A. Improvements in the Argonne system are described and a proposed extension of the system for precision energy measurements in the 2–5 MeV range is discussed.
Sampling Device for Liquid Droplets
Authors: Nash J. H. , Leiter G. G. , Grimm F.
Published: February 2005

An inertial impaction sampling device was developed for the purpose of collecting samples of liquid droplet clouds dispersed in a wind tunnel. The device is based on Stoker's smoked slide technique, which enables one to determine the diameters of impacting droplets by measuring the diameters of the impressions left in a soot coating on a glass slide. Incorporated into the sampler design is a rotary shutter mechanism which momentarily exposes eleven slides to the droplet cloud. The exposure time of the shutter can be adjusted so that it is commensurate with the density of the droplet cloud.