bluuebunny/crossref_metadata_2025 huggingface dataset:
Noninterrupting Method for Measuring Pulsed Charged Particle Beam Currents
Authors: Lineberger W. C. , Hooper J. W.
Published: February 2005

A noninterrupting method for measuring a charged particle beam current consisting of a series of periodic pulses is presented. The pulsed beam is allowed to pass through a high permeability toroid on which is wound a multiturn coil. If the distance traveled by a beam particle during one pulsing period is large compared with the toroid dimensions, then the voltage induced in the coil consists of a series of impulses, the time integral of each impulse being proportional to the beam current. Since this voltage is equal to that induced in the coil by a one-turn loop wound on the toroid and carrying a current identical to the beam current, it is possible to vary this current, and employ the multiturn coil as a null indicator to indicate equality of the beam and loop currents. If now a capacitor adjusted to resonate with the multiturn coil is placed across the coil, the sensitivity of the null circuit is increased by a factor equal to the Q of the resonant circuit. Using this resonant magnetometer and a 1000-cps chopping rate, currents of 3×10−7 A peak have been measured with an accuracy of ±10−8 A.
Measurement of Magnetic Thin Film Rotational Properties and Uniformity
Authors: Ellis David M. , Bader Clifford J.
Published: February 2005

A previous paper by the authors [Rev. Sci. Instr. 33, 1429 (1962)] described an instrument which relates magnetization vector position in a thin film to rf mixing behavior under a crossed-wire probe. The instrument permits nondestructive observation of small areas of the film and affords high angular resolution. This paper describes provisions for automatically indicating and recording the magnetization angle as the film is traversed by the probe. These provisions extend considerably the usefulness of the instrument in studies of film behavior and uniformity.
Optimization of Particle Injection into a Synchrotron
Authors: Lichtenberg A. J.
Published: February 2005

A technique is developed for obtaining the phase space density distribution within the acceptance of a synchrotron if the distribution of the emittance is known. It is shown that the matching of an injector emittance to a synchrotron acceptance depends not only on the phase space boundary but also on the phase space density distribution. The problem of maximizing the charge accepted by a synchrotron with respect to the initial accelerating voltage is considered. Two cases are treated analytically which, while highly idealized, illustrate the general method and give upper and lower bounds on the voltage. A numerical computation is carried out to obtain the optimum synchrotron voltage at injection for a practical synchrotron injection system.
Apparatus to Measure the Thermal Conductivity of Powders in Vacuum from 120 to 350°K
Authors: Watson Kenneth , Bauman Curtis A.
Published: February 2005

An apparatus, enclosed in a sand-cast aluminum vacuum chamber capable of retaining pressures of 10−5–10−6 Torr, was used to measure the thermal conductivity of powder samples in vacuum. The base of the sample was heated by the temperature bath on which it rested and the top surface of the sample radiated into a cavity which was maintained at liquid nitrogen temperature (77°K). The thermal conductivity of the powders was calculated from the emitted flux, the sample thickness, and the bath temperature.
High Temperature Vacuum Furnace for Diffusion Studies
Authors: Piper Thomas C. , Dyben John
Published: February 2005

A high temperature vacuum furnace using electron bombardment heating has been designed and constructed for studies of diffusion in refractory materials. The furnace is designed to operate in the temperature range of 1200 to 2300°C for prolonged periods of time. The specimen temperature is controlled to ±2°C by a servo system using a thermocouple attached to the specimen crucible for the servo input.
Automatic Synchronous Excitation of Suspended Systems
Authors: Hunt F. V.
Published: February 2005

The sensitivity and the signal-to-noise ratio of electrically deflected measuring instruments, such as magnetometers or galvanometers, can be increased significantly by reversing the exciting current periodically at the fundamental resonance frequency of the suspended system and observing the peak amplitude of the oscillatory dynamic deflection. If these current reversals are made to occur exactly at the midpoints between successive zeros of deflection, the oscillations of the suspended system will be stably maintained at the resonance frequency with a ratio of dynamic to static deflection of approximately 4/δ, where δ is the logarithmic decrement for free oscillation. This note describes electronic apparatus devised for controlling automatically the required quadrature timing of the current reversals. The circuits comprise a photocell-actuated Schmitt trigger, a bistable flip-flop, a timing capacitor, and a voltage comparator. Small timing errors due to finite slit width and hysteresis in the voltage comparator are of opposite sense and can be made to cancel.
Solid-State Detectors for Beta-Ray Spectroscopy below 4.2°K
Authors: Chin J. , Hirshfeld A. T. , Hoppes D. D.
Published: February 2005

Surface barrier detectors operated at temperatures below 4.2°K are found to be sensitive to beta radiation throughout the volume of the silicon wafer and to give good resolution for conversion electrons (8.3 keV FWHM at 482 keV). The pulse height and resolution for a 1-mm-thick wafer are found to improve slightly with increasing reverse bias in the region of 300 to 530 V.
Integrating Video Microdensitometer
Authors: Will G. , Nolden H. W. , Dickey V. F.
Published: February 2005

A sensitive integrating microdensitometer for evaluation of diffraction films is reported. The instrument is simple in construction and requires no critical alignment. Contrary to general designs the scanning is done with the receiver by a Vidicon television pickup tube serving both as light sensitive element and scanning device. Circuits for processing the video signal are described.
Surface Balance for Production of Rapid Changes of Surface Area with Continuous Measurement of Surface Tension
Authors: Mendenhall R. M. , Mendenhall A. L.
Published: February 2005

A surface balance is described for production of dynamic changes of area of films adsorbed at a gas-liquid interface. It has been used to demonstrate reduction of surface tension to nearly zero by surface active agents derived from mammalian lungs.
Fast-Neutron Detector with Discrimination against Background Radiation
Authors: Mendell R. B. , Korff S. A.
Published: February 2005

A detector that measures neutrons between 1 and 10 MeV in a mixed background of charged and neutral radiation was developed for use in cosmic-ray studies. The detector consists of liquid scintillator NE213 surrounded by a thin shield of plastic phosphor NE102 for charged particle rejection. Both scintillators are viewed by a single photomultiplier, in an adaptation of the pulse-shape discrimination technique.
Nanosecond Pulse Technique for Multiple Front Studies in Shock Tubes
Authors: Lubin M. J.
Published: February 2005

A technique for the production of well-defined, precisely timed nanosecond pulses of X-band microwave power is described. A system for the investigation of extremely fast electron density fronts in shock tubes is outlined utilizing the transmitted and reflected pulses generated by this technique. The transmitted and reflected pulses are displayed on a 2000-Mc, rastered oscilloscope.
Refractive Index Monitor Employing Fresnel's Principle
Authors: Conlon R. D.
Published: February 2005

An instrument is described, based on the reflectance principle of Fresnel, which will monitor the refractive index of a stationary liquid or moving stream. The device uses a unique ``rod prism'' optical system which serves as collimator, prism, and optical bench. Advantages of the device are high sensitivity, low cost, and simplicity of construction. Applications have been made to column chromatography, liquid-liquid chromatography, fractional distillation, reaction kinetics, and process stream monitoring.
Camera for X-Ray Diffraction Topography
Authors: Spencer W. J. , Brown E. J.
Published: February 2005

A simple camera designed to obtain x-ray diffraction topographs of single crystals is described. The extinction technique, as developed by Lang, to study dislocations and other structural imperfections, is used. Topographs of silicon and quartz are shown. The dislocation image widths in a (220) diffraction from silicon are about 20 μ.
Bright-Field Bubble Chamber Illumination Using a Beaded Reflective Screen
Authors: Powell Wilson M. , Oswald Larry , Griffin Gary , Swartz Frank
Published: February 2005

Bright-field illumination using a beaded reflective screen is accomplished in the 30-in. heavy liquid bubble chamber by using separate light sources for each lens. The resolution obtainable is about four times as great as with dark-field illumination.
Radio-Frequency Bridge for Pulsed Nuclear Magnetic Resonance
Authors: Lowe Irving J. , Barnaal Dennis E.
Published: February 2005

A symmetrical rf bridge for pulsed nuclear magnetic resonance experiments is described. The bridge is non-microphonic and permits the quick damping of the transients from rf driving pulses without the degrading of free induction decay signals.
100-Mc Digitron—A Digital Time Analyzer
Authors: Lundy R. A.
Published: February 2005

An instrument is described which measures microsecond time intervals by counting pulses from a 100-Mc CW oscillator; a commercially available scaler is employed as the major component. The over-all differential non-linearity of the instrument is ≤10−2. Data are stored in a magnetic core memory. The deadtime associated with measurement and storage has been minimized to permit use in experiments with pulsed accelerators.
Vapor Sources for Vacuum Deposition of Superconductive Thin-Film Circuitry
Authors: Learn Arthur J. , Spriggs R. Spencer
Published: February 2005

Radiatively heated ovens have been used as vapor sources for vacuum deposition of superconductive films, primarily tin and lead. They delivered uniform deposition rates in the entire range tested from tenths of angstroms per second to ∼100 Å/sec. For the experimental arrangement employed, a deposition rate of 1 Å/sec is found by calculation to correspond to an effusion rate from the oven of 2×10−5 moles/cm2/sec. By effectively reducing the length of the oven opening to zero and increasing the ratio of oven diameter to opening diameter to about four, emission characteristic of a surface source was obtained for the same range of deposition rates. For one such oven of typical dimensions, a chart is included by use of which compromise may be made between effective source enlargement, due to self-scattering effects at the source, and deposition rate.
Automatic Neutron Diffractometer for Three-Dimensional Structure-Factor Determination
Authors: Arndt U. W. , Willis B. T. M.
Published: February 2005

This fully automatic single-crystal diffractometer employs the Eulerian hoop geometry. It is under punchedtape control and the three independent shafts are set simultaneously for each reflection to an accuracy of 0.03° using a moiré fringe positioning system. The reflection is then measured by moving the crystal in steps across the reflecting position. The time on each step is variable, being determined by a monitoring counter, and the number of steps is under program control. Results are both printed in plain language and punched on a paper tape, ready for direct processing in a computer.
Frequency-Swept and Proton-Stabilized NMR Spectrometer for all Nuclei Using a Frequency Synthesizer
Authors: Baker Edward B. , Burd L. W.
Published: February 2005

The high-resolution proton-stabilized, and frequency-swept spectrometer of Baker and Burd was limited to proton spectra. A modification of this instrument suitable for all magnetic nuclei is described, based upon the use of a Rhode and Schwarz frequency synthesizer. This modification provides generation and detection of an unmodulated signal at the frequency of another nuclear species, while retaining the features of proton stabilization and precalibration on a frequency scale of the older instrument. Frequency scans from 10 cps to 2 kc may be shifted in precise increments by means of crystal oscillators and the lock-on features of the synthesizer. In going from one nuclear species to another, ratios of magnetogyric ratios are given automatically to high precision. Examples of spectra are given.
Inexpensive 50 000 Pictures Per Second Framing Camera
Authors: Wadsworth J. , Stokes F. E.
Published: February 2005

A framing camera has been built based upon a very simple image multiplier. The image multiplier consisted of two layers of ¼-in.-diam glass rod (glass blowers' cane) crossed at right angles. At each intersection a real image of the event was produced. A 6×6 in. image multiplier produced some 576 separate images of the event. A transfer lens allowed these images to be projected on to a sheet of 8×10 in. film. A Nipkov disk was used to scan the image multiplier to produce a framing sequence up to a rate of 50 000 pictures/sec. It was considered that this framing rate could easily be extended beyond 106 pictures/sec using a Jacob's optical focal plane shutter. The camera has the faults of parallax and optical distortion, but in the present application of the camera these are minimized by using a grid stationed at the event. It is considered that the camera is superior to those based upon image dissection devices. The camera was designed to be continuously available for approximately 3 msec, and was fitted with a crudely synchronized shut-off shutter to prevent overwriting when used in the present application.
Design of Low Voltage Electron Guns
Authors: Simpson J. Arol , Kuyatt C. E.
Published: February 2005

It is shown that by use of a multistage technique in which electrons are drawn from a cathode by a high potential and decelerated to the required final energy, guns can be designed capable of forming beams in which the current is limited only by space charge in the beam itself. The design principles and procedures are given and illustrated by two examples of electron guns giving highly collimated beams and operating at energies of 30 and 500 eV. The measured currents obtained are somewhat greater than the space charge limited beam maximum because of ion neutralization.
Quartz Crystal Thermometer for Measuring Temperature Deviations in the 10−3 to 10−6 °C Range
Authors: Smith W. L. , Spencer W. J.
Published: February 2005

Measurement of temperature deviations in the 10−3 to 10−6°C range has been made, using a specially designed 5-Mc quartz crystal unit. The crystal unit consists of a 5° Y-cut crystal plate in a glass bulb. The oscillator is a Pierce-type transistor circuit similar to those presently in use in ground station frequency standards. The crystal units have a temperature-frequency coefficient of approximately 80 parts per 106/°C. The crystal Q is of the order of 3 million, and the oscillator has a short time stability of 3 pp 1010, giving a temperature sensitivity of 3.8×10−6°C for periods of the order of 10 sec. To measure temperature deviations of a few microdegrees requires the ability to measure frequency deviations of a few parts in 1010. However, to measure temperature deviations of a few tenths of a millidegree, it is necessary only to measure frequency deviations of a few parts in 108.
High Temperature Furnace with a Sharp Temperature Gradient
Authors: Lewis J. , Huang S.
Published: February 2005

A high temperature furnace with a sharp temperature gradient has been designed and constructed. A maximum temperature gradient of 2550°F/in. was obtained. The versatility of this design may permit many uses in materials research. Its capability of growing a silicon-iron single crystal was demonstrated.
Response of Semiconductor Detectors to Fission Fragments
Authors: Britt H. C. , Wegner H. E.
Published: February 2005

Measurements with a Cf252 spontaneous fission source have shown that semiconductor detectors exhibit a pulse-height defect for fission fragments, and that this defect is greater for the low-energy, heavy-mass group than for the high-energy, light-mass group. It has also been shown that the defect decreases with increasing bias voltage or average electric field strength within the depletion region. However, for a given electric field strength, the defect was found to be approximately independent of the type and resistivity of the detector. These results are consistent with the hypothesis that the pulse-height defect arises from an inability to collect all of the hole-electron pairs in the dense plasma produced by an energetic fission fragment.
Inductance Potentiometer Measuring Piezo-Susceptibility
Authors: Broersma S.
Published: February 2005

The para- and ferromagnetic susceptibility has been determined at 500 bar hydrostatic pressure by placing a hollow Delrin rod with sample and oil inside a mutual inductance device. In a single test case the plastic and O-ring connections could withstand 1000 bar pressure. The effect of a displacement of the sample by the pressure is diminished by using secondary coils containing a light middle section and two heavy end sections. The actual potentiometer consists of a small resistance in series with the primary coil shunted by resistance decade boxes as voltage divider. This provides a linear scale. Three of these dividers are connected through a large resistor, for the loss voltage, or a small condenser, for the induced voltage, to a fixed but adjustable resistance in series with the secondary coils. The three bridges are placed in parallel. The sensitivity of the mutual inductance potentiometer is 3 μμH. Ferric polysaccharides with a mass susceptibility ranging from (230 to 7200)×10−6 have been investigated. The piezo-susceptibility, defined as σ=(χ−χ0)/χ0p, is about −25×10−6. For ferromagnetic samples σ≈2×10−6 bar−1.
Ultra-High Vacuum Use of Bayard-Alpert Ionization Gauges
Authors: Hartman Thomas E.
Published: February 2005

Comparisons are made between the collected ion current vs electron emission current for a ``nude'' gauge (Veeco BGT-75) and a glass enclosed gauge (Veeco RG-75) both of the Bayard-Alpert type. The ion current is directly proportional to the electron current for the nude gauge, when the electron current is 100 μA or less, down to ion currents as low as the x-ray limit of the gauge which is 3×10−10 Torr. Good agreement between the glass and nude gauges is obtained over the limited range of electron currents where the glass gauge exhibits proportional behavior. A getter-ion pumped ultra-high vacuum system was used for the experiments.
Phase-Lock System for the General Radio 1209-B Oscillator
Authors: Andresen H. G.
Published: February 2005

Design parameter and performance of a simple automatic phase-control system for a GR 1209-B triode oscillator are described. The frequency modulation of the oscillator was achieved by varying the B+ voltage of the oscillator tube, so that the resonance circuit does not have to be modified, and the described system will change neither the frequency range nor the calibration of the GR 1209-B oscillator.
Sensitive Automatic Torque Balance for Thin Magnetic Films
Authors: Humphrey F. B. , Johnston A. R.
Published: February 2005

An automatic torque balance has been constructed for use in studying the magnetic properties of thin ferro-magnetic films. The automatic servo force balancing technique using a photoelectric pickoff has been applied to a fused-silica torsion fiber suspension. A sample up to 600 mg in weight can be handled. The data are automatically recorded by an X-Y plotter. Sensitivity of 10−6 dyn-cm and a response time of a fraction of a second have been obtained, providing a significant improvement over similar instruments previously used. An appropriate set of coils provides the magnetic field H. Since the torque on a sample is given by M×H=L, measurement of torque affords a means of studying the behavior of the magnetization M. Provision is made for observing torque either parallel or perpendicular to the film surface. The sensitivity available will permit the study of 1-cm-diam films as thin as one-half an atomic layer under ideal conditions. Examples are given of the measurement of the saturation magnetization, remanent magnetization, anisotropy constant, and coercive field on a 35-Å film, showing the quality of the data. The anisotropy field and the squareness are calculated from the above quantities. Observations of rotational hysteresis loss are also discussed.
Angular Modulation of the Magnetic Field in Electron Paramagnetic Resonance Experiments
Authors: Dorain Paul B. , Locker Donald
Published: February 2005

An analysis of the use of angular modulation of the dc magnetic field used in electron paramagnetic resonance is presented. The equations which are derived show that angularly dependent paramagnetic resonance lines may be separated from angularly independent lines. Experiments with Cr2+ in CdS show agreement with the theory.
Achromatic Magnetic Mirror for Ion Beams
Authors: Enge Harald A.
Published: February 2005

A new type achromatic or nearly achromatic deflecting magnet for ion beams is discussed in this paper. The magnetic field in the x-y (median) plane is given by B=0 for x<0 and Bz=Gxn for x>0. The particles enter the field through the origin at an angle α with the x axis, go through a loop of 180°+2α, and leave the field by again crossing the y axis at the origin or close to the origin. Several cases are studied with the field exponent n=1 or close to unity and with deflection angle 270°(90°) or nearly so.
New Design for a Gas-Flow Proportional Counter
Authors: Riggs F. Behn
Published: February 2005

This paper describes a compact design for a gas-flow proportional counter. Externally adjustable end plates for correcting the electric field allow pulse-height distribution curves comparable with those from long counters, although the counting volume is 1¼ in. in diameter and 1116 in. long. A transistorized preamplifier inside the counter case provides clear pulses with low background in a low impedance line. The gas-flow proportional counter described here has three significant features: (1) low noise, approximately 1% of the Fe Kα pulse height; (2) low impedance output from the first preamplifier; (3) energy spread less than 20%, in spite of short length and large diameter.
High-Volume Sampler for Atmospheric Carbon Dioxide
Authors: Fergusson Gordon J.
Published: February 2005

A new sampler that has been successfully used in jet aircraft for collection of atmospheric carbon dioxide at altitudes up to 50 000 ft is described. The sampler uses type 4A molecular sieve to absorb the CO2 and will quantitatively absorb the CO2 from air flowing through the sampler at rates up to 500 liters/min. Ten liters of CO2, which is sufficient for accurate C14 measurements, can thus be obtained in one hour.
Improving the Tunnel Diode Univibrator
Authors: Whetstone Albert L.
Published: February 2005

Experience has shown that nanosecond logic operations such as fan-in, fan-out, coincidence, and pulse discrimination can be performed with tunnel diode univibrators with a resulting economy and simplicity. A method of reducing or controlling the deadtime of the univibrator is presented with the result that the logic operations can be carried out on pulse pairs spaced well under 10 nsec.
Etch-Shadow Extraction Replica in Fracture Studies
Authors: Banerjee B. R. , Hauser J. J. , Capenos J. M.
Published: February 2005

A new replica technique for electron microscopy of fracture surfaces is described, which can reveal the relationship between the microstructural features of metals and alloys and the detailed topography of their fracture surfaces. This etch-shadow extraction replica technique combines in one replica the salient features of shadowed-surface replicas and precipitate-extraction replicas. Thus a bridge is provided between the fracture topography, which is governed mainly by the effects of fracture-velocity changes, and the significant microstructural features such as precipitates, grain boundaries, etc.
Device for Measuring Orbital Velocities of Particles in an Underwater Wave Field
Authors: Beardsley G. F. , Knollman G. C. , Hamamoto A. S. , Eisler J. D.
Published: February 2005

A flowmeter is described which has been designed and constructed for the purpose of determining planar orbital velocities of particles in an underwater wave field. The instrument responds primarily to hydrodynamic drag force and is relatively insensitive to fluid-acceleration forces. Orbital speeds of from 1 to at least 40 in./sec can be measured, and flowmeter response is independent of orbital frequency up to several cps. Flutter tendencies and spurious effects, perhaps attributable to vortex shedding, have been suppressed. Typical results are cited of experimental observations using the orbital velocimeter under wave action within an oceanographic tank.
Evaporant Sources for the Deposition of Pinhole-Free Films
Authors: Vergara W. C. , Greenhouse H. M. , Nicholas N. C.
Published: February 2005

A new family of sources for vacuum evaporation has been developed for the deposition of pinhole-free films of insulators, semiconductors, and conductors. These sources make use of the fact that a flat plate will scatter particles of molecular size in all directions while reflecting macroscopic particles specularly. This directional separation makes it possible to divert the macroscopic particles away from the substrate. Homogeneous, pinhole-free films can be deposited with these sources at relatively high evaporation rates at close source-to-substrate distances. The use of these sources leads to reproducible films on a high yield basis. The same principle can be used in other applications requiring the filtering of vapors.
Measurement of Internal Friction in Thin Films
Authors: Weiss Gerald P. , Smith Donald O.
Published: February 2005

A technique for measuring internal friction in thin films (∼2000 Å thick) has been developed. The film is deposited onto a 1-μ-thick ribbon of fused quartz having a Q∼5000 and which is clamped at one end. The ribbon and film are set into clamped-free flexural vibration (∼100 cps) and the vibration is monitored by means of a light beam and photocell. The measurement of the vibration decay constant is expedited by using a logarithmic amplifier. Film relaxation peaks with Q∼300 can be measured at temperatures up to several hundred °C. As an example of the use of the technique, the Snoek relaxation of C in bcc Fe has been measured in a 2500-Å Fe film.
Extension of the NBS P2 Chamber Calibration to 260 MeV
Authors: Swanson William P. , Carrigan Richard A. , Goldwasser Edwin L.
Published: February 2005

The NBS P2 ionization chamber has been calibrated for use in bremsstrahlung beams of maximum energy E0 in the range 150–260 MeV, by a pair-spectrometer method, normalized to the previous NBS calibration at E0=170 MeV. The response of the P2–4 chamber at 20°C, and 760 mm Hg, at 149, 199, 229, and 258 MeV was found to be 2.720, 2.514, 2.430, and 2.360 μC/J, respectively, with errors in the range 1.8–2.0%. The calibration of the Edwards-Kerst copper ionization chamber was also checked in this energy range by a comparison method.
Direct Melting-Point Calibration of a High-Temperature X-Ray Camera
Authors: Wilkinson J. D. , Calvert L. D.
Published: February 2005

Detailed measurements in a high-temperature x-ray camera have shown that optical observations in polarized light of the melting of suitable specimens in silica capillaries provide a satisfactory temperature calibration with an internal consistency of ±1°C. The measurements covered the range from room temperature to 800°C. The thermal gradients within the specimen were also measured. These were reduced from 7 to 2°C (at 600°C) by a simple radiation shield. Calibration against the lattice spacings of a silver specimen (consistency ±2°C) was not suitable in the present case and would only be valid if conductivity and emissivity differences between standard and specimen were absent. The use of a movable thermocouple gave erroneous results.
Improved Counterbalanced Sphere Viscometer for Use to 1750°C
Authors: Riebling E. F.
Published: February 2005

An improved counterbalanced sphere viscometer has been designed for use with molten oxides at temperatures up to 1750°C. It can provide an automatic qualitative and quantitative record of bob velocity during vertical movement. This feature has increased the usefulness and sensitivity of this type of instrument, particularly in the 1- to 100-P range. The instrumentation includes a linear variable differential transformer and recorder as the velocity determining device. A simplified method of correcting density results for surface-tension effects is described. Several additional phenomena associated with the limitations and sensitivity of this type of viscometer are discussed.
Apparatus for Determining the Thermal Conductivity of Solids in the Temperature Range from 20 to 200°C
Authors: Schröder J.
Published: February 2005

A feature of the method described is that it involves neither temperature nor heat-flow measurements. The procedure consists merely of taking a stop-watch reading (over a few minutes) and finding a value on a calibration chart. The two flat ends of a cylindrical sample, about 18 mm in diameter and 1–30 mm in length, are put in contact with two silver plates which are kept at constant temperatures by means of two boiling liquids of suitable boiling points, viz. differing by about 10–20°C. The time is measured in which a quantity of heat flows, in the steady state, through the sample. This quantity is determined very simply by the quantity of liquid evaporated at the ``cold'' end and which is collected as a condensate. In practice, two calibrated samples are measured first and a calibration line is plotted from which the thermal resistance of subsequent samples can be found at a glance. It is then not necessary to know the exact boiling points of the two liquids, nor the absolute amount of evaporated liquid, nor its heat of vaporization. A measurement takes about 15 min and the error is not more than ±3%. The construction of the apparatus and the performance of measurements in the temperature range of from 20 to 200°C are described in detail. Moreover this article shows a new way of measuring the conductivity of very small samples (e.g., small single crystals).
Aluminum Oxide Humidity Element for Radiosonde Weather Measuring Use
Authors: Stover C. M.
Published: February 2005

This article describes a new aluminum oxide humidity sensing element. The element was developed primarily for use in radiosonde weather measuring equipment. It has a fast response over the entire humidity range and through a broad temperature range of −80 to +135°F. By using specially designed testers, measurements can be made which were previously unobtainable. The elements are small and lightweight, can be made inexpensively of readily available materials, and can be mass produced.
Liquid-Gas Film Calorimeter for Deformation of Metals
Authors: Williams R. O.
Published: February 2005

A device has been constructed for measuring the changes in internal energy of metals and alloys during deformation. The basis of the method is the quantitative utilization of the heat released in the sample to vaporize a pure liquid under equilibrium conditions, and measurement of the volume of gas produced. The liquids which have been used are N2, CCl2F2, and CCl3F, having boiling points of −196, −30, and 24°C, respectively.
Color Scheme for Spatial Resolution Using Liquid Scintillators
Authors: Munsee J. H. , Reines F.
Published: February 2005

A detector has been devised which contains in different regions liquid scintillators of different spectral emission characteristics, thus enabling signals arising in those regions to be distinguished from each other. The spatial discrimination so achieved can be applied to problems of low level β− counting in which it is desired to reduce the background due to gamma rays. A study was made of five liquid scintillators, four of which have emission maxima in the range 4310 to 4660 Å and one with its maximum at 3640 Å, and various optical filter-scintillation combinations were tested. The beta, gamma discrimination possibilities of the color scheme were examined in a preliminary manner using C14 as the β− source and Cs137 as the source of gamma rays.
Some Developments of the Discharge Chamber
Authors: Charpak G. , Massonet L.
Published: February 2005

A discharge chamber has been constructed with electrodes of transparent metallic mesh. By the addition of quenching agents, mainly I2 vapor, to noble gases at atmospheric pressure, and the use of pulses of one or several microseconds duration, it is shown that a great number of discharges connecting the two electrodes can develop simultaneously, starting from the ionized path of a particle. Pulses in the microsecond range of 2 to 3 kV/cm are used, thus allowing the easy operation of large sensitive volumes. Tracks of good resolution are observed, with a variation of the luminosity as a function of the primary ionization. Repetition rates up to 104/sec are reached. Sparks following the trajectory of particles inclined at angles of 45° with respect to the electrodes are observed.
High Velocity Drive for Mössbauer Experiments
Authors: Cohen R. L. , McMullin P. G. , Wertheim G. K.
Published: February 2005

A drive capable of producing controlled velocities in excess of 100 cm/sec is described. The drive consists of a loudspeaker ``motor'' coupled to a velocity transducer. Feedback is used to make the velocity follow an input waveform accurately. The system uses standard parts and is easy to build.
Four-Window Cell and Cryostat for High Pressure Studies at Liquid Helium Temperature
Authors: Fitchen D. B.
Published: February 2005

A compact gas high pressure cell for measuring the optical properties of solids at low temperatures under pressures up to 10 kilobars is described. Using helium gas as the pressure-transmitting medium, the pressure is purely hydrostatic at 78°K and nearly hydrostatic at 7–12°K. Techniques are discussed for sealing windows of sapphire for optical studies, of beryllium for x irradiation, and dummy windows for electrical connections. A cryostat which can be accommodated in most recording spectrophotometers is also described.
Simple High Sensitivity Microbalance for Use in Ultra-High Vacuum
Authors: Haller I. , White P.
Published: February 2005

A piezoelectric quartz crystal microbalance, utilizing a commercially available crystal, is described. It is bakeable for ultra-high vacuum use. It has been employed in adsorption studies and for measurement of deposition rates in condensation and polymerization processes.
Semigraphical Solution of Focusing and Transmission of Quadrupole Lens Systems
Authors: Draper James
Published: February 2005

A semigraphical method is presented for evaluating the focusing conditions and the acceptance solid angle of quadrupole lens systems. The method is illustrated for a specific triplet magnetic quadrupole system for which the predictions are confirmed experimentally.
Automatized X-Ray Line Profile Analysis
Authors: Keller H. , Segmüller A.
Published: February 2005

X-ray line profiles are measured fully automatically by means of a preprogrammed step scan. The intensity data are taken by means of the fixed count method and punched into paper tape by an electronic clock. The evaluation of the intensity data and the Fourier analysis of the line profiles is performed on an IBM 1620 computer.
Low Insertion-Loss, Capacitively Scanned Goniometer for Faraday Rotation Measurements in the vhf Range
Authors: Gschwendtner A. B. , Swenson G. W.
Published: February 2005

The theory and design of a low insertion-loss electrical device to simulate a rotating dipole for Faraday rotation measurements in the frequency range 20–60 Mc is discussed. Experiment involving satellite emissions and lunar reflections are described.
Thermoluminescent Dosimeter Reading System
Authors: Kenney G. N. , Cameron J. R. , Zimmerman D.
Published: February 2005

Two instruments have been developed for measuring the thermoluminescence of LiF. The ``clinical reader,'' suitable for routine clinical use, is simple and convenient to use. It has a standard deviation of from 1 to 5% and its components cost approximately $500. The ``research reader'' is more versatile and produces glow curves. Both readers use a 35-mg sample of loose powder and can be used with a variety of thermoluminescent materials.
Zone Refining of Aluminum
Authors: Bratsberg H. G. , Foss D. , Herbjo/rnsen O. H.
Published: February 2005

The procedure of zone refining Super Purity Al is described. The impurity content has been studied by neutron activation and spectrographical means, and the ratio R293°K/ R4.2°K has been measured. The purest material has a resistance ratio of 26 500 in bulk.
Mass Spectrograph for the Analysis of Solids
Authors: Hickam W. M. , Sweeney G. G.
Published: February 2005

A double-focusing mass spectrograph of the Mattauch type has been constructed for the analysis of solids. Operating pressures are achieved by means of ionic and cryogenic pumping. The radio-frequency spark and thermal source are provided for ionizing the sample. Positive- or negative-ion spectra are recorded either photographically or electrically. Instrument performance and experimental results are described. Areas of investigation include the use of O18 pressure in the instrument as an aid in the identification of ionic species, the attainment of a single exposure on the photographic plate containing equivalent information to that conventionally recorded in five exposures, and the utilization of the spark source as a microprobe.
Amplitude Modulation Method for Producing Sidebands in NMR Experiments
Authors: Alexakos Louis G. , Cornwell C. D.
Published: February 2005

The use of amplitude modulation for the generation of sidebands offers certain advantages in NMR experiments, particularly when relatively large modulation frequencies (say above 1 kc) are required. For the Varian 40- and 60-Mc high resolution spectrometers, minor circuit modifications are described by means of which usable sideband signals are produced for modulation frequencies up to 70 kc, with amplitude reasonably constant from 200 cps to 40 kc.
X-Ray Diffractometer Attachment for Direct Observation of Evaporated Thin Films
Authors: Vook R. W. , Schoening F. R. L.
Published: February 2005

An ultra-high vacuum apparatus in which materials can be evaporated onto substrates at various temperatures has been developed. Without breaking the vacuum, x-ray diffraction observations can be made over the angular 2θ range normally used on an x-ray diffractometer. Continuous pumping during evaporation, anneal, and measurement is obtained by use of an ion pump.
Fluorescent-Type Ultraviolet Radiation Detector
Authors: Robinson M. S. , Rumpel W. F.
Published: February 2005

A detector has been developed showing excellent intensity linearity with several phosphors for intensities ranging from 0.2×10−6 to 60×10−6 W/cm2. It is sensitive to radiation wavelengths below 3900 Å or photon energies above 3.2 eV. The wavelength response of several phosphors was determined for the mercury emission lines in the ultra-violet region at 3660, 3130, and 2537 Å. Thermopile measurements of the line intensities were obtained to calibrate the detector output.
Measurement Of Low Resistance and the ac Resistance of Superconductors
Authors: Zar Jacob L.
Published: February 2005

The resistance of highly conductive materials is measured by an induction method that does not require a direct electrical connection to the test specimen. Instead, the test sample is used as a short-circuited secondary winding of a transformer. The method is suited to specimens where lead correction errors would introduce difficulty, or where the temperature or field environment requires that the sample be located at some distance from the instruments. Resistances of the test specimen from 10−5 to 10−2 Ω are suitable for this method. It has been applied to determining the resistance of hard superconductors at 4.2° and at frequencies of 100 to 30 000 cps. Various niobium-zirconium alloys all followed a characteristic resistivity curve with ρ proportional to f0.5 at high frequencies and ρ proportional to f1.7 at f<500 cps.
Isochronal Differential Microcalorimeter
Authors: Arndt R. A. , Fujita F. E.
Published: February 2005

An isochronal differential-type microcalorimeter has been designed and constructed. As a result of its simple design it is very easy to handle the samples and assemble the calorimeter. Important to the operation of the calorimeter is a program, also working on the differential principle, that provides linear temperature rise of the samples. This calorimeter is used to measure very small energy releases such as those found in precipitation, stored energy, etc. It is demonstrated that the calorimeter is easily capable of measuring 0.005 cal with a probable error of the order of 1 to 2%.
Vacuum Ultraviolet Spectrometer
Authors: Alexander E. , Fraenkel B. S.
Published: February 2005

A grazing incidence vacuum spectrometer is described. It is based on a 2-m, 30 000-lines/in., Siegbahn glass grating. Both plate holder and grating are held on arms fastened to the axis of the Rowland circle. The wavelength range extends up to 2300 Å. Instrumental considerations for obtaining high resolution in the short wavelength range are discussed.
High-Field Liquid H2-Cooled Aluminum-Wound Magnet
Authors: Purcell John R. , Payne E. G.
Published: February 2005

A high-field magnet using high purity aluminum for the conductor and cooled by forced circulation of liquid hydrogen is described. Within the bore of 3 in. i.d. by 5.7 in. long a maximum field of 70 kG is attained with a total electric power expenditure of 9 kW.
Relative Intensity Measurements in Microwave Spectroscopy
Authors: Esbitt Alan S. , Wilson E. Bright
Published: February 2005

A method is described for the measurement of peak intensity ratios of gas phase microwave absorption lines. Large errors associated with multiple reflections in the waveguide have been eliminated by careful design and the use of ferrite isolators. Detector nonlinearities have been neutralized by using a precisely calibrated step attenuator allowing both lines involved in a ratio to be displayed with approximately the same amplitude. Means of minimizing additional sources of error are discussed. Application of the method to a number of problems indicates that ratios accurate to a few percent can be obtained.
Radio-Frequency Excited Plasma Tunnel for Laboratory Studies of Supersonic Plasma Flow Fields
Authors: Carswell Allan I.
Published: February 2005

A description is given of a supersonic, low density plasma tunnel employing rf excitation of the gas stream. The facility, which has been designed to be of laboratory proportions, provides clean, supersonic plasma streams at velocities up to about Mach 2. The static stream pressures available are in the range from about 0.1 to 10 Torr and jets up to 2 or 3 cm in diameter are produced. A discussion of the important design features is given and the application of this facility to several studies of supersonic plasma flow fields is described.
Retractable Low Temperature Targets for High Energy Physics Experiments
Authors: Chambers B. , Hofstadter R. , Marcum A. , Yearian M.
Published: February 2005

A system is described which allows as many as five different low temperature targets to be positioned vertically inside a vacuum system. The targets normally contain liquid hydrogen or deuterium. The vertical travel is obtained by using a bellows system in such a way that the over-all external height of the system is constant. A maximum travel of 4 in. can be obtained.
Electronic Variable Delay for Tracing Characteristic Curves of Coincidence Circuits and Time-to-Height Converters
Authors: Birk Meir , Kerns Quentin A. , Nunamaker Thomas A.
Published: February 2005

Automatic tracing of characteristic curves of coincidence circuits and time-to-height converters has been accomplished by utilizing a tunnel diode circuit, which provides an electrically controlled time delay continuously varying from 30 to 65 nsec. An input pulse starts a current ramp through the tunnel diode, which generates an output pulse on triggering. The moment of triggering, however, is programmed by a control voltage which dictates the instantaneous value of the initial current flowing through the tunnel diode. Measurements of the delay vs control voltage relationship show no deviation from linearity greater than the experimental error of ±15 psec. Time jitter, characterized by the full width at half-maximum of the output-pulse time distribution, is less than 30 psec. A coincidence resolution curve displayed on the screen of an oscilloscope and a height-vs-time curve of a time-to-height converter traced by an X-Y recorder are shown.
Device for the Measurement of Friction at Ultrahigh Vacuum
Authors: Brueschke E. E. , Eckman B.
Published: February 2005

A friction measurement device has been developed which permits continuous measurement of static and kinetic coefficient of friction at ultrahigh vacuum. Sliding motion inside the vacuum chamber is accomplished by using a disk rotated by a zero-leakage, direct-drive rotary seal. The coefficient of friction is measured using a strain-gauge system which is compatible with the ultrahigh vacuum test environment. An example of the type of results obtained with the device is given. The apparatus has been continuously operated at pressures in the 10−10 Torr region.
Electrodeless Determination of Electrical Conductivities of Melts at Elevated Temperatures
Authors: Yosim S. J. , Grantham L. F. , Luchsinger E. B. , Wike R.
Published: February 2005

An electrodeless method for measuring the electrical conductivities of metallic and semiconductor melts at elevated temperatures is described. The transformer ``eddy current'' method, which was capable of measuring conductivities from one to greater than 10 000 (Ω-cm)−1, was used. The system was calibrated with Hg at 25°C and tested with Hg to 300°C and Bi to 550°C. The specific conductivities of various compositions of Bi–BiI3 solutions were measured at 500°C and compared with those measured by an electrode method. The accuracy of the method decreased with decreasing conductivity.
Microwave Power Leveler for K Band
Authors: Rinehart Edgar A. , Legan Robert L.
Published: February 2005

A device has been developed for regulating milliwatts of microwave power in the 24-kMc region. The power leveler has been shown to operate over the electronic sweep range of a K-band reflex klystron, and to regulate power to within ±0.5%.
Compressed Gas Gun for Controlled Planar Impacts Over a Wide Velocity Range
Authors: Thunborg S. , Ingram G. E. , Graham R. A.
Published: February 2005

A description is given of the mechanical characteristics and performance of a compressed gas gun capable of accelerating precisely aligned flat-faced projectiles over a wide velocity range. Predetermined reproducible velocities may be achieved between 150 and 5700 ft/sec with an angular misalignment between the impacting surfaces as small as 1.3×10−4 rad. The impact occurs in a vacuum with pressures as low as 10−4 mm Hg. The gun has an inside diameter of 2½ in., a length of 100 ft, and uses either air or helium at pressures as high as 5000 psi. The gun is particularly suited for experiments in which a well-defined impact is desired.
Injection of Intense Neutral Beams into a Tandem Accelerator
Authors: Wittkower A. B. , Rose P. H. , Bastide R. P. , Brooks N. B.
Published: February 2005

A single-stage tandem accelerator, which utilizes the principle of neutral-beam injection, is described. Ten microamperes of high energy negative hydrogen ions have been obtained. These ions may be injected into a second twostage tandem accelerator, thus obtaining higher energies for nuclear studies. By reversing the polarity of the injector terminal, positive hydrogen ion currents in the 100-μA range have been obtained.