bluuebunny/crossref_metadata_2025 huggingface dataset:
Proportional Counter Proton-Recoil Spectrometer with Gamma Discrimination
Authors: Bennett E. F.
Published: February 2005

A proton-recoil methane proportional counter has been used as a neutron energy spectrometer in the presence of conversion electrons from background gamma rays. A difference in the rise time of the voltage profile for conversion-electron and recoil-proton events of the same total ionization was made the basis for an electronic gamma-neutron discrimination technique. Use of the gamma rejection technique was equivalent to an effective reduction in gamma sensitivity of the detector by a factor of 450. Spectroscopic information on a broad incident neutron spectrum was extended from the region above 350 keV to that above 80 keV.
Magnetic Susceptibility Measurements of Small Samples. II. Solutions
Authors: Gordon R. G.
Published: February 2005

A microtechnique for measuring the magnetic susceptibility of paramagnetic compounds in solution is described. Solutions containing less than 10−8 mole of solute have been measured, which represents a sensitivity increase of more than 104 over the classical Gouy method. The method depends upon balancing magnetic forces in an inhomogeneous magnetic field against density gradients in the solution.
Electrohydrodynamic Precipitator
Authors: Stuetzer Otmar M.
Published: February 2005

A contaminated fluid is charged and pumped into an electrodeless collection space, where particulates are precipitated. An approximate theory of precipitation is given; it is supported by experimental evidence. The method is especially suited for cleaning insulating liquids.
Dynamic Mechanical Properties Tester for Low Audio and Subaudio Frequencies
Authors: Keiper David A.
Published: February 2005

A dynamic mechanical properties tester is described for use in the low audio and subaudio frequency range on various types of flabby material, including biological tissue. The moving element of the device is supported by a gas bearing with negligible springiness and friction and contains about 2.5 g of mass. A single coil in a magnetic field is used for both driving the moving element and measuring the vibration response.
Versatile Bubble-Chamber Track Measuring Stage
Authors: Bolze Ernest M. , Ayer Frederick
Published: February 2005

A measuring stage for bubble chamber film, having some interesting features in both its film transfer mechanism and its stage motor drive, is described. Power for the stage motion is supplied by pairs of motors geared to differentials, the speed of one motor being controllable. Lead screw speed is, therefore, continuously variable in both directions. Measurement of coordinates of points on a track with the assistance of a track centering device is outlined in principle; details are given elsewhere in this issue. The film transfer mechanism will accomodate four stereo-views on separate films on any width from 35 to 70 mm and any length from 100-ft spools to 1000 ft, wound on cores, with the maximum ease of convertibility.
Bubble Chamber Track-Centering Device with Digitized Output
Authors: Pickup Eric , Rappe Edwin F. , Wall Gaylord , Ayer Frederick
Published: February 2005

A means for automatically determining the coordinates of a point, quickly and accurately, at the center of a bubble chamber track is described. A coarse setting of operator-controlled cross hairs, supported by a toolmaker's stage, is made and the distance between the cross hairs and the track center is found by means of a system based on a vibrating slit which scans a portion of the track. The distance is reduced to digital form and printed out on tape along with the coordinates of the coarse stage setting. A computer routine then determines the true position of the point on the track.
Constant Energy Monochromator with Independent Dispersion Control
Authors: Stupp Edward H.
Published: February 2005

A monochromator system is described which has a constant output energy as a function of wavelength with an accuracy limited by the blackness of a radiation thermocouple. This is accomplished through the variation of the temperature of the radiant source thus providing for independent slit control. The wavelength range considered is from 550 to 1500 mμ. The system is adaptable to other spectral regions for which thermal sources of radiation are available.
Alpha Gauge for the Measurement of Small Density Thicknesses
Authors: Gardner R. P. , Ross H. H.
Published: February 2005

An alpha-particle gauge has been developed based on a transmission, total-count principle. It consists of a thick alpha source and a surface-barrier detector. This simple combination eliminates many of the practical disadvantages of previous alpha-gauge systems. Without mechanical or electronic adjustment, air density can be measured with a 1-sec time constant over the range from 0–1.1 mg/cm3 with a maximum standard deviation of of 5.9×10−4 mg/cm3.
Fast Neutron Time-of-Flight Spectrometer
Authors: Lefevre H. W. , Borchers R. R. , Poppe C. H.
Published: February 2005

A fast neutron time-of-flight spectrometer for use with a tandem accelerator is described. Charged-particle bursts of less than 2-nsec duration and with peak currents of 15 to 20 μA are produced by bunching the negative particle beam before acceleration and chopping the positive particle beam after acceleration.
Image Force Velocity Selector for Charged Particles
Authors: Kantor Frederick W.
Published: February 2005

A velocity selector for charged particles can be made utilizing, exclusively, image forces. The velocity of the emerging particles depends only on machining and fundamental constants. Electron velocities less than 500 m/sec appear feasible.
Simple Ratio Photometer
Authors: Hefele J. R. , Lundberg J. L. , Salovey R.
Published: February 2005

We describe a simple photometer which measures the ratio of the intensity of scattered light to the intensity of incident light in dilute solutions and pure liquids. The intensity of the mercury arc and the sensitivity of the dual triode difference amplifier are sufficient to determine liquid turbidities at 5790 Å with blue light sensitive photomultiplier tubes.
Thin-Film Bolometer
Authors: Glick H. S.
Published: February 2005

The thermal characteristics of the thin-film resistance thermometer for measurement of electromagnetic energy fluxes have been investigated. It has been found that when γh/(α1t)½≪1, the temperature-time history of the thin film is mathematically the same as that of the surface of a semi-infinite slab heated by a constant energy flux. The antenna properties of the thin-film gauge have been analyzed using a simple antenna model and equivalent circuit. The relation between the Poynting flux and the ``apparent'' constant energy flux has been investigated experimentally for two cases, and it has been found that the analysis predicts values of energy fluxes that are about 40% below the measured values.
Proportional Counting Technique for Radiocarbon Measurements
Authors: Nydal Reidar
Published: February 2005

A proportional counting system for radiocarbon dating is described in this article. The CO2 counter has an effective volume of 1.2 liters and operates at a pressure of 2 atm. The total background is 1.10 counts/min and the standard net count on recent carbon is 16.0 counts/min. Maximum measureable age is 43 000 years. The end terminals of the counter have a few original details which serve to reduce inactive counter volume and the end effects. The ground capacity of the center wire has been reduced to a very small value (10 pF). Anticoincidence shielding is provided by a multiple-anode proportional counter. It is filled with C3H8 to a pressure of 1.3 atm and can operate continuously for at least one year without refilling. The counter walls of the ring counter and the CO2 counter are connected together and supplied with the same high voltage. Shielding against γ rays is provided by a 22-cm-thick iron shield around the counting unit, and by a shell of 3.5-cm old lead between the CO2 counter and the ring counter.
Controlled Flash Heating of Metal Filaments
Authors: Pasternak R. A. , Fraser Edward C. , Bergsnov-Hansen Björn , Wiesendanger H. U. D.
Published: February 2005

A simple inexpensive instrument for flash heating metal filaments has been designed which is being used in studying sorption phenomena at very low pressures and in measuring heat capacities and total emissivities of metals. The instrument permits selecting both absolute heating rates and their time dependence; in particular, filament temperatures increasing linearly with time can be obtained. Furthermore, the heating circuit allows the attainment of a preselected maximum filament temperature without appreciable over-shooting. This paper describes the concept and design of the device; detailed experimental results are being reported elsewhere.
Field Emission Spectrometer
Authors: Russell Allan M.
Published: February 2005

An apparatus is described which measures the energy distribution of electrons extracted from solids, particularly semiconductors, by high electric fields. The energy spectra of these electrons are directly related to the location of allowed electronic states at the surface of the solid. Investigation of a range of energies and direct output of the energy spectra are obtained through the use of modulation and phase sensitive detection. Details of the spectrometer are described including samples of the output spectra.
A 170-Liter Heavy Liquid Bubble Chamber
Authors: Prodell A. G. , Steinberger J.
Published: February 2005

A 170-liter Columbia-Brookhaven heavy liquid bubble chamber has been operated at Brookhaven National Laboratory in a magnetic field of 15 kG. The bubble chamber was designed with a retro-directive system of illumination which produces bright field optics. Details of the chamber, the magnet, and the optical system are given.
Electrodeless Plasma Conductivity Probe Apparatus
Authors: Olson Robert A. , Lary Edmund C.
Published: February 2005

A means for measuring the electrical conductivity of a fluid without the use of electrodes has been developed. A probe, consisting of a cylindrical single-layer solenoid enclosed within an insulating tube, is used in conjunction with an rf oscillator-detector to measure the ohmic dissipation of a small amount of rf power in the fluid. The probe samples the conductivity of the fluid in its immediate vicinity, and may therefore be used to resolve conductivity profiles in an operating MHD device, for example. Since the surface of the probe is an insulator, it is possible that the influence of Hall effects and electrostatic sheaths may be effectively eliminated under certain conditions. Electrolytic solutions have been used in calibration of the instrument. Instrumentation has been developed for the application of the measuring technique to plasmas. Probes have been operated successfully in the positive column of a hydrogen glow discharge and in a 4500°F rocket nozzle flow.
Probe for the Measurement of Albedo Electron Flux in a High-Energy Ion Beam
Authors: Hubach R. A.
Published: February 2005

A probe has been developed to measure the flux of electrons traveling in a direction opposite to that of the ions in a high-energy ion beam. The probe is of the Langmuir type and will ideally obey the Mott-Smith, Langmuir theory for positive probe potentials. With this probe the albedo electron flux has been measured in a beam of 1- to 2-kV cesium ions.
Constant Acceleration Transducer Employing Negative Feedback for Use in ``Mössbauer Experiments''
Authors: Rubin David
Published: February 2005

A triangular voltage is integrated and the output current fed to a vibrator so as to produce linearly changing velocities. The output voltage of a velocity pickup coil is then compared to the triangular input voltage in a negative feedback arrangement which further linearizes the velocity.
Dynamic Magnetic Measurements by Use of Damped Oscillatory Fields
Authors: Elder Tait , Barte William
Published: February 2005

Full magnetic hysteresis loops, obtained by underdamped discharge of a capacitor through a solenoid, were used to study loop distortion produced by eddy currents, protracted or delayed flux changes, and instrumental errors. Pulsed field loops obtained for γFe2O3 powder with 14 000-Oe maximum field closely overlapped loops obtained statically with one-tenth this field amplitude. In contrast, an apparent coercive force of 110 Oe was obtained with the pulsed field method for a sample of 0.158-cm-diam iron wire having a static coercive force of 3.6 Oe. Almost two-thirds of the observed coercive force was attributable to eddy currents. Instrumental errors were less than 10 Oe and the residual coercive force was identified with the protracted flux change which has sometimes been attributed to magnetic viscosity in iron. Instrumental difficulties involved delay, distortion, or imperfect integration of high frequency components in detector coil signals, cumulative integration errors associated with low frequency components from nearly saturated specimens, and pickup. The detection system described is also suitable for quasistatic (slowly traced hysteresis loop) measurements.
Floating Zone Growth of Single Crystal Alkali Halides
Authors: Warren Roger W.
Published: February 2005

A general discussion is given of the main factors affecting the successful attainment by induction melting of stable floating zones in a wide variety of materials. The emphasis is on poor conductors, for which the problems involved can usually be solved. Details of the apparatus and procedures used in the floating zone growth of NaCl, KCl, KBr, KI, and LiF single crystals are given, as well as specifications of the quality of such crystals as determined by various tests.
AGC Amplifier to Correct for Effects of Light Source Variations in Spectrofluorometric Measurements
Authors: Eisenberg L. , Rosen P. , Edelman G. M.
Published: February 2005

An automatic gain control amplifier is described which is designed to correct for fluctuations in the light source of a recording spectrofluorometer. Means are also provided for correcting for the spectral response of the spectrofluorometer components. Two input signals to the AGC amplifier, one the fluorescent signal S2, and the other a reference signal S1 (which senses the light source variations present in S2), are obtained by use of a conventional beam splitter. Variations in S1 cause corresponding changes in gain A in such a way that the output voltage of the AGC amplifier is proportional to the quotient S2/S1. Thus, common variations in the input signals are canceled. Test results show that the instrument corrects for variations in light intensity as high as 20% with less than 1% error. Small step variations in light intensity, typically 10% or less, are corrected for within 200 msec.
Linac Beam Position Monitor
Authors: Bergere R. , Veyssiere A. , Daujat P.
Published: February 2005

After a brief review of the structure of electron pulses from a linear accelerator and the properties of the electrical and magnetic fields set up by a beam of relativistic electrons, the authors describe a beam position monitor designed and used by them with the linear accelerator at CEN Saclay. A description of operation then follows, with indications of possible applications.
Furnace Mounting and Control System for Ainsworth Vacuum Automatic Recording Balance
Authors: Garn Paul D. , Geith Charles R. , DeBala Stephen
Published: February 2005

A commercially available vacuum automatic recording balance has been equipped with program control and furnaces so that it may be used for thermogravimetric studies. The complete system has been tested at pressures less than 0.1 mm Hg. Comparatively light-weight furnaces are used. For convenience of operation, radiation shields take the place of the major part of the insulation.
``Stripper'' Measuring Instrument for Recording Variations of Threshold and Channel Width
Authors: Binard L. , Vanhorenbeeck J.
Published: February 2005

The instrument described makes possible the investigation of the stability of a pulse height analyzer. It provides pulses whose amplitudes, adjusted by a feedback circuit, follow the two boundaries of a channel. The connection from the analyzer to the pulse generator is made by a double rate meter circuit which enables the simultaneous recording of the threshold and channel-width variations of a pulse height analyzer.
Image Loop Probe for Measurement of Microwave Surface Currents
Authors: Dressel Ralph W.
Published: February 2005

A shielded, image loop probe suited to precision measurements of surface current distributions at microwave frequencies has been constructed. Its design permits continuous rotation of the probe element so that the vector direction of the current flow may be determined. Tests evaluating the probe errors indicate good accuracy can be achieved in measurements of the phase, amplitude, and direction of a surface current at 10 000 Mc.
Optical Measurement of Spectra of Two-Dimensional Functions
Authors: Uberoi Mahinder S.
Published: February 2005

The principle of an optical computer for the measurement of two-dimensional spectral and cross-spectral densities is described. The performance of one of the experimental arrangements is checked by measuring the spectral densities of a simple two-dimensional function. The apparatus may be used to compute the Fourier transform of a two-dimensional function.
Semiconductor Diodes and Transistors as Electrical Thermometers
Authors: McNamara A. G.
Published: February 2005

Electrical thermometers for laboratory experiments, environmental testing, and flight performance of rocket-borne equipment may be realized with simple semiconductor circuits. The devices described here utilize the variation with temperature of voltage across a forward-conducting p-n junction. This voltage variation of approximately 2 mv/°C is virtually linear over the entire test range of −40 to +100°C. A diode used in conjunction with a microammeter to measure the voltage across the diode is most convenient for laboratory use. For airborne use, where a signal varying from 0 to 5 v is required for telemetry, the transistor circuit is ideal. The latter circuit, which amplifies its own base-emitter junction voltage variations, requires only a single transistor and 3 resistors. Adjustment of two of the resistance values enables the user to select any temperature range to be covered with the desired sensitivity.
Experiments with Fluorescent X Rays in the 10- to 50-Å Wavelength Region
Authors: Dowell L. G. , Berwaldt O. E.
Published: February 2005

Apparatus for the production, dispersion, and detection of soft fluorescent x-rays (10 to 50 Å) is described. The apparatus includes a new type of gaseous discharge x-ray tube capable of operating at 3000 v and 200 ma, a servo-type vacuum controller for maintaining constant x-ray tube current, and built-up films of heavy-metal soaps for use as analyzing crystals. Photographs are included of fluorescent spectral lines of carbon from graphite (Kα, λ=44.5 Å) and of copper (Lα, λ=13.3 Å) obtained, respectively, in 2 and in 4½ hr.
Another Method for Recording Breakdown Phenomena in Air
Authors: Kontaratos A. N.
Published: February 2005

An experimental method for recording breakdown phenomena in air of atmospheric pressure and under quasi uniform fields is described. The traces of the discharge are recorded on a photographic film parallel to the applied field, the breakdown being initiated by an auxiliary spark produced next to the sensitive surface of the film and in time-coincidence with the application of the main field.
Direct Viewing and Rapid Photographic Recording of X-Ray Diffraction Patterns
Authors: Goetze G. W. , Taylor A.
Published: February 2005

Experiments on the application of x-ray image intensifiers of the Fluorex-type and of transmission-type secondary electron image intensifiers (Astracon tubes) to the direct observation and recording of x-ray diffraction patterns have proved highly successful. Further improvements can be obtained by combining a Fluorex tube directly with an Astracon tube. By this means, the useful signal strength is so improved that movies at standard frame speed can be made which record the changing Laue pattern from a rotating crystal. The theory of such intensifiers is discussed and it is shown how still further improvements are possible if the optical coupling in the system is improved by incorporating a fiber optics window at the input of the Fluorex-Astracon tube. It is further shown that a fiber optics adaptor can be used as an analog computer to convert the x-ray diffraction pattern from a single crystal into an exact representation of the reciprocal lattice which can be viewed directly at the output of such a tube.
High Mode Tunable Cavity for Microwave-Gas Interactions
Authors: Estin A. J.
Published: February 2005

A high-Q resonant microwave cavity, operating in the TE01n (n=10, 11) mode, is described. A fused quartz liner, with suitable inlet and pumping lines, is used to contain gases, so that interactions between the molecular transitions and the electromagnetic radiation can be generated. Techniques are discussed for suppression of unwanted modes of oscillation, for dielectric tuning of the cavity, and for elimination of radiation through a large port.
Making Crystal Elements for Optical Masers
Authors: Bond W. L.
Published: February 2005

Methods are given by means of which crystal maser rods have been made with the ends parallel to better than 10″ and flat to better than 1/10 wave of visible light.
Acoustic Thermometry
Authors: Apfel Joseph H.
Published: February 2005

A new technique for measuring temperatures by means of the velocity of sound in a gas is described. A closed-end, gas-filled pipe is excited to longitudinal acoustic resonance, and the resonant frequency is measured. The temperature of the gas is then determined from the well-known relations between the temperature and the velocity of sound. The generation and detection of acoustic waves are carried out by a transceiver which is remote from the measuring region and which is connected to the cavity by a small-diameter, gas-filled tube. The technique is particularly well suited to high-temperature studies in nuclear-radiation environments.
Radiosonde for Atmospheric Refractive Index Measurements
Authors: Deam A. P.
Published: February 2005

An instrument for transmitting a carrier frequency analog of atmospheric radio index of refraction is described. The signal transmitted is received at a remote point through the use of a phase lock type of receiver. It employs a ceramic coaxial cavity, one-half wavelength long, as a sensor, and the nominal operating frequency is 403 Mc. The instrument, when operated with other cavities, offers the laboratory gas dielectric investigator a convenient tool for studying real components of gas dielectrics. Operation can be easily extended to higher frequencies by the use of suitable cavities and solid state multipliers.
Some Experimental Techniques of Low-Temperature Radiation Damage Studies
Authors: Chaplin R. L. , Shearin P. E.
Published: February 2005

Radiation damage studies of metal specimens have been achieved by using a Van de Graaff accelerator to supply energetic electrons. The irradiating electrons are magnetically deflected so that the electron beam bombards a well-defined rectangular area. A method is described which is used to determine the location of the beam with respect to the position of the specimen. A low temperature thermal switch is discussed in terms of its theroetical and and experimental behavior. A practical method for improving the thermal contact between the specimen and its holder by using the helium exchange gas technique is described. Estimates of the degree of thermal contact between specimen and specimen holder are possible because of the particular electrical circuit in the experimental chamber.
Compression Apparatus for Powder X-Ray Diffractometry
Authors: Steinfink H. , Gebhart J. E.
Published: February 2005

A compression apparatus has been constructed which is an integral part of a Norelco diffractometer shaft. The diffraction pattern of a sample can be obtained while it is under pressures up to 30 000 psi.
Separation Scheme for High Energy Particles by Differential Energy Loss and Momentum Analysis
Authors: Marcowitz S. , Ratner L.
Published: February 2005

A simple, low cost separation scheme using differential energy loss is described. The expected parameters of the ANL-ZGS secondary beams provide a framework for the design of a P̄, K− beam at 6 Bev/c for bubble chamber use. Magnet stabilities of the order of 0.01% are required. The π−, P̄, K− ratio at the chamber is about 1:8:8 with 3.2 P̄ and 3.0 K− per pulse for a ±0.25% initial momentum ``bite''. A calculation is also made for a 50-Bev/c beam to show that it seems feasible to use this method at energies higher than any that have hitherto been produced.
Low Impedance Transmission System for Driving Cryogenic Circuits
Authors: Dumin David J.
Published: February 2005

The possible advantages and disadvantages of driving cryotron circuits with a low impedance transmission system instead of a high impedance system are discussed. It is shown that although losses are higher in a low impedance cable, a reduction in the signal coupled between cables in a cryotron system is possible when low impedance cable is used. Two low impedance generators are described. These generators have a maximum frequency between 500 kc and 1 Mc. The rise time is less than 2 nsec and can be improved when the generators are packaged in strip line module form. Pulse amplitude is about 1.5 A. Pulse width is variable by use of a delay cable.
Apparatus for Measuring the Temperature Dependence of Photo-Hall Effects in High-Resistivity Photoconductors
Authors: MacDonald Harold E. , Bube Richard H.
Published: February 2005

Apparatus has been designed and constructed capable of measuring the photo-Hall effect for mobilities as low as 0.1 cm2/V-sec, in photoconductors with resistivity as high as 1010 Ω-cm, over the temperature range from 77 to 450°K. Temperature control of the photoconductor crystal by thermal conductivity through gaseous helium eliminates many of the problems associated with temperature control by direct thermal contact to the crystal. Voltage signals down to 100 μV are detected by vibrating reed electrometers, using five contacts to the crystal.
Manufacture of Solid Organic Standard Light Sources of Low Intensity
Authors: Pepin T. J. , Ney E. P.
Published: February 2005

A manufacturing technique is described by which one can make low intensity (∼5×10−6 ergs/cm2 sec sr in units of astronomical photographic intensities at λ=4300 and Δλ=1290 Å) standard light sources by the polymerization of an organic plastic scintillator containing a low energy β emitter.
Magnetic Susceptibility Measurements of Small Samples
Authors: Gordon R. G.
Published: February 2005

The paramagnetic or diamagnetic susceptibility of microgram amounts of solid samples can be measured by a null method in which the force of gravity balances the force on the sample due to an inhomogeneous magnetic field. The method measures the largest principal susceptibility of magnetically anisotropic crystals.
Method for Controlled Multicomponent Sputtering
Authors: Sinclair W. Robert , Peters F. G.
Published: February 2005

A method for sputtering simultaneously from electrically independent electrodes is described. The important design consideration is that the electrodes (cathodes) are enveloped by a single Crooke's dark space. Using this technique, alloy films (or in the case of reactive sputtering, mixed compound films) can be obtained. Since the electrodes are independent, the composition gradient (in depth) of the film can be varied at will by proper variation of applied voltages.
Study of a Focused Beam from the Duoplasmatron Proton Source
Authors: McKeever Richard , Yokosawa Akihiko
Published: February 2005

Aberrations of the preaccelerator focusing electrodes were studied experimentally by obtaining emittance diagrams for a beam of 38 and 60 mA. Aberrations observed were similar to those obtained from previous ray-tracing calculations. According to the calculations, the cause of aberrations is improper distribution of the radial field in the exit portion of the lens. More distortion of the phase-space diagram was observed for the higher beam current than the lower one. The observed emittance area increased by more than a factor of two when the beam current was changed from 38 to 60 mA. Even if aberrations were entirely eliminated, this fact may raise a serious problem in beam matching for a large beam current. A technique for measuring the emittance of the beam at 200 kV was developed and the details are described.
Reflecting Variable Bent Crystal Spectrometer
Authors: Elion H. A. , Ogilvie R. E.
Published: February 2005

A reflecting variable bent crystal spectrometer is described which in some forms varies between Johann and Johansson arrangements. The variable bent crystal and its spectrometer arrangement differ from the Harker concept. The variable control features of this spectrometer permit compensation for tolerances, application, and aging. As a result this combination of events has already resulted in achieving experimental signal-to-noise ratios as high as 3100 to 1 using a mica crystal on pure silicon. Other features permit direct comparison of relative x-ray intensities without diffraction volume correction.
New Wide-Range Pressure Transducer
Authors: Dimeff John , Lane James W. , Coon Grant W.
Published: February 2005

A new transducer has been developed that will measure pressure over a wide range by sensing the damping of a vibrating diaphragm immersed in the gas whose pressure is being measured. It is capable of measuring pressures from approximately 10−5 to 200 mm Hg with an accuracy of about 1% over a large portion of the range. The device overcomes many of the shortcomings characteristic of other gauges; it is small and rugged, with a fast response time at low pressures, and lends itself well to automatic operation.
Temperature Dependence of Decay Time and Intensity of Alpha Pulses in Pure and Thallium-Activated Cesium Iodide
Authors: Senftle Frank E. , Martinez Prudencio , Alekna Victor P.
Published: February 2005

The intensity and decay time of Po210 alpha particle scintillations produced in pure and thallium-activated cesium iodide have been measured with a fast electronic system as a function of temperature down to 77°K. Three modes of decay due to alpha excitation have been observed for CsI(Tl), and two for CsI. Other than the 7- and 0.55-μsec modes (at room temperature) reported in the literature for CsI(Tl), an additional temperature-independent mode of about 1.3 μsec has been detected between 77 and 150°K. In CsI a fast temperature-dependent mode of decay (≈100 nsec) was observed between 100–200°K in addition to the known principal mode.
Bubble Chamber Control and Alarm Circuits Using Solid State Elements
Authors: Fechter H. , Sztankay Z.
Published: February 2005

Power transistors delivering 8-A pulses of 2-msec width are used to drive low impedance coils in Ross and Barksdale valves. Unijunction transistors and Thyristors are used to replace all relays and lamp flasher elements in compact, reliable alarm units of new design. Life tests equivalent to many years operation at accelerator sites have been carried out. There has not yet been any failure in operation.
Controlled Atmosphere Kyropoulos Growth of Alkali Halide Single Crystals
Authors: Patterson David A.
Published: February 2005

The apparatus described in this paper can be used to grow alkali halide single crystals of several hundred grams from the melt in less than 48 h per crystal. The growth is carried out in a cylindrical quartz enclosure in a selected gas atmosphere which is maintained at a slight positive pressure by continuous inflow of gas. The gas flow also provides two salt-free windows on a special Pyrex lid so that illumination and observation are possible throughout the growth process. Techniques of the growth procedure and provisions for automatic growth and termination are also described.
Measurement of Betatron Oscillation Frequencies on the UCLA 50-MeV Cyclotron
Authors: Clark David J. , Richardson J. Reginald
Published: February 2005

The vertical and radial betatron oscillation frequencies have been measured on the UCLA 50-MeV spiral-ridge cyclotron. The technique used was that of rf knockout, in which the internal beam was passed through a pair of exciter plates which provided an rf electric field. When the frequency was equal to the betatron frequency a detectable increase in betatron oscillation amplitude or ``knockout'' occurred. The knockout as a function of exciter frequency shows a number of resonances rather than a single one. This provides a measurement of radial as well as vertical betatron frequency. Comparisons of the measured frequencies with those calculated from magnetic field measurements are given and show satisfactory agreement.
Tensile Testing Technique for Submicron Specimens
Authors: Lemkey F. D. , Kraft R. W.
Published: February 2005

A tensile testing instrument of the soft type which has been specifically designed to facilitate accurate axial alignment of submicron whiskers or filaments is described. The load is applied by a dead-weight loading mechanism similar to that used in chain balances and strain is measured photographically. The limiting feature on the accuracy of the results is the diameter variation which occurs within individual whiskers rather than the instrument. Tensile data are presented for a 0.35-μ-diam Cr fiber extracted from a unidirectionally solidified ingot of Cu-Cr eutectic alloy.
Tilting Stretching Stage for the Elmiskop Electron Microscope
Authors: Phillips V. A. , Hugo J. A.
Published: February 2005

In studying the mechanism of deformation, it is often desirable to be able to stretch a thin sample inside an electron microscope while the specimen is under observation. Dislocation movements and interactions can be directly observed. A new specimen stretching stage for the Siemens Elmiskop electron microscope is described which combines the advantages of tilting, fast response, sensitivity, and reversibility. A uniform strain is applied.
Simple Ice Calorimeter
Authors: Valleé R. E.
Published: February 2005

The construction and operation of an all glass ice calorimeter which allows the rapid and moderately precise (approximately 0.5%) measurement of heat changes in a system is described. In addition to the usual advantage of an ice calorimeter of being able to measure slow heat changes, the instrument described here is extremely simple to construct and operate. The use of a calibrated capillary tube to determine the volume change due to melting or freezing of ice eliminates the need of an analytical balance and simplifies operation of the instrument.
Spark Chamber Track Measuring System
Authors: DeShong James A.
Published: February 2005

A system is described for the projection, digitizing, and recording of photographed spark chamber tracks. A Slo-Syn-driven projector automatically frames the film and projects the tracks on a screen mounted in a precision commercial plotting board. A reticle projector, mounted on the plotting board pen holder, is manually positioned by means of the plotting board drive tapes which also drive the encoders of an accumulating digitizer system. A photoelectric gap counting device can be substituted as an alternate for one of these encoders. The all-transistor digitizer system is equipped with manual switches for labeling of tracks, inserting frame numbers, etc., and has a versatile output format on seven hole paper tape. The paper tape with its track coordinate information is used as the input for computer programs designed to calculate the particle physics evidenced by the track.
Low Voltage He3-Filled Proportional Counter for Efficient Detection of Thermal and Epithermal Neutrons
Authors: Mills William R. , Caldwell Richard L. , Morgan Ira L.
Published: February 2005

Neutron counters using He3 gas at absolute pressures up to 10 atm have been constructed and tested. The relative detection efficiency for thermal, epicadmium, and fast neutrons was measured as a function of pressure from 1 to 10 atm, and compared with similar data from a boron trifluoride counter of the same size filled to a pressure of 65 cm of B10F3 gas. The ratio He3/BF3 increases approximately linearly with pressure for epicadmium and fast neutrons, reaching values of 26.6 and 21.6, respectively, at 10 atm He3 pressure. This ratio shows a saturation effect for thermal neutrons, becoming 4.45 at 10 atm He3 pressure. The gamma-ray response has been found to be low with proper pulse shaping. High voltage plateau curves for 3- and 7-atm counters are given and indicate operating regions at least 100 V wide at a counter high voltage of about 1200 V.
Total Reflection of Neutrons from Metallic Mirrors
Authors: Bally D. , Todireanu S. , Rîpeanu S. , Belloni M. G.
Published: February 2005

Total neutron reflection from Cu, Fe, Cd, and glass mirrors was studied. The variation of the reflection coefficient vs glancing angle for a neutron wavelength of 1.161 Å was measured. The results obtained show that passing from a polished mirror to a ground mirror leads to a fourfold decrease of the reflection coefficient and a threefold increase of the half-width of the rocking curve. The following values for the scattering lengths were obtained: fFe=(9.16±0.13)10−13 cm; fCu=(7.46±0.15)10−13 cm; fCd=(4.9±0.2)10−13 cm. The penetration depth of totally reflected neutrons was measured and a value of 130 Å was found for a copper mirror.
New Tensile Testing Machine for Thin Specimens
Authors: Kuhlmann-Wilsdorf D. , Raghavan K. Srinivasa
Published: February 2005

A new tensile machine for thin specimens is described. Specially designed grips for both films and thin wires, and other features of the machine are described, and it is explained how the difficulties encountered in conventional machines are avoided. The actual testing procedure is given.
Generation of Uniform Magnetic Fields by Means of Air-Core Coils
Authors: Franzen Wolfgang
Published: February 2005

The generation of uniform magnetic fields over extended regions of space by means of circular coils of large cross-sectional area is analyzed. It is shown by an extension of Garrett's theory of axially symmetric magnetic fields that the optimum shape of the coil cross section can be found analytically without numerical integration over the winding area. The theory is illustrated by application to Helmholtz coils and double Helmholtz coils of rectangular cross section. Choice of the optimum dimensions makes it possible to generate very uniform fields of great intensity.
Design and Construction of a Glass Envelope Closely Coaxial to a High-Power Electron Beam
Authors: Snyder J. A. , Steed E. C.
Published: February 2005

A close-wound helix of 0.010-in.-diam tungsten wire has been successfully bonded into the bore of a 24-in.-long, 0.625-in.-diam glass tube by shrinking the glass over the mandrel-supported helix. The additional problem of furnishing a nonmagnetic glass-to-metal seal on one end of the glass cylinder has been answered by adapting a new seal combination of molybdenum and alumino-silicate glass in cylindrical form.
Instrumentation for Ultrasonic Attenuation Studies
Authors: Kamm G. N. , Bohm H. V.
Published: February 2005

Pulse echo-type instrumentation for ultrasonic attenuation studies is described. It incorporates a commercial ultrasonic pulse generator for operation from 10 to 200 Mc, and assembled components to extend the range to 350 Mc and higher. In addition to the transmitter, receiver, and display components, it includes circuits to select and measure the echo pulse and equipment for automatic recording. Details of the circuits and of the sample holder used at 350 Mc at liquid helium temperatures are presented.
Selective Pumping of Light and Heavy Gases with a Molecular Pump
Authors: Apgar E. , Lewin G. , Mullaney D.
Published: February 2005

For some plasma experiments high purity hydrogen or deuterium at pressures of 10−3 Torr or less is required. It is shown that a molecular pump can be used as a combination pumping, gas injection, and gas purification system. The gas is admitted to the fore vacuum side and streams back to the high vacuum side. This does not materially affect the pumping of heavy impurities. Performance data for this mode of operation are given for the Pfeiffer pump TVP-500.
Properties and Preparation of Thin Antimony Films of High Uniformity
Authors: Condas George A.
Published: February 2005

The transmission vs surface density (thickness) relationship has been determined for thin antimony films. Data are given for both white and monochromatic light (4500, 5380, and 6650 Å). The results are more accurate than those usually tabulated since the surface densities were determined directly from these films. These films were primarily evaporated from evenly coated thin nickel rings, giving films of extreme uniformity. Holland's surface density distribution for films from ring evaporators was found to give an accurate representation of these films. Films of the largest area of constant thickness were produced when the ratio of the evaporation distance to the ring's inner radius was approximately 1.3.
Method to Eliminate Noise During the Transmission of Radio Pulses
Authors: Waibel E.
Published: February 2005

The wide frequency emission band of noise signals which interfere with signals of radio transmitters is used for eliminating these noise signals. They are received separately beside the telemetering frequency and are quenched by a suitable anticoincidence circuit.
Silicon Dioxide Passivation of p-n Junction Particle Detectors
Authors: Madden T. C. , Gibson W. M.
Published: February 2005

Silicon p-n junction particle detectors present unusual passivation problems because of the shallow diffusions and large exposed junction areas involved. The use of silicon dioxide films for reducing the ambient sensitivity of junction detectors has been investigated, and grown-oxide films produced with high pressure steam have been studied in detail. The dependence of ambient sensitivity on such parameters as bulk silicon resistivity, diffusant, and diffusion temperature has been investigated. Methods of fabrication of ambient insensitive diodes and more complicated guard-ring structures are also discussed.
Radio Telemetering from Magnetically Suspended Rotors
Authors: Robinson T. K. , Beams J. W.
Published: February 2005

A method of radio telemetering temperature with miniature circuits from magnetically supported spinning rotors is described. The circuits are stable and give rotor temperatures with precision of 0.01°C. They are especially useful in the magnetically supported equilibrium ultracentrifuge but are applicable to all types of high speed rotors.
Quest: An On-Line Event-Processing Routine
Authors: Alston Margaret H. , Braley James E. , White Peter
Published: February 2005

An on-line computing system called QUEST can be used by a physicist to analyze unusual bubble-chamber events. The production version of a program called PACKAGE has been modified so that the physicist can control the progress of a specific event through the subroutines of PACKAGE. Feedback from the computer to the operator permits him to decide what hypothesis he should try next, depending upon the results already obtained. Because the physicist requires time to think what to do next, the QUEST system has been designed so that it can interrupt and then restore other programs.
Full Circle Goniostat for Diffraction Intensity Data
Authors: Mueller M. H. , Heaton L. , Sidhu S. S.
Published: February 2005

A full circle goniostat is described for obtaining three-dimensional diffraction intensity data. This instrument permits a complete 360° motion in both φ and χ and a limited manual ω adjustment. Electronic angle setting and readout are provided, which facilitate automatic collection of intensity data.
He−, H2−, and Other Negative Ion Beams Available from a Duoplasmatron Ion Source with Gas Charge Exchange
Authors: Carter E. B. , Davis R. H.
Published: February 2005

Negative helium-ion beams have been produced in a commercial negative-ion source in which positively charged beams from a duoplasmatron ion source are converted in a gas charge exchange canal. Beams of negative helium ions with currents up to 30 mμA have been injected into a tandem Van de Graaff accelerator, and α-particle beams have been obtained from the accelerator with energies up to 19 MeV and currents up to 20 mμA. The results of several experiments which were performed to determine the source operating characteristics for negative helium ions are presented. In addition to the peak corresponding to the He− beam, many other peaks are observed in the momentum distribution of the beam from the negative ion source. Confirming evidence has been found for the existence of the H2− ion.
Double Magnetic Suspension
Authors: Beams J. W.
Published: February 2005

A double magnetic suspension is described in which the lower rotor is magnetically suspended from the upper rotor which in turn is magnetically suspended. The upper rotor may be made to surround the lower (or inner) rotor. Consequently, the effective magnetic suspension and vacuum chamber surrounding the inner rotor may be made to spin at approximately the same speed as the inner rotor (or within a few rps). This greatly reduces the rotor's deceleration when it is coasting freely.
Design and Use of an Acid Polishing Machine
Authors: Dyer L. D.
Published: February 2005

An improved acid polishing machine for dislocation-free polishing of copper is reported and its operation described. The main improvements are a compact axial tilt device, provision for rapid interruption of the polishing and inspection of the sample, and a more rigid shaft confinement and alignment. Some useful aids in the chemical polishing techniques are also reported.
New Type of Positive Ion Detector for the Simultaneous Measurement of Two Beams
Authors: Daly N. R.
Published: February 2005

A positive ion detector has been developed that is capable of simultaneously measuring two ion beams. It is made up basically of two scintillation detectors back to back. Ion beams enter a chamber on either side of a thin dividing partition. They are attracted to two electrodes at 40 kV where they release secondary electrons. A magnetic field directed along the axis of the incoming positive ion beam deflects the two electron beams so that they strike opposite walls of the ion detector. Two small organic phosphors situated in the walls at the electron impact points produce light signals that are recorded by photomultipliers. Focusing of the electron beams and the efficiency of detection for gas and heavy metal ions have been investigated. Measurements of tungsten isotopic ratios have shown that the stability of the system is such that the precision of measurement is defined almost entirely by the statistics on the number of ions counted.
Sensitive Null-Balance Pressure Transducer
Authors: Oertel Gerhard
Published: February 2005

A pressure transducer is described which operates by balancing the pressure to be measured with that due to a known hydrostatic head. The precision is ±0.0025 psi over a range of about 1 psi with less than 0.0025-psi drift in 8 h, and it requires very small fluid displacement. However, it can be used only where response to frequencies above about 0.2 cps is not required. A differential transformer monitors the height of the meniscus in one arm of a flexible, mercury-filled U tube. This meniscus is displaced by changes in pressure transmitted hydraulically from a sensing head. The output of the transformer controls a servomechanism that continually restores the meniscus to its original height by raising or lowering the other arm of the U tube. Changes in pressure within the sensing head thus cause proportional changes of height of the mobile arm of the U tube, which are monitored and recorded.