bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Parameter Multichannel Recorder-Analyzer System
Authors: Rockwood Curtis C. , Strauss Michael G.
Published: February 2005

A system is described in which nuclear events characterized by three parameters are recorded in digital form on magnetic tape by the record station. The completed tape is then analyzed off-line by the search station. Events of a typical experiment may consist of two pulse heights and a neutron time-of-flight, two pulse heights and an angle, or three coincident pulse heights. Each parameter is encoded by eight binary characters (bits) or 256 channels; thus, the number of different combinations is (256)3 or approximately 17×106. Each event is recorded as three eight-bit numbers across a 24-track, 1¼-in. magnetic tape. The tape is advanced in steps of 0.01 in. per event at low counting rates in order to conserve tape, and is moved continuously at high counting rates in order to achieve a recording rate of 170 events per second. During search of the recorded tape, restrictions are imposed on two parameters. If both are satisfied, the third variable of the corresponding event is tallied in one quadrant of a 1024-word core memory. There are four such restriction gates, one for each memory quadrant. In a neutron experiment, for example, a single pass of a 2500-ft tape with 3×106 events lasts only 3⅓ min and produces four time-of-flight spectra, each with uniquely selected energy ranges of two coincident gamma rays as parameters. The four spectra may be viewed on a cathode-ray tube or read out simultaneously by a typewriter, punched paper tape, and X-Y recorder at a rate of 5 min per spectrum of 256 channels. For experiments with low coincident counting rates, this system provides an efficient method for accumulating and analyzing data. The entire system is made with solid-state components, including 2100 transistors and 3300 diodes.
Improved Probe Apparatus for Measuring Contact Resistance
Authors: Chaikin Saul W. , Anderson Jack R. , Santos George J.
Published: February 2005

An apparatus, employing a fine-wire probe, for the detection of insulating surface films on metal surfaces is described. A chemical cleaning procedure to prepare reliably clean palladium and gold surfaces is reported, and examples of the reproducibility of the method are given. Examples of the use of this apparatus include: the detection of high resistance areas on relay contacts taken from sealed relays, and a study of insulating base metal oxide impurities in commercial relay contacts. In the latter work, a sensitized paper test showed areas of iron and copper deposits on the contacts which could be correlated with areas of high resistance as indicated by the probe.
Simple Broad-Range Magnetic Spectrometer
Authors: O'Connell James S.
Published: February 2005

The focusing properties are given for a broad-range magnetic spectrometer formed by inclined plane pole faces.
A One-Mev/Nucleon Sloan and Lawrence Heavy-Ion Linear Accelerator
Authors: Nassibian G. , Bennett J. R. J. , Broadbent D. , Devons S. , Hoisington R. W. R. , Miller V. E.
Published: February 2005

A description is given of a small heavy-ion linear accelerator based on the use of a twin transmission line as first suggested by Sloan and Lawrence. Ions are accepted if their e/m values are ⅛ or greater (relative to the proton) and are accelerated to a final energy of 1.04 Mev/nucleon. The accelerator has 40 drift tubes fitted with focusing grids, and about 350 kw of pulsed rf are needed for ions of e/m=⅛. The radio frequency is 25 Mc, and the accelerator is pulsed at up to 50 pps with a pulse length of 500 μsec. Injection velocity is 0.007 c, corresponding to a dc acceleration from the ion source through 180 kv for an ion of e/m=⅛. Ions are produced in a pulsed dc arc of the Penning type operating in a magnetic field of 1000 gauss and the dc accelerating voltage is supplied by an electrostatic generator. Typical pulsed meter currents so far obtained are, for He+, input 4 ma, output 150 μa; for N2+, input 3 ma, output 75 μa. The accelerator is the first stage of three which will take the ions to a final energy of 10 Mev/nucleon. The second and third stages, which are under construction, will be cavity resonators of the Alvarez design.
Development of a 100-ma Proton Source and Lens System for the Bevatron Mark-II Injector
Authors: Allison Robert W. , Cork Bruce , Richter Robert M. , Smith Joseph F. , White Glenn E. , Zajec Emery
Published: February 2005

A Von Ardenne-type ion source and lens system has been developed for use as a preinjector to the 18-Mev strong-focusing linear accelerator. Proton beams of 120 ma at an ion production efficiency of 83% have been obtained. A magnetic beam-confining system has been built, and a beam of 85 ma has been transported 82 in. The beam energy was 370 kev, and its emittance was 100 mrad-mm. The beam diameter was 1 cm. This is within the linear accelerator's calculated acceptance of 179 mrad-mm.
Generator for Producing High Concentrations of Small Ions
Authors: Whitby K. T.
Published: February 2005

An arrangement of a needle and a sonic orifice has been developed which is capable of converting the corona current into free small ions with 100% efficiency. Positive and negative ion concentrations of 1011 ions/cm3 in the sonic jet and total ion outputs of 1014/sec have been achieved using 2.5 cfm of free air at 30 psig through a116−in. orifice. Theoretical and experimental studies of the ion decay rate in the jet show that the concentrations drop off approximately as the square of the distance from the ionizer.
Calibrated Scintillator Probe for Determining Energy Distribution, Density, and Mean Energy of the Electronic Component of a Pyrotron Plasma
Authors: Ellis Robert E. , Carlson Norris W.
Published: February 2005

A method of determining some of the characteristics of a deuterium plasma generated and confined in a magnetic-mirror machine is described. In this case the electronic component of the plasma is characterized by a mean energy considerably greater than the ionic component. The mirror configuration readily allows detection of the flux of particles which escape through the mirror loss cone from the plasma confined between the mirrors. Scintillator probes placed near a mirror and outside the confinement region do not interfere with the confined plasma. By the use of thin aluminum absorbers placed in front of the scintillator, a determination was made of the energy distribution of the electron flux as a function of time during the decay of the pulsed mirror field. Such measurements were used to infer plasma conditions by consideration of the processes resulting in the leakage of plasma particles through the mirror. In determining the density of the plasma, the correction to be made to the integral of electron flux over time is based on conclusions as to plasma stability and the known decay rate of the pulsed magnetic field.
Image Intensifier with Electron-Optical Demagnification Using Combined Electric and Magnetic Fields
Authors: Zacharov B.
Published: February 2005

A demagnifying image intensifier is proposed using parallel converging electric and magnetic fields. The design of such a tube is considered and the results of calculations for the particular case of conical fields are presented; the diameter of a typical disk of confusion for a linear demagnification of 5:1 and minimum flux density of 10−2 weber/m2 is found to be <0.004 cm. Suggestions are made for a tube incorporating an intermediate stage of electron multiplication.
High Resolution Focusing Čerenkov Detector for High Energy Particles
Authors: Hill D. A. , Caldwell D. O. , Frisch D. H. , Osborne L. S. , Ritson D. M. , Schluter R. A.
Published: February 2005

A focusing differential Čerenkov counter of high velocity resolution using a gas radiator has been developed and used in relativistic particle beams. The optical and mechanical features are described. The velocity β can be varied continuously from 0.81 to 1.00. These counters give a velocity resolution Δβ/β of 0.0025 (half-width at half-maximum) at β=0.9985 and an average efficiency for a 4-in. diameter particle aperture of 0.7 in a particle beam collimated to ±1°. The sources of spurious response and the ultimate limitations of counters of this type are discussed.
Infrared Spectroscopy of Melts and Hygroscopic Glasses
Authors: Mackenzie J. D. , McDonald R. S. , Murphy W. K.
Published: February 2005

Two techniques have been developed for the measurement of the infrared absorption of glasses at room temperature and of their melts up to 1000°C. In a vertical film apparatus, dehydration and the control of sample thickness may be carried out simultaneously. At high temperatures, the breakage of the film through flow is circumvented by a horizontal film arrangement. By the formation of suitable thin films in situ, rapid absorption of water is prevented. These methods are thus particularly suitable for highly hygroscopic materials where the conventional KBr disk technique is unsatisfactory. The advantages of the two techniques are demonstrated by measurements carried out on glassy and liquid B2O3 up to 1000°C.
Electrical Conductance Cell Assembly for Precise Measurements with Carbonates, Oxides, and Fluorides up to 1000°C
Authors: Janz George J. , Lorenz Max R.
Published: February 2005

A conductance cell assembly is reported of the capillary design with a cell constant sufficiently high to permit precise electrical conductance measurements with the standard type precision conductance bridge circuits. Important features are the use of single crystal grade MgO for construction of the capillaries that determine the resistance for the electrolyte in the conductance cell, and the use of such materials as gold, or gold-palladium alloy to construct the various other components of the cell that contact the molten salts. The suspension of the MgO crystal capillaries is of a novel design which permits removal of the capillaries from the assembly for inspection or cleaning, and yet holds these firmly and securely in position during measurements. It is shown that recently published values of electrical conductance for molten KCl and KNO3 may be used as standards for calibration of such cells at high temperatures.
New Method for Measuring Sputtering in the Region Near Threshold
Authors: McKeown Daniel
Published: February 2005

A new method is described by which a plated quartz crystal oscillator is used for the measurement of sputtering. The crystal is placed in a molecular beam and sputtering of its plating is measured by the frequency change of the oscillator. The relationship between the frequency change of the oscillator and the change in plating mass of the crystal is given. The method is extremely sensitive. Sputtering of less than a millimicrogram of plating can be measured. A wide range of material can be used to plate the crystal. A crystal oscillator sputtering gauge was built by using a frequency counter with a digital readout to record the oscillator frequency. The operation of the gauge is illustrated by preliminary measurements on the sputtering rates of gold in an argon beam between 0 and 100 ev. Other uses of the gauge, such as a neutral beam detector, are also discussed.
Resonant Beam Extraction from an A. G. Synchrotron
Authors: Hammer C. L. , Laslett L. Jackson
Published: February 2005

The resonant extraction method previously proposed for the normally constant gradient synchrotron has been extended to alternate gradient accelerators. It is found that perturbation field gradients which contain circular functions of arguments 2νx, 2νx+1, 2νx+2 are particularly effective in causing the radial betatron oscillations to grow exponentially at a particular azimuthal position. The analytical procedure for predicting which perturbations give optimum results, and digital computer calculations verifying these predictions, are presented.
Calculations of Properties of Magnetic Deflection Systems
Authors: Penner S.
Published: February 2005

A convenient matrix method for calculating properties of magnetic deflection systems is presented. This method is applicable to particle beams of small spatial and angular extent, and small energy spread. Equations for quadrupole lenses and for deflecting magnets are given. Examples are given to show the procedure for calculating the parameters of magnet systems.
Device for Evaporating Multiple Films
Authors: Androes G. M. , Hammond R. H. , Knight W. D.
Published: February 2005

A description is given of the construction and operation of a device which is capable of producing multiple layers of evaporated films. Uniform strands of a metal and of a dielectric are alternately cut into bits, which are evaporated completely, the size of each bit determining the thickness of the corresponding layer. Each layer of metal may be continuous, or divided quite uniformly into small particles, depending on the conditions of the experiment. In the latter instance, the result may be a rather concentrated monodispersed colloid. The preparation of a specimen containing 60 000 layers of tin, approximately 40 A thick, and constituting 10% of the total volume, is described. Evaporated nylon has been found to be a satisfactory insulator between the layers of metal; Mylar film, 0.00025 in. thick, works very well as a substrate. Several other uses for the evaporating machine are suggested.
Optical Characteristics of a Mechanical Neutron Monochromator with Helical Slots
Authors: Bally D. , Tarină E. , Pirlogea P.
Published: February 2005

The expression of the function f(λ) defining the transmission of a mechanical monochromator with helical slots when the incident neutron beam is limited by a Soller collimator has been calculated. The influence of the total reflection from the collimator walls upon the function f(λ) was also studied. The paper describes a mechanical monochromator with helical slots devised for the suppression of the higher-order Bragg reflections from a crystal. Measurements with this monochromator have served to check the calculations.
Measurement of Nanosecond Scintillation Decay Times
Authors: Dreeskamp H. , Ghosh A. K. , Burton Milton
Published: February 2005

An experimental method for measuring scintillation decay times of the order of nanoseconds is described. The method involves a repetitive time selection technique; i.e., in a sense, it is the electronic equivalent of the original Becquerel phosphoroscope. The complete circuitry is shown and some illustrative results are given.
Accurate Amplitude Distribution Analyzer Combining Analog and Digital Logic
Authors: Brubaker T. A. , Korn G. A.
Published: February 2005

A new precision analyzer yields digital readout of probability or probability density for random waveforms at low audio frequencies. A preamplifier-limiter conveniently increases a half-volt slicing interval to 20 v or more, and a sample-hold circuit permits the slicer to work slowly and accurately. The use of analog computer techniques permits convenient assembly of such instruments from inexpensive commercial plug-in amplifiers and decimal counters. Some statistical theory is also presented.
Apparatus for Methane Synthesis for Radiocarbon Dating
Authors: Fairhall A. W. , Schell W. R. , Takashima Y.
Published: February 2005

A simple apparatus is described whereby any quantity of CO2 up to several moles can be converted to methane in one step by catalytic hydrogenation using a ruthenium catalyst. The conversion is very rapid, the entire operation being carried out in about 3 hours. The over-all yield is greater than 98%, and the methane is of high purity.
Technique for the Cinephotomicrographic Study of Etching Phenomena
Authors: Tint G. Stephen , Damiano Victor V.
Published: February 2005

A device was constructed to photograph, on motion picture film, the etching behavior of zinc monocrystals. This apparatus consists of: (1) a transparent cell to hold sample and etchant; (2) a microscope with vertical illuminator; and (3) a motion picture camera driven by an electric motor. Several sequences of these pictures are reproduced, showing the continuous formation of spiral-like etch patterns.
Measurement of Tunnel Diode Negative Resistance
Authors: Todd Carl David
Published: February 2005

Several methods for the measurement of rd, the magnitude of tunnel diode negative resistance, are presented. A null indication technique capable of very accurate measurements is discussed along with necessary procedures to prevent oscillation. A test fixture which will allow stabilization of most tunnel diodes, even those for which the resistive cutoff frequency exceeds the self-resonant frequency, is described.
Photo-Proton Spectrometer
Authors: Murray K.
Published: February 2005

A detector system is described which can be used to observe protons in the energy range 2–10 Mev, with a discrimination factor against γ-ray background greater than 100 to 1 for γ-ray intensities less than 103/sec entering the scintillator. The instrumental linewidth of the detector is about 7% for 5-Mev protons.
Effect of Long Wavelength Harmonics on Double Crystal Diffractometer Measurements
Authors: Batterman Boris W.
Published: February 2005

It is shown that large errors due to long wavelength harmonics can occur in the determination of integrated intensities and halfwidths with a double crystal spectrometer. For example, in measuring the integrated intensity of the (333) reflection of silicon with Mo Kα radiation, an error of a factor of 4 is possible due to 3λ radiation from the white spectrum which is simultaneously diffracted by the (111) planes. The amount of error is dependent upon the particular experimental arrangement (tube voltage and allowed horizontal divergence being the most important factors), and can be reduced, and in most cases eliminated, by use of an appropriate filter.
Microcell for Infrared Studies on Pure Liquids at High Pressures
Authors: Schamp Homer W. , Maisch William G.
Published: February 2005

A small internal optical cell which can be used to study the infrared absorption of pure liquids to 12 000 atmospheres is described. The sample is sealed in a small plastic bag which is held between two sapphire plates. The distance between the plates can be set to accommodate the different absorptive capacities of various liquids.
Method for Measuring Time-Average Concentration in a Turbulent Wake of Electrolyte
Authors: Sparks Robert E. , Hoelscher H. E.
Published: February 2005

A method is described for measuring time-average concentration profiles in the fully developed turbulent wake of a circular cylinder having a porous wall through which a solution of electrolyte was flowing. The study was carried out in the flow field of a water tunnel. The sensing element employed was an electrical conductivity probe. The method involves the use of a thermal averaging device and a sensitive recording dc bridge. The method is very sensitive and is capable of high precision.
High Speed Oscilloscope with Electron Optical Magnification Using Four-Pole Lenses
Authors: El-Kareh Auguste B.
Published: February 2005

A new method of high speed oscillography has been investigated. This makes use of four-pole lenses which enable the deflection of the beam to be magnified in only one desired direction. By magnifying the deflection by a factor k in both directions as in the conventional oscilloscopes, one loses in intensity by a factor k8/3. If, however, a magnification in one direction is used, the loss is only k4/3.
Observations on Pulsed Spark Chambers
Authors: Fischer Joachim , Zorn Gus T.
Published: February 2005

The spark formation time in rare-gas pulsed spark chambers was investigated as a function of the pulse voltage under various conditions of electrodes, gap lengths, gases, delay times, and clearing fields. An explanation of these formation times was found in terms of a simple process of electron multiplication leading to rapid gas breakdown. Notes on the construction of a thin foil spark chamber and on thyratron pulsers for use with spark chambers are also given.
Accuracy of Track Location in Spark Chambers. I
Authors: Rutherglen J. G. , Paterson J. M.
Published: February 2005

Several spark chambers with a sensitive area of about 6×6 in. have been constructed using 0.005-in. aluminum plates and 0.25-in. glass frames as spacers. These were tested with cosmic rays, using neon, argon, and neon-argon mixtures as the filling gas. A spark gap triggered by scintillation counters was used to apply a high voltage pulse to the plates. Photographs of the sparks produced were analyzed to determine the accuracy with which the track of the cosmic ray could be located. It was found that the electrons nearest the negative clectrode are the ones which determine the position of the spark. The results give a basis on which to design a spark chamber system to give any desired accuracy of track location and direction.
Interference Comparator for the Calibration of Line Standards Directly in Terms of Standard Wavelengths
Authors: Baird K. M.
Published: February 2005

An interference comparator has been built for the routine calibration of line standards or scales by direct reference to the vacuum wavelength of the 0.606 μ line of Kr86 which has recently become the international standard of length. The principles of construction and the performance of the comparator are given; it is shown to yield an accuracy of calibration which is mostly limited by the nature of present-day line standards or scales, viz., a few hundredths of a micron in lengths up to one meter.
Acid Cutting and Acid Polishing of Copper Crystals
Authors: Young F. W. , Wilson T. R.
Published: February 2005

An acid saw and an acid polisher for cutting and polishing copper crystals are described. Evidence is presented that the cutting and polishing do not introduce dislocations into the crystals. Using these techniques, copper crystals with a dislocation density of 5×103/cm2 have been prepared.
Smear Camera Technique for Free-Surface Velocity Measurement
Authors: Davis W. C. , Craig B. G.
Published: February 2005

An optical technique which permits recording the position of a very small region of a surface as a function of time is described. The surface must reflect light specularly, the arrangement must allow some space in front of the surface, and the radius of curvature of the surface must be large compared with the distance over which the position is of interest. There are no other restrictions on the surfaces to which the technique may be applied. The apparent position of the image of an object reflected in the free surface to be studied is recorded with a moving-image smear camera, and velocity is obtained from the record of position as a function of time. This technique has been used to measure velocities between 5×103 and 5×105 cm/sec in times as short as 3×10−8 sec for research with high explosives.
Single Pulse Method for Measurement of Electrical Double Layer Parameters
Authors: Riney J. S. , Schmid G. M. , Hackerman Norman
Published: February 2005

An electric analog of an electrochemical cell is assumed to consist of a constant ohmic resistance, representing the bulk electrolyte, and a parallel combination of resistance and differential capacity, representing one interface. The response of the model to a rectangular current-time function is given in terms of circuit components. The interface parameters are not assumed to be constant and the equations yield instantaneous values for each of them. A pulse generator is described, which is capable of closely approximating the required current-time function. Results of measurements made on Pt and dropping Hg are presented.
Electrical Leads for Pressure Vessels to 30 Kilobars
Authors: Cornish R. H. , Ruoff Arthur L.
Published: February 2005

A convenient labor-saving method of introducing up to eight (and more, if necessary) electrical leads into a one-half inch diameter pressure chamber (which is applicable with liquid media to pressures in excess of 30 kilobars) is described.
Investigation of Narrow Well in NaI (Tl) for Reduction of Iodine K X-Ray Escape when Measuring Continuous X-Ray Spectra with Collimated Photon Beams
Authors: Epp Edward R. , Weiss Herbert
Published: February 2005

A technique described previously by Hettinger and Starfelt for the reduction of iodine K x-ray escape when measuring narrow collimated beams of continuous x rays with a NaI(Tl) scintillation spectrometer consisted of confining the photon beam to a small well in the crystal to reduce the solid angle through which iodie K x-ray escape is possible. This technique was evaluated for tungsten characteristic radiation (∼60 kev) and was reported to provide a very substantial reduction in the escape peak. The present paper describes an investigation of this technique at lower photon energies (10 to 60 kev). A tail was observed to appear on the low energy side of the photopeak of magnitude showing inverse dependence on photon energy. This distortion of pulse-height response is large enough to indicate that the well crystal technique is unsatisfactory when making measurements of continuous x-ray spectra in the energy region where the escape of iodine K x rays is an important factor. The likely explanation is that light losses associated with the well itself are responsible for the observed tails since reflecting liners were not present. Introduction of a reflecting liner into the well was found to reduce the tail effect considerably.
Pulse Shape Discrimination in Stilbene Scintillators
Authors: Daehnick W. , Sherr R.
Published: February 2005

A simple, sensitive pulse shape discriminator is described, which was designed to permit detection of low energy neutrons in the presence of a very high γ-ray background, and at high counting rates. An improvement relative to discrimination circuits published so far was obtained by incorporating a fast crystal diode switch for the separation of the fast and slow parts of the scintillator de-excitation pulse. This device greatly reduces interference effects of nearly coincident detector pulses and also permits better pulse matching and comparison. The best discrimination was obtained for moderate sensitivity and counting rates, where out of 105 detected γ rays about one was erroneously admitted. A detailed description of the circuit and accessories is given, and results of test runs at a 20 Mev FM cyclotron are presented.
Amplitude-Distribution Analyzer
Authors: Pipkin E. L.
Published: February 2005

Instrumentation to automatically record amplitude distribution curves is described. Basically the method employed is that proposed by Landon in which one measures the relative lengths of time that a signal is equal to, or less than, a given amplitude. A digital approach, similar to that of Davenport, is made. However, instead of modulating a pulse train with the studied signal, as done by Davenport, the described analyzer mixes the amplitude of a high frequency sinusoid with the studied signal, producing greater stability and requiring less bandwidth. The amplitude is scanned by reducing the amplitude of the carrier sinusoid, while keeping the rms value of the studied signal constant. The distribution curves of a random noise sample and of two sinusoids, the latter of which are used in calibration of the amplitude axis, are presented.
Alkali Metal Vapor Spectral Lamps
Authors: Bell William E. , Bloom Arnold L. , Lynch James
Published: February 2005

Efficient electrodeless discharge spectral lamps have been developed that are suitable for transmission monitoring of optically polarized quantum systems. The lamps have a surface brightness close to the theoretical limit with substantially no self-reversal. The limiting intensity fluctuations observed appear to be that of photon shot noise. Predicted life of the lamp is in excess of 5000 hr.
System for the Precision Measurement of Long-Time Change of an Inhomogeneous Magnetic Field
Authors: Zingery W. L.
Published: February 2005

The long-time stability of an inhomogeneous magnetic field is measured with a precision of 3×10−5. The system is instrumented for short-time dependence on component stability while referencing on a precision homogeneous field with NMR. An InAs Hall effect sensor is positioned in the gap of a permanent magnet assembly. The Hall voltage is balanced by a low voltage reference source. Without changing the reference voltage the Hall probe is placed in the field of a 6-in. electromagnet whose field is varied to again obtain null, then is measured with an NMR gaussmeter. The time requirement on component stability is about one minute. The Hall probe is temperature controlled to ±0.01°F.
Design and Construction of Multi-Ring Apparatus for Use at High Pressures
Authors: Christiansen E. B. , Kistler S. S. , Gogarty W. B.
Published: February 2005

A derivation is presented of equations which can be used in the design of high pressure apparatus utilizing multiring support. The use of these equations is illustrated by the design calculation for a multi-ring apparatus known as the anvil assembly. The particular assembly described uses three rings for external support. This assembly is capable of developing average pressures of 160 000 atm for minimum periods of two weeks. The methods and materials used in the fabrication of the assembly are also presented.
The Tensimeter, a New Vacuum Gauge
Authors: Anderson R. C. , Cooke G. M. , Kenyon L. C. , Mathiasen R. L.
Published: February 2005

The Tensimeter was developed to meet the need for a more dependable laboratory vacuum gauge which would be useful over the range of pressures from atmospheric down to a fraction of a millimeter of Hg absolute. The principle of operation involves using the boiling point of a pure compound as a measure of the pressure of the connected system. A description and calibration data are included. The advantages of the Tensimeter arise from the fact that it tolerates atmospheric water vapor which is usually present in petroleum distillations and causes other gauges to read incorrectly. It is small and convenient to use and does not require recalibration. It also produces an electrical signal which can be used for recording and control of subatmospheric pressures.
Compact Apparatus for High Temperature Modulus of Rupture Measurement
Authors: Shaffer Peter T. B.
Published: February 2005

By means of a compact graphite apparatus, modulus of rupture may now be determined at temperatures in excess of 2350°C. The design is such that the apparatus may be used in any furnace with a hot zone 4 in. in diameter by 6 in. high, protected by an inert atmosphere.
Fused Salt Spectrophotometry I. Furnaces for a Cary Model 14 Spectrophotometer
Authors: Morrey John R. , Madsen Anthon W.
Published: February 2005

Furnaces which can be readily installed or removed from the sample and reference compartments of an unmodified Cary model 14 spectrophotometer are described in some detail. Heat requirements to 800°C are given for these units.
Improved Electron Filter Lens
Authors: Simpson J. Arol , Marton L.
Published: February 2005

A filter lens of improved characteristics obtained by use of an intermediate image is described. The design has the advantage of longer focus and increased aperture while maintaining an energy resolution, at 5-kev primary energy, of less than thermal spread of the initial beam.
Amplifier for the Generation of Accurately Controlled Microsecond Pulses
Authors: Gunn J. B.
Published: February 2005

A description is given of a pulse amplifier whose output voltage can be accurately controlled by the setting of a ten-turn potentiometer. The output amplitude and pulse lengths are variable up to 1000 v, 2.6 amp, and 10 μsec, respectively. An accuracy of 2 v is achieved, independently of external conditions, by the use of strong negative feedback to compare the output with a reference dc voltage. The various sources of error are discussed.
Thermal Behavior in Vacuum Zone Refining
Authors: Donald D. K.
Published: February 2005

The temperature distribution and the total radiated power are computed for a bar undergoing zone refining in vacuum, using a one-dimensional analysis. Radiated power experiments were performed on Al, Ge, Gd, Si, Ni, Fe, Pt, Pd, V, Mo, Ta, and W using an electron-bombardment zone-refining furnace operated with space-charge limited current. The experiments agreed well with the prediction P=4π(eσk/5)12R32T52 for a very thin bar with an infinitesimal zone length.
Automatic Development of Nuclear Emulsions
Authors: Bovet C. A. , Jeannet E.
Published: February 2005

An automatic device to develop nuclear plates has been built in our Laboratory. The replacement or the dilution of the liquids and the changes and stabilization of the temperatures are controlled by an electronic program device using a transparent tape and a connection matrix. This system presents the advantage of great flexibility and ensures total reliability. Use is made of temperature development in wet conditions. Tests showed homogeneity and reproducibility within 1%.
Modified Chromatograph to Record Helium Content of Natural Gas Streams
Authors: Klingman Charles L.
Published: February 2005

The construction and procedure for use of a special-purpose chromatograph designed to analyze small amounts of helium in natural gas streams are described. The successful use of ordinary solenoid valves for column switching is unique. Automatic-zero circuitry is also mentioned. The instrument has proved to be useful in the reduction of wasted helium in the outlet gas streams from helium extraction plants.
Simple Apparatus for Comparative Density Measurements
Authors: Pelsmaekers J. , Amelinckx S.
Published: February 2005

An apparatus has been constructed for comparative density measurements in solids. The method is based on the measurement of the level of flotation of a series of specimens in a known density gradient, introduced in a column of liquid. The description of the apparatus, a discussion of the method, the measuring procedure, and the precision is given.
High Temperature Knudsen Effusion Sampling System
Authors: Panish Morton B. , Reif Liane
Published: February 2005

A simple electron beam furnace for Knudsen effusion studies is described. Temperatures as high as 2700°K have been maintained in this system at pressures of the order of 10−6 mm Hg.
Level Indicator for Permanent Installation in Liquid Helium Storage Dewar
Authors: Zimmerman J. E. , Root R. C.
Published: February 2005

A liquid helium level indicator suitable for a variety of applications is described. It consists essentially of a super-conducting inductance and coaxial condenser, along with a transistorized variable frequency oscillator and an rf voltmeter to detect the resonance. The resonant frequency is very nearly a linear function of the height of liquid helium in the coaxial condenser. The indicator probe may be mounted permanently in a narrow-necked storage or experimental Dewar, since the small-diameter lead-in wire does not interfere with the operation of transferring liquid to or from the vessel.
Sample Preparation for Transmission Electron Microscopy of Germanium
Authors: Riesz R. P. , Bjorling C. G.
Published: February 2005

Bulk samples of germanium have been reduced to sections thin enough for transmission electron microscopy. The apparatus and techniques of this virtual-electrode electrolytic etching process are described in detail with emphasis on the geometric control obtained. An example is given of an electron transmission micrograph of a 500-A-thick section.
Electronegative Gas Detector
Authors: Fox R. E. , Malmberg P. R. , Gosser R. B.
Published: February 2005

An electronegative gas detector has been developed which is capable of measuring one part of SF6 in 107 parts of air. The operation of the instrument is based on the differences between various electronegative gases in the rates of electron attachment at low electron energies, and on the differences of mobilities of the resulting negative ions in an electric field. The instrument operates at atmospheric pressure (E/p∼1 v/cm-mm Hg) and uses a modulated ultraviolet light source to produce at a photocathode pulses of photoelectrons which are attached to produce negative ions. The differences in cathode-anode transit times of the negative ions result in different phase shifts of the observed cathode current. The measured phase shifts serve to indicate the amount of electronegative gas present.
Cryostat for Irradiating at 4.2°K
Authors: Sosin A. , Neely H. H.
Published: February 2005

A cryostat for irradiating at 4.2°K is described. In this device, it is possible to irradiate samples with no intervening foils, to measure at 4.2°K, to study annealing in situ to over 100°K, and to achieve recovery beyond 350°K. A sample holder utilizing the high thermal conductivity of copper and sapphire is discussed.
Compact High-Temperature Vacuum Furnace
Authors: Austerman Stanley B.
Published: February 2005

A small furnace design is described. The furnace is heated by electrical resistance in a refractory metal tube which is surrounded by radiation shields and a water-cooled housing arranged in a compact assembly. The heater tube can be replaced readily without disassembling the furnace. The furnace can be heated to a temperature of 2200°C or higher in vacuum or nonoxidizing atmosphere.
``Verni-Ray,'' an Instrument to Measure the Uniformity of Thin Foils
Authors: Benveniste J. , Mitchell A. , Schrader C. , Zenger J.
Published: February 2005

The ``Verni-Ray,'' an instrument using an alpha source and a solid-state detector in conjunction with a pulse-height analyzer, has been designed to yield relatively fast topographical mappings of the surface density of thin foils to an accuracy of 5 μg/cm2.
Resiliently Isolated Pressure Pickup to Record Explosive Disturbances
Authors: Barden R. G.
Published: February 2005

The principle of resilient isolation has been employed in the design of a capacity-type pressure pickup in order to reduce the recording of spurious ringing effects. Continuous operation at high pressures and temperatures is possible. Use of the pickup in engine combustion studies has shown that the natural frequency of 120 kc is sufficient for all but the occasional extremely severe reaction. Frequencies recorded have extended to 430 kc.
High Current Step Generator
Authors: Weibel Erich S. , Jones Ieuan R.
Published: February 2005

A new circuit is described for the generation of current step functions of long duration, having a short rise time and yielding a large steady current. The following set of values has been achieved: rise time, 1 μsec; duration, 320 μsec; current, 5000 amp.
High Vacuum Apparatus for Studying the Luminescence of Solids
Authors: Gandy Harold W.
Published: February 2005

A high vacuum device has been designed and constructed for the investigation of luminescence from powdered or single luminophor samples when excited by several means. In the present design, many samples can be investigated at temperatures both above and below that of ambient without the necessity of breaking the vacuum of the system. The samples may be excited either by an electron beam, a beam of electromagnetic radiation, or co-excited by both.
Thermal Response of Bridgewires used in Electroexplosive Devices
Authors: Rosenthal Louis A.
Published: February 2005

The thermal equations for a bridgewire or equivalent electroexplosive device are presented. When sinusoidal current passes through such a thermally sensitive resistance, it is capable of generating a third harmonic voltage which is a measure of the ability to follow the instantaneous cycling power fluctuations. By measuring the variation of this third harmonic with frequency it is possible to determine the thermal time constant.
Continuous Rotation Scattering Chamber of New Design
Authors: Verba J. , Hawrylak R.
Published: February 2005

A scattering chamber, consisting of a fixed cylinder upon which a cylindrical sleeve slides in helical motion, has been designed and constructed. This chamber allows continuous rotation under vacuum over an angular range from −5° to +165°. With a moderate increase in dimensions it would be practical to extend the angular range to ±175°.
Measurement of the Time Dependence of Scintillation Intensity by a Delayed-Coincidence Method
Authors: Bollinger L. M. , Thomas G. E.
Published: February 2005

A new method for the measurement of the time dependence of the light intensity from scintillators is described. An important aspect of the method is the ease with which it can be applied to all modes of excitation. The results of measurements on the time dependence of the scintillators for several modes of excitation are presented.
Parameters Affecting the Performance of Large Liquid Scintillation Counters
Authors: Kerr Vernon N. , Hayes F. Newton , Anderson Ernest C.
Published: February 2005

The performance of large liquid scintillation counters as a function of counter size, photocathode area, solution transparency, and inner wall reflectivity is treated mathematically in an empirically derived equation. The use of the equation allows a degree of quantitation of the light output of the counter, and figures show the effect of varying parameters upon this light output.
Nonlinearity Correction for X-Ray Detectors
Authors: Bernstein Stanley , Canon Max
Published: February 2005

An expression has been developed whereby coincidence losses occurring in an x-ray spectrometer unit can be readily evaluated. Equivalent departures from linearity are given when the x-ray tube is operated at constant potential, full-wave, and half-wave rectified. A quantitative relationship is obtained between the apparent increase in the absorption factor (for a foil of a fixed thickness) at high counting rates and the peak operating voltage of the x-ray tube for a given element.
Properties of Thermal Mixers
Authors: Schneider M. V. , Tschopp W.
Published: February 2005

A description is given of the properties of a linear thermal detector irradiated by a modulated radiation field and operated simultaneously with a periodic bias current. The method is a generalization of the more common operation of passive thermal detectors with a constant dc bias and may be applied for barretters with a sufficient small time constant. A barretter has been developed with a time constant of approximately 14 μsec in air and 3 μsec in a hydrogen atmosphere such that modulation frequencies up to 10 kc, and for hydrogen filling up to 50 kc, are still feasible.
Resolving-Power Multiplier for Mass Spectrometers
Authors: Kendall B. R. F.
Published: February 2005

A detailed description is given of a device which is capable of increasing the effective resolving power of a mass spectrometer. An improvement in resolution by a factor of eight has been achieved. The design is based on a general analog technique for improving the resolution of analytical instruments. The device, which can be regarded as a resolving-power multiplier, consists of an electronic analog mass spectrometer connected to memory and feedback circuits. Fully resolved spectra are displayed on the screen of an oscilloscope. Information sufficient for the design, construction, adjustment, and operation of similar systems is given. Results obtained with experimental resolving-power multipliers are described.
Properties of Lead Thermal Switches at Low Temperatures
Authors: Reese William , Steyert William A.
Published: February 2005

The electrical resistivity of polycrystalline lead and the resistance of soldered contacts to the lead have been measured at 1.16 and 4.2°K in magnetic fields up to 7000 gauss. The thermal conductance of a simple lead heat switch was measured in both the normal and the superconducting states in fields up to 3000 gauss in the temperature range of 0.15–0.5°K. Assuming the best linear fit for the temperature dependence for the conductivity of the normal state, the ratio of the thermal conductance of the switch (lead plus contacts) in the 3000-gauss normal state to that of the superconducting state was found to be (T/K°)−2.3, however, the numerical factor varied strongly with magnitude and orientation of the field. As a magnetic field was slowly removed from the superconducting lead, heating corresponding to the irreversible exit of trapped flux was observed. The design of lead thermal switches is discussed.
Removal of Higher Orders in the Thermal Region from a Neutron Crystal Spectrometer
Authors: Duggal V. P. , Thaper C. L.
Published: February 2005

A Be ``single crystal'' filter was used to eliminate higher-order contamination in the thermal neutron energy range from the monochromatic beam of a single crystal neutron spectrometer employing Ge(111) as monochromator. It is shown that 6.4-cm Be crystal filter is sufficient to suppress higher order contamination to less than 0.5% in the neutron energy range ∼0.02–0.06 ev and the attenuation of the primary beam is a factor of 2–3 in this energy range.
Radiation Imaging Technique for Thermal Conductivity Measurement Above 1000°C
Authors: Glaser P. E. , Merra S. , Sepetoski W. K. , Comstock D. F. , Emslie A. G.
Published: February 2005

Imaging techniques and apparatus have been developed for measurement of thermal conductivity of small size samples at temperatures from 1000°C to the melting point of the material. Details of the method for heating the sample in an electric arc imaging furnace, measuring the temperature distribution over the sample surface with an optical pyrometer, and measuring the heat flux leaving the back of the sample with a thermopile are given. A computational procedure is described suitable for machine computer use.
High-Field Optical Magnetometer
Authors: Alers Perry B.
Published: February 2005

A direct-reading magnetometer, based on the Faraday effect and designed to measure steady magnetic fields ranging to 180 kilogauss, is described. The magneto-optic rotations are produced in a block of optical glass 1.23 cm thick and are read by a phase comparison technique. Rotations of the order of 0.1°(= 100 gauss) can be detected.
Differential Pirani Gauge for Measuring Dynamic Pressure in a Rarefied Gas
Authors: Sarafa Z. N. , Soo S. L.
Published: February 2005

A differential Pirani gauge has been developed for the measurement of the difference between the dynamic pressure and static pressure in a rarefied gas. Pressure differential to the accuracy of 0.01 μ Hg can be maintained at 1 μ Hg ambient pressure.
Vacuum Ultraviolet Monochromator
Authors: Hartman P. L.
Published: February 2005

A new focusing vacuum monochromator is described which incorporates features making available a simple and flexible double monochromator with a single control. The focusing is provided with a linear motion coupled to a nearly balanced linkage system which, coupled to the grating, satisfies the conditions of the Rowland mount. Entrance and exit slits, variable in width, are offset to either side of the plane of the Rowland circle, which is of one-meter diameter. Transparent window valves allow isolating the lamp and detector chamber from the monochromator, maintaining vacuum while making visual or near uv checks through the instrument. A filter wheel is built in to obviate some of the difficulty with scattered radiation when the instrument is used singly. Two units have been built and mounted as to allow changeover to the double system. The latter has yet to be tried but, used individually, they make nice instruments.
Photoelectric Triggering of Flash Photography of a Low Pressure Helium Cloud Chamber
Authors: Frederick David E. , Smith J. H.
Published: February 2005

A photoelectric detector system has been constructed which triggers a photographic flash lamp whenever a random, heavily ionizing event appears in a low pressure helium diffusion cloud chamber. 83–93% event detection efficiency for alpha-particle recoils of at least 1.8 MeV kinetic energy occurring in a 10-in. chamber was obtained by reflecting constant intensity light from the vapor condensation along the path of a charged particle recoil into a light pipe system arranged so that five electron multiplier phototubes each viewed about one-fifth the chamber area. The equipment and operation are described and comments are made on the detection efficiency.