bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of the Hilbert space properties of the Veneziano model operator formalism
Authors: Brink L. , Frampton P. H. , Nielsen H. B.
Published: February 2004

The domains of definition of the operators used to factorize the generalized Veneziano model are studied within the Hilbert space defined by the harmonic oscillator creation and annihilation operators aμ(r)†, aμ(r). These individual operators may not be well behaved, although, of course, the matrix elements used in the conventional operational factorization are well defined. Concerning the individual operators, it is shown that the ground-state vertex written as V(p)=exp[−∑r=1∞ (p·a (r)+)/√ r]exp[∑r=1∞ (p·a (r))/√ r] is nowhere defined within the Hilbert space; the product with a twisting operator Ω(q)V(p) is, however, densely defined, as is the symmetrical three-reggeon vertex. The propagator D(p) is bounded everywhere, away from its poles. The twisting operator Ω(p) is undefined on finite occupation states, but is densely defined on a subset of coherent states; its Hermitian conjugate Ω+(p) is densely defined on both finite occupation and coherent states. It is found that a suitable rewritten form of the product D(q)V(p) is densely defined for certain values of momenta; this relates to the fact that off-mass shell states satisfying (L0−L−r−1)|Φ =0, where Ln are the conventional gauge operators, are better defined than those satisfying (L0−L−r+r−1|Φ′ > =0.
Preparation of Nearly Pure Orthohydrogen and Paradeuterium
Authors: Depatie D. A. , Mills R. L.
Published: February 2004

A simple device, based on preferential adsorption at 20°K, for preparing liter quantities of 99% orthohydrogen or paradeuterium is described and some typical results are given. A straightforward analysis explains the experimental results and suggests a mechanism of enrichment.
Thermal Conductivity and Heat Capacity of 7740 Pyrex below 4°K and in Magnetic Fields to 90 kG
Authors: Fisher R. A. , Brodale G. E. , Hornung E. W. , Giauque W. F.
Published: February 2004

The thermal conductivity of Pyrex 7740 glass has been measured over the temperature range 0.4 to 4°K and in magnetic fields from 0 to 90 kG. As expected, the conductivity was unaffected by the field. The glass had an iron content of 0.02%. The heat capacity of Pyrex, at constant magnetic fields, has been measured over the above range of temperature and field. There was a considerable field effect due to the iron content. The variation of temperature with field was measured on a series of isentropes and this enabled the evaluation of the entropy. The change of temperature of Pyrex during adiabatic demagnetization at various values of the entropy is shown as a graph for this typical sample. A description of the apparatus used for the measurement is included.
Precision Temperature-Controlled Water Bath
Authors: Harvey M. E.
Published: February 2004

The water bath described was designed primarily to furnish an improved environment for microwave microcalorimeters, but would also be useful for thermometer calibration, standard cells (suitably insulated), and other physical and chemical measurement systems. The bath and its associated temperature controller operate at any temperature between 18 and 28°C which is not more than 6°C below the ambient temperature. The bath provides a temperature stability of ±25 μ°C over a 24 h period when measured with a 100-sec time constant. The short-term stability measured with a 0.7 sec time constant is between ±70 and ±7 μ°C, depending on the location within the bath and the magnitude of the energy exchange between the heating and cooling mechanisms. The bath temperature change caused by an ambient temperature change of 2°C is less than 5 μ°C.
Rotating Sample Holder for X-Band Ultrasonics
Authors: Dooley John W. , Tepley Norman
Published: February 2004

A rotating sample holder to perform ultrasonic experiments at X-band frequencies within a cryostat of inner diameter 37 mm has been constructed. Details of 0.953 cm diam by 0.628 cm long brass reentrant cavities which are tuned and rotated from outside the cryostat are given. In a novel approach, two cavities are coupled to the same waveguide.
Design for Orientation of Balloon-Borne Equipment
Authors: Anderson Gerald A.
Published: February 2004

Presents the design of a system to orientate a balloon-borne instrument package about a vertical axis. Pointing accuracy obtained is ±1.5°. An independent photographic recording system measures the azimuth angle with respect to the star Polaris to ±0.1°. The instrument package is rotated against a light-weight reaction wheel, which is designed for maximum moment of inertia. A pulse-width modulation system is used to drive the orientation motor. A flux-gate magnetometer, used for the sensor element, causes the instrument package to be orientated with respect to the horizontal component of the earth's field. The instrument, a gamma-ray telescope, is oriented in the north-south plane and is tilted at an angle with the vertical which will correspond with the elevation of the suspected gamma-ray source when the source crosses the local meridian.
Study of Fragmentation Patterns by Beam Modulation Mass Spectrometry
Authors: Boyer Myron H. , Murad Edmond , Inami Y. Harry , Hildenbrand Donald L.
Published: February 2004

A new mass spectrometric technique is described by which information can be obtained on the specific progenitor or progenitors of a mass peak. The method comprises modulating the neutral beam at an appropriate frequency and observing the ion signal with a phase-sensitive detector. Measurement of signal intensity at different phase angles with respect to a point of origin provides a curve from which can be extracted information on the relative contribution of different species in the neutral beam to the ion signal. A theoretical analysis of the method is described, and theoretically calculated intensity vs phase angle curves are presented for some systems of interest. Curves for AlF are compared with experimental data and very good agreement demonstrated. Preliminary data on the pressure ratios of monomer, dimer, and trimer in LiF vapor are discussed.
Comparison of the Spherical Deflector and the Cylindrical Mirror Analyzers
Authors: Hafner H. , Simpson J. Arol , Kuyatt C. E.
Published: February 2004

The calculated performance of electrostatic analyzers of the cylindrical and spherical deflection type are compared. It is shown that considering geometrical terms through the third order the cylindrical device is significantly superior.
Gauge for Measuring Impulsive Pressure in a Container Subjected to Large, Time-Varying Applied Voltages
Authors: Grabowsky W. R. , Durran D. A.
Published: February 2004

A pressure gauge consisting of a strain-gauge transducer, bridge, and decoupler is described for the measurement of time-varying pressures in the presence of an electrical noise environment typical of capacitor discharge systems. In particular, the transducer of the gauge has been subjected to large, time-varying applied voltages, Vmax≈103 V and [(dv/dt)]max≈5×106 V/sec,and large, time-varying magnetic fields, Bmax≈2×104 G and [(dB/dt)]max≈5×106 G/sec,with no ill effect on the output of the gauge. At least an order of magnitude increase in these quantities (i.e., Vmax, etc.) is believed possible without serious effect on the gauge output. The gauge can be statically calibrated, has a rise time of ∼4 μsec, and can be compensated for electronic drift.
Medium-Sensitivity Microbalances for Measuring Forces Exerted by Molecular Beams
Authors: Marsden D. G. H.
Published: February 2004

Two servo-controlled balances designed to measure forces exerted by molecular beams are described; usable sensitivities are of the order of 10−5 dynes. One balance is designed to measure accommodation coefficients on interchangeable targets, which may be heated up to 1000°C. The other, in conjunction with an ion-gauge, may be used to measure absolute molecular beam fluxes and mean incident energies in both single and binary mixed beams.
Guarded Double Field Meter
Authors: Gathman Stuart
Published: February 2004

An instrument is described for absolute measurements of components of electrostatic fields in the free atmosphere near the earth's surface. This apparatus provides a guarding system to minimize field distortion at the measurement site. A method utilizing models in an alternating electric field is used to evaluate the augmentation factor of the instrument as well as the effectiveness of the guarding system. The instrument has been used to measure horizontal electric field and to make vertical field profiles. It is also used simultaneously with a field meter flush with the earth to make an analog record of space charge density.
Time-of-Flight Velocity Analysis of Atomic and Molecular Beams
Authors: Hagena Otto F. , Varma Ashok K.
Published: February 2004

A systematic analysis of the time-of-flight (TOF) method for measuring the distribution of speeds in molecular beams is presented. The conditions required for resolving a given beam speed distribution are evaluated by calculating the TOF signal for a finite open time τ of the beam shutter. The halfwidth of the TOF signal Δt exceeds the ideal half width Δt0(for τ→0) by not more than 2.5%, if the resolution R=Δt/τ is equal to or larger than 5. The peak signal amplitude Um is not less than 0.8 U0/R, where U0 is the signal corresponding to the unchopped beam (τ→∞). Design criteria for beam chopper and detection system are discussed in terms of the resolution, the range of speeds to be measured, and the optimum signal-to-noise ratio. A TOF system used for the detection of high-intensity molecular beams with large speed ratio, as well as for low-intensity scattered beams, is described and typical experimental results are presented.
Measurement of Small Density Differences: Solutions of Slightly Soluble Gases
Authors: Blair L. M. , Quinn J. A.
Published: February 2004

An experimental technique has been developed for measuring small liquid density differences. The technique is particularly useful for determining densities of solutions of slightly soluble gases. Density differences as small as one part in 105 can be detected with precision. We have demonstrated the applicability of the technique by measuring the density of aqueous solutions of CO2 and of SO2. For such determinations it appears that this technique is superior to any of the conventional methods of measuring densities.
Voltage Controlled Attenuator
Authors: Kindlmann Peter J.
Published: February 2004

A voltage controlled 50 Ω attenuator using photoresistors, variable over a range of 1.5 to 10 dB with a 0 to 10 V control voltage, is described. Useful frequency response is dc to 300 MHz, corresponding to a rise time of approximately 1 nsec. The programming speed is limited by the response of an incandescent bulb. The device can handle inputs of up to 50 V, provided an average power dissipation of 400 mW is not exceeded.
The Atom-Probe Field Ion Microscope
Authors: Müller Erwin W. , Panitz John A. , McLane S. Brooks
Published: February 2004

A serious limitation of the field ion microscope has been its inability to identify the chemical nature of the individually imaged atoms. The newly conceived atom-probe FIM is a combination probe-hole FIM and mass spectrometer having single particle sensitivity. During observation, the observer selects an atomic site of interest by placing it over a probe hole in the image screen. Pulsed field evaporation sends the chosen particle through the hole and into the spectrometer section. Preliminary results show that field evaporation of tungsten under poor vacuum conditions occurs as triply or quadruply charged WO, WN, WO2, and WN2 ions, while under better conditions doubly and possibly triply charged tungsten can be observed. Mo–Re alloys always produced doubly charged molybdenum and rhenium ions when examined in the atom-probe. Wide applications for the study of short range order in alloys, the chemical nature of precipitates and impurity atoms, and information regarding the imaging properties of various atom species, of both the substrate and adsorbed material, are foreseen.
New Device for Current Measurement in Exploding Wire Circuits
Authors: Malewski Ryszard
Published: February 2004

A method of improving the response time of a coaxial shunt is described. The faster response time is achieved by including within the measuring tube a compensating pickup loop. The measuring tube is formed by winding together several layers of resistance foil. An exact and two approximate formulas for calculation of the degree of compensation are given. The typical shunt described has a rise time of 9 nsec, a similar uncompensated shunt a rise time of 125 nsec.
The Northwestern University 50 cm Liquid Helium Bubble Chamber
Authors: Walker R. J. , Block M. M. , Kenyon I. R. , Koetke D. , Keren J. , Malhotra P. , Mazur P. , Winzler H.
Published: February 2004

The Northwestern University 50 cm liquid helium bubble chamber had its engineering run at the University of Chicago cyclotron in October 1965, after a construction and testing period of just under 2 yr. The chamber dimensions are approximately 50×25×32 cm, and the water-cooled magnet can provide a field of 30 kG. The chamber and magnet, which weigh about 2.2×105 N, can be lifted into a beam site while in operational condition, and the chamber and magnet require a space of only 7.6×4.5 m in the beam line. The expansion is performed by a bellows located above the magnet. A repetition period of 1.2 sec/pulse has been achieved continuously. The optical system uses dark field illumination with three cameras which view the entire chamber with a maximum stereo angle of 16°. The cameras use 35 mm film and have a demagnification of 1/12. The chamber has produced approximately 106 useful photographs in three separate runs, and these pictures are currently being analyzed.
The Monopole Mass Spectrometer
Authors: Dawson P. H. , Whetten N. R.
Published: February 2004

Monopole mass spectrometer characteristics were determined by analyzing ion trajectories under various operating conditions. The trajectories were computed by numerical integration of the Mathieu equations of motion. The mode of operation was chosen to correspond with that in general use, with ion injection being parallel to the axis of the instrument. The simulation was made specific by considering a monopole under operating conditions such that an ion with m/e=72 spends 12 rf cycles within the field. Information was obtained concerning peak shape, sensitivity, and resolution. The influence of entrance and exit slit dimensions and of rod-Vee block spacing was determined.
New Ferroelectric Hysteresis Curve Tracer Featuring Compensation and Virtual Sample Grounding
Authors: Tsui Y. T. , Hinderaker P. D. , McFadden F. J.
Published: February 2004

A new compensable hysteresis curve tracer for ferroelectric measurements is described. This was developed because of the need to measure ferroelectricity in slightly conducting materials. Unlike conventional hysteresis circuits, one side of the sample is virtually grounded through the use of an operational amplifier. The voltage source is grounded and there are no restrictions imposed on the oscilloscope input impedances in comparison with their respective sources. An additional feature of this new tracer is that both compensated and uncompensated hysteresis loops can be displayed simultaneously on a dual beam oscilloscope.
Digital Reader of Oscilloscope Trace Photographs
Authors: Jobes F. C.
Published: February 2004

A device for reading ordinary Polaroid oscilloscope trace photographs has been assembled from an oscilloscope, an oscilloscope camera, a 400 channel analyzer, and some control circuitry. This device reads the coordinates of 400 points along a trace by scanning in the y direction until the trace is found for each of 400 x positions. A photomultiplier tube looking through the back of the Polaroid print detects the trace. The reading, which is stored digitally in the analyzer until printed out, has an accuracy of better than 1%. This technique can be adapted to other types of trace photographs and can use other digital devices as well.
Versatile Double Crystal X-Ray Goniometer
Authors: Bond W. L.
Published: February 2004

A double crystal goniometer is described. It has been found useful for determining the degree of perfection of crystals. It can detect deviations of atomic planes of the order of 1″ and differences of spacing of the order of 5 parts/1 000 000. The goniometer is very easily adjusted for any crystal and is quite stable with respect to temperature changes and vibration.
Apparatus for Inducing High Uniaxial Compressive Stresses in Crystals
Authors: Schetzina J. F. , McKelvey J. P. , Cresswell M. W.
Published: February 2004

A vise capable of exerting uniaxial forces in excess of 2×109 dynes and operable between 77 and 300 K is described. The strain induced in the crystal being compressed is measured via a strain gauge bonded directly to the surface of the specimen. The applied stress may be varied smoothly to greater than 1010 dynes/cm2 and a resistance bridge resolves the induced strain in the stress direction to 2×10−6. Some preliminary high stress piezoresistance data for p-type germanium are included.
Vibrating Coil Magnetometer for Measurements on Type II Superconductors
Authors: Farrell D. E.
Published: February 2004

Problems involved in the measurement of magnetization in type II superconductors are briefly considered. A simple vibrating coil magnetometer has been developed for use at temperatures above 1.5 K with a sensitivity of 10−4 emu, permitting quantitative tests to be made of some recent developments in the theory of type II superconductors.
Techniques of Ultrasonic Paramagnetic Resonance
Authors: Meyer H. C. , McDonald P. F. , Donoho P. L.
Published: February 2004

Ultrasonic paramagnetic resonance (UPR) techniques are given for recording the derivative of UPR absorption with respect to magnetic field and for measurement of spin relaxation rates. The X-band pulse echo, spin relaxation spectrometer utilizes high power pulses from one magnetron to saturate the spin system. Low power pulses from another magnetron are then used to monitor the recovery from saturation by varying the delay between the saturating and monitoring pulses.
New Type of High Speed Valve
Authors: Inoue N. , Uchida T.
Published: February 2004

A new type of high speed operating valve for theta pinch devices in plasma physics research is described. The valve is thin enough to be set between the theta pinch coil and the discharge tube. The operation of the valve depends on the force exerted between two parallel electric currents. The gas is injected from the wall of the discharge tube so that an amount of gas is initially confined in the discharge region. Azimuthal distribution of the gas admitted is found to be uniform by measurement with a fast ion gauge. The opening time of the valve is less than about 350 μsec. The amount of gas admitted for a given setting is reproducible to less than ±5%.
Functional Ion Laser Based upon a Thermionic Hollow Cathode Discharge
Authors: Huchital D. A. , Rigden J. Dane
Published: February 2004

An ion laser based upon a thermionic hollow cathode discharge is described. The anode and the cathode are a pair of hollow metal cylinders that are spaced by a series of metal apertures along the axis of a solenoid. The laser is necessarily operated in a flowing gas mode; argon or krypton flows through the cathode tube and is pumped out through a high conductance sideport. The arc runs from the inside of the cathode tube at a point where the gas pressure is approximately 1 Torr. The characteristics of a variety of cathode types are discussed. The collimating structure consists of a number of relatively widely spaced metal apertures supported either on insulating rods or resting directly on the vacuum wall. The device is simple and completely demountable. A number of multiwatt versions of this design are discussed. The results of controlled life tests are presented and the expected useful lifetime of the laser is discussed.
Resolution Determination in Field Emission Energy Analyzers
Authors: Young Russel D. , Kuyatt C. E.
Published: February 2004

The influence of energy analyzer transmission function on measured field emission energy distributions has been evaluated by folding a Gaussian transmission function into the field emission total energy distribution. The resulting distributions at 0, 4.2, 20.3, 77, and 300 K are plotted as a function of the field- and work-function-dependent parameter d, and for the special case φ=4.40 eV, F=3.0×107 V/cm. A criterion is established for determining the width of an analyzer transmission function from distributions measured at the above temperatures. It is shown that the slope of the log of the energy distribution is changed by less than 1% when the analyzer width is changed from 0 to 100 mV.
Liquid Helium Cryostat for Resistance Thermometer Calibration
Authors: Duda C. R.
Published: February 2004

A cryostat designed primarily for intercomparison of platinum resistance thermometers in the range 10 to 300 K is described. A vented, ``inverted'' Dewar is introduced as a simple means to provide both rapid cool-down and thermal isolation without the necessity of temporary vacuum seals. Adiabatic conditions are automatically maintained, resulting in a system easily stabilized to within 30 μK/min throughout the entire range.
Multichannel Electronic Counter Chronograph for Determining Detonation Velocities in Explosives
Authors: Fuehrer H. R. , Emmons D. L.
Published: February 2004

The multichannel time intervalometer (MTI) was designed and fabricated for use in detonation wave measurements. The electronic chronograph was designed to measure short elapsed time events, relative to a start pulse which results from detonation, occurring during relatively long observation periods. The MTI used a quartz crystal as a frequency source and employs high speed transistor components which are capable of providing accurate measurements of detonation velocities. Attaining this capability in a portable unit with its direct read-out feature enhances the experimenter's ability to study short duration events such as explosive behavior.
Variable Gap Capacitive Detector for the Measurement of Ultrasonic Displacement Amplitudes in Solids
Authors: Peters R. D. , Breazeale M. A. , Paré V. K.
Published: February 2004

A variable gap capacitive detector has been developed for displacement amplitude measurements of longitudinal ultrasonic waves in the frequency range 5 to 100 MHz. The gap spacing is controlled by differential gas pressure. With this device it is possible to maintain a constant detector capacitance for measurements of the temperature dependence of the third order elastic constants. This improves the precision of the measurements considerably.
New Type of Position-Sensitive Detectors of Ionizing Radiation Using Risetime Measurement
Authors: Borkowski C. J. , Kopp M. K.
Published: February 2004

A new method was developed for determining the position of ionizing events by measuring the risetime of output pulses from detectors having high resistance collectors. Several prototype detectors, such as proportional counters, pulse ion chambers, and surface barrier detectors, were constructed and tested for this purpose. These detectors were treated as infinite RC lines with distributed parameters, and the position-dependent risetime of the output pulses was measured by crossover timing after double RC differentiation. With these detectors the impact locations of x rays, thermal neutrons, and alpha particles were determined. The spatial uncertainty obtained with 400 mm long proportional counters was 0.5 mm FWHM, for 22 keV x rays, 6 mm FWHM for thermal neutrons, and 0.66 mm FWHM for 242Cm alpha particles. A spatial uncertainty of 1.25 mm FWHM was obtained with a pulse ion chamber for 242Cm alpha particles. This method of determining the position of an ionizing event gives good linearity and spatial resolution with relatively simple electronic circuitry.
Timing Circuit for Rotating Prism, Q-Switched Lasers
Authors: Alon Yosef
Published: February 2004

An electrical discharge starting signal is required in advance of prism alignment for operating a rotating prism laser Q switch. Prism alignment time marking pulses obtained by a single sensor can be used to provide the desired advance pulses, independent of prism speed. A method of achieving this with a single electronic analog operation of high inherent stability is described. A complete circuit design, based on this method, is included. A timing stability of 1 μsec over the prism cycle range of 2–10 msec is achieved. Maximum time advance is 1.5 msec, and the output is adequate to fire most high power lasers.
Laboratory Facility for Ionospheric Reaction Studies
Authors: Hirsh M. N. , Eisner P. N. , Slevin J. A.
Published: February 2004

This paper describes techniques employed in the laboratory investigation of charged and neutral particle reactions of importance in the ionosphere. Atmospheric gases at densities appropriate to the D region, contained in a large reaction chamber, are irradiated by a spatially uniform flux of 1.5 MeV electrons. The resulting reactions are studied by a combination of resonant cavity measurements of electron density, mass analysis of positive and negative ions, and optical emission spectroscopy, both during continuous beam irradiation of the gas and in the radiation afterglow. Mechanisms and rates for molecular production and loss processes have been investigated using this apparatus under conditions resembling those in the ionosphere, with negligible competition from diffusion losses to the container walls. In addition to descriptions of the techniques, the paper includes examples of measurements made with the experimental system.
Procedure for Determining the Parameters from a Fission Fragment Energy Spectrum
Authors: Long A. B. , Wehring B. W. , Wyman M. E.
Published: February 2004

A silicon surface-barrier detector may be evaluated by determining certain parameters from a fission fragment energy spectrum recorded by that detector. This paper describes the computer program ANLZE which determines these spectrum parameters in a consistent manner by using a combination of smoothing and fitting routines in the analysis of the data. The effect of the statistical uncertainty of the data on the values of the parameters determined by the program is discussed for various fitting procedures.
Admittance Probe Method of Measuring Time Resolved Plasma Electron Temperatures
Authors: Sprott J. C.
Published: February 2004

It is shown that the plasma electron temperature in electron volts is given by the product of the ion saturation current and the probe-to-plasma resistance at the floating potential. An ac capacitance bridge circuit is described which will measure this resistance with a response time that approaches the ion transit time across the sheath. The method is demonstrated by a measurement of electron temperature in the Wisconsin toroidal octupole.
Ion Source for Mass Spectrometers
Authors: Alexandru Gr.
Published: February 2004

An ion source for a mass spectrometer allowing the simultaneous introduction and measurement of sample and reference standard is described. It is useful for detection of very small differences in isotopic composition of elements. The residual background interference on the measurements is considerably reduced.
CW Transmission Spectrometer for Direct Detection of Nuclear Acoustic Resonance Utilizing Magnetic Field or Frequency Modulation
Authors: Melcher R. L. , Bolef D. I. , Merry J. B.
Published: February 2004

A continuous wave transmission spectrometer operating in the radio frequency range has been developed for direct detection of nuclear acoustic resonance (NAR) in solids. The inherent flexibility of a spectrometer of this type makes possible studies over a wider range of frequencies and ultrasonic powers than is attainable by the more conventional marginal oscillator acoustic spectrometer. With the transmission spectrometer one can observe both absorption and dispersion of acoustic waves, while with the marginal oscillator one is limited to NAR absorption only. An additional feature is the ease of operation of the transmission spectrometer as compared to the marginal oscillator technique. Both magnetic field and frequency modulation have been used with the transmission spectrometer. Certain advantages of frequency modulation, especially with respect to investigations in bulk conductors, are cited.
An X-Ray Method for Accurate Determination of Lattice Strains of Crystals
Authors: Kobayashi Jinzo , Yamada Noboru , Azumi Tadahiko
Published: February 2004

A simple x-ray strainmeter is described which enables us to determine small lattice strains of crystals with the sensitivity of 2×10−6 even in the region of 45° of Bragg angle. The principal feature of this apparatus lies in the large camera radius of 2630 mm. The strainmeter permits not only determination of the thermal expansion at 1°C but also measurement of piezoelectric constants of minute crystals where conventional resonance-antiresonance methods cannot be used. The practical application of this apparatus for detection of small spontaneous lattice strain, say 3′40″ of pure shear xy of Fe–I-boracite, which has recently been found to be ferroelectric in its low temperature form, is demonstrated.
Image Intensifier System for Dynamic X-Ray Diffraction Studies
Authors: Reifsnider Kenneth , Green Robert E.
Published: February 2004

A cascaded image intensifier has been incorporated in a system which permits study of dynamic changes in x-ray diffraction patterns. An RCA C70021A three stage, magnetically focused, image tube is coupled by a f/0.87 Super-Farron lens to a 15.2 cm diam fluorescent screen to permit direct viewing of transmission x-ray diffraction patterns. The image on the output phosphor is of sufficient intensity to be viewed directly, to be recorded cinematographically, or to be displayed by vidicon pick-up on a television monitor.
New Interpolation Formula for Carbon Resistance Thermometry
Authors: Hetzler M. C. , Walton D.
Published: February 2004

A new interpolation formula for use in carbon resistance thermometry is suggested, and the results of fitting the formula to experimental R vs T data for resistors manufactured by the Speer Company are described. The maximum difference between the calculated and measured temperatures was 1%. The formula was also found to give good agreement with measured temperatures when extrapolated to temperatures somewhat above or below the region covered by the calibration points.
Fluorescent Screens for Monochromatic X-Ray Diffraction Patterns on Polaroid Film
Authors: Herglotz Heribert K.
Published: February 2004

The quality of x-ray diffraction patterns made with copper radiation and recorded on Polaroid film by use of a fluorescent screen can be significantly improved. Screens with zinc sulfide layers dimensioned for complete utilization of copper radiation and reduced conversion of the continuous spectrum provide a sixfold reduction in background compared to that of patterns prepared with commercial screens.
Resonant Helices and Their Application to Magnetic Resonance
Authors: Volino F. , Csakvary F. , Servoz-Gavin P.
Published: February 2004

We show that helices can be used as resonant systems. We describe resonant helices for electron paramagnetic resonance in X-bands and develop a comparison between their sensitivity and the sensitivity of a normal resonant cavity. For cylindrical samples less than 3 mm diam, the helix is more sensitive and can produce more intense microwave magnetic fields.
Sensitive Tiltmeter Utilizing a Diamagnetic Suspension
Authors: Simon Ivan , Emslie Alfred G. , Strong Peter F. , McConnell Robert K.
Published: February 2004

A tiltmeter of the horizontal pendulum type is described whose mass consists of a diamagnetic material suspended in a potential well of a suitably shaped magnetic field. The depth of the potential minimum determines the restoring force acting upon the mass and consequently the pendulous frequency and sensitivity of the instrument. In this manner the elastic forces usually supplied by fine springs or fibers are replaced by field forces and the mass is free to respond to tilts or accelerations without any trace of friction of external (Coulomb) or internal (anelastic) origin. The required amount of damping is obtained from eddy currents induced in the seismic mass by its motion in the field. The instrument requires no power to operate the suspension and it can be used over a wide range of temperatures. Under usual environmental conditions, it requires no temperature control. Some of the preliminary results obtained with the tiltmeter in measurement of earth tides are discussed.
Simple Method of Preparing Pure Ozone
Authors: Griggs M. , Kaye S.
Published: February 2004

A simple method, using the silent electric discharge technique, for producing (100%) pure ozone in the laboratory is described.
Small 10 kG Pulsed Magnet
Authors: Roth Robert O. , Gilleland John R.
Published: February 2004

A small magnet pulsed at 2000 cps is described. The method of construction by interlacing spirals of Teflon and copper is discussed. The field produced is through a volume of approximately 1 cc. The total volume of the coil and water jacket is 30 cc.
Combined 3He Cryostat and Pulsed ESR Spectrometer
Authors: Bohan Thomas L. , Stapleton H. J.
Published: February 2004

A system is discussed which has been used to measure spin lattice relaxation times as brief as 1 μsec using pulse techniques at temperatures between 0.24 and 4.2K. The 3He refrigerator used to obtain cooling below 1.1K is given the most attention and is of interest because of the degree to which it was designed specifically for paramagnetic resonance experiments. In addition, the microwave spectrometer is described briefly.
Probe for Detection of Voids in Liquid Metals
Authors: Chen John C. , Kalish Sheldon , Schoener George A.
Published: February 2004

A probe was developed for detection of vapor or gaseous voids in liquid metals. With a sensing element of ≈0.5 mm diam, it is possible to obtain indications of point conditions. Probe response is of the order of 1 msec to a step change from liquid to void or vice versa. The probe is suitable for use in liquid metals at temperatures up to 900°C.
Electrostatic Energy Analyzer for Studying Gas-Focused Electron Beams and Their Background Media
Authors: Stephanakis Stavros , Bennett Willard H.
Published: February 2004

An analyzer is described which is especially suitable for the study of electrostatically self-focusing electron beams and their associated background media, and, in general, for media which by their nature are very sensitive to direct insertion of probes or other diagnostic devices. The basic difficulties with devices of this nature, namely, (a) the continually changing work functions of metal surfaces due to sorbed films and (b) the lens effect defocusing due to nonuniformities of the potential in the neighborhood of grid wires, have been identified and effectively overcome. The analyzer is employed flush with the boundary of the medium under study and it incorporates a shielding electrode so that the disturbance of the medium is insignificant. When the dimensions of the instrument are scaled so that the space charge effects are absent, it can be utilized successfully to detect energy spreads as small as a few tenths of an electron volt.
Electron Bombardment Ion Source for Low Energy Beams
Authors: Dworetsky S. , Novick R. , Smith W. W. , Tolk N.
Published: February 2004

A high current, electron bombardment ion source of simple design and suitable for low energy ion beam production is described. The source produces ion beams in the energy range from a few electron volts to several kilo-electron volts with an energy spread of a fraction of 1 eV, with high current density (5 μA/cm2 at 25 eV), and without the problems associated with rf ion sources. The source has been used successfully to produce low energy beams of noble gas ions such as He+ and Ar+ without metastable contamination, as well as for H2+ and N2+.
Uniformity of Response from Large Area Plastic Scintillation Detectors
Authors: Gillespie C. R.
Published: February 2004

Using only two 8055 photomultipliers and no light pipes, photomultiplier geometries were found which gave rather uniform response over 1.7 m2 surfaces of single and double sheets of 2.5 cm thick Pilot Y plastic scintillator. The detector response obtained had a standard deviation from the mean of 2.8% for single sheets of Pilot Y scintillator and 3.7% for double sheets.
Holographic Interferometer for Isopachic Stress Analysis
Authors: Chau Henry H. M.
Published: February 2004

Application of holography to photoelasticity is briefly discussed, with emphasis on its potential in isopachic stress analysis. A complete holographic interferometer is described. The method of wavefront reconstruction simplifies the optical requirements in conventional two-beam interferometry. By employing a photochromic recording medium, the technique of real-time interference becomes a practical and convenient process. Examples of isopachic fringe patterns obtained by this interferometer are shown.
Standing Wave Methods for Measuring Permittivities at Meter and Decimeter Wavelengths
Authors: Grant Edward H. , Keefe Susan E.
Published: February 2004

Methods are described for measuring the complex relative permittivity ε=ε′−ε″ of liquids using coaxial line apparatus. The determinations can be carried out over a wide range of frequency and temperature. A description is given of a cell consisting of a section of short-circuited line with a detector probe projecting from the inner conductor. By use of a computer, values of ε′ and ε″ may be obtained for liquids having attenuation coefficients extending over a considerable range.
Ultrahigh Vacuum Electron Microscope
Authors: Braski D. N. , Gibson J. R. , Kobisk E. H.
Published: February 2004

A Hitachi HU-11B electron microscope has been modified for ultrahigh vacuum operation. Differential sputter ion pumps are used to evacuate the entire microscope column, which was extensively modified to be compatible with the high vacuum, low contamination environment. Excellent beam stability and resolution have been observed with column pressures as low as 5×10−8 Torr, but the image intensifier has proved unsatisfactory for high resolution readout.
Zone Refining Techniques for Liquid Organics
Authors: Carides J. N.
Published: February 2004

A zone refiner especially adapted for refining organic materials with melting points near or below room temperature is described. The chief modification in this refiner as compared to previous models is that we immerse the entire apparatus—charge tube and heaters—in a liquid coolant. A preliminary model was made and results are given.
Apparatus for Mechanical Testing of Soft Crystals at High Pressure
Authors: Gelles S. H.
Published: February 2004

Apparatus which has sufficient sensitivity for the tensile testing of soft single crystals at pressure levels to approximately 30 kilobars is described. This equipment makes use of a tensile yoke and a load cell based on a linear variable differential transformer within the high pressure fluid. Strain is measured externally by monitoring the movement of the loading piston with a linear variable differential transformer and the load-displacement relationship is displayed on an X-Y recorder. Discussion of the calibration procedure and performance of the apparatus is included.
Hydraulically Actuated Combustion Gas Sampling Valve
Authors: Zvonow V. A. , Stewart H. E. , Starkman E. S.
Published: February 2004

A hydraulically actuated sampling valve suitable for extracting high temperature (2700 K), high pressure (60 atm) gases from the chamber of an internal combustion engine has been developed and successfully operated during recent studies of engine contribution to air pollution. The valve, easily constructed, provides capability for large variation in sample size and duration of opening with adjustable sample timing through 360° or more of crank angle, thus allowing extremely flexible operation and eliminating many of the limitations found with other valve types.
Accuracy of Rotation around an Axis
Authors: Masry S. E.
Published: February 2004

The rotation of a rigid body around an axis and its deviation from pure rotation are discussed. It is shown that the determination of this deviation requires the measurement of the position of three points of the body in three dimensions. It is also shown that accurate determination of this deviation for the purpose of applying corrections to the measurements of an instrument is impracticable. A method for determining the changes in the direction of the axis of rotation and for estimating their effect on the measurements is explained.
X-Ray Monochromator Configurations and a Monochromator Design for X-Ray Single Crystal Diffractometers
Authors: Mathieson A. McL.
Published: February 2004

A brief discussion of monochromator configurations for x-ray diffractometers is presented, corresponding to an extension, into an additional dimension, of the basic arrangement of the earlier two crystal ionization spectrometer. For post-monochromators, i.e., a monochromator located to intercept the beam diffracted by the specimen crystal, a simple neat design is given which can allow rotation of the monochromator and detector, as a unit, around the axis of the diffracted beam to any specified angle Φδ. Suggestions for the use of this device are made, including its application as a polarization analyzer to assess the extinction characteristics of the specimen and monochromator crystals.
Automatic Vacuum Microbalance of the Pivot Type
Authors: van Lier J.
Published: February 2004

An automatic vacuum microbalance of the pivot type has been built and tested. The balance is very stable over long periods of time and requires only infrequent calibration. Automation is accomplished by the use of an inexpensive solid state null indicator. The sensitivity of the balance is 88 μV/μg in the most sensitive range. Zero shifts have been reduced to a minimum by a novel frame construction. The main limitation of the present system is the precision of the recorder. The system is designed for loads of up to 2 g.
Dynamic X-Ray Diffractometer for Measuring Rheo-Optical Behavior of Crystals in Polymer Solids
Authors: Ito Taisuke , Oda Takashi , Kawai Hiromichi , Kawaguchi Tatsuro , Keedy Daniel A. , Stein Richard S.
Published: February 2004

A dynamic x-ray diffraction technique, employed to follow the responses of polymer crystals—one of the structural units of crystalline, high polymeric materials—to mechanical excitation of sinusoidal strain induced to bulk specimen is described. The descriptions for such responses are made in terms of the in-phase and out-of-phase components of the diffracted intensity by the crystals. From these, one may obtain the change in orientation of reciprocal lattice vector and deformation of lattice spacing of specific crystal planes with the change in the external periodic strain. The photoelectric switching circuits are described which repetitively activate four sets of scalers to count the continuously fed signals of the detected x-ray at particular strain phase intervals for each. The dynamic diffraction by the crystals can be evaluated by comparing the accumulated intensities among the four scalers.
Direct Reading Instrument for Silicon and Germanium Four-Probe Resistivity Measurements
Authors: Swartzendruber L. J. , Ulmer F. H. , Coleman J. A.
Published: February 2004

A direct reading instrument of moderate precision (about ±5%) has been developed for the rapid measurement of resistivity and its uniformity on silicon and germanium samples with a wide variety of shapes and sizes. An in-line, four-point probe and two analog computing circuits, to set the required geometrical correction factors, are used in the instrument. The main features of the instrument are the simplicity of its construction and the facility with which the resistivity measurements can be accomplished.
Transducerless Method for Ultrasonic Flaw Testing in Metals
Authors: Wallace W. D. , Houck J. R. , Bowers R. , Maxfield B. W. , Gaerttner M. R.
Published: February 2004

An ultrasonic method for detecting flaws in metals has been developed which does not require physical contact with the metal in order to excite or detect the ultrasonic signal. The method of direct electromagnetic generation of ultrasound in the presence of magnetic fields has been used to detect both artificial flaws and naturally occuring inhomogeneities in aluminum bars and rods. Results are presented which demonstrate that this technique may offer some advantage over conventional transducer methods.
Indirectly Heated Thermistor for Measuring Ocean Currents
Authors: Caldwell Douglas R.
Published: February 2004

A current meter system for the measurement of the magnitude and direction of ocean bottom water currents is described. Speeds as low as 1 mm/sec have been measured at depths of 4 km.
Replicator for Ice Crystals
Authors: Odencrantz F. K. , Humiston L. E.
Published: February 2004

A vapor replicator for ice crystals is described. It is simple to construct and easy to operate in the laboratory or field. The dimensions are not critical. The most satisfactory temperature of operation and the filament current should be determined by trial operation. The replicator will also replicate water droplets and wet surfaces.
Generation of Smeared Out Electron Beams for Experiments on Weak Plasma Turbulence
Authors: Chang J. , Böhmer H. , Raether M.
Published: February 2004

It is shown that electron beams, suitable for experiments on weak plasma turbulence, can be produced by passing the beams through aluminum foils of a few thousand angstrom thickness. Measurements of the beam distribution function and the transmission as a function of foil thickness are presented.
High Precision, High Pressure Mercury Differential Pressure Manometer
Authors: Ruska W. , Kao J. , Chuang Sheng-yi , Kobayashi Riki
Published: February 2004

The design, development, and performance of a differential pressure mercury manometer for use at high pressure with high precision is reported and described. The instrument has an accuracy of ±2 μ for a differential pressure range of 96 mm Hg at total pressures to 800 kg/cm2.
New Method for the Measurement of the Q Factor of Cavities and its Application to Research in Solid State Physics
Authors: Leibrecht Klaus
Published: February 2004

We have developed a device for dynamic measurements of the quality factor of high Q resonating cavities by plotting the dispersion curve of the resonator on the screen of an oscilloscope. The width of the dispersion curve is well defined by the two extremes. We built our apparatus at 9000 Mc because our aim was measurements on neutron irradiated glasses, the dielectric losses of which, expressed as the power factor tanδ, seem especially significant at these frequencies. We used a 2K25 reflex klystron as rf generator and the standard X-band waveguide plumbing. The method can be used, however, at any frequency at which one works with waveguide or coaxial techniques.
Inexpensive Photon Counting System for Raman Spectroscopy
Authors: Miller S. A.
Published: February 2004

This paper describes a simple photon counting system for use with photomultipliers in the detection of weak light signals.