bluuebunny/crossref_metadata_2025 huggingface dataset:
Diamagnetic Levitation Using Pyrolytic Graphite
Authors: Waldron Robert D.
Published: February 2005

Stable diamagnetic levitation of masses in excess of one gram has been accomplished in entirely passive systems using pyrolytic graphite and permanent magnets. Analytical and experimental data are given on two vertical thrust bearing assemblies. Extremely low frictional losses were determined from the rate of rotor deceleration in vacuum. Dissipation in a 4 cm diam rotor at 100 rpm was in the nanowatt range. Parametric studies are presented and possible applications discussed.
General Monte Carlo Multivertex Event Generator
Authors: Bordner C. A. , Brenner A. E. , Ronat E. E.
Published: February 2005

A self-contained easily expanded Monte Carlo program for the study of interactions in high energy physics is described. The program is capable of generating events and plotting results for a very wide class of reactions, including those governed by Lorentz invariant phase space and, also, those exhibiting resonances or other non-trivial matrix elements. The performance of the basic program and the method of extending its scope are demonstrated in two examples showing the required input and resulting output.
Radiation Damage in Mylar Exposed to Minimum Ionizing Protons
Authors: Hennessy J. J. , Moore W. H.
Published: February 2005

Mylar D strips have been exposed to 1016 protons in the circulating beam of the Cosmotron and the deterioration of their mechanical properties as a function of the dose is presented. The breaking strength has a threshold decrease at 1.0×1015 and falls to half value at 3.0×1015 protons/cm2. An estimate of the radiation dose has been made.
Design of Slotted Disk Velocity Selectors
Authors: Kinsey James L.
Published: February 2005

Some design principles for slotted disk velocity selectors for molecular beams are set forth. Systematic methods are described for finding a set of disk spacings so that the minimum number of disks is required for sideband elimination. The resulting design permits operation of the velocity selector in several modes having different resolution and transmission properties.
Apparatus for NMR Studies at High Pressure
Authors: Cleron V. , Coston C. J. , Drickamer H. G.
Published: February 2005

An apparatus has been developed which permits NMR measurements at somewhat higher pressures than was previously possible. It makes use of supported taper pistons of chrome oxide with pyrophyllite or boron nitride as the supporting material. With a sample 2 mm thick, pressures of 40 kbar are obtainable; with a sample 0.9–1.0 mm thick, pressures as high as 80–90 kbar may be possible. Data of line width vs pressure are presented for Teflon and polyethylene, and the effect of pressure on the structure of these materials is briefly discussed.
Performance of a High Sensitivity Near Infrared Detection System
Authors: Carr W. N. , Miller E. A. , Leezer J. F.
Published: February 2005

The performance of a synchronous detection system using a cooled phototube (type S1 cathode) is described. Detailed measurements including those using an ultralinear semiconductor photosource indicate that the system responds linearly within 1% per decade of incident flux variation. A tunnel diode discriminator increases the signal-to-noise ratio by a factor of up to 5. The over-all sensitivity obtained is ∼3×103 photons/sec or 5×10−16 W at 0.8 μ wavelength (phototube temperature −78°C). A field effect transistor amplifier with a relatively fast (390 cps) chopping rate is employed. In a spectrometer application in which the detection system is used in conjunction with a conventional monochromator (0.35 transmission, f/8 optics, and 0.005 μ/mm dispersion), a system sensitivity threshold of 4×10−12 W/cm2 μ sr is obtained at 0.8 μ wavelength.
Continuous Measurement of Solid Propellant Burning Rates
Authors: Osborn J. R. , Burick R. J. , Panella R. F.
Published: February 2005

An experimental system is presented for the direct and continuous measurement of the burning rates of solid rocket propellants under conditions closely approximating those of a solid rocket motor. The system involves a positioning type servomechanism which moves a sample of solid propellant within a two dimensional rocket motor such that the receding burning surface of the sample is maintained at a fixed position with respect to the motor. Since the burning surface remains fixed, the direct measurement of the velocity of the propellant feed mechanism for adjusting the position of the propellant sample yields the burning rate. The servomechanism incorporated a 50 m Ci 137Cs source of gamma rays coupled with a scintillation probe for detecting the position of the burning propellant surface. The output of the probe was converted into a voltage by a ratemeter. It was then amplified and compared to a standard voltage which was proportional to a desired propellant surface position. The resulting difference was amplified for the purpose of driving a 0.6 hp servomotor which positioned the burning surface of the propellant sample. The size of the sample was approximately 2.5 cm square by 10 cm long. The experimental data were obtained with the above servomechanism for two composite propellant formulations. The data were obtained for a range of pressures from 8.8 to 35.5 kg/cm2, and for burning rates ranging from 0.40 to 0.8 cm/sec. The data correlated well with previously published data. A theoretical analysis of the servomechanism was performed to determine system stability and performance. An optimization analysis of the servomechanism system yielded optimum operating parameters.
Application of Fourier Transform Spectroscopy to Magnetic Resonance
Authors: Ernst R. R. , Anderson W. A.
Published: February 2005

The application of a new Fourier transform technique to magnetic resonance spectroscopy is explored. The method consists of applying a sequence of short rf pulses to the sample to be investigated and Fourier-transforming the response of the system. The main advantages of this technique compared with the usual spectral sweep method are the much shorter time required to record a spectrum and the higher inherent sensitivity. It is shown theoretically and experimentally that it is possible to enhance the sensitivity of high resolution proton magnetic resonance spectroscopy in a restricted time up to a factor of ten or more. The time necessary to achieve the same sensitivity is a factor of 100 shorter than with conventional methods. The enhancement of the sensitivity is essentially given by the square root of the ratio of line width to total width of the spectrum. The method is of particular advantage for complicated high resolution spectra with much fine structure.
Diffused Semiconductor Low Temperature Thermometers
Authors: Herder T. H. , Olson R. O. , Blakemore J. S.
Published: February 2005

It is known that thermometers of good sensitivity and excellent reproducibility for low temperatures can be based on the temperature dependence of extrinsic electrical conductivity in a semiconductor. Uniformly doped germanium single crystals are customarily used for this purpose; however, the present paper reports on the performance of experimental semiconductor thermometers made by diffusion techniques. Thermometer elements were made both by diffusion of arsenic into germanium, and by diffusion of boron into silicon. For both of these systems, the conductance-temperature characteristic of a diffused layer was qualitatively similar to the conductivity-temperature characteristic of a uniformly doped thermometer bar. However, diffused thermometers suffered appreciable changes of resistance on thermal cycling, to an extent corresponding with temperature errors as large as 0.1° at 4.2°K. This compares unfavorably with the submillidegree reproducibility attainable with uniformly doped bridge shaped bars. Attempts to improve the stability of diffused layers are discussed.
Versatile High Pressure Mössbauer Apparatus
Authors: Debrunner P. , Vaughan R. W. , Champion A. R. , Cohen J. , Moyzis J. , Drickamer H. G.
Published: February 2005

An apparatus has been developed which permits high pressure Mössbauer resonance studies to 300 kbar. It can be operated with either the source or the absorber under pressure. The pressures are established by x-ray diffraction measurements, and calibration curves are presented for both the supported taper and Bridgman anvils cells. A motion device involving magnets and phosphor bronze springs, with an adjustable mount, is described. Circuits necessary to control the motion, and to distribute the signals from two devices operating in parallel, are outlined.
Digital Recording of Spectra. Conversion of Perkin-Elmer Model 521 Infrared Spectrometer
Authors: Peterson Norman C. , Bauman Robert P. , Price Irving W.
Published: February 2005

A double beam, optical null infrared spectrometer has been adapted for digital recording without interfering with the normal operating modes of the instrument. A photoelectric dial reader operates a solid state switching circuit at each calibration mark of the wave number dial to cause a digital voltmeter to read the voltage across the linear transmittance slidewire of the spectrometer, while the spectrometer operates in the absorbance recording mode. The digital voltmeter operates a paper tape punch, permitting computer processing of the spectra.
Thin Film Magnetoresistance Magnetometer
Authors: Hebbert R. S. , Schwee L. J.
Published: February 2005

A thin film alloy of Ni-Fe-Co is etched such that it resembles electrically a Wheatstone bridge except that the arms of the bridge are magnetoresistive. The resistance of one arm increases and the other decreases when in the presence of a magnetic field. The primary feature of this magnetometer is its fast response time. Tests have shown that it has a flat response to alternating magnetic fields with frequencies as high as 65 MHz which was the limit of our test equipment. We have reason to believe that our present system will measure pulses with risetimes as fast as 4 nsec with less than 5% error.
Method for Studying Sputtered Particles by Emission Spectroscopy
Authors: Sawatzky Erich , Kay Eric
Published: February 2005

An f/6.8 scanning spectrometer with a photomultiplier output was used to monitor the presence of particles sputtered from a target surface by ion bombardment. The ion source was a conventional duoplasmatron providing a high density, high energy ion beam. The density of sputtered particles available for analysis was of the order of 108 cm−3. A fraction of these particles was electronically excited by a high density, low energy electron beam, and the emission spectra characteristic of the target material were recorded with either an electrometer or a phase sensitive detector. Some intense atomic copper lines were easily observed when a Cu target was bombarded with 5000 eV Ar+ ions. The intensities of these lines have been analyzed to obtain the sputtering yield and some relative excitation functions for copper. A comparison between the conventional mass spectrometric technique and the present scheme is presented.
High Pressure 3He Gas Scintillation Neutron Detector
Authors: Aamodt R. Lee , Brown Leon J. , Smith Gordon M.
Published: February 2005

Construction details are given for a He gas scintillation neutron detector which operates to 238 atm at room temperature. A bakeable pressure-vacuum manifold, on which the detector is evacuated and filled, also serves to remove contaminants from the DPS waveshifter. The detector appears stable when permanently sealed off. Curves are given for light output vs pressure, and some effects of impurities on such curves are noted. Measurements were made of relative sensitivity to 60Co gammas and Pu-Be neutrons. The gamma flux required to induce a current equal to that from 1 neutron/cm2 sec is 15 MeV/cm2 sec when the scintillating gas is 4He, and 23 MeV/cm2 sec when it is 3He.
Spark Chamber for Gamma-Ray Astronomy
Authors: Frye G. M. , Smith L. H. , Hruschka A. A. , Goff J. R. , Zych A. D.
Published: February 2005

A spark chamber system is described which is designed to detect γ rays in the cosmic radiation on high altitude balloon flights. It has (1) an acceptance cone of 30° half angle; (2) time resolution of 150 msec; (3) energy resolution from 30 to 500 MeV; and for a 100 MeV γ ray, (4) a conversion efficiency of 12.4%, and (5) angular resolution of 3°. Events are recorded photographically. The system is triggered by a large scintillator above the chamber in anticoincidence with a scintillator-Čerenkov telescope beneath. Only the chamber and high voltage components are pressurized. A magnetometer direction monitor locates the γ ray direction to ±3° in right ascension and declination. The system has operated successfully on day and night flights and has a total weight of 80 kg.
Apparatus for Thin Sample Ultrasonic Measurements
Authors: Gelles I. L. , Bomhard C. H.
Published: February 2005

A detailed description is given of an apparatus which makes possible the propagation of ultrasonic pulses through very thin solid samples (foils, films, fine wires, whiskers, etc.). The apparatus includes means for mounting the sample, independent transducer supports, and means for bringing sample and transducer into nondestructive contact. Several sample holding devices and micromanipulator adaptations are described. The over-all measurement system is briefly described together with a few typical results for metal foil and fine wire specimens. Some applications of the apparatus are listed.
Method for Rapidly Reversing Magnetic Field in Shorted Superconducting Coil
Authors: Harding John T.
Published: February 2005

A shorted superconducting coil carrying a persistent current can be made to reverse its field in less than 5 msec by subjecting the coil to an increasing external reverse field. The superconducting coil opposes a change in its interior field until its critical current is exceeded, whereupon rapid extinction of the persistent current occurs thus admitting the external field.
E×B Energy Analyzer for Electrons
Authors: Barr W. L. , Perkins W. A.
Published: February 2005

A simple electron energy analyzer has been used to measure energy distribution functions of the ``hot electron plasma'' produced in a compression mirror machine. The analyzer is located in a region of a steady 1.2 kG field so that electrons which escape from the 23 kG mirror field have most of their transverse energy transformed into the parallel component. This parallel component of energy is determined by the transverse drift in a region of mutually perpendicular electric and magnetic fields; low velocity electrons drift farther as they spend more time in the E×B field region, and vice versa. Electrons are detected by being accelerated onto a plastic scintillator which is viewed through a light pipe by a photomultiplier. Good time resolution is obtained, but since only one narrow energy band can be observed on each shot, the electric field is varied between shots to measure the complete energy spectrum. The magnetic field of the analyzer joins smoothly with the plasma containment magnetic field so that the electrons do not pass through a zero field region. With the 1.2 kG field, the analyzer works well for electron energies up to 20 keV; at higher energies the energy resolution decreases, and at very low energies (<100 eV) secondary electrons cause difficulties.
Simple High Speed Framing Cameras
Authors: Courtney-Pratt J. S.
Published: February 2005

J. Wadsworth and F. E. Stokes recently described a simple high speed camera. They formed an array of images using crossed rods of glass to form an array of small camera lenses, and each lens of this array formed a separate frame. They exposed successive frames by rotating a Nipkow disk in front of the crossed glass rods. Some years ago, I made some high speed cameras working on similar principles, but using lenticular plates as the array of camera lenses. Sequential operation could be by Nipkow disk or by control of the light sources, which could be an array of sparks, or more simply, the moving spot of a cathode ray tube. Rates of recording were in the range 105 to 106 pictures per second. The cameras are very simple and of low cost. They allow one to record long sequences of pictures. Picture quality was low but there is a reasonable prospect of improvement.
Rapid Transfer of Magnetic Energy by Means of Exploding Foils
Authors: Maisonnier Ch. , Linhart J. G. , Gourlan C.
Published: February 2005

Rapid transfer of magnetic energy to an inductive load is usually done by discharging a condenser bank, but it can, in principle, also be done by using inductive storage. The problem then is how to open quickly a switch carrying a large current. Using a thin (10 μ) cylindrical foil of aluminum as a switch, energies of the order of 104 J have been transferred into an inductance of about 10−8 H in a few times 10−7 sec. An elementary theory of the explosion of the foil is presented, and it is shown to agree well with experimental results. Technical problems associated with the construction of such a fast switch can be considered solved up to an energy level of at least 100 kJ.
Tunnel Diode Chronotron Circuit for Picosecond Range
Authors: Venable William H.
Published: February 2005

A multichannel circuit has been devised for measuring short time intervals directly with a sequence of timing circuits. The output is in the form of counts per time interval with one and only one output count per pair. Time intervals can be measured from less than 5 psec up to any length of time for which it is practical to build a delay line. With coaxial lines used as delay lines, the timing standard deviation in the Nth channel is (1.4+0.36N)½ psec. The temperature drift of a single channel without temperature compensation is 5 psec/°C and is not cumulative in a long chain of circuits.
Evaluation of Faraday Shielded Stix Coils for Ion Cyclotron Resonance Heating of Plasma
Authors: Dodge N. B. , Kristiansen M. , Dougal A. A.
Published: February 2005

The spatial waveform of the azimuthal electric field Eθ of the Stix coil is investigated. Methods are developed to improve the Eθ waveform by making it more nearly sinusoidal. Varying the spacing between individual coil turns in the coil section, along with the use of a ``squirrel cage'' type Faraday shield, is found to give a more nearly sinusoidal waveform. The effect of a number of Faraday shields on the Eθ waveform is also presented and it is found that certain types of shields, notably the single slit copper cylinder shield, introduce distortions into the accelerating (Eθ) field. The efficiency of these shields in reducing the longitudinal electric field Ez is reported. Several are found to be efficient Ez shields, except for a Faraday shield placed outside the Stix coil. The effect of Faraday shields on the equivalent circuit parameters of the Stix coil is also determined, and the variation of these parameters among the various shields is tabulated.
Stepper Magnet with 20 Channels for Preventing Superimposition of Tracks in Bubble Chamber
Authors: Faltens Andris , Barale John
Published: February 2005

This report describes a 20 channel ``stepper'' magnet assembly designed to cause the incoming Bevatron particle beam to scan across the 1.83 m hydrogen bubble chamber in discrete steps. The purpose of this device is to avoid superimposing tracks. Stepping was triggered by an ``events'' counter placed in the beam. The system was built with low voltage, silicon controlled rectifiers. Magnet pulsing was accomplished in two parts, rapid rise of field was produced by a fast circuit and pulse length was maintained by a slow circuit. Cost was approximately $15 000, exclusive of the surplus components.
Cosmic Ray Induced Dark Current in Photomultipliers
Authors: Young Andrew T.
Published: February 2005

Čerenkov light flashes produced by cosmic rays traversing the window of an end-on photomultiplier create a fundamental noise limitation that cannot be reduced by cooling the tube. Although the cosmic ray pulse rate is only 1 or 2 cm−2/min, the individual pulses may be hundreds of times larger than single electron pulses. Thus in dc or charge integration photometry, cosmic ray noise can exceed thermionic dark current noise at temperatures as high as +10°C. These assertions are based on the observed behavior of EMI 6256 and 9558 tubes. The implications for photometry of faint astronomical sources are discussed.
Interference Microtopography with Incoherent Light
Authors: McCutchen C. W.
Published: February 2005

Conventional coherent illumination provides the interference at high orders necessary for microtopography. However, the resulting interferogram is not a true, undistorted contour map of the specimen, nor is there any direct method of assessing the distortion. In addition, coherent illumination gives poor resolution, and when vertical illumination is used reflections in the objective reduce the contrast. These problems are all ameliorated by using incoherent illumination limited to a small range in angle relative to the plane of the reference reflector but unconfined in azimuth, i.e., the illumination produced by an annular source in the back focal plane of the illuminating lens.
Interferometer for Shock Tube
Authors: Besse Arthur L. , Kelley Joseph G.
Published: February 2005

A Twyman-Green arrangement with a narrow laser beam and twin photomultipliers is used to obtain positive indication of the direction of fringe movement, resolution of 1/12 of a fringe, and good discrimination against shock induced radiation. The instrument has been successfully applied to the study of ionization behind strong argon shocks.
Capacitance Thermometer for Rotator
Authors: Takami K. , Matsuura K.
Published: February 2005

An LC resonant circuit containing a temperature sensitive capacitor of a ferroelectric material such as barium strontium titanate has been utilized above its Curie temperature as a sensing element in a thermometer, by measuring its resonant frequency without any direct connection. This light weight, small size, and connection-free sensing circuit is especially suited to multipoint thermometry for a high speed rotator. Check of the accuracy of this thermometer was carried out under the operating condition of the rotator using a thermometer, and it was found that accuracy of 1 to 2°C was obtainable in the range from 15 to 200°C. Application of this thermometer to the turbogenerator was examined, and usefulness of this method was demonstrated.
Proportional Counter for Detection of Ions and Atoms in Kiloelectronvolt Energy Range
Authors: McClure G. W. , Allensworth D. L.
Published: February 2005

A proportional counter designed as a detector of ions and neutral atoms for use in collision experiments at kiloelectron volt energies is described. Response to 1–40 keV H+ ions and 5–40 keV Ar+ and N+ ions is investigated. Particles enter the detector from an attached evacuated chamber through a thin film covered narrow slit or through a differentially pumped open aperture. Construction of the counter and performance with both types of aperture are described. Performance is evaluated in terms of two statistical measures of the differential pulse height distribution—the most probable pulse height and the pulse height spread. Sufficient data are given to permit evaluation of the proportional counter as an ion energy spectrometer. Measurements of scattering and energy loss of protons in the thin film window are described.
High Pressure Vessel for Measurement of Pressure Induced Phonon Energy Shifts by Inelastic Scattering of Neutrons
Authors: Lechner Ruep
Published: February 2005

A pressure vessel for neutron inelastic scattering experiments at 3000 atm maximum pressure is described. Rather thin walls with good neutron transmission properties are obtained by making the vessel of five cylinders, each of a high strength aluminum alloy, which are shrunk one upon another. This ``compound cylinder'' has a total wall thickness of only 13.5 mm for a (cylindrical) sample volume of 30.6 mm diameter and 65 mm length. The whole range 2π of scattering angles is accessible. Certain relations are given which were used in calculating optimal cylinder dimensions. Experiments with a lead single crystal show a reduction of Bragg peak intensity to 76% if the crystal is mounted in the vessel. A typical measurement at 3000 atm gives an increase of 2% in phonon energy.
Measuring Seebeck Coefficients on High Resistivity Materials
Authors: Mette Herbert , Loscoe Claire
Published: February 2005

Measurements of the Seebeck coefficient on samples possessing resistivities between 1012 and 1014 Ω cm are accomplished by establishing a temperature difference between two electric contacts and reading the resulting voltage difference on a sensitive vibrating reed electrometer. Electrostatic pickup (through the ambient and gradient heating systems, the thermocouple leads, or from charges released through contact of the lead wires with a dielectric support) is eliminated in the most sensitive electrometer range by rigorous shielding procedures, which are described. The method was tested by measuring Seebeck coefficients between 30 and 80°C on metallo-organic ferrocene crystals of 0.5 mm thickness.
Vapor Source for Vacuum Evaporation of Compounds
Authors: Spriggs R. Spencer , Learn Arthur J.
Published: February 2005

The advantages and assembly of a vapor source for the deposition of compounds are discussed. The source consists of a molybdenum block honeycombed with holes. The material to be evaporated is contained in the holes. The block is heated by tungsten cathode heaters embedded in the sides of the molybdenum block. A detailed description is given of the source assembly and its operational characteristics for evaporation of cadmium sulfide. Experimental data are presented concerning spatial flux distribution and the flux density. In addition, possible effects of hole geometry on the nominal area from which evaporation takes place are discussed.
Detector for Measurement of Ultrasonic Strain Amplitudes in Solids
Authors: Gauster W. B. , Breazeale M. A.
Published: February 2005

A capacitive detector has been developed for strain amplitude measurements of longitudinal ultrasonic waves in the frequency range from 5 to 100 MHz. The sensitivity of the device is such that displacement amplitudes of the order of 10−10 cm can be detected. As a check of the technique, quantitative measurements of the harmonic distortion of ultrasonic waves in a single crystal of germanium were made. From the results, some combinations of third order elastic constants are calculated and are compared with values obtained with the same sample by another method.
Gauge for Continuously Measuring Rate of Rainfall
Authors: Semplak R. A.
Published: February 2005

A gauge for continuously measuring rainfall rate is discussed. In this gauge, water flows through a channel type capacitor which is coupled to an oscillator, thus the frequency of the output voltage changes with rain rate. The calibration curve can be expressed mathematically as the sum of two exponentials, f=f0½[exp(−K1R) +exp(−K2R)] where f0 is the frequency corresponding to dry condition, R the rain rate, and K1 and K2 are constants. One hundred gauges have been fabricated and calibrated, and statistics of these calibrations are presented. Based upon the measured data, capacitance rain gauges are found suitable for situations where continuous rainfall rate data are desired. The output of the gauge is in a form readily adapted for computer reduction.
Cosmic Ray Charge Spectrometer
Authors: Parnell T. A. , Palmatier E. D. , Mace R.
Published: February 2005

A gas filled Čerenkov radiation detector has been combined with solid detectors to measure the charge and flux of relativistic primary cosmic rays. Data from a high altitude balloon flight, using a NaI crystal as ΔE/Δx detector, indicate a clear separation of protons from α particles. The resolution may be improved with a solid Čerenkov detector replacing the NaI crystal.
Versatile Gated Discriminator with Adjustable Paralysis Useful in Fast-Slow Coincidence Experiments
Authors: De Volpi A. , English J. J. , Metz A. J. , Porges K. G. , Rudnick S. J.
Published: February 2005

The discriminator described incorporates a number of features useful in nuclear applications. The paralysis, or deadtime, is adjustable from 100 nsec to 10 msec; at a fixed temperature it is stable to within ±1%, even for pulse pair separations approaching the paralysis time: hence deadtime corrections are correspondingly accurate. Two pairs of 100 MHz logic outputs and a separate scaler driver output are provided. The scaler output can be controlled by external coincidence gating or blocking signals. These gating provisions make it possible to connect a dual module (without additional circuitry) as a single channel analyzer, as an antiwalk discriminator for precise coincidence timing, or even as a coincidence circuit. The primary application is, however, coincidence counting when one or more side channels are needed for amplitude selection. The coincidence gating provision of this discriminator permits one to dispense with lengthy external delay compensation required by conventional energy selecting coincidence schemes. The similarity of the three approaches—conventional slow-fast, conventional fast-slow, and gated fast-slow—in terms of coincidence computations and accidental monitoring is demonstrated, and criteria are presented to aid in selection of one technique over the others.
Simple Mechanical Light Discriminator For Recording of Luminescence
Authors: Peled S. , El-Hanany U. , Yatsiv S.
Published: February 2005

A mechanical device for obtaining fluorescence spectra is described. The elimination of the exciting radiation and stray light in this device is highly effective, so that very weak fluorescence signals can be recorded without optical filters.
Electron Microprobe and Electron Microscope Investigation of Identical Areas
Authors: Estill W. B. , Robertson M. M.
Published: February 2005

A new technique, called ``identical area microscopy,'' allows direct comparison of the results of optical, electron probe, and electron microscope studies of the same area. Although the contamination film which builds up on a specimen during electron probe studies can adversely influence analysis, it proves to be an excellent surface replica for electron microscope studies.
Apparatus for Measurement of Bulk Modulus
Authors: Wostl W. J. , Buehler R. J. , Dresser T.
Published: February 2005

The scarcity of accurate bulk modulus data on many liquids led to the construction of an apparatus to determine both adiabatic and isothermal bulk modulus values. The apparatus is designed for highly compressible liquids such as pentane as well as relatively ``hard'' liquids like water or crude oils. The temperature range of the instrument is from 0 to +50°C, and the pressure range from 0 to 300 kg/cm2. The precision in adiabatic bulk modulus measurements with this apparatus has been determined for water for which the derived error is 0.1%.
Spectral Response System for Processing Photocathodes
Authors: Ioannou John T. , Theodorou Dimitri G.
Published: February 2005

A processing system for photocathodes has been developed whereby the variation of the spectral response of the photocathode can be continuously monitored throughout processing. The design details of the system are given together with some examples which show the variation of the spectral response of an S-20 photocathode during various steps in processing. This system should lead to procedures for controlling the luminous sensitivity in any portion of the visible spectrum, better predictable photocathode-to-photocathode uniformity, and reduced processing time.
Instrument for Lunar Surface Chemical Analysis
Authors: Turkevich Anthony , Knolle Karlfried , Emmert Richard A. , Anderson Wayne A. , Patterson James H. , Franzgrote Ernest
Published: February 2005

An instrument has been designed and constructed which utilizes the interactions of monoenergetic alpha particles with matter for surface chemical analysis. The source of alpha particles is a radioactive nuclide, such as 242Cm. The energy spectra of backscattered alpha particles are measured with semiconductor detectors. Other detectors (with gold foils over them to eliminate alpha particles) register protons from α,p reactions. Transistorized electronics provide 128-channel pulse height analyzers for both alpha and proton spectra. The first prototype instrument designed for the presently planned Surveyor Lunar Missions weighs less than 4 kg and uses less than 1.3 W.
Apparatus for Measurement of Friction and Adhesion at Ultrahigh Vacuum
Authors: Brown R. D. , Burton R. A.
Published: February 2005

An apparatus is described which has been used to measure both friction and adhesion over a wide temperature range (−168 to 538°C) at ultrahigh vacuum (pressures as low as 5×10−10 Torr). By using sealed reentrant tubes, a number of major gas sources such as electrical wiring and insulation, thermocouples, heaters, and strain gauges are eliminated from inside the vacuum chamber. The specimen normal load is introduced through a gimbals mounted, bellows sealed arm projecting into the vacuum chamber. For friction experiments, the gimbal ring is oscillated by an external motor and crank, thus causing reciprocating sliding of a pin type specimen while in contact with a flat specimen. The variations of friction and adhesion with temperature were measured on the apparatus, confirming its effectiveness as a basic instrument.
Near 100% Efficiency Ion Detector for Use with Quadrupole Mass Filter
Authors: Marchand P. , Paquet C. , Marmet P.
Published: February 2005

A 14-stage Ag-Mg Allen type electron multiplier is used as an ion detector with a large exit aperture (5 cm diam) quadrupole mass filter. A simple lens system provides sufficient focusing on the first dynode of the multiplier to insure near 100% ion collection and extremely stable detection. A pulse height distribution for single ion impacts closely similar to that expected using Poisson statistics is obtained. Arguments as to the system's efficiency as well as details of the construction of the multiplier are given.
Shunt Triggered Flashtube Illumination System Design
Authors: Sondericker J. H.
Published: February 2005

The advantages and design flexibility gained by use of the shunt trigger method are discussed. A typical circuit is described which is used to turn on a series ignitron and simultaneously ionize the xenon flashtube. The trigger pulse has an amplitude of 30 kV with a peak current of 100 A. Its rate of rise with a flashtube load is better than 40 kV/μsec with a half width of less than 1 μsec.
Experimental Considerations for Polaroid Film X-Ray Photographs
Authors: Peters E. T. , Kulin S. A.
Published: February 2005

Polaroid type 57 sheet film (ASA 3000) has been evaluated as a means for recording x-ray Laue and pinhole diffraction photographs; both transmission and back reflection geometries have been employed. Consideration has been given to the effect of x-ray tube target material, tube voltage and current, exposure and processing times, collimator size, and specimen-to-film distance on resultant pattern quality. Examples are given which illustrate the the ability to obtain high quality Polaroid film patterns in considerably less (5 to 20%) time than is required for comparable wet process films.
High Voltage Impulse System
Authors: Finkelstein David , Goldberg Philip , Shuchatowitz Joshua
Published: February 2005

An alternative to the Marx circuit for the production of high voltage, high current pulses is developed. It employs a water-immersed spiral-wound stepup transformer to go from a capacitor bank charged to 100 kV to an output of 1 MV. A method for using such a transformer to pulse charge a second capacitor bank efficiently without very tight coupling is derived. It is shown that for total transfer of energy (except for dissipation) the two resonant frequencies of the primary and secondary LC circuits (each measured with the other circuit open) should be equal, while the two normal mode frequencies of the coupled circuit should be in the ratio of 2:1, implying a coupling coefficient of 3/5. The design and operation of such a system is described.
Kinetic Friction of Textile Yarns: Improved Measuring Instrument
Authors: Knapton James J. F.
Published: February 2005

A versatile instrument for measuring the kinetic friction of textile yarns over any test object is described. The instrument incorporates new features for more precise friction evaluation, such as a feedback control for continuous testing and an accurate system for applying constant input tensions of any desired value. The instrument collects friction data continuously, using the established technique of measuring the input and output yarn tensions over the test object, by use of differential capacitor transducers accurate to ±0.1 g. Using Howell's model of kinetic friction, the relationship describing the dependence of the friction force F on the normal load W for a worsted yarn over metal has been shown to be given by F=0.637 W0.782. Kinetic measuring of yarn/metal, yarn/yarn friction can be performed on most types and counts of yarn.
Time Resolved Electrical Measurements in High Current Discharges
Authors: Cassidy E. C. , Zimmerman S. W. , Neumann K. K.
Published: February 2005

A method for measurement of the resistive component of the instantaneous voltage across a sample installed in a high voltage, high current circuit is described. Simultaneous measurement of the current permitted time resolved determination of electrical energy dissipation, power, and resistance of the sample. The system was calibrated calorimetrically, and measurements were made with exploding wire samples.
High Efficiency Solid State Neutron Telescope for 15–35 MeV Neutrons
Authors: Flynn E. R. , Bryant H. C.
Published: February 2005

High detection efficiency for a neutron telescope spectrometer is achieved without the usual sacrifice in energy resolution by replacing the standard radiator by a series of radiators, each of which is backed by a silicon transmission detector. By adding the pulses from the transmission detectors, with appropriate gains, to the pulse from the final thick detector, in which the proton recoil stops, a signal is produced which is proportional to the energy of the proton recoil, with an energy uncertainty of one-half the energy lost by the proton in a single radiator. Thus the energy resolution is determined, for small recoil angles, by the thickness of a single radiator, whereas the detection efficiency is determined by the sum of the radiator thicknesses. Details of operation, efficiency calculation, data analysis, and several spectra demonstrating the performance are discussed. Possible extensions and improvements of the system are considered.
Increasing Synchrocyclotron Currents and the Space Charge Limit
Authors: Rainwater James
Published: February 2005

Until MacKenzie recently emphasized the dominating role of space charge beam blowup at small radii in synchrocyclotrons, the importance of this factor was not appreciated. Much largely futile effort had been expended on attempts to increase average beam currents by improving other factors. Lawson's extension of MacKenzie's treatment for ordinary cyclotrons is considered in more detail, with numerical examples and a detailed discussion of the extension of the theory to synchrocyclotrons. In addition, a simpler semi-empirical formula is obtained which gives a good match to existing currents in all present synchrocyclotrons. Current gains up to a factor ∼100 should be feasible, and a discussion is given as to how such an improvement might be gained by modifications of existing synchrocyclotrons.
Three Phase, 1.5 MW, Electronic Line Regulator for the Berkeley 88-Inch Cyclotron
Authors: Smith Bob H. , Harris Everett L.
Published: February 2005

Six hundred power transistors on water-cooled heatsinks are connected in a Kerns actuator circuit to modulate the power line feeding the Berkeley 88-Inch Cyclotron. The regulator senses the rectified three phase line voltage and attenuates the frequency components between 0.001 and 200 Hz to 0.03% of the average value. Elimination of these components from the main power line removes the need for expensive wide band regulators for each of the many critical high power loads in the building. The paper discusses the design considerations and construction techniques of this regulator.
Detection of Pulse Pile-Ups with Pulse Overlap to Pulse Height Converter
Authors: Monier L. F. , Tripard G. E.
Published: February 2005

A new type of pile-up rejector, using a pulse overlap to pulse height converter, is described. It is operated at the output of a double delay line clipped amplifier and has a resolving time better than 20 nsec.
Photoelectrically Actuated Timing Device for Use with Microhardness Tester
Authors: Russell R. R. , Holik A. S.
Published: February 2005

A reliable, inexpensive timing device has been constructed for use with the Kentron microhardness tester. This device, which consists of a photoelectric switch coupled to an electric timer, enables the duration of loading to be precisely controlled, provides a convenient method for measuring the loading rate, and facilitates adjustment of the tester. The use of this timing accessory increases the efficiency of operation of the microhardness tester and reduces operator error, thereby improving the accuracy and reproducibility of microhardness testing results. The device should be adaptable to other hardness testers.
Enhanced Photoelectron Emission Between 200 and 1300 Å
Authors: Samson James A. R. , Cairns R. B.
Published: February 2005

The photoelectric yield of a metal has been shown to increase with increasing angle of incidence of the radiation. The reflected radiation is reused to cause further photoemission until the incident radiation is entirely absorbed. Using an eighteen sided aluminum polygon to totally absorb the radiation, the photoelectric yield of the polygon compared to that of a single plate used at normal incidence was increased by a factor of 5.5 at 209 Å and by 40% at 1216 Å. The yield of the polygon cathode was in excess of 16% between 200 and 1000 Å with a maximum yield of 28% at 350 Å.
Mass Spectrometric Sampling Probe for Discharge Plasmas
Authors: Böhme D. K. , Goodings J. M.
Published: February 2005

A versatile sampling technique is described which permits a more definitive study of ion extraction and plasma sheath formation in discharge plasmas. The ionic species from the plasma are sampled into a quadrupole mass spectrometer through a metal leak arrangement which itself acts as a probe. This behavior is substantiated by sampling probe characteristics, and charge density and electron temperature determinations for a flowing microwave discharge plasma in nitrogen at low pressure.
Laser Radar (Lidar) for Meteorological Observations
Authors: Northend C. A. , Honey R. C. , Evans W. E.
Published: February 2005

This paper describes an experimental high powered, Q switched, ruby laser radar or lidar designed for meteorological applications and upper atmosphere studies being conducted by the Environmental Sciences Division, Range Development Department, Pacific Missile Range, Point Mugu, California. The lidar system equations, detailed design, operation, and recommendations for design improvements are discussed, and typical observational data are presented to illustrate the uses of this new meteorological instrument.
Apparatus for Direct Determination and Continuous Recording of Internal Friction at Constant Amplitude
Authors: Butera R. A. , Craig R. S.
Published: February 2005

An apparatus is described in which internal friction at constant amplitude is continuously determined in terms of directly measured electrical and mechanical parameters of the system without recourse to a secondary method of calibration. The specimen, in the form of a wire, serves as the torsion member in a torsion pendulum which is maintained in sustained oscillations by an electromechanical system employing positive feedback. Attached to the inertia member of the torsion pendulum are two coaxial coils which are located in the field of a permanent magnet. The emf generated in one of the coils (pickup coil) by the motion in the field is amplified, converted into a square wave and fed back into the other coil (the driver) through a gain control circuit. The power fed back into the driver coil is controlled by a servoloop in such a way as to maintain the amplitude of oscillation constant. The internal friction is proportional to the setting of the gain control unit in the driver circuit and is displayed continuously on a strip chart recorder. Internal friction values measured on this device agree to within better than 2% with those measured from the logarithmic decrement.
Laboratory Instrumentation for Testing and Calibration of In Situ Probes for Lower Ionosphere, Mesosphere, and Stratosphere
Authors: Oster A. L. , Dolezalek H.
Published: February 2005

A system has been developed in which the conditions of gas composition, pressure, velocity, and ionic properties of the lower ionosphere, mesosphere, and stratosphere can be simulated. It consists of a special type of wind tunnel, pumps, and tanks, and a particular ion source; the gas flowing through the system is supplied from bottled gases. It can be operated continuously for a pressure range from 760 to less than 10−2 Torr, the minimum pressure corresponding to a height of 80 km in the terrestrial atmosphere. Velocities can be varied from zero to more than Mach 1. The system is utilized to test and calibrate in situ probes for the described environments.
Cryostat for Combined EPR and Optical Studies
Authors: Andrews R. A. , Kim Y. W.
Published: February 2005

The design of a cryostat which allows simultaneous electron paramagnetic resonance studies and optical absorption measurements is given. Details of the microwave cavity, whose coupling can be adjusted from outside the cryostat, optical characteristics, and sample positioning mechanism are included. In addition, discussion of possible use of the cryostat for x irradiation or uv irradiation of samples at low temperature is given. Provisions for electron-nuclear double resonance measurements and temperature variation of the sample are also discussed.
Use of Multichannel Analyzer Averaging in Frequency Swept Spectroscopy
Authors: Reichert Jonathan F. , Pereli Julius
Published: February 2005

An electronic programming device is described which allows the standard multichannel analyzer averager to be used in spectroscopy where the frequency is the independent variable. The standard electronic counter and digital-to-analog converter are incorporated in the circuit presented.
Correction of Free Induction Decay Distortions due to Finite Bandwidths of Pickup Coil and Receiver
Authors: Barnaal D. E. , Lowe I. J.
Published: February 2005

The effects of the finite bandwidth of the pickup coil, amplifier, and detector on free induction decay shapes are calculated. The results show that it is normally necessary to correct for the finite bandwidth of these elements, and a procedure for doing this is presented. The circuit of a broad band, balanced, rf phase sensitive detector is given.
Hydrofluoric Acid Solution Calorimeter for Slow Reactions
Authors: Tischer R. E.
Published: February 2005

A newly constructed modified Bunsen calorimeter is capable of measuring the heat of solution of slowly dissolving materials. Its construction, operating characteristics, and the results of an electrical calibration are discussed. Quantities of heat up to 1000 cal can be measured with a reproducibility of ±0.2% for reactions taking as long as 90 min. The heat of solution of ZnO in a hydrofluoric-nitric acid mixture was measured to check its performance. The value obtained, −257.83±0.26 cal/g, is in agreement with the value reported in the literature.