bluuebunny/crossref_metadata_2025 huggingface dataset:
Apparatus for the Measurement of Optical Rotation of Solutions at High Pressure
Authors: Gill S. J. , Glogovsky Robert L.
Published: February 2005

A polarimeter was constructed so that the sensitive optical components could be subjected to the same pressure within a high pressure optical bomb, thereby avoiding the problem of large double refraction effects from two winddows under a large difference of pressure. One of two Polaroids within the high pressure bomb is rotated through a fixed angle by a mechanical coupling with a solenoid driven magnet. The transmission of light for a given wavelength setting is measured in both Polaroid positions by means of a Beckman DU spectrophotometer. The sensitivity of the apparatus is ±0.01° in the range of 0–5° rotation. The apparatus has been specifically designed for pressure studies to 2000 atm, although the method is inherently capable of even higher pressures.
``Thumbtack'' Accelerometer for the 1.5–150 kc Range
Authors: Hertelendy P. , Reynard P.
Published: February 2005

A special-purpose mechanical vibration detector using a piezoelectric sensing element is described. Also, one application, a method of calibration, and some limitations of the device are discussed. Its chief merits are (1) low impedance, (2) a nearly point contact, and (3) low transverse-to-longitudinal sensitivity.
Charge-Storing Technique for Measuring Small Conduction Currents Under Microsecond Pulse Conditions
Authors: Watson P. K. , Sharbaugh A. H.
Published: February 2005

A new technique has been developed for measuring small conduction currents due to microsecond duration pulses of voltage; the method is equally applicable to longer duration pulses. It uses a charge-storing technique in which the conduction current through the sample is integrated on a capacitor whose voltage is measured after the high voltage pulse is terminated. The sensitivity of the method can be increased by integrating charge over a large number of pulses. With high voltage pulses as short as 1 μsec, the technique enables one to measure currents of 1 μA with an accuracy of about 5%.
On-Line Analog Generation of Joint-Interval Histogram
Authors: Schulman Joseph H. , Thorson John
Published: February 2005

The joint-interval histogram for adjacent intervals within any temporal sequence of events can be plotted with a simple analog circuit and an oscilloscope.
X-Ray Spectrophotometer for Simultaneous Analysis of Several Elements
Authors: Jacobson Bertil , Lindberg Björn
Published: February 2005

A multichannel recording x-ray spectrophotometer has been developed for quantitative analysis of macroscopic objects, such as liquid or solid specimens or the human body. The equipment comprises a special x-ray tube for generating monochromatic radiation by secondary emission, a system composed of servo-controlled absorption wedges, a scintillator photomultiplier unit for sensing the x-ray intensities of the radiation that has transversed the object and the wedges, and electronic feedback loops from the photomultiplier to the servo motors controlling the wedges. A set of stationary wedges and a photomultiplier are included to eliminate fluctuations in the x-ray intensities. The wedges are composed of, or contain, the elements being analyzed. The servo-controlled wedges are automatically kept in such a position that the intensitites of the monochromatic x rays are constant at the scintillator photomultiplier. When the object is placed in the beam the wedges are automatically withdrawn a certain distance, the displacements constituting a quantitative measure of the amounts of the analyzed substances in the transversed volume of the object. Nondestructive quantitative analysis of unprepared specimens takes a few seconds.
Efficiency in a Tetrahedral-Anvil Press as Related to Anvil and Pyrophyllite Size
Authors: Banus M. D. , Nye Susan D.
Published: February 2005

The efficiency of a tetrahedral-hinge high pressure apparatus was studied using four anvil sizes from 38.1 to 63.5 mm on the edge and the transitions of bismuth I-II (25.4 kbar), thallium (37 kbar), and barium (59 kbar) as calibration points. Efficiency is defined as the pressure of the transition divided by the applied pressure (load per anvil area) to obtain the transition. The sizes of tetrahedra were varied to determine maximum efficiency at each pressure. Correlation of these data with those of previous workers shows (1) that the maximum efficiency for each transition is constant for anvils from 12.7 to 63.5 mm on the edge; and (2) that the size ratio giving maximum efficiency is a function of pressure. These data are discussed in relation to the flow and compression of pyrophyllite in the gaskets and cavity.
Scratch Test for Measuring Adherence of Thin Films to Oxide Substrates
Authors: Karnowsky M. M. , Estill W. B.
Published: February 2005

The adherence of films on oxide substrates is measured by a scratch-test technique using a commercially available hardness tester. Test results viewed by transmitted light on transparent substrates show (1) how contamination can cause failure of potentially-adherent film and (2) how a potential adherence (on a well-cleaned substrate) is related to the free energy of formation of the metal oxide.
Spark-Gap Trigger System
Authors: Schrank G. , Henry G. , Kerns Q. A. , Swanson R. A.
Published: February 2005

The construction and operation of a trigger system designed to fire a 30-kV 5000-A spark gap with a minimum of delay following the arrival of a small signal pulse is described. In the particular experiment for which the system was designed and used a 150-MeV/c muon is detected with scintillators on three 6199 phototubes, and the output pulse of the attached tunnel-diode triple-coincidence circuit is amplified and used to trigger the gap, which switches a current pulse through an inductive load. Approximately 32 nsec are needed from passage of the muon to the coincidence output, and approximately 25 nsec are required from the coincidence output to the time of complete breakdown of the gap. These delays represent the shortest times that we could achieve with the particular boundary conditions under which the circuit had to operate, i.e., these delays include all cables, light pipes, etc. in the working apparatus. Sufficient detail is given to show how additional savings of nanoseconds could be made under different operating conditions.
Silicon Photodiode Vacuum Ultraviolet Detector
Authors: Tuzzolino A. J.
Published: February 2005

The photosensitivity of silicon surface-barrier photodiodes has been measured over the photon energy range from 4.9 to 21.2 eV (2537 to 584 Å). The photodiodes are operated in the reverse-bias mode at room temperature. The sensitivity of a typical photodiode with approximately 100 Å of gold on the sensitive surface is 0.16 electron per photon at 2537 Å and 1.1 electrons per photon at 584 Å. Photosensitivity did not vary more than a few percent over the sensitive area. The operating characteristics of these devices are reported and the use of the silicon photodiode directly, or in combination with sodium salicylate, as a vacuum ultraviolet detector is discussed.
Optical Systems for Observing Surface Topography by Frustrated Total Internal Reflection and by Interference
Authors: McCutchen C. W.
Published: February 2005

If surface topography is examined by frustrated total internal reflection, light leaves the object plane in a direction displaced from the normal by at least the critical angle. If the optical system is arranged with its axis parallel to the emerging light, there will be distortion and tilting of the Guassian image plane. These disappear if the axis of the optical system is made normal to the object plane, but the system must then deal with light entering it at greater than the critical angle. A microscope objective can do this if its numerical aperture exceeds 1. A device has been designed to adapt a conventional microscope for the study of topography, both by frustrated internal reflection and interference. Low magnification systems for use with frustrated internal reflection are also discussed.
Source of Uniform-Sized Liquid Droplets
Authors: Schneider J. M. , Hendricks C. D.
Published: February 2005

A method useful in the production of streams of uniform-sized liquid droplets, which are uniformly spaced relative to one another, is discussed. An extension of the method which is useful for the production of single droplets of known size is also given. The method is based on the principle that a cylinder of liquid is dynamically unstable under the action of surface tension. A capillary wave is launched onto a cylinder of liquid or jet which selects a particular mode of instability. The process of the disintegration of the jet is thereby regularized to the extent that extremely uniform droplets result. The size of the droplets is controlled by the inside diameter of the capillary tube through which the liquid flows, and therefore, the size can be varied over wide limits. By charging individual droplets and using electrostatic means to deflect them out of the stream, individual droplets can be isolated.
Interchangeable Hearth Arc Furnace
Authors: Kruger O. L. , Armstrong J. L.
Published: February 2005

A laboratory arc furnace that can be used for making buttons and castings of special shapes is described. The furnace was constructed so that copper hearths of various configurations could be rapidly interchanged. Convenience of operation inside a glove box was one of the principal considerations in its design.
Feedback Corona Regulator
Authors: Thomas John B.
Published: February 2005

A coaxial corona voltage regulator is described that operates in atmospheric air and provides an adjustable operating voltage. An order-of-magnitude improvement in stabilization over passive corona regulators is achieved with a feedback loop controlling the gas temperature in the vicinity of the discharge wire by resistive heating of this wire.
High Power rf Pulse Generator
Authors: Weibel Erich S.
Published: February 2005

A circuit is described which is capable of delivering radio frequency pulses at very high power levels. In a first test 10 MW of power at 2 Mc were delivered to a 4-Ω load. The pulse duration was only 3 periods; but it could be increased by a factor of 30 or more. The power level could be increased by a factor of 5 to 10.
High Pressure—High Temperature, X-Ray Diffraction Apparatus
Authors: Barnett J. Dean , Hall H. Tracy
Published: February 2005

A tetrahedral-anvil press has been developed that permits x-ray diffraction powder measurements at pressures to 75 kb and temperatures to 1000°C. A counting technique, rather than photographic film, is used for x-ray detection. Sample tetrahedra of compressed LiH, boron, and boron-filled plastic are used in place of the pyrophyllite customarily used for this purpose. Two possible entrance pupils are used for the x-ray beam; (1) through an anvil face, and (2) through one of the compressible gaskets. Examples of the use of this versatile apparatus for determining crystal structures (KCl, Ba, and Sn), volume compressibility (Ba), lattice-parameter changes (BN), and phase diagrams (Sn) are given.
Velocity Spectrometer for Mössbauer Experiments
Authors: Kankeleit E.
Published: February 2005

An electromechanical feedback system for Mössbauer spectroscopy with a velocity range of 2×10−5 to 60 cm/sec is described. A reference signal of the desired waveform (triangle, parabola, etc.) to drive the feedback system is produced by the multichannel analyzer and with the help of operational amplifiers. The linearity of the system for a triangular velocity waveform is better than 0.5% during 98% of the half-period.
Apparatus for Obtaining Homogeneous Ingots
Authors: Houzvicka Frank , Parker Sidney G. , Wilson Oran
Published: February 2005

An apparatus was built for casting several homogeneous, indium antimonide ingots of identical composition. The resulting ingots enabled one to study zone refining parameters.
Effect of Extended Fringing Fields on Ion-Focusing Properties of Deflecting Magnets
Authors: Enge Harald A.
Published: February 2005

This paper presents the result of calculations on ion deflection and focusing in magnets that have realistic, extended fringing fields rather than sharply cutoff fringing fields. The most important effects of the change from sharp cutoff to extended fringing fields are (a) displacements of the beam center line at entrance and exit (a ``zeroth-order'' effect), and (b) reduction of first-order z-direction (``vertical'') focusing. When the pole boundaries are curved or an effective curvature is caused by the proximity of pole-piece corners, there are further first-order effects on the trajectories. These effects can be minimized, and in practice made negligible, by correct centering of the beam relative to the pole-piece corners at entrance and exit.
Flashing-Light Spectrophotometer for Studying the Fast Reactions Occurring during Photosynthesis
Authors: Ke Bacon , Treharne R. W. , McKibben C.
Published: February 2005

Details on the construction of a spectrophotometer for measuring fast absorption changes occurring during photo-synthesis are described. Repetitive, intense light flashes with 20-μsec duration were used to initiate the reaction. The pulse generator is capable of producing two flashes, either simultaneously or with variable time separation. The monochromatic monitoring light was split into the sample beam and the reference balancing beam. The photo-multiplier outputs were fed to a differential circuit so that net absorption changes could be measured. Besides a wideband oscilloscope, a computer of average transients was also used to extract small signals from a high noise background. Thus, transient optical density changes as small as 0.0001 could readily be measured. The performance of the apparatus, especially in conjunction with the CAT computer, was illustrated with the absorption change at 515 mμ in Chlorella and spinach chloroplasts.
Dynamic Adiabatic Calorimeter: An Improved Calorimetric Apparatus
Authors: Solomons Cyril , Cummings John P.
Published: February 2005

An apparatus and technique for the simple but rapid determination of specific and latent heat data are described. The apparatus records automatically the energy-temperature plot for the sample on a conventional emf vs time strip-chart recorder; most of the components required are commercially available. The calorimetric assembly embodies the major advantages of adiabatic, heat-flow, differential-thermal-analysis, and thermal-analysis calorimeters. An accuracy of ±2% can be readily attained; with some care, errors can be reduced greatly in many cases.
Apparatus for Stress-Rupture Testing of Filaments in a Controlled Environment
Authors: Jech R. W. , Springborn R. H. , McDanels D. L.
Published: February 2005

A stress-rupture apparatus was designed and built for testing filaments and wires having a diameter of 20 mils or less in a controlled atmosphere to prevent oxidation. Four tests may be run simultaneously at different stresses and temperatures (to 1427°C), and the stress-rupture life of each filament can be measured independently and automatically.
Pulsed Nuclear Resonance Apparatus
Authors: Clark W. Gilbert
Published: February 2005

The description of a complete pulsed nuclear resonance spectrometer suitable for experiments in solids is given. Its major features are the ability to operate at any frequency between 2 and 30 Mc, an rf pulse output power of 5 kW over most of this range, a receiving system recovery time of 5–10 μsec at 10 Mc, a sensitivity usually limited by thermal noise in the receiver coil, use of phase coherent detection, the availability of a wide variety of pulse sequences, and good long and short term stability of the entire system. Brief instructions for operating the apparatus are included. A method of using the ``boxcar'' integrator to record directly the steady-state absorption (χ″) or dispersion (χ′) is explained.
Tensile Machine for Small Specimens
Authors: MacCrone R. K. , Thornton P. H. , Kuhlmann-Wilsdorf D.
Published: February 2005

A very sensitive and accurate tensile machine suitable for straining small single crystal specimens in the form of foils and wires is described. A load elongation curve of a gold foil is presented to show the performance achieved.
High Resolution Differential Čerenkov Counter
Authors: O'Donnell R. M. , Frisch D. H. , Smith S. R.
Published: February 2005

A particularly simple high resolution differential Čerenkov counter has been constructed and tested in beams of positive particles of 3.75 and 6 BeV/c momentum. The π meson, K meson, and proton peaks were well separated, and had full widths at half-height of about 10−3 in Δβ. The total efficiency of the counter was 63%. The K peak to K-π valley ratio was 200 to 1 at 3.75 BeV/c and 375 to 1 at 6.0 BeV/c. The limitations of the counter for use at higher momenta are discussed briefly.
Digital Technique for Rapid Measurement of Time Lags
Authors: Binns D. F. , Hood R. J. , Dargan C. L.
Published: February 2005

A commercial 10-Mc digital chronometer has been used to measure time lags to breakdown in SF6/air mixtures. This method is much quicker than taking measurements from oscillograms and gives greater accuracy when a very wide range of time lags occurs for the same experimental condition. Precautionary measures against pickup from high voltage circuits are described, together with a method of producing pulses suitable for starting and stopping the chronometer.
Simple Technique for Introducing Electrical Leads into a High Pressure Vessel
Authors: Davis L. A. , Gordon R. B. , Tien J. K. , Vaisnys J. R.
Published: February 2005

Electrical leads can be easily sealed into a pressure vessel by the use of suitably prepared epoxy cement. This technique produces a high pressure plug capable of withstanding at least 24 000 atm of hydrostatic pressure. The vessel with which the plug is used is described briefly.
Liquid Scintillator Anticoincidence Guard
Authors: Moe M. K. , Jenkins T. L. , Reines F.
Published: February 2005

A study was undertaken to determine the reduction in cosmic ray background which can be obtained by anti-coincidence techniques. A 50-liter liquid scintillation detector was set to register all cosmic ray events depositing more than 10 MeV. With a minimum shielding over the detector's basement location of 60 g/cm2, all but one in 103 events were accompanied by a pulse greater than 100 keV in a 1500-liter liquid scintillator anticoincidence guard. An additional 600 g/cm2, in the form of 35 tons of concrete block and bags of iron ore over the detector and anti-coincidence guard, reduced the unaccompanied events to 1 in 104, or 7.7 counts/h through 0.35-m2 effective horizontal area.
Magnetic Tape Recording and Reproducing of Atmospheric Noise with a Wide Dynamic Range
Authors: Bolton Earl C.
Published: February 2005

To properly evaluate the performance of radio systems in the presence of atmospheric noise, it is necessary to be able to reproduce atmospheric noise of various known amplitude distributions whenever necessary. However, conventional tape recording techniques cannot be used because of the large dynamic range of atmospheric noise. This paper describes a tape recording and reproducing system which has been developed that can record and reproduce atmospheric noise with a dynamic range of 90 dB. The frequency range is 1 to 25 kc with a one-half octave bandwidth and, by using frequency conversion, frequencies from 25 to 500 kc may be recorded with a maximum bandwidth of 10 kc.
Windowless X-Ray Tube Spectrometer for Light Element Analysis
Authors: Wyckoff Ralph W. G. , Davidson Franklin D.
Published: February 2005

A windowless tube spectrometer is described for the x-ray ``fluorescent'' analysis of the light elements down through fluorine. The high efficiency of x-ray excitation makes possible the analysis of elements as light as sodium when present in less than 1% and of fluorine in larger amounts.
Pulse Generator System for Fast-Reaction Experiments using a Time-of-Flight Mass Spectrometer
Authors: Riney J. S. , Gardiner W. C.
Published: February 2005

A transistorized pulse generator system for chemical kinetics experiments with a time-of-flight mass spectrometer is described.
Study of High Speed Photomultiplier Systems
Authors: Hyman L. G. , Schwarcz R. M. , Schluter R. A.
Published: February 2005

Section I describes steps taken to optimize the pulse shape and dynamic range from a 56 AVP photomultiplier. Section II discusses a model for the response of a photomultiplier. The parameters used in this model are obtained from direct measurements on a 56 AVP photomultiplier. Monte Carlo methods, as well as analytic techniques, are used to predict quantities such as distribution of triggering times, pulse shapes, etc. It is found, for example, that in the resolution of small time differences the predictions using the Monte Carlo method and the analytic treatment are in good agreement. The time resolution as predicted by the model is compared to experiment.
3He Neutron Spectrometer Using Pulse Risetime Discrimination
Authors: Sayres A. , Coppola M.
Published: February 2005

A 3He filled proportional counter can be used for neutron detection in the range 100 keV to 8 MeV by using the 3He(n,p)T reaction. The major limitation as a neutron spectrometer is that the 3He recoil distribution, arising from the elastic scattering of the higher energy neutrons present, masks the 3He(n,p)T peaks due to lower energy neutron groups. Since a 3He recoil and a proton of equal energies have difference specific ionizations and, therefore, different ranges in the counter filling, one thus has a means to distinguish between pulses from the 3He(n,p)T and 3He(n,n)3He reactions. For appropriate operating conditions the risetime of the pulses for these two events will be different. By converting this risetime to a pulse height and only accepting pulses with long risetimes [which correspond to protons from the 3He(n,p)T reaction], one has a neutron spectrometer useful in an energy interval between the maximum neutron energy present and that energy for which the proton range equals the range of the maximum energy 3He recoil. Spectra of monoenergetic neutrons obtained with a 3He filled proportional counter and the pulse risetime discrimination are presented to illustrate the energy range over which this detector may be used as a neutron spectrometer. Under typical operating conditions, spectra of the 24Mg(d,n)25Al, 28Si(d,n)29P, 32S(d,n)33Cl reactions were obtained to illustrate the performance of the spectrometer.
Investigations of Traveling-Wave Separators for the Stanford Two-Mile Linear Accelerator
Authors: Altenmueller O. H. , Larsen R. R. , Loew G. A.
Published: February 2005

Two traveling-wave rf structures, which are prototypes of devices to separate mass components of multi-BeV particle beams, have been designed and fabricated. Deflection characteristics have been studied by measuring the deflection of a 40-MeV electron beam.
Method of Measuring the Velocity of a Continuously Flowing Plasma
Authors: Cooney J. A.
Published: February 2005

A method of measuring the mean velocity of a flowing plasma is described. In this method ``blobs'' of plasma are extracted from the body of the flow by an electrostatic gating technique. Then the time of flight of the ``blob'' for a given distance is measured. Measurements of plasma velocities of 2×105 cm/sec have been made at total particle densities of 1012/cm3.
Temperature Measurements Using Small Quantities of Cerium Magnesium Nitrate
Authors: Abel W. R. , Anderson A. C. , Wheatley J. C.
Published: February 2005

A study is made of the requirements of a mutual inductance system suitable for precise temperature measurements using about one gram of cerium magnesium nitrate. The mutual inductance is measured by a commercial version of the electronic bridge originally proposed by Pillinger, Jastram, and Daunt [Rev. Sci. Instr. 29, 159 (1958)]. A discussion of the effects of spurious magnetic materials, of nearby paramagnetic salts, and of the vacuum jacket is given. The linearity and stability of the electronic bridge, as well as the effects of external circuitry, are also discussed. Results are given for the properties of two coil sets with cerium magnesium nitrate thermometers used to test the stability of the bridge and the validity of expressions for mutual inductance obtained in the text. It may be concluded that if solid air can be kept away from the coils, the long term instabilities for a 1-g thermometer lead to errors of about 0.004°K−1 in 1/T. A comparison between ballistic and 17-cps bridge measurements down to 0.015°K showed that 1/T* as determined by the two methods was the same with an error of less than 0.1%.
Hydrogen Pressure Regulator with High Absorption Rate
Authors: Reifenschweiler O.
Published: February 2005

By evaporating titanium in an argon atmosphere a deposit consisting of a very fine powder (particle size about 100 Å) is obtained on the inner wall of a metal cylinder. After this powdered titanium has been made to absorb whatever hydrogen isotope is being used, the gas pressure is adjusted by heating the metal cylinder to a certain temperature. Compared with more familiar systems, this pressure regulator has the advantage that equilibrium pressure establishes itself very quickly. One application of the regulator is in sealed-off neutron tubes.
Cylindrical High Temperature, High Pressure Apparatus
Authors: Witteman W. J. , Werkman Th.
Published: February 2005

A description is given of a cylinderical high pressure apparatus which can be used in the pressure range of up to 100 000 atm and for temperatures of up to 1500°C. The high pressures are generated by means of a pressurized rubber tire acting on three identical segments. Each segment is provided, near the center of the apparatus, with a tungsten carbide cylinder. The high pressures are transmitted to the surfaces of a pyrophyllite sample holder when the three tungsten carbide cylinders with parallel axes are brought together. The high pressure calibration was based on the observed linear relationship between the water pressure in the tire and the transition points of, respectively, bismuth, thallium, and barium. It turns out that the pressure is practically independent of the axial coordinate. A thin-walled graphite cylinder with a wall thickness of 0.1 mm, used for heating purposes, is placed along the axis of the sample holder. This graphite cylinder is insulated from the sample by means of boron nitride, and there was no difficulty in making separate contacts for the furnace and the sample. Temperature indication during the operation of the apparatus was obtained by measuring the resistance of p-type germanium. In the testing of this apparatus at higher temperatures, up to 1500°C, synthetic diamonds of about 0.3 mm were produced.
Design and Construction of a New Coaxial Electrical Discharge Pin
Authors: Wasley Richard J. , O'Brien Joseph F. , Henley Darwin R.
Published: February 2005

A new design for coaxial electrical discharge pins for recording rapid transient events, e.g., motion of shock disturbances, has been developed. The method of construction involves vapor plating techniques for the deposition of the dielectric and outer conductor. The performance of these pins (``Sigma'' pins) has been measured at pressures from nearly 0 to 360 kbars. The response time (the time interval between 10 and 90% of the linear portion of the total amplitude of the signal received) of the pin is less than 0.005 μsec.
Selective Amplifier of Variable Frequency and Bandwidth
Authors: Seed T. J.
Published: February 2005

The development of a feedback network with a single component frequency control for selective audio frequency amplifiers is described. When used in conjunction with an adjustable over-all feedback factor, the network has allowed the design of a 105-dB amplifier with bandwidths of 30, 100, and 400 cps, tunable over a frequency range of 400–6500 cps. The design criteria are readily applied to other frequencies and bandwidths.
First- and Second-Order Magnetic Optics Matrix Equations for the Midplane of Uniform-Field Wedge Magnets
Authors: Brown K. L. , Belbeoch R. , Bounin P.
Published: February 2005

The first- and second-order matrix equations for the magnetic optics of the midplane of uniform-field wedge magnets have been derived. The calculations include rotated input and output wedges and curved surfaces on the input and output faces. A second-order matrix algebra has been developed to handle beam transport optics for multiple element systems in a manner similar to that which has been used in the past for the first-order beam transport optics.
Current Regulator for Ultraviolet Light Source
Authors: Scouler William J. , Mills Elwin D.
Published: February 2005

In optical experiments where double beam techniques are not applicable, a stable light source is desirable. This paper describes a current regulator for a dc cold cathode hydrogen gas discharge used as an ultraviolet light source. In addition to the discharge current, the light output depends on factors such as gas pressure, but reasonable stability is obtained by simple precise current regulation of ±0.1%.
Spark Chamber Data-Handling System Using Television Cameras
Authors: Anderson Herbert L. , Barna Arpad
Published: February 2005

A spark chamber data recording system directly compatible with an IBM 7094 computer is described. The basic information-gathering elements are two closed-circuit television cameras scanning parallel to the spark chamber plates. The spark coordinates are digitized and recorded on digital magnetic tape. Basic considerations, operation, and results of linearity and cosmic ray tests are given.
Self-Supporting Specimens for Transmission Electron Microscopy
Authors: Solow Max
Published: February 2005

Self-supporting specimens were prepared for transmission electron microscopy. These specimens were disks which fit directly into the specimen holder of the Hitachi HU-11 electron microscope and had a thin central region with a relatively thick supporting rim. This form of specimen was made possible by the technique of electrocutting, which made it practical to cut a 3.2-mm disk from a sheet of metal. The procedure and the theory of this technique are discussed briefly. The electron micrographs of these self-supporting specimens of aluminum and molybdenum show very few bend extinction contours and other evidence of extraneous distortion compared to the electron micrographs made from specimens prepared by the conventional technique. Another advantage of this new technique is that specimens can be repolished; this makes it easy to get very thin areas and to remove contamination.
Cryogenic System for the Production of Very Thin Targets
Authors: Parks P. B. , Beard P. M. , Bilpuch E. G. , Newson H. W.
Published: February 2005

A windowless gas target chamber has been developed for the production of very thin, but uniform, targets to be used with accelerated charged particle beams. The target reaction chamber is appended to a cryostat which is capable of containing liquid helium as the primary refrigerant. The temperature of this chamber can be adjusted so that condensation of the gas in the vicinity of the beam path is minimized. The cryostat freezes out the gas which escapes the reaction chamber. To date, we have used this new cryogenic technique to observe the 2D(d,n) reaction and the (p,n) reactions in 11B, 40A, and 37Cl. Very narrow resonances (widths ≤450 eV) were discovered in the 40A(p,n)40K reaction near the neutron threshold. The narrowest observed widths in the yield curve are 140±10 eV. These were observed with a target whose effective density was found to be 3.0±0.3×1016 atoms/cm2.
Measurement of Power at Short Millimeter Wavelengths
Authors: Davis Q. V. , Clarke J. L. , Morris R. G. T.
Published: February 2005

This paper describes a range of calorimeters and bolometers for the measurement of small powers in the 4, 2, and 1-mm bands. A method of using bolometers to measure power down to the limit set by bolometer flicker noise is discussed and typical performance figures are given.
Vacuum Fatigue Tester
Authors: Steverding B.
Published: February 2005

A vacuum fatigue tester is constructed which allows transmission of high bending momenta into the vacuum chamber without decreasing the high vacuum quality. The equipment operates under constant load conditions and without electronic controls.
New Impedance Method for Determining Viscoelastic Constants
Authors: Spitznagel Edward L. , Potzick James E. , Catanese Carmen A.
Published: February 2005

A method is described to measure all four viscoelastic constants of a fluid by means of a rigid sphere vibrating in the fluid. Preliminary measurements at low audio frequencies give the shear viscosity to within an average error of 4%.
Neutron Decay Spectrometer
Authors: Karam R. A. , Parkinson T. F.
Published: February 2005

The neutron decay spectrometer depends on the spectral analysis of protons born from the decay of neutrons to determine the energy distribution of the neutrons. It comprises a containment magnet for confining the decay protons, a magnetic analyzer, and a detection system. It is shown that the average speed of the decay protons is equal to the speed of the parent neutron. The spread in the speed of the protons from the decay of monoenergetic neutrons determines the resolution possible with this method of spectrometry. The calculated energy spread varies from 30 to 2.7% over the neutron energy range 10 keV≤En≤5 MeV. The instrument was used to measure the neutron spectrum of the University of Florida Training Reactor, and the 1/E distribution was obtained and compared with the calculated spectrum.
Semiconductor Cathode Preparation for Field Emission Microscopy
Authors: Savage William R.
Published: February 2005

Bulk samples of semiconductors can be cut into rough blanks and reduced to sharply pointed conical cathodes suited for field emission microscopy. The apparatus and etching techniques for this process are described for some elemental and compound semiconductors.
Slide Rule Method for Indexing Electron Diffraction Patterns
Authors: Roser W. R. , Thomas G.
Published: February 2005

A convenient and rapid slide rule method for solving electron diffraction patterns is described.
Nonsaturating Quantameter for Very High Intensity Gamma-Ray Monitoring
Authors: Fischer H. , Schaerf C.
Published: February 2005

We describe a new type of gamma-ray monitor which is capable of handling the very high intensities now available from linear electron accelerators. This device provides an output proportional to the incident power. Unfortunately, it is not an absolute monitor.
Thin Heater Calorimeter
Authors: Hager Nathaniel E.
Published: February 2005

An easily constructed calorimeter is described which can determine specific heats on an absolute basis with an estimated accuracy of 2%, with a sample temperature rise of less than 2°F. Sheets of sample material are rolled with a metal foil heating element into a cylinder resembling a jelly roll. A thin foil thermocouple is inserted at least 0.25 in. from the roll surface. It is established that there is a brief period after heating is begun when the material near the thermocouple is heated adiabatically; from the recorded temperature rise rate and other readily available data, the sample specific heat is computed. The sample assembly is readily placed in a bath or an oven to obtain values at temperatures other than room temperatures. Measurements are reported for polyethylene terephthalate, polyvinyl chloride, and polyethylene, the latter two from liquid nitrogen temperature to decomposition temperatures. It is suggested that the same principles can be used with modified techniques to measure specific heats of conductors, rigid sheets, or liquids.
Simple High Pressure X-Ray Powder Camera
Authors: McWhan D. B. , Bond W. L.
Published: February 2005

A simple high pressure x-ray powder camera is described. The pressure vessel is a disk of three parts ``amorphous'' boron and one part epoxy resin which is pressed between tungsten carbide anvils. The sample can be oscillated in the camera. Pressures of ∼100 kbar have been reached. The phase transition in lanthanum metal reported by Bridgman at 24 kbar and room temperature is associated with a change from a double hexagonal close-packed to a face-centered cubic structure.
Three-Phase Superconducting Motor
Authors: Jones J. D. , Matthews P. W.
Published: February 2005

A three-phase motor is described which has one or more loops of superconductor for its rotor and uses superconducting field coils. The theory of the motor is outlined, including the case when flux is frozen into the rotor. The predictions of the theory are compared with the experimentally observed torque produced by the motor.
Ultraclean Furnace Utilizing Radiation Heating
Authors: Kinsel T.
Published: February 2005

The design of several furnaces using radiant heat transfer is discussed and their thermal properties given. In these furnaces, visible radiant energy from high power, tubular lamps is used to heat samples. It is demonstrated that this type of heating leads to less contamination during high temperature heat treatment. In addition, it is shown that thermal gradients may be established in semiconductor samples by proper choice of wavelength for the radiant energy. This is utilized in the fabrication of diffused junction diodes with improved reverse breakdown voltages.
Silicon Controlled Rectifier Circuit for the Control of High Wattage Projection Lamps
Authors: Wilson John R. , Oppenheimer Frank
Published: February 2005

A way was found to extend the life of the lamp-associated components on bubble chamber film projectors in use at the University of Colorado. The method chosen has the further advantage of extending actual lamp life through the gradual manner in which the lamp is turned on. The circuit has two high current silicon controlled rectifiers which serve as switches for the lamp current. The rectifiers are phase-controlled by a simple multivibrator which can be adjusted to suit the operator. A complete schematic diagram is given, and difficulties with SCR circuits are discussed.
Cryostat Design Permitting Localized Temperature Control from 20 to 870°K
Authors: Robinson J. C.
Published: February 2005

A cryostat for heat treating small specimens over wide temperature ranges is described. With this device it is possible to rapidly raise, lower, or hold the temperature of a small specimen without the use of a mechanical type of heat switch arrangement. A low inertia, high temperature heater is also discussed.
Curled Light Pipes for Thin Organic Scintillators
Authors: Gibson William A.
Published: February 2005

An economical technique is described for heat bending light pipes from rectangular sheets of plastic. The method is useful for coupling organic scintillators with a thickness less than ¼ in. and a few inches wide to 2-in. photomultipliers. Quantitative comparisons of these light pipes with a light pipe machined from a solid block of plastic are described. The results show good light transmission is easily attained with the ``curled'' pipes.
B & L 505 Spectrophotometer Modifications for Measuring Spectral Response of Photodetectors
Authors: Licht S.
Published: February 2005

Modifications to the Bausch and Lomb model 505 recording spectrophotometer, to allow the instrument to measure the spectral response of photodetectors, are described. Although originally performed for silicon photoconductors, the techniques are applicable for any type of photosensitive device.
Direct Measurement of Atomic Lifetimes: Helium
Authors: Holzberlein T. M.
Published: February 2005

A complete system for direct observation of decay of excited states is described. It comprises an inverted triode excitation tube with coaxial symmetry, capable of responding to an electrical cutoff with a risetime of about 10 nsec. Tests in helium have shown that in its present form it can give reliable lifetimes at least as small as 30 nsec.
Electrical Analog of Multiresistivity Systems Using Single Resistivity Media and Amplifier Circuits
Authors: Haupin Warren E.
Published: February 2005

A model is constructed from material of a single electrical conductivity. Current amplifiers, having a low insertion voltage loss, increase or decrease the current flow at boundaries representing changes in conductivity. By making the amplifier gain proportional to the required conductivity change at the boundary, the correct potential field is maintained throughout the model. This new technique overcomes the difficult chore of obtaining graded materials of accurate electrical conductivities.
Use of Silver Chloride Seals for Cesium Vapor Devices
Authors: Eichenbaum A. L. , Norman F. H. , Sobol H.
Published: February 2005

A study of the utility of silver chloride (AgCl) seals for devices employing cesium vapor at pressures up to 0.1 mm Hg was carried out. Mass spectroscopic studies revealed that silver chloride reacts with hot cesium vapor. The reaction rate is, however, sufficiently slow to permit long-life seals in cesiated tubes. A cesiated tube using an AgCl seal has been operated over an extended period without any signs of seal damage.
Increased Photographic Sensitivity for Time-Resolved Mass Spectrometer Data Recording
Authors: Meyer Richard T.
Published: February 2005

A tenfold increase in photographic sensitivity has been achieved for time-resolved mass spectrometer data recording with an oscillographic high speed drum camera. This has been accomplished by an optimized selection of CRT phosphor, photographic film, electron beam accelerating potential, lens aperture, sweep rate, and film processing.
Method for Accelerating Flat Plates to High Velocity
Authors: Balchan A. S. , Cowan G. R.
Published: February 2005

High velocity plates are useful in research, especially in the study of matter under high pressure. A scheme has been devised and tested for driving a thinner driven plate to a higher velocity than a driver plate of the same impedance. The increase is obtained in a collision process in which the driver strikes a buffer layer of lower impedance which is backed by the driven plate. The complex wave pattern has been examined in the acoustic approximation of constant impedance to obtain estimates of the optimum impedance ratios for several configurations which do not spall the driven plate. Experiments with head-on collisions observed by high speed photography and with oblique collisions observed by flash x radiography have demonstrated the technique in both single and multistage arrangements. The results agreed well with the acoustic approximation when the impedance ratio was evaluated at one-half of the pressure level obtained in the initial impact of driver against buffer. Photographic observation of the plate surface indicated substantially no breakup over a free run distance sufficient for the plate to reach terminal velocity.
Calibration System with Microinch Precision at Temperatures to 500°C
Authors: Spanner J. C. , Brenden B. B.
Published: February 2005

A reference system for the evaluation and calibration of microdisplacement readout systems is described. The basic reference system consists of several pieces of precision readout and positioning equipment, a high temperature test chamber, and a specially designed linkage system. The case temperature of the transducer under calibration is maintained constant to within ±0.5°C for temperatures to 500°C. A quartz and Invar linkage system provides a minimum expansion method of coupling linear motion, through a heat shield, from the readout equipment to the transducer located in a test chamber. The reference system is periodically calibrated in the plant Metrology Laboratory and a basic reference system precision of ±0.3% or better for operational ranges from 0.004 to 0.500 in. has been established.
Analysis for Oxygen by Gas-Phase Polarography at Low Temperatures and Low Pressures: A Prototype Assembly
Authors: Halpert Gerald , Madsen Andrew C. , Foley R. T.
Published: February 2005

The design of a prototype model of an oxygen analyzer is presented. This unit utilizes the gas polarographic principle and is capable of analysis for oxygen over the temperature range of from −20 to 80°C and at pressures to as low as 10 mm Hg absolute. The unit can operate for two months unattended. It has a range of 0.001 to 100% oxygen with an accuracy of 1%. The design parameters are discussed and a critique of the unit is made. Temperature dependence is discussed, as are the other pertinent characteristics of the analyzer.
Technique for Measuring Amplitudes of Small Surface Waves
Authors: Muenz K. , Marchello J. M.
Published: February 2005

A photographic method for measuring the amplitude of small waves on a liquid surface has been developed. The technique makes use of the refractive properties of the wave surface and involves elementary optical considerations. Measurement of frequency and wavelength are also discussed.
Precision Over-Under Four-Point Probe with a Small Probe Spacing
Authors: Schumann P. A. , Sheiner L. S.
Published: February 2005

The design of an over-under four-point probe for resistivity measurement of semiconducting material is given. The minimum probe spacing obtainable with this probe is 2.0 mils (50.8 μ). A comparison between this four-point probe at a spacing of 5.3 mils (135 μ) and others for the measurement of nonepitaxial slices is given. A thickness correction factor for these slices is calculated. The small probe spacing obtainable with this probe makes it possible to map the resistivity variations across slices accurately and to measure N/N+ or P/P+ epitaxial layer resistivity.
Heater Lead Problem in Calorimetry
Authors: Ginnings D. C. , West E. D.
Published: February 2005

A study has been made of calorimetric errors resulting from the use of potential leads effectively at the midpoints of current lead segments between a calorimeter and its surrounding shield. An experimental arrangement is suggested to avoid errors due to thermal conduction along potential leads. Using a mathematical analysis, errors due to different thermal contacts between current lead and the calorimeter and shield are also considered. It is concluded that when accuracies of better than 0.1% are desired, careful consideration should be given to heater lead design.
Fast Nitrogen Light Source
Authors: Mancebo Lloyd
Published: February 2005

A submicrosecond flash lamp with a megalumen output has been developed for calibrating scintillation detectors in the field. When operating at 6 kV, a 50-nsec pulse is produced with jitter less than 10 nsec. The output is centered about 3600 Å and is 1000 Å wide.
Materials for Ultrahigh Pressure Sealing in Bridgman Anvil Devices
Authors: Vaisnys Rimas J. , Montgomery Peter W.
Published: February 2005

The properties of various materials have been evaluated for use as sealing rings in the high pressure (100 kbar) Bridgman anvils. An epoxide, Eccobond 104, and a reconstituted mica, 6S Isomica, have been found to be suitable substitutes for the conventionally used material, pyrophyllite. These materials are superior to pyrophyllite in ease of fabrication, electrical resistance, and ability to retain thick (0.020–0.026 in.) samples. The epoxide is sufficiently transparent to x radiation to permit its use as a gasket in high pressure diffraction studies. The pressure generated in samples when the sealing ring is made from the reconstituted mica is very close to the average (force per area) pressure. Samples of silver chloride thicker than 0.015 in. are free of pressure gradients.