bluuebunny/crossref_metadata_2025 huggingface dataset:
Mattauch-Herzog Type Mass Spectrograph with Corrected β-Dependent Image Defects for All Masses
Authors: Takeshita Isao
Published: February 2005

An earlier work on a Mattauch-Herzog type mass spectrograph with a two-stage electrostatic field is extended to investigating the conditions for simultaneous elimination of αβ and β2 aberrations for all masses. In the course of study, the condition for obtaining a real image of ion source between two electrostatic fields is abandoned, and by this extension two series of solutions are found in neighborhood of φe2=π/√2. The design parameters are numerically computed and tabulated for several examples. The α2 aberrations are calculated and the total image defects are evaluated and found to be very small for a wide mass range.
Measurement of Strain and Velocity of Ultrasonic Surface Waves
Authors: Serafin R. J. , Fryberger D. , Epstein M.
Published: February 2005

A technique for the measurement of velocity and strain of acoustic surface waves is proposed. It utilizes very thin vacuum deposited conductors in an applied magnetic field, which permits an unimpeded evaluation of the strain, velocity, and power of a propagating ultrasonic surface wave. The proposed method of measurement is simple and accurate. An example of a 10 MHz surface wave on glass is utilized to illustrate the measurement of particle velocity and power density of the longitudinal component of the wave.
500 MHz Ring Counter
Authors: Tan Z. C.
Published: February 2005

This paper describes a new tunnel diode-transistor ring counter employing current mode operation. With suitably shaped input pulses it is capable of operating reliably at input repetition rates in excess of 500 MHz.
Elastic Strain Measurement in the Interior of Crystalline Materials by Means of X-ray Diffraction
Authors: Bainbridge D. W.
Published: February 2005

A new technique is described which provides for the study of x-ray diffraction from a small selected region in the interior of a body. The method is of particular value for the measurement of interior elastic strain and will permit the complete evaluation of a triaxial state of stress. The collimation is appropriate for studies of either single crystals or polycrystalline material. Evaluations on single crystals of LiF with Mo Kα1 demonstrate that a conventional line x-ray source provides useful diffracted power from a crystal volume of less than 10−4 cm3 located at a depth below the surface exceeding 0.3 cm. A strain reproducibility of better than 2×10−5 was attained in measurements at several depths in an unstrained crystal, and elastic strain evaluations were made through the thickness of a single crystal beam loaded in four-point bending.
Gravity Gradiometer Computer Model for Simulated Gradient Contour Mapping
Authors: Berman David
Published: February 2005

Considerations for gravity gradiometer application have established the need for predicting gradiometer response to mass distributions of particular interest. A digital computer program has been developed to simulate the rotating gravitational mass sensor, and to map the gradient contours of the gravitational field created by an arbitrary mass distribution. This analysis demonstrates the interaction of the gradiometer with seond and higher order gravitational gradients. The information about the mass distribution of an object was found to increase with the gradient order. Considered in this study is the ``cruciform'' mass sensor, now being developed by Hughes Research Laboratories. This rotating gradiometer is theoretically capable of measuring the second, sixth, tenth, etc., order gradient. We are presently engaged in laboratory experiments which combine with these computer results in the understanding of gradient-sensor interaction. This paper gives a basic introduction to gravitational tensors, followed by a mathematical formulation of the gradiometer model. Computer results are included which demonstrate the gravitational gradient contours associated with some selected mass distributions.
High Precision Magnetic Float Densimeter
Authors: Millero Frank J.
Published: February 2005

A simple, versatile, magnetic float densimeter that can be used to measure the density of liquids as a function of temperature is described. The system has been calibrated with water from 20 to 50°C demonstrating a sensitivity of 0.3 ppm and a precision of 2 ppm. The accuracy of the densimeter has been verified by measuring the densities of NaCl solutions at 25°C. Excellent agreement with previously published data was achieved.
Detection Efficiency of a Continuous Channel Electron Multiplier for Positive Ions
Authors: Burrous Clifford N. , Lieber Albert J. , Zaviantseff Vladimir T.
Published: February 2005

The relative detection efficiency of a curved continuous channel electron multiplier has been measured for H+, H2+, 3He+, 3He++, He+, Ne+, and A+ ions over a 500-eV energy range. The detector's efficiency is presented as a function of the incoming ion's energy, velocity, and degree of ionization. Preacceleration was employed to reduce the falloff in efficiency for energies below 3 keV.
Preparation of Thin Foils for Electron Microscopy by a Rotating PTFE Holder
Authors: Caplan Ivan L.
Published: February 2005

An improved disk electropolishing technique, developed for the preparation of thin foil electron microscope specimens, eliminates the problem of premature perforation of specimens. Its rotating holder design prevents gas bubble adherence while maintaining low-voltage, low-temperature operation.
High Level NQR Spectrometer
Authors: Gill D. , Hayek M. , Alon Y. , Simievic A.
Published: February 2005

A regenerative autodyne wired as a cathode biased grid-dip-meter is equal to Wang's spectrometer [Phys. Rev. 99, 566 (1955)] in sensitivity and far superior in reliability. Detailed description of an autodyne used in chlorine NQR is presented.
Monochromator for the Extreme Ultraviolet
Authors: Jaklevic R. C. , Leblanc L. J. , Juenker D. W.
Published: February 2005

The off-plane Eagle mounting has distinct advantages over other types in the construction of grating monochromators for the extreme ultraviolet. A description is given of an adaptation of that principle, employing a Rowland grating movement and a simple drive mechanism to achieve good resolution with little mechanical complication. Differential pumping in three stages allows operation without windows and still attains pressures in the 10−9 Torr range in the measuring chamber.
Glass Bellows Manometer for Ultrahigh-Vacuum Devices for a Range of 1 to 760 Torr
Authors: Boschi Luis A. , García Eduardo A.
Published: February 2005

A thoroughly bakeable Pyrex glass bellows manometer has been made. It has the precision of a mercury one, and also the advantages of low cost and easy construction. The bellows displacement is measured photoelectrically.
New Automation Technique for Constant Velocity Mössbauer Spectrometers
Authors: Knauer Robert C. , Mullen James G.
Published: February 2005

A new technique for automating a Mössbauer mechanical spectrometer is described, which permits arbitrary velocity increments to be programmed on a tape prior to data collection. This novel feature permits optimum efficiency in accumulating data and allows considerable flexibility in measuring particular lines in a Mössbauer spectrum. The system is completely automated and does not require the use of a multichannel analyzer. The velocity stability and uniformity of the complete automated system described was better than 0.1%, and the measured line width for 57Fe in a thin absorber was only 10% greater than the theoretical limit.
Calorimeter for Simultaneous Measurement of Thermal Properties and Dimensional Changes
Authors: Antoniou A. A. , Litvan G. G.
Published: February 2005

A calorimeter is described for the simultaneous measurement of the heat capacity and length changes of absorbent-adsorbate systems between +25 and −45°C. The heat capacity of sodium chloride between 0 and −28°C is given and is found to agree with previous results within 0.6%. The calorimeter is also suitable for studies of heats of adsorption and solid state reactions such as hydration and phase transition.
Closed-Cycle Refrigeration at 1.85°K
Authors: Collins S. C. , Stuart R. W. , Streeter M. H.
Published: February 2005

The growing need for refrigeration at temperatures below the boiling point of helium—particularly to maintain superfluid helium in a superconducting linear accelerator for long periods of time—has led to the development of a closed-cycle refrigerator in which the refrigerative powers of the helium vapor at pressures as low as 0.02 atm can be utilized. Effective use of the cold vapor in a heat exchanger makes possible a several-fold increase in the capacity of a refrigerating system, as compared to conventional open-cycle techniques.
Fast Vacuum-uv Light Source for Gas Phase Flash Photolysis
Authors: Welge K. H. , Wanner J. , Stuhl F. , Heindrichs A.
Published: February 2005

A flash photolysis device is described which makes irradiation down to the LiF-cutoff (∼1100 Å) in long reaction vessels feasible. The number of quanta per flash entering the reaction cell between ∼1100 and 1400 Å and ∼1100 to 1650 Å is measured by chemical actinometry. The light pulse has a 1/e duration of less than 2 μsec, largely independent of the discharge energy and the length of the light source.
Pyroelectric Laser Calorimeter
Authors: Astheimer Robert W. , Buckley Robert E.
Published: February 2005

A laser calorimeter has been developed based on the pyroelectric effect. This radiation sensing mechanism is independent of the temporal and spatial distribution of incident energy. Calibration with sources of known power and comparison with other methods of measurement indicate an absolute accuracy of better than ±5%.
Helium Vapor Cooled Current Leads
Authors: Efferson K. R.
Published: February 2005

A new technique is described for constructing vapor cooled leads used to introduce electrical currents into liquid helium. Using this method, leads can be constructed to carry optimum currents ranging from low values (less than 100 A) to very high values (several thousand amperes). The current carrying elements are small (No. 38) silver-plated copper wires woven into the shape of cylindrical tubes (i.e., electrostatic shielding). This fine division of the current carrying elements allows very good heat exchange with the helium boil-off gas. Helium losses are approximately 2.71×10−3 liter/h A for a pair of leads operating at the optimum current.
Improved Method of Measuring X-Ray Tube Focus
Authors: Parrish William
Published: February 2005

The intensity distribution and dimensions of the x-ray tube focus can be recorded accurately and rapidly by scanning with a pair of molybdenum rod slits and a scintillation counter. Two methods were used: (1) the image-forming slit mounted near the x-ray tube remains fixed and the image is scanned with another slit mounted on the detector; (2) both slits and detector are translated as a unit across the focus. The vignetting was analyzed and can be made negligible in both methods. Magnification of the image is not possible with method (2), but it has the advantage of minimum vignetting and easier alignment.
Fast Carbon Bolometer for Observing Thermal Pulses
Authors: Cannon W. C. , Chester M.
Published: February 2005

A carbon bolometer, used as a high speed thermometer for observing heat pulses in solids at low temperatures, is described. In conjunction with a KCl substrate, the carbon bolometer was compared with a thin film superconducting bolometer. The carbon bolometer was found to have a frequency response flat to at least 2.5 kHz.
Effect of High Pressure On a Strain Gauge Load Cell
Authors: Hanafee J. E. , Radcliffe S. V.
Published: February 2005

A load cell employing foil strain gauges is described for measuring small uniaxial loads (5×104 to 2×106 dynes) applied magnetically to develop bending stresses in crystals under hydrostatic pressures up to 15 kbar. Two calibration methods of direct loading at pressure were used—a magnetically operated plunger and dead weight loading. It was established that the change in gauge output (the ``pressure effect'') during increase of pressure at no-load is in keeping with previous work. However, the gauge factor, as determined by the load cell response after balancing at pressure, decreases with increasing pressure. For the strain gauges used here, the decrease is approximately linear and at 10 kbar is as much as 20%.
Plane Layer Type Apparatus for Gas Thermal Conductivity Measurements
Authors: Teagan William P. , Springer George S.
Published: February 2005

A simple plane horizontal layer type apparatus is described for measuring thermal conductivities of gases over a wide pressure range. Experimental results obtained with argon, nitrogen, and air indicate that thermal conductivities and thermal accommodation coefficients can be determined with the apparatus within about 2% accuracies at pressures ranging from free molecule to continuum conditions.
Focusing of Charged Particles with Hemispherical Grids
Authors: Reynolds R. , Scherb F.
Published: February 2005

A theoretical analysis has been carried out to determine the trajectories of charged particles incident upon a pair of concentric spherical grids, where the inner grid is maintained at a large accelerating potential with respect to the outer grid. The results show that under certain conditions a beam of charged particles incident on the outer grid is sharply focused inside the inner grid. These results were confirmed experimentally using hemispherical grids and electron beams.
New Microwave Interferometric Device Using Lecher Wires for High Spatial Resolution
Authors: Makios W.
Published: February 2005

The following describes a Lecher system with finlines for providing the transition to waveguides which is suitable for incorporation in microwave interferometers. This device gives a spatial resolution perpendicular to the wires which is smaller than the wire separation, even for 4 mm waves, i.e. smaller than λ/2.
Four-Stage Mass Spectrometer of Large Radius
Authors: White F. A. , Forman L.
Published: February 2005

A research mass spectrometer has been constructed comprising four analyzing elements; two electrostatic and two magnetic 90° lenses, each with a mean radius of curvature of 50.8 cm. The instrument can be programmed for the mass and energy resolution of both primary and secondary ion species, making the spectrometer an attractive tool for studies of sputtering, charge exchange, and dissociation phenomena. A high isotopic abundance sensitivity (∼108/1) has also been achieved, a figure of merit that is important in nuclear measurements and special tracer applications.
Double Mechanical Heat Switch for Calorimetry Below 1°K
Authors: Ancsin J. , Lamarche J. L. G.
Published: February 2005

A double mechanical heat switch suitable for calorimetry in the 0.2 to 5°K range is described. The lowest temperatures are achieved by adiabatic demagnetization of a paramagnetic salt. One switch makes or breaks contact between the salt and the bath, whereas the other is between the salt and the specimen. The performance of the device is illustrated by the description of an experiment in which 1.8 moles of pure magnesium metal was cooled from 1.4 to 0.15°K in 35 min. On opening the thermal switch, a temperature rise of 0.03°K was observed.
High Speed Electromagnetic Shutter
Authors: Pirroni J. S. , Stevens R. R.
Published: February 2005

A high speed electromagnetically driven shutter has been constructed and used. This shutter is of the closed-open-closed variety, and is characterized by highly reproducible open duration time and negligible jitter. The shutter action is obtained when a thin plate carrying an open slit slides past a fixed slit. The moving slit is driven by the mutual repulsion of two parallel conductors carrying current in opposite directions. The present model has a total open time of 35 μsec, but this can easily be reduced by modifications of the shutter geometry. The application of this instrument to short duration absorption spectroscopy is described.
Theoretical Main Beam Profiles for the Kratky Small Angle Camera
Authors: Krigbaum W. R. , Godwin R. W.
Published: February 2005

A geometrical procedure is developed for determining the theoretical profile of the main beam intensity for the Kratky low angle x-ray diffraction camera. Agreement of experimental and theoretical profiles for a variety of camera geometries is excellent. In contrast to an estimation of the beam width by extrapolation, which may be misleading under certain circumstances, the experimental determination of the entire profile provides an accurate check of the camera alignment for all operating conditions. Furthermore, the area under the theoretical profile furnishes a relative measure of the total useful main beam intensity. This information may be used to determine the optimum values of the camera parameters for operation at any desired maximum resolution.
Microvolumetric Measurements with an Automatic Toepler Pump
Authors: Dietz Russell N.
Published: February 2005

An improved design in Toepler pumps is presented as well as the design of a new variable-time control box. The pump operates completely automatically with no contact of grease with the mercury. Complicated grease-free valves are also not required.
Precision Flow-Microcalorimeter
Authors: Stoesser P. R. , Gill S. J.
Published: February 2005

A design for a flow-microcalorimeter is described. The instrument uses a two hundred junction thermopile detector between twin calorimeter regions. Mixing of two thermally equilibrated solutions is accomplished without a vapor space or mechanical stirring in one of the twin cells. The attendant heat effects are measured using servo-controlled electrical heating. Well controlled thermal shields are used to provide both precise thermal equilibration of the solutions and adequate isolation for the twin calorimeter elements. Heat effects of 1 mcal have been measured with a precision of 1% for a steady state experiment where two reactants are mixed together at equal flow rates of 10−3 cc/sec and the attendant heat effects are measured during a 100 sec time interval. A pulsed flow experiment in which mixing of 0.1 cc of each reactant is allowed to occur for the same time interval is also feasible, but gives measurements with lower precision.
Velocity Determination in Bubble Chambers
Authors: Barkas Walter H.
Published: February 2005

The kind of information that can be obtained from a bubble chamber track is analyzed and the statistical reliability of each parameter is given. Practical matters entering into the measurements are discussed.
Re-entrant Hysteresis Loop Tracer
Authors: Wolfe R. , Haszko S. E.
Published: February 2005

A simple method has been developed for displaying and measuring the important features of re-entrant hysteresis loops of ferromagnetic wires. A conventional ac loop tracer is modified by the addition of a pulse generator and an extra coil coaxial with the specimen. A current pulse in this coil is used to nucleate a reverse domain in the wire at the appropriate time so that domain walls are available to be moved by the field coil. The loop traced on the oscilloscope then shows the wall motion coercivity. When no current pulse is used, the conventional rectangular loop which shows the nucleation field is displayed. If the pulses are generated at half the applied field frequency, the inner and outer loops are displayed alternately and appear to be superimposed. This loop tracer has been used to measure the normal re-entrancy of permalloy wires, the stress-induced re-entrancy of ribbons with positive magnetostriction constants, and an unusual type of re-entrancy in nickel wires. With appropriate modifications this technique can be applied to other specimen configurations and loop tracers.
Acoustic Technique for Use in Some Solidification Rate Studies
Authors: Bailey J. A. , Dula A.
Published: February 2005

An acoustic technique is described for following the motion of the solid-liquid interface during the freezing of a quantity of water where the heat transfer is unidirectional. It is shown that the experimental data compare very favorably with both direct observation and a numerical solution to the transient heat conduction problem and also conform to a relationship observed previously, namely, ε = qt½+C, where ε is the thickness of the ice layer, t is the time, and q and C are constants. The effect of superheat on the shape of the solid-liquid interface is clearly demonstrated.
Secondary Emission of AgMgOCs Dynodes and its Dependence on the Temperature
Authors: De' Munari G. M. , Mambriani G. , Giusiano F.
Published: February 2005

A simple method for investigating the temperature dependence of the photomultiplier gain is described. The gain of the AgMgOCs dynodes of four 56AVP was measured as a function of the temperature between 90 and 300°K. The dynode gain was found to be independent of the temperature, at least within a few per cent. This ensures that the secondary emission, too, is constant within the above given temperature range. Moreover, the secondary emission as a function of the energy of bombarding electrons is temperature independent.
Two-Crystal, Vacuum Monochromator
Authors: Deslattes Richard D.
Published: February 2005

Design and construction of a vacuum two-crystal instrument for high resolution spectroscopy at long wave-lengths is reported. The instrument provides for coordinated rotations of both crystals, source, and detector. The usable scan range is 8° in Bragg angle and is limited only by the characteristics of the tangent drive system.
Bridge Network for Measuring Very Small Impedances from 4.2 to 300°K with a Null-Detector Sensitivity of 10−11 Volt
Authors: Bak C. K. , Dalsgaard E.
Published: February 2005

An ac measuring technique devised primarily for measuring galvanomagnetic effects in metals is presented. The instrument may, however, be useful whenever it is desired to measure and record continuously impedances in the range 10−3 to 10−8 Ω. The sample assembly is disscussed in some detail. Measurements with the bridge show that in the temperature range 300°K to 4.2°K the noise level changes from 30×10−11 V to 10−11 V without any zero shift, and as a result the lower limit for the impedance range changes from 10−6 Ω to less than 5×10−8 Ω.
Magnetic Amplifier for Use at 4.2°K
Authors: Foiles C. L.
Published: February 2005

A magnetic amplifier used at 4.2°K to measure small dc voltages is described. A sensitivity of 5×10−3 μV was obtained without any precaution other than second harmonic detection for eliminating ac noise. Suggestions for increased sensitivity and comparisons with other techniques are given.
Liquid Metal Sample Holder for Low Angle X-Ray Diffraction
Authors: Brady George W. , Greenfield A. J.
Published: February 2005

A transmission apparatus for the x-ray diffraction of liquids is described. Its main advantages are: (1) precise determination of the intensity in the range of scattering angle 0°<2θ<30°, (2) easy adaptability of commercially available equipment for its construction, and (3) simple temperature control from room temperature up to 250°C. Results obtained with the apparatus are presented, and in a short appendix possible sources of error in the use of a conventional pulse height analyzer for monochromatization are briefly discussed, illustrating the necessity of crystal monochromatization.
Observed Behavior of a Thermistor Bead Flow Meter
Authors: Pigott M. T. , Strum R. C.
Published: February 2005

Rasmussen [Rev. Sci. Instr. 33, 38 (1962)] has analyzed thermistor bead flow meters, treating constant current and constant temperature modes of operation, and summarizing the velocity dependence of the dissipation constant by means of a single curve. This paper treats a third mode of operation in which neither the bead current nor its temperature is kept constant: the bead's resistance is one leg of a dc Wheatstone bridge, and the bridge unbalance voltage is a measure of the flow velocity. Three results are reported. (i) The dissipation constant possesses two regimes of behavior, one being that noted by Rasmussen, but the other characterized by a velocity dependence featuring a nonmonotonic slope when the bead's temperature approaches that of the medium; (ii) the Wheatstone bridge unbalance voltage, initially, is almost linearly dependent on the velocity; and (iii) the ratio of velocity to bridge unbalance voltage achieves a plateau on which this ratio is nearly independent of thermistor power.
Lateral Extensometer for Brittle Materials
Authors: Singh Madan M. , Kim Yung Sam
Published: February 2005

A design for an extensometer for measuring lateral deformations in brittle materials using LVDT's is presented. The system is sensitive enough to measure the small changes in diameter that occur in such situations, but is simple and inexpensive. The instrumentation technique also allows a choice of electronic equipment, thus making it more versatile. The extensometer may be used for lateral deformation measurements in both compression and tension experiments.
Balanced Dynamic Capacitor Electrometer
Authors: Fermor J. H. , Kjekshus A.
Published: February 2005

The principles of a new method for the detection and measurement of potential difference are given, together with a description of a prototype instrument. The basis of the method consists of the use of two cyclically varying capacitors in conjunction with two resistors, or equivalent elements, to provide an ideal transducer. Devices based on this principle have input resistances which are limited only by leakage from the input conductor, and are suitable for measurements in circuits of very high resistance. Important features of the new arrangement are a completely passive input equivalent circuit, a short response time, and an improved signal-to-noise ratio as compared with existing electrometers.
Apparatus to Measure Mid-Infrared Spectral Emittance of Cold Powers in a Vacuum
Authors: Goetz Alexander F. H. , Bauman Curtis A.
Published: February 2005

A compact apparatus enclosed in a stainless steel vacuum chamber was used to measure the 8–13 μ emittance of silicate powders under simulated lunar conditions for purposes of compositional analysis. Samples with surface temperatures as low as 180°K could be measured. The sample was contained in the removable lid of a constant temperature bath and its upper surface allowed to radiate into a cavity maintained at liquid nitrogen temperature (77°K). The spectral emittance was computed by matching the observed spectrum with a Planck function at high emittance wavelength intervals. System response was determined with an internal calibrating blackbody maintained at 273°K.
New Instrumentation Techniques for the Measurement of Infrasonic and Gravity Waves
Authors: Fehr Uri , Ben-Ary B. , Ryan John D.
Published: February 2005

An improved sensor and calibration techniques for the measurement of infrasonic and gravity waves are described. The sensor is a modified, Moore sailplane rate-of-climb indicator, which produces a linear electrical output for pressures between 103 and 10−2 dynes/cm2, with a flat frequency response between 22 and 0.001 cps. It is a stable instrument, light and easily adapted for balloon payloads and other field experimentation. The calibration techniques provide controlled sinusoidal pressure at various simulated altitudes and atmospheric temperatures. Several present and future applications of the techniques are discussed, as well as some of the methods used in these applications to effectively control wind, temperature, ground motion, and other extraneous noise sources.
Low Friction Air Supported Pulley and Its Use in Floating Wire Measurements
Authors: Edwards V. R. W. , Osborne A. E.
Published: February 2005

The construction of a low friction, air supported pulley for use in floating wire measurements and the methods used to test its performance are described. The quality of the results obtainable in floating wire measurements with such an air bearing is illustrated by several measurements performed on a 100 cm radius, 180°, double-focusing magnetic analyser at the Rutherford High Energy Laboratory. The use of bearings of this type as pivots for bullion balances, and the possibility of employing such a modified bullion balance to measure the Newtonian constant of gravitation G to increased accuracy are considered.
Apparatus for Studying Gas Diffusion, Electrical Properties, and Related Phenomena in Solids
Authors: Pronko P. P. , Krouse H. R.
Published: February 2005

A simple cell in combination with a mass spectrometer and multichannel recorder provides interesting approaches to the study of gas diffusion and electrical phenomena in solids. The apparatus permits (1) studies of the directional dependence of gas diffusion in a solid, (2) observation of the effect of electric fields on gas diffusion in solids, and (3) simultaneous measurements of electrical conduction and gas diffusion in solids. It also appears that this apparatus may yield information about the energy states occupied by rare gas impurity atoms in ionic crystals.
Radiofrequency Separated Beam at the AGS
Authors: Foelsche H. W. J. , Hahn H. , Halama H. J. , Lach J. , Ludlam T. , Sandweiss J.
Published: February 2005

Spatial separation of undesired particle components from high energy kaon, pion, and antiproton beams is achieved by means of an rf separator consisting of two transverse deflectors, set 40 m apart and operated at 2.856 GHz. Elimination of two contaminants is possible if their difference in transit time between deflectors equals a multiple of one rf cycle. In the system described this occurs, for example, at 12.80, 9.04, and 7.38 GeV/c if kaons are desired. The actual useful beam system involves the magnetic optics necessary to form a momentum analyzed beam with Δp/p=1% and to transport the particles over 129 m between an external target at the Brookhaven Alternating-Gradient Synchrotron and the 80 Inch Bubble Chamber. The design of the magnetic optics for the momentum analysis section, the separator stage, and the post analysis section is discussed. For proper operation, the rf beam separator described requires deflectors which are capable of imparting a transverse momentum pT≥18 MeV/c to traversing particles. A 3 m long iris-loaded structure operating in a backward wave hybrid mode with dipole character was selected. The necessary multi-MW rf pulses are generated by a microwave system which consists of a phase locked source, TWT, triode, and klystron amplifiers, as well as associated modulators. A phase servo maintains the prescribed phase relationship between deflectors. The separated beam has been tested and run as kaon and pion beams. The system has, in general, performed according to expectations. Preliminary performance data indicate for example at 12.8 GeV/c an average yield of eight K− mesons per pulse with 0±15% background.
Principles, Current Practice, and Applications of Potentiometers Based on Poggendorff's Second Method
Authors: Abramowitz Abraham
Published: February 2005

It is shown that any bilateral voltage divider may be operated backwards as a current divider in the Ayrton shunt mode (Julie element). The use of Poggendorff's second ``compensation'' method in the construction of constant resistance potentiometers is surveyed. A design of a constant resistance potentiometer (Julie nanovolt potentiometer) using a constant current source in conjunction with a Kelvin-Varley slide operating as a current divider is described and its advantages discussed. Applications are suggested for constant current sources used with current dividers. These are (a) simplified potentiometers, (b) defection potentiometers, (c) self balancing potentiometers, (d) servo error detectors, and (e) current balances. The symmetry of Poggendroff's two methods is indicated.
Ultramicrotome for Hard Tissue
Authors: Murphy A. P. , McNeil G. L. , Neal R. J.
Published: February 2005

An ultramicrotome has been designed specifically for cutting hard materials such as tooth enamel. Thermal and mechanical stability have been achieved by utilizing a special marble base. At near room temperature, the coefficient of thermal expansion measured parallel to the quarry bed is negligible. A massive block of this marble, properly oriented, is used as a one-piece base. An Invar thermal expansion rod, rigidly anchored to the base, extends through a 7.5 cm hole to the front of the block. A unique positive drive moves the specimen past the knife and ensures that its lateral position during cutting is precisely reproducible and independent of wear or play in the drive mechanism. This instrument is now in routine use in this Laboratory to prepare ultrathin sections of fully matured adult human dental enamel. Electron micrographs of such sections are presented. Ultrathin sections have also been cut successfully of metals, ceramics, and soft biological tissue.
Magnetic Effects on the Transmission of Electrons through an Aperture and Their Application to the Retarding-Potential-Difference Technique
Authors: Anderson N. , Eggleton P. P. , Keesing R. G. W.
Published: February 2005

The effect of magnetic fields on the transmission of electrons through an aperture is discussed as a function of the field strength and aperture diameter. The effect of a potential barrier on the source distribution is calculated. These results are then applied to an R.P.D. calculation for two potential barrier configurations, using a linear excitation function. Distortion of the excitation function and the occurrence of negative difference signals are discussed. It is concluded that the effects of nonlinear transmission function and barrier modification are sufficient to explain many of the secondary attendant phenomena arising in the R.P.D. technique.
New Method of Measuring Linear Dichroism in the Ultraviolet: Application to Helical Polymers
Authors: Jaffe Joseph H. , Jaffe Halina , Rosenheck Kurt
Published: February 2005

A new method of measuring linear dichroism is described wherein the determination is carried out with a single spectral run without moving either sample or polarizer. It makes possible, for the first time, reliable quantitative measurements of dichroism. As examples, spectra (down to 180 mμ) of dichroic films of poly-L-lysine and of deoxyribonucleic acid are presented.
Modified Hot-Wire Type Thermal Conductivity Cell
Authors: Springer George S. , Ulbrich Roger H.
Published: February 2005

A modified hot-wire type thermal conductivity cell suitable for measuring the effects of the finite length of the test cell on the heat transfer from the hot wire is described. With the apparatus in vertical position, measurements were made in argon, neon, and helium over a wide range of pressures and temperatures, indicating the use of the apparatus and the magnitude of the effects of pressure, temperature, and test cell length on the heat transfer.
Nanosecond Bifilar Wound Transformers
Authors: Bosshard R. , Zajde C. , Zyngier H.
Published: February 2005

A new technique for the construction of pulse transformers using bifilar lines is described. Risetimes shorter than 0.5 nsec and decay times larger than 10 μsec may be obtained. Small size and ease of construction suggest that more elaborate transformers capable of more complicated analogue operations, such as addition or subtraction, could become practical. An example shows an arrangement which starting from two voltages, V1 and V2, provides V1+V22, −V1−V22, −V1+V22, and V1−V22.
Quadrupole Magnetic Lens Using Permanent Ceramic Magnets
Authors: Jagger J. W. , Riley P. J.
Published: February 2005

A quadrupole lens pair is described utilizing permanent ceramic magnets. The field gradient is 470 Oe/cm, across a 7.94-cm aperture. Variation in lens strength is achieved by driving the lenses over a mild steel magnetic shunt welded to the inside of the beam tube. The lenses are of relatively low cost, light weight, and simple construction. Of the two units described, when used at full strength, the smallest lens pair brings a 10-MeV proton beam to a focus in a distance of 4 m from it.
Technique for Obtaining True Hydrostatic Pressures to 60 kbar
Authors: Barnett J. Dean , Bosco Charles D.
Published: February 2005

A sample is enclosed in a liquid-containing steel capsule 3.81 cm in length and 1.27 cm in diameter, which in turn is placed in the pyrophyllite cube normally used as the sample chamber of a 2000-ton hexahedral press. When pressure is applied in the normal manner, it is transmitted to the enclosed sample by a 1:1 mixture of isopentane and pentane. Successful measurements utilizing six electrical leads into the sample region have been made. A manganin gauge to 60 kbar is demonstrated and used to study previously unobserved time-dependent pressure variations attributed to the pyrophyllite flow in the solid-media apparatus.
Study of Pressure Calibration and Pressure Distribution in a Piston-Cylinder High Pressure Press
Authors: Tamayama Masaaki , Eyring Henry
Published: February 2005

The pressure loss in a high pressure vessel of a piston-cylinder press has been studied at the bismuth (I-II) and (II-III) transitions. This was accomplished by measuring the abrupt diminution of volume of bismuth, which was surrounded by a solid pressure transmitting medium, at the pressure-induced phase transitions. The study of pressure loss has been made by measuring three pressure losses which are defined as follows: (1) Pressure loss I is due to the interfacial friction between the cylinder and the piston. (2) Pressure loss II is due to the interfacial friction between the cylinder and the solid pressure transmitting medium which separates the piston and bismuth. (3) Pressure loss III originates within ``the sample-containing cross section of the cylinder'' and is due to the internal friction of the medium. Experiment showed that the pressure loss III is the largest among the pressure losses. The difference between the true pressure on the bottom of a sample and the average pressure on the top of the piston due to pressure loss III has been formulated. This pressure loss study has been applied to the pressure calibration of a high pressure furnace containing a sample under investigation and also to the drawing of a diagram of pressure distribution in the furnace.
Rubidium Vapor Magnetometer for Near Earth Orbiting Spacecraft
Authors: Farthing W. H. , Folz W. C.
Published: February 2005

This paper describes the instrumentation and in-flight performance of the rubidium vapor magnetometers being flown by the National Aeronautics and Space Administration on the POGO satellites. An optically pumped, self-oscillating rubidium magnetometer was selected as being most compatible with the objectives of the study and with the spacecraft capabilities. A four absorption cell configuration is used to reduce the effect of the null zones inherent in these instruments and to obtain accuracies compatible with the scientific objectives of the program. Scalar magnetic field data are obtained in both digital (PCM) and analog (frequency multiplex) form. Instrument performance parameters are monitored through both main frame and subcommutated PCM data. The first instrument orbited was aboard OGO-II which was launched on 14 October 1965. This instrument has returned a large quantity of data, and is still operating when sufficient spacecraft power is available. The accuracy of the data is determined, apart from orbit accuracy, by spurious phase shifts within the instrument. These arise from such sources as optical axis misalignment, electronic nonlinearities and frequency dependence, and propagation delay over the long cables connecting sensor and electronics. The magnitude of the resulting error is inversely proportional to the phase slope of the dual cell absorption line. The total effect in the POGO instrument of these sources of error is an accuracy of better than 1.5γ over the entire instrument range of 15 000 to 64 000γ.
Tungsten-Rhenium Thermocouples for Use at High Temperatures
Authors: Asamoto R. R. , Novak P. E.
Published: February 2005

Tungsten-rhenium thermocouple systems were evaluated for use in measuring temperatures between 1600 and 3000°C. Temperature-millivolt relationships were extended from 2300 to 3000°C for bare-wire W3Re/W25Re and W5Re/W26Re thermocouples in vacuum. The performance of W26Re sheathed, high-fired beryllia-insulated thermocouples was limited only by the melting point of the beryllia insulation (∼2550°C). The thermoelectric output of high-fired thoria-insulated thermocouples sheathed in W26Re was determined and found to be reliable up to at least 2850°C, when corrected for electrical shunting through the insulation. Stability of high temperature thermocouples using thoria insulation was within ±0.3 mV (±40°C) when held at 2425°C for 148 h.
Oxidation Resistant, High Temperature Ceramic-to-Metal Seal Compatible with Cesium
Authors: Hill Russell J. , Knopp C. F.
Published: February 2005

A method of making ceramic-to-metal seals is described. The technique is based on a nickel-titanium intermetallic compound which is ductile and has a wide composition range. The compound is used as a braze which wets ceramics, such as sapphire, very easily to form hermetic seals. The braze may be made in an argon stream and does not rely on a vacuum. The seals can be made quickly and easily and are very stable towards the liquid metal cesium, and may be used in air up to 800°C for extended periods of time.
Control System for Frequency Stabilizing a 6328 Å Gas Laser
Authors: White A. D.
Published: February 2005

The design, construction, and performance of a laser frequency control system using two optical discriminators to achieve both long and short term frequency stability are described. The design philosophy emphasizes the active rather than the passive approach to stabilization; consequently, the system should be applicable to situations where intrinsic stability is difficult to achieve by mechanical or thermal techniques alone.
Photoemissive Yield of Cs3Sb Photocathode and Its Dependence on Temperature
Authors: De'Munari G. M. , Mambriani G. , Giusiano F.
Published: February 2005

A method which allows measurements of the photoemissive quantum yield of a Cs3Sb cathode of a photomultiplier is described. The method consists of an accurate control of the photocathode polarization to separate its eventual effects from the dependence of the quantum yield on the temperature. Measurements thus performed on four 56AVP phototubes have been interpreted as an up-to-now unknown variation of the quantum yield due to the temperature. The measurements suggest that the Cs3Sb could exist in two states, one of which, never noticed before, is stable only below (260±2)°K (the transition temperature), and which moreover is very sensitive to the absorbed energy. This low temperature state has a low quantum yield (for whitish-blue light), which, depending on the absorbed energy, can be even five to seven times lower than the yield of the usual high temperature state of Cs3Sb.
Superconducting Parametric Amplifier for the Measurement of Small dc Voltages
Authors: Ries Roger P. , Satterthwaite C. B.
Published: February 2005

A new device capable of measuring minute dc voltages is described, and a simple theory which describes the operation and predicts the performance is presented. Experimental amplifiers have demonstrated dc sensitivities which closely approach the maximum attainable by any device. Their performance characteristics agree satisfactorily with the theory. Sensitivities of 4×10−14 V with a source resistance of 4×10−7 Ω and a time constant of ≈ 1 sec have been obtained at 4.2°K. The ultimate sensitivity appears to be limited only by the noise present in the source itself.
Cylindrical Capacitor as an Analyzer I. Nonrelativistic Part
Authors: Sar-el H. Z.
Published: February 2005

The dynamic and optical properties of the cylindrical capacitor for nonrelativistic charged particles were studied for certain arrangements of the source and some interesting features were found. A point source embedded in the inner cylinder on the common axis of the capacitor can be imaged for any angle of emission θ0 between 0 and π/2. Each angle θ0 has its corresponding K0 factor incorporating the geometrical and electrical parameters of the device. K0 and θ0 together determine uniquely the distance between the source and its image on the common axis of the capacitor. There exists a first order focus for all angles of emission except θ0=42°18.5′; for the latter there is a second order focus. The figures of merit of this analyzer concerning resolution and transmission were found to be better than those of other forms of the cylindrical analyzer. However, the deflecting voltages required in the new device are higher. The calculations were checked experimentally for θ0=π/4.
Measurement of Time Differences in the Range Milli- to Picoseconds
Authors: Hauser U. , Knissel G. , Moritz J. , Schneider U.
Published: February 2005

The application of the internal electronics of a commercial sampling oscilloscope, modified by a few additional components which do not interfere with the normal functions of the oscilloscope, as a very fast time-to-amplitude converter for measurements of short time differences is described. The electronic modifications and their functions are reported. The electronic time resolution has a FWHM of 3.2×10−11 sec, a slope decay t1/2 of 5×10−12 sec, and certainly can be improved. The range of measurable time differences lies between some picoseconds and some milliseconds.
Ultrastable Voltage Source to 10 kV Using Capacitive Feedback
Authors: Brookshier William K.
Published: February 2005

A unique system has been developed with the capability for use as a voltage monitor or regulated voltage source to a stability level as good as 1 ppm/12 h, or 0.1 ppm/15 min. The system employs a precision capacitor charged to a voltage level matching the level of interest, so that it provides optimum discrimination against amplifier noise and also obviates the need for a voltage divider. A useful voltage range from 1 kV to 10 kV has been demonstrated and there is reason to hope that the technique can be applied at higher voltage levels. The short term stability, for time intervals of 1 hour or less, is superior to that obtainable from a conventional system containing the usual voltage reference, voltage divider, and dc amplifier.
Series Interferometer for the Diagnosis of a Large Diameter Theta-Pinch
Authors: De Angelis A. , Martellucci S.
Published: February 2005

An optical interferometer, particularly suitable for the refractive diagnosis of large dimension plasmas is described. Throughout the work, the theory of the instrument is revised in view of plasma applications. Subsequently, a detailed description of a 12 m long series interferometer working on a large diameter theta-pinch is given. During the experiment, both a Q-switched ruby laser and a pulsed arc lamp have been used.
High Resolution Zero-Crossing Detector for Long Crossover Times
Authors: Bucher W. P. , Hollandsworth C. E.
Published: February 2005

A circuit designed to detect the zero-crossing of bipolar pulses having crossover times of 100 nsec or greater is described. True zero-crossing detection is accomplished by using an external strobe to generate a pedestal which is then applied to a tunnel diode, normally biased off, allowing it to switch when the input signal crosses zero. Tests with scintillation pulses show that amplitude-dependent timing errors are less than 0.25 nsec for a pulse-height range of 100. The principal application of the circuit is in the separation of scintillation pulses according to their pulse shapes.
Application of Fermat's Principle to Magnetic Spectrometers
Authors: Bounin Paul
Published: February 2005

The principle of Fermat (or of Maupertuis) contains implicitly the entirety of geometrical optics. It is used in the present paper to find the trajectories of charged particles passing through magnetic systems possessing a plane of radial symmetry. A general formula is given for the calculation of the aberrations at image points. The method is illustrated in its application to certain systems of special interest in which specific second order aberrations cancel. The method outlined herein is believed to possess the advantage of relative simplicity and directness when compared to more general formulations.