bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Operation of a Beta-Ray Spectrometer
Authors: Kelly W. C. , Metzgar K. J.
Published: February 2005

Apparatus has been developed which permits the collection of data with a magnetic lens beta-ray spectrometer without requiring the attendance of the operator. The apparatus adjusts the focusing current and finds the time to accumulate a given number of counts. Forty-five sweep speeds are possible giving momentum intervals between plotted points ranging from 0.106 gauss-cm to 255 gauss-cm.
An Automatically Recording Magnetic Balance
Authors: Eisler Joseph D. , Newton George R. , Adcock Willis A.
Published: February 2005

An automatically recording magnetic balance is described which uses an electromagnetic feedback to balance the force on a sample placed in a non-uniform magnetic field. This apparatus has been used for the quantitative determination of the ferromagnetic phases present in iron hydrocarbon synthesis catalysts and for studying the reactions of gases with iron compounds. Typical data are presented.
Sensitive Recording Alternating-Current Hall Effect Apparatus
Authors: Pell E. M. , Sproull R. L.
Published: February 2005

An apparatus is described which will measure mobilities of the order of 10−2 cm2/volt sec in semiconductors. It is especially suited for measuring Hall voltage in samples of very low conductivity—as low as 10−11 ohm−1 cm−1. This sensitivity is achieved by use of a magnetic field which is automatically reversed every six seconds, an oscillator of frequency 24 cps, and an ac amplifier and phase sensitive detector with a recorder output. Such an arrangement lends itself to quick independent testing of the component units and easier interpretation of unusual experimental results. A novel feature is the use of an Amplidyne control circuit for regulation of the magnet current and reduction of the time required to reverse the magnetic field.
Methods in Electron Microscopy of Solids
Authors: Heidenreich R. D.
Published: February 2005

Methods of replicating solid surfaces for electron microscopy are reviewed and compared. Preparation of metal surfaces for electron microscopy is discussed, and the advantages of employing electron diffraction techniques in evaluating prepared surfaces are pointed out. Examples of the application of replicas include steel, precipitation in alloys, such as Alnico 5, and studies of slip in aluminum. Growth spirals on the surfaces of crystals of n-paraffins are demonstrated. The use of thin metal sections and of emission electron microscopy in studying metallic structures is discussed, and examples are given.
Rotor Temperature Measurement and Control in the Ultracentrifuge
Authors: Waugh David F. , Yphantis David A.
Published: February 2005

Moving rotor temperatures may be measured with a precision of ±0.03°C and an accuracy of 0.1°C in a vacuum centrifuge. The method does not use physical contact with the rotor but utilizes the infrared radiation from the rotor. A reference temperature is maintained in a mass of metal (reference block) placed near and shielding the base of the rotor. A copper disk, shielded also by the reference block, assumes a temperature between rotor and reference block temperatures through radiation exchange. The various temperatures and temperature differentials are determined by copper-constantan thermocouples. Heat conduction through thermojunction leads and copper disk supports, and radiation exchange between copper disk and reference block have been minimized, the copper disk maintaining a temperature 0.72 of that between reference block and rotor.

On acceleration the rotor cools, the opposite effect occurring during deceleration. Such changes are shown to be due to the adiabatic changes concomitant with the production or release of stress in the rotor. At 60,000 rpm a change of −0.9°C is observed on acceleration. On correction for kinetic heating this becomes −1.0°C. Such changes have not generally been taken into account.

By installing a chamber heating coil in addition to refrigeration, the moving rotor temperature may be kept to within ±0.05°C of a chosen temperature for indefinite periods.
Apparatus for Zeeman Effect Measurements on Microwave Spectra
Authors: Eshbach J. R. , Strandberg M. W. P.
Published: February 2005

Apparatus and experimental techniques for Zeeman-effect measurements on microwave spectra are described. The method uses a wave-guide type absorption cell and provides for either π- or σ-type observations. Molecular rotational and nuclear gyromagnetic ratios are found to be measurable to about 1 percent accuracy.

A method is presented for sign determination of these gyromagnetic ratios using circularly polarized microwaves. The microwave components used in setting up the circularly polarized waves are described.
Continuously Recording Radioactive Hemoglobinometer
Authors: Guyton Arthur C. , Ritter Robert M. , Satterfield James H.
Published: February 2005

A radioactive method, employing hemoglobin with incorporated Fe59, for continuously recording hemoglobin concentration in the blood of a living animal is described. This method records hemoglobin concentration independently of oxygenation of the blood and independently of the rate of blood flow through the apparatus. The only error that has been found in the method is statistical variation in the level of recording in accordance with the usual ``shot'' effect that is inherent in radioactive disintegrations. This statistical variation becomes less the greater the quantity of radioactive iron administered to the animal. For most purposes five microcuries per kilogram of Fe59 gives a satisfactory recording, and this quantity of radioactive iron is at least 50 times less than the maximal safe-handling dose.
The IMFL Anemoclinometer—An Instrument for the Investigation of a Fluctuating Velocity Vector
Authors: Martinot-Lagarde A. , Fauquet A. , Frenkiel F. N.
Published: February 2005

The IMFL anemoclinometer is an instrument measuring the magnitude and direction of a fluctuating fluid velocity. As a result of a measurement, three pressure differences are obtained from which the vector velocity is found. Contrary to some similar instruments, the anemoclinometer is not moved during a test and can, therefore, be easily used to obtain recordings.

Three variants of the IMFL anemoclinometer are described and their application to experimental measurements is discussed.
The Pumping Speed of a Circular Aperture in a Diaphragm Across a Circular Tube
Authors: Bureau A. J. , Laslett L. Jackson , Keller J. M.
Published: February 2005

Measurements are reported of the pumping speed, for molecular flow, of a circular hole located coaxially in a diaphragm across a circular cylindrical tube. A study is specifically made of the conductance between points not immediately adjacent to the diaphragm but separated by an axial distance L. A theoretical derivation of the conductance leads to the expression KA[1−A/A0C+34LD0AA0]−1,where A and A0 are, respectively, the areas of the aperture and tube, D0 represents the diameter of the tube, K = (RT/2πM)½, and C is a dimensionless factor which has been evaluated as a function of relative aperture size. C takes on values from C=1 for A small to C=4/3 for A=A0. The experimental data indicate that the reciprocal of the conductance per unit area of the aperture does vary in an approximately linear fashion with A/A0, in concordance with the theoretical expression in which the slow variation of the coefficient C is of little effect. It is suggested that knowledge of the pumping speed for the case considered may be of value in measurements of speed at other parts of a kinetic vacuum system.
The Measurement of Turbulent Velocity Fluctuations by the Method of Electromagnetic Induction
Authors: Grossman Lawrence M. , Charwat Andrew F.
Published: February 2005

A method is described for measuring the component velocity fluctuations in the turbulent flow of a fluid by investigating the induced potential gradients in flow transverse to a steady magnetic field. Experimental equipment and procedures for calibration and reduction of data are discussed. Measurements of the rms component velocity fluctuations in the radial and axial directions for the flow of water in a circular pipe are presented.
A Method of Pulse Integration Using the Binary Scaling Unit
Authors: Glass F. M. , Hurst G. S.
Published: February 2005

In some cases it is desirable to determine the dose resulting from certain types of ionizing radiation by weighting the pulses produced in a proportional counter by their height. An instrument that automatically integrates pulses in such a fashion is described. The pulses actuate one or more of a series of discriminators which are biased at successively higher voltages. The discriminators are connected into successive stages of two binary scaling units in such a way that the total number of counts recorded is proportional to the height of the initial pulse.
Initial Adjustment of the Mach-Zehnder Interferometer
Authors: Price E. W.
Published: February 2005

A relatively simple method is described for adjustment of a Mach-Zehnder interferometer for parallel image planes and for white light fringes. Auxiliary apparatus required consists of one plane mirror and one pinhole, which may be incorporated as permanent parts of the interferometer.
Some Properties of Plastics and the Use of Plastic Apparatus at Low Temperatures
Authors: Giauque W. F. , Geballe T. H. , Lyon D. N. , Fritz J. J.
Published: February 2005

Some properties of methyl methacrylate plastic have been investigated at low temperatures to supply design data needed for the construction of plastic apparatus. The diffusion rates for air and helium have been measured at temperatures from 260 to 300°K. The diffusion coefficient k (expressed as cm3 (N.T.P.) sec−1(cm Hg−1)) is given roughly by the following relation: log10k=[(−2.85×103)/T]−1.68 for airand log10k=[(−1.28×103)/T]−4.95 for helium.

The change in length of a 30-cm rod has been measured at 298.7°, 273.16°, 194.7°, 77.3°, and 20.4°K by comparison with quartz using a depth micrometer gage. The coefficient of expansion is tabulated as a function of temperature, increasing from 0.6×10−5 at 20°K to 8.0×10−5 at 300°K. Hysteresis and geometrical distortion accompanying cooling are shown to be very small. Complex apparatus containing many seals, including various sorts of electrical leads, has been shown to be vacuum tight when tested in liquid helium II. A method of connecting a vacuum line at room temperature and a plastic apparatus at low temperatures by means of a metal tube liner-diluted rubber cement seal is described. The adsorption of helium gas has been measured at 4.2 and 1.2°K and at pressures from 4×10−4 to 4×10−1 mm.
An Instrument for the Measurement of Cardiac Output
Authors: Powers S. R. , Rossi H. H. , Papper E. M.
Published: February 2005

A modification of the injection technique for the determination of cardiac output is presented in which the injected material is a radioactive isotope (Na24). The measurement is performed with a recording unit which consists of a counting chamber, a counter with conventional amplifier, a count rate circuit with a short RC constant (1 second), and a recording milliammeter. The instrumentation is described and a simple method is given whereby the cardiac output may be determined from the trace of the recorder.
Circular Sweep Chronograph for Single Millisecond Time Intervals
Authors: Linz Arthur
Published: February 2005

A chronograph is described which measures single time intervals up to 1000 microseconds with an accuracy of ±10 millimicroseconds. The instrument consists of a 100-kc counter chronograph with a 10-microsecond circular sweep to interpolate between scaler readings. Suitable pulse sharpening circuits and a five tube, high speed gate circuit in which the pulses defining the timing interval form the edges of the gate are also described. The possibility of extending the precision of the time measurement to ±1 millimicrosecond is indicated.
The Fundamental Limit of Sensitivity of Photometers
Authors: Wilson Richard
Published: February 2005

The general problem of the statistical fluctuations in the detection of light quanta by photocells is considered. The various methods of detection of the photoelectric current are compared and the extent to which each method approaches the limiting sensitivity is discussed. It is shown that light intensities of the order of 1 quantum per second can be detected with present apparatus.
A Recording Device for Surface Temperature Measurements
Authors: Sasaki Nobuji , Kamada Akira
Published: February 2005

By means of a small heating coil, the temperature of a thermocouple junction is made to oscillate regularly between two temperatures T1 and T2. Simultaneously the junction makes about one contact every two seconds with the surface being measured. A short-period galvanometer in the thermocouple circuit produces on a moving photographic film a serrated sine curve whose serrations vanish once for every half-oscillation at a point that corresponds to the surface temperature T3, provided T3 lies between T1 and T2. This mode of measurement minimizes disturbances due to air currents.

Alternatively, use of a thermocouple with two adjacent junctions is proposed. A simple but accurate portable thermostat for maintaining reference junctions temperatures somewhat higher than room temperature is also described.
Extension of the Carbon 14 Age Method
Authors: Kulp J. Laurence , Tryon Lansing E.
Published: February 2005

The use of a 1-in. mercury shield around the screen wall counter inside the anticoincidence ring of cosmic-ray counters makes it possible to reduce the background from 5 cpm to 2 cpm for an active counting volume 8 in. in length and 2⅝-in. in diameter. This makes it possible to extend routine C14 age measurements from about 25,000 to 30,000 years.
Wide-Range Logarithmic Radiation Meter
Authors: Bell R. E. , Graham R. L.
Published: February 2005

A logarithmic radiation meter is described using as detector, a photomultiplier and scintillation phosphor. A one-tube feedback circuit varies the voltage applied to the photomultiplier so as to hold its anode current constant for different incident radiation intensities. The voltage applied to the photomultiplier is then a nearly logarithmic measure of the radiation intensity over a range of 104. Circuit details and experimental results are given of a battery-operated portable model and an ac operated model which incorporates means for correcting the slight compression towards one end of the scale found in the portable model.
Upper Level Precession Photography and the Lorentz-Polarization Correction. Part I
Authors: Burbank Robinson D.
Published: February 2005

The precession camera can be used to record the entire reciprocal lattice out to 1 rlu using one crystal orientation. For the data so recorded to be useful it is necessary to have the Lorentz polarization correction in some convenient form. The correction has been computed at about 1300 points in reciprocal space. In the present paper (Part I) the computation is presented as a series of sections showing 1/L.p as a function of ξ and ζ at constant values of τ. In the succeeding paper (Part II, by Grenville-Wells and Abrahams) the correction is presented as a function of ξ and τ at constant values of ζ, where the sections at constant ζ have been obtained by graphical means from the sections at constant τ.
Modulation Effects in Nuclear Magnetic Resonance
Authors: Burgess James H. , Brown Richard M.
Published: February 2005

The perturbing effect of magnetic field modulation in nuclear magnetic resonance under conditions of high resolution is discussed. When the modulation frequency is greater than the resonance line width, sideband resonances separated in frequency by the modulation frequency are observed, having line shapes of either absorptive or dispersive form or a mixture of the two depending on the phasing of the lock-in detector. The form and distribution of these sidebands is satisfactorily accounted for using Bloch's equations.
Remote Opening and Sealing of Metal Tubes
Authors: Loh L. T. , Neill H. W. , Nichols M. H. , Wenzel E. A.
Published: February 2005

``One-shot'' methods of opening and sealing metal tubes are described. These methods were developed for taking high altitude atmospheric samples in metal bottles carried aloft by rockets and are performed by pyrotechnic means. The sealing is done by cold welding.
A Torsion Pendulum of Improved Design for Measuring Damping Capacity
Authors: Jensen James W.
Published: February 2005

The construction of a torsion pendulum with an improved method of alignment and minimized friction losses is described. An optical recording system is employed, using a moving film camera with film velocity variable from 1 inch per hour to 60 inches per second to record amplitude decay of freely vibrating specimens. Simplicity of operation permits semiskilled personnel to obtain 6 to 10 records per hour of high damping Mn–Cu specimens. Sample records demonstrate how variations from 0.002 percent to over 33 percent in damping capacity may be measured at torsional stresses ranging from several hundred to about 20,000 psi.
An Optical Cell for Use with Liquid Helium
Authors: Duerig William H. , Mador Irving L.
Published: February 2005

A low temperature cell is described that permits spectral absorption and emission measurements, as well as high energy irradiation of materials held at liquid helium temperatures. The liquid helium capacity of one liter is sufficient for up to 24 hours of continuous operation. Any substance whether it be solid, liquid, or gas at room temperatures can be studied. The all-metal cell is entirely portable and can be employed with a number of instruments without modification. A sylphon bellows arrangement permits vertical displacement within the cell of the samples under study.
A Photoelectric Method of Timing Freely Falling Particles
Authors: Christiansen E. B. , Barker Dee H.
Published: February 2005

A method of timing particles, falling freely in a fluid medium, is described. The method utilizes the light reflected from a particle as it passes the fields of view of two photomultiplier cells. The method has been used in a study of shape and density effects on settling rates of particulate matter in air and in water.
A Recording Stress Relaxometer
Authors: McLoughlin J. R.
Published: February 2005

A recording stress relaxometer is described. This instrument measures the lateral deflection of bowed steel strips in the load-measuring element. The deflection is measured electrically by means of a linear differential transformer coupled to a recording potentiometer through an ac electronic voltmeter. The recording stress relaxometer maintains the strain in the sample constant to 0.001 inch during complete relaxation of the stress. It can be used on materials with moduli ranging between 107 and 1011 dynes/cm2. It is also suitable for use as a simple tensile tester.
Carbon Thermometer-Heaters for Use at Low Temperatures. Effects of Particle Size and Adsorption of Hydrogen or Helium
Authors: Geballe T. H. , Lyon D. N. , Whelan J. M. , Giauque W. F.
Published: February 2005

Measurements of the electrical resistance of carbon blacks have been made for various particle sizes, from 1° to 295°K. The smaller sizes have larger resistances and larger negative temperature coefficients of resistance. The effect of magnetic fields at liquid helium temperatures is very small in all cases but increases somewhat as particle size decreases. The effect of adsorption of helium gas on the electrical resistance is very small at the temperatures of liquid hydrogen. At the temperatures of liquid helium the resistance at first increases, and then decreases below the original value, as the amount of helium absorption is increased to saturation. A similar effect is observed when hydrogen is adsorbed at liquid hydrogen temperatures. When adsorbed hydrogen or helium gases are pumped off, the effect is found to be reversible within the small limit of error.
A Bridged Tee Detector for Nuclear Magnetic Resonance
Authors: Waring Charles E. , Spencer Richard H. , Custer Robert L.
Published: February 2005

The circuit of a bridged tee network for the measurement of nuclear magnetic resonance is described. This circuit was used to measure the field strength of a large air core solenoid. The balance equations for the bridged tee network are: W2=1/L(C1C2C1+C2),R=L(C1+C2)r.The probe contained one ml of No. 20 lubricating oil with B and S No. 17 copper wire wound directly on the proton sample cell to give convenient resonance capacities and a convenient resonant impedance (500 to 25,000 ohms) near the 20-mc working frequency. The simplicity of construction, the general utility, and the adaptability to ordinary laboratory apparatus prove the circuit to be excellent for detecting nuclear magnetic resonance.
New Low-Holdup High-Efficiency Laboratory Distillation Column
Authors: Ray James D.
Published: February 2005

A new type distillation column similar to a Vigreau column is described which has the indentations perpendicular to the wall of the tube. It was found that the indentations gave optimum performance if at an angle of 90° to the axis of the column. A jig is described which facilitates making indentations in glass tubing so as to result in a high precision of indentation spacing.
Storage Tube Type Mass Spectrometer Recorder
Authors: Magari Saburo , Hotta Kokichi
Published: February 2005

By replacing a pen and ink recorder, a multiple trace oscillograph, an ordinary oscilloscope, and a vibrating reed electrometer by a storage tube-type recorder, and a scintillator type ion detector, a trace of mass peaks obtained from not only various scanning speeds but also nonrepeated phenomena can be seen on the oscilloscope for a wanted duration. The mass spectrometer with this recording assembly will be useful for industrial monitoring and for research work.
Two-Million-Volt Electrostatic Accelerator for Hypervelocity Research
Authors: Friichtenicht J. F.
Published: February 2005

A 2 000 000-v Van de Graaff positive ion accelerator has been modified to accelerate micron-sized charged particles for studies of high speed impact and for micrometeor simulation. Modification was accomplished by replacing the ion source by a particle charging and injection system. The particles are contact charged to values resulting in electric field strengths at the surface of the particle of about 2.5×109 v/m. Using iron spheres, final velocities up to 14 km/sec have been observed. Techniques for measurement of particle parameters have been developed and measurements of the focusing properties of the modified accelerator are discussed.
Sensitive Pyrometer with High Relative Reproducibility
Authors: Hehenkamp Theodor
Published: February 2005

The accuracy of measurement of temperature and particularly temperature distribution in current heated wires can be considerably improved by using semiconducting light-sensitive resistors as a pyrometer. They feature almost exponential dependence of their resistivity on temperature of the hot wire and insensitivity against changes in ambient temperature.
Multiplication and Division Using Silicon Diodes
Authors: Kahn Herbert L.
Published: February 2005

The logarithmic characteristic of a silicon diode is used to perform division, multiplication, and the extraction of square roots. Curves of results are given, showing an accuracy of better than 2% in division and about 3% in multiplication, over a range in excess of two decades. Applications of the principles to an automatic gain control circuit and a speed suppression system are presented.
Magnetostrictively Tuned Optical Maser
Authors: Bennett W. R. , Kindlmann P. J.
Published: February 2005

A helium-neon maser of the plane parallel Fabry-Perot type has been constructed in which both the angular adjustments and the plate separation may be controlled through magnetostrictively produced distortion in a rigid Nilvar mounting frame. The maser has been designed with the eventual use of negative feedback frequency stabilization in mind. Orthogonality is maintained in both angular coordinates over a range of about 15″ and the maser has been found to remain within these limits over many days of continuous operation under normal laboratory conditions. Two methods of operation are described : the first permits simultaneous and independent adjustment of both the plate angular alignment and the plate separation. The second method, though requiring less auxiliary equipment, only permits control over the two angular coordinates. Some of the mechanical design considerations and construction details are also discussed. It is felt that the present interferometer design is considerably less susceptible to mechanical instability than others reported to date.
New Bridge Circuit for Comparing Four-Terminal Resistors
Authors: Pearlstein Edgar
Published: February 2005

A dc bridge circuit for the comparison of three four-terminal resistors is described. It is an extension of the Kelvin double bridge arrangement, which, effectively, enables four-terminal resistors to be connected in series. The bridge is used for the direct measurement of the sum or difference of two low resistances in terms of a standard. The exact balance equation is quite complicated, but can be approximated with excellent accuracy by X1/A+X2/B—X3/C=0, where X1, X2, and X3 are the four-terminal low resistances, and A, B, and C are large resistances.
A 17-Inch Diameter Shock Tube for Studies in Rarefied Gasdynamics
Authors: Liepmann H. W. , Roshko Anatol , Coles Donald , Sturtevant Bradford
Published: February 2005

A shock tube for studying problems in rarefied gasdynamics is described. The motivation for operating at low density (to increase the length and time scales of certain interesting flows) and the effect of low density on the performance and design of the shock tube are discussed. In order to guarantee uniform and reproducible shock waves of moderate strength, the configuration of the tube is conventional. However, innovations are introduced (for example in the suspension, the pumping system, and the diaphragm loading and rupturing mechanism) to simplify the operation of the large facility. Care in the design of the tube as a vacuum system has resulted in a leak rate of less than 0.01 μ Hg per hour. A series of shakedown runs at relatively high pressures has shown, for example, that the reproducibility of a given shock Mach number is ±0.6%.
Absolute Microwave Refractometer
Authors: Vetter M. J. , Thompson M. C.
Published: February 2005

A microwave refractometer has been developed in which a calibrated servo-controlled tunable cavity resonator is made to follow the variations in the resonant frequency of the sampling resonator. Considerable improvement has been realized in calibration stability and simplicity of operation over earlier instruments. Accuracy of 1 ppm or better is obtained over periods of weeks.
Automatic Rotational Viscometer and High-Pressure Apparatus for the Study of the Non-Newtonian Behavior of Materials
Authors: Gabrysh A. F. , Eyring H. , Ma Shao-mu , Liang Kai
Published: February 2005

The automatic concentric-cylinder rotational viscometer described here records flow curves of shear stress versus rate of shear. It provides an automatic means of increasing and decreasing the applied rates of shear and an automatic control of the time that each shear rate is applied to the sample. In as much as flow properties may change rapidly with time and shear rates, this automatic control is important for materials which are time dependent. Presently, with proper selection of the axle and transmission gears, the cup's rotational speed can be automatically varied from zero to 1830 rpm. A switch permits the operator to select a constant shear rate and record shearing stress changes as a function of time at any point of this range. By simply replacing the gear sets, a speed of approximately 2750 rpm can be achieved. The time required for the speed to change from zero to a preset maximum, at constant acceleration, is controlled by voltage changes through a Variac which affords a continuous range from 11 to 300 sec. Shear rates of up to 4090 sec−1 are obtained. The cup and bob are aligned coaxially and mechanically fixed. Added cup-bob features for bob-flushing effectively control effects of frictional heating within the sample. Other apparatus described here provides a means to measure the consistency of greases, near the ``pseudo solidification'' point induced by high pressures. The flow curves of greases which have a critical solidifying pressure reveal characteristics suggesting stiffer consistencies at increasingly high pressures. A 6-tank ``reservoir'' of hydraulic fluid is used where the fluid under compression and the tensile stresses in the steel of the tanks are used to completely eliminate the antagonistic ``ripples'' in the pressure which are caused by the action of the pump. Pressures of 0–50 000 psi are easily and safely obtainable with this apparatus.
Vibrating Membrane Electrometer with High Conversion Gain
Authors: Dimeff John , Lane James W.
Published: February 2005

A vibrating membrane transducer is used as the sensing element for a high sensitivity electrometer. The method of operation provides an increased conversion gain by using a special circuit in which the electrometer current controls the displacement amplitude of a membrane forced to vibrate at its resonant frequency. The experimental transducer produces an alternating output voltage, is small and rugged, and has a conversion gain three orders of magnitude greater than electrometer transducers in current use.
Plastic Scintillator Response to 1–10 keV Photons
Authors: Meyerott A. J. , Fisher P. C. , Roethig D. T.
Published: February 2005

The linearity and absolute detection efficiency of several different plastic scintillator-phototube combinations have been determined for photon energies between 1 and 10 keV. Fluorescent x-ray techniques were used to provide monochromatic photon beams which were allowed to impinge on the scintillator or, alternately, on a proportional counter monitor. Indications were obtained of nonlinear photoelectron/photon response for photons having energies less than a few keV. Clearly nonlinear behavior was obtained for conversion efficiencies expressed as photoelectrons/keV of photon energy absorbed.
Nanosecond Pulsing for Van de Graaff Accelerators
Authors: Moak C. D. , Good W. M. , King R. F. , Johnson J. W. , Banta H. E. , Judish J. , duPreez W. H.
Published: February 2005

A pulsed ion source capable of delivering 10-mA proton bursts with durations of approximately 1 nsec is described. Critical design constraints are discussed and used to illustrate the general procedure for meeting various experimental requirements. The system consists of a Duo-Plasmatron ion source, a lens-chopper combination, and a klystron buncher which uses the entire accelerator as a drift path to produce bunched ion bursts at the target. The equipment has been fitted into the terminal of the ORNL 3-MV Van de Graaff accelerator. Since no accessory bunching magnets are used, ion bursts can be delivered to many different target stations. An external diverter system is used to vary the repetition rate from 106 sec−1 down to 3×104 sec−1.
Monitoring the Magnetostriction of Thin Films During Vacuum Deposition
Authors: Tolman C. H. , Oberg P. E. , Rubens S. M.
Published: February 2005

A device has been constructed which monitors the magnetostriction of magnetic films prepared by vacuum deposition techniques. The substrate upon which the film is deposited is stressed mechanically during deposition, thereby applying alternate tensile and compressive states of strain to the depositing film. A localized alternating magnetic field is employed as an anisotropy orienting field and is used also to switch the state of magnetization of the film. The substrate is strained at a low repetition rate, and the depositing film is switched magnetically at a high rate. The periodic stress application to the film and the associated strain-induced anisotropy modulate the flux reversal output; the resulting signal is detected by a pickup coil. The phase and amplitude of the modulated signal are a function of the magnetostriction and the corresponding film composition. The monitor is mounted in the vapor path so that a representative film element is deposited on the stressed substrate. Zero magnetostriction of the sample, as determined by the monitor, has been found to correspond to zero magnetostriction of arrays of film elements deposited at the same time. The monitor makes possible automatic control of magnetostriction through control of source composition.
Preparation of CrBr3 Samples
Authors: Dillon J. F. , Teague M.
Published: February 2005

It has been difficult to shape the various samples needed for ferromagnetic resonance, optical, and microwave optical experiments on chromium tribromide. These difficulties have been largely overcome by a technique in which the crystals, rigidly immobilized, are sheared over an edge while immersed in liquid nitrogen.
Precise Ferromagnetic Resonance Magnetometers for Differential Measurements in Fields Characterized by Large Gradients
Authors: Hempstead C. F. , Sibilia J. T. , Kostelnick J. J.
Published: February 2005

Design considerations, construction details, and measured performance of two magnetometer systems utilizing microwave ferromagnetic resonance in small single-crystal spheres of stoichiometric yttrium iron garnet (YIG) are presented. One system is for general use at ambient temperatures, while the second is designed for high precision measurements at liquid helium temperatures. These instruments are capable of measuring magnetic field strength to a precision of approximately one part in 104 even when the field is characterized by gradients as large as 1000 G/in. Since the YIG spheres employed are only 0.015 in. in diameter, these magnetometers come close to being ideal point probes.
Interferometer for Electrochemical Investigations
Authors: O'Brien R. N.
Published: February 2005

A description and the details of construction of an interferometer producing Fizeau type fringes is given. The instrument is suitable for observing concentration changes in electrolyte at a working electrode. Interferograms are presented which were taken with still and motion picture cameras.
Apparatus for the Determination of Diffusion Coefficients in Fused Salts (NaNO3) at High Pressure
Authors: Tricklebank S. B. , Nanis L. , Bockris J. O'M.
Published: February 2005

An apparatus for the determination of diffusion coefficients in fused salts at pressures up to 2 kbar, together with the necessary experimental techniques, is described. Values of the self-diffusion coefficients of 22Na in NaNO3 at 350°C are (2.10±0.09)×10−5 cm2 sec−1 at 1 bar, (1.90±0.05)×10−5 cm2 sec−1 at 400 bar, and (1.77±0.05)×10−5 cm2 sec−1 at 800 bar. The activation volume for the self-diffusion of 22Na in NaNO3 is 10.7±1.4 cm3 mole−1.
Theory of Boil-Off Calorimetry
Authors: Jacobs Robert B.
Published: February 2005

The usual formulation used to compute heat flow in boil-off calorimetry ignores the sensible heating of the vapor in the calorimeter. A formulation which includes this heating is derived; a single temperature measurement (of the vapor leaving the calorimeter) permits this effect to be computed. As the required temperature measurement has not been given for reported experiments, the vapor heating effect cannot be computed directly for those cases. Therefore, an expression for the computation of this temperature is derived theoretically and applied to reported experiments. It is shown that, even in optimally designed calorimeters, the sensible heating of the vapor can be appreciable, and that the use of the usual formulation can introduce significant error in the computed heat flow. Finally, it is indicated how this error can explain, at least partially, the Heat Paradox which has been observed in insulation and Dewar evaluation tests.
Versatile Triangular Sweep Generator
Authors: Weir W. D. , Enke C. G.
Published: February 2005

A versatile, all-electronic cyclic linear-sweep generator is described. This device produces a symmetric or asymmetric triangular waveform of high quality with sweep rates continuously variable from 5 mV/sec to 2000 V/sec, independent of amplitude; positive and negative sweep limits are independently variable from 0–3 V relative to a reference level which is itself variable with respect to signal ground. Provision is made for controlling the output voltage at a preset level prior to initiation of the sweep, and the sense of the initial sweep may be selected. The cyclic sweep may be halted at either limit, either mechanically or electronically. An auxiliary output provides a square wave with peak-to-peak amplitude equal to the peak-to-peak amplitude of the triangular waveform, based at signal ground, and with period regulated by the sweep rate controls.
Automatic Toepler Pump with Built-In Gas Quantity Meter
Authors: Gilissen R. , De Meester P. J. , Flipot A. J.
Published: February 2005

A description is given of an automatic Toepler pump for collection and measurement of gas quantities. The pump, the construction of which is simple and inexpensive, has proven to be reliable and easy to manipulate, while the measuring sensitivity relative to other systems is increased. For collecting and measuring of the gas only one mercury reservoir is required; many difficulties inherent to other types are thus avoided. The simultaneous measurement of volume and pressure, as well as the calculation of the amount of gas, is given.
Efficiency of a 85Rb Filter in Optical Pumping of 87Rb
Authors: Davidovits P. , Knable N.
Published: February 2005

The population of the F=2 sublevels of the 2S½ state of 87Rb may be enhanced at the expense of the F=1 levels by illuminating the 87Rb with 87Rb resonance radiation which is first passed through a 85Rb cell, thus removing the component of light which stimulates transitions from the F=2 levels. The effectiveness of the 85Rb cell in transmitting the hyperfine line which produces population inversion while rejecting the depumping lines has been measured.
Transistor Circuit for Adapting a Multichannel Analyzer to Neurophysiological Work
Authors: Sittler O. Dayle , Tsao Peter
Published: February 2005

A simple transistor circuit is described to adapt a commercial multichannel pulse-height analyzer, without altering its circuits, for neurophysiological studies. With this circuit, nerve impulses, or tape-recorded nerve impulses, can be sorted out according to their sizes by a multichannel analyzer.
High Temperature Differential Resistance Bridge Calorimeter
Authors: Engel T. K. , Jordan K. C. , Otto G. W. , Scott D. M.
Published: February 2005

The construction and transient operation of a differential resistance-bridge calorimeter which has successfully operated up to 700°C are described. Heat capacity and latent heat of transformation are measured in the calorimeter by absolute methods. The heat capacity of nickel and the heats of fusion of bismuth and cadmium are presented and agree well with previously published data.
THE DIMENSIONS OF LOW FREQUENCY QUARTZ OSCILLATORS
Authors: Hitchcock R. C.
Published: February 2005

The frequencies of the Curie cut quartz oscillator plates from 60 to 320 kc/sec are shown to be discontinuous functions of the dimensions.

The K, ``meters per millimeter,'' is shown to vary from 90 to 145.

It is suggested that the use of relative power measurements will insure a single frequency crystal operating at minimum damping.
A CAPILLARY MANOMETER SYSTEM FOR PREPARING MIXTURES OF GASES WITH A VERY HIGH RATIO BETWEEN COMPONENTS
Authors: Adams Elliot Q. , Charpentier E. R. H.
Published: February 2005

A capillary manometer system for the preparation of gas mixtures with a ratio of components of 1,000,000 or more is described. It comprises three substantially identical pairs of manometers, with appropriate pressure regulators. Conservation of desk space is secured by placing the capillaries in a vertical position.
A METHOD FOR DETERMINING CRITICAL CONSTANTS AND ITS APPLICATION TO DIPHENYL (C6H5·C6H5)
Authors: Cork J. M.
Published: February 2005

A relatively simple method, leading to an evaluation of the critical constants characteristic of a substance as well as the liquid and saturated vapor densities with varying temperatures is described. The method is employed in the case of diphenyl (C6H5·C6H5) giving values of the critical pressure, temperature and density, of 31,400 mm Hg., 528°C and .343 gms/cm3 respectively.
A VACUUM-TUBE VOLTAGE REGULATOR FOR ALTERNATORS
Authors: Verman Lal C. , Richards L. A.
Published: February 2005

A vacuum tube voltage regulator for ac power units is described, with two novel features. First, saturation current from the filament of a thermionic tube is used as the control element; and second, a feed-back stablization system is employed which makes it possible to obtain stable regulated voltage conditions with high sensitivity. It gives voltage regulation of 1.5% at full load unity power factor as compared to 45% with fixed excitation. The regulator also functions as an overload circuit breaker. Results of tests conducted under steady, transient, and short circuit conditions are given. Finally some further improvements are suggested.
RADIATION THERMOPILE DESIGN
Authors: Firestone F. A.
Published: February 2005

Previous formulas for the design of radiation thermopiles to be used with a Thomson galvanometer are summarized and new formulas for the design of thermopiles for use with D'Arsonval galvanometers are developed.

A design of thermopile is described in which the cold junctions almost entirely surround the hot junctions thus reducing drifts. In this design, each element is constructed as a separate unit and when all are completed they are simply stacked up and fastened together with one screw, thereby minimizing the danger of breakage. The whole thermopile fits into a cubical evacuated case only 10 mm on an edge and, being so small, it can be used directly in front of an elliptical mirror which forms a small hot image, in some cases increasing the deflection due to a given radiation by a factor of 3. By a slight modification of the spectrometer, a thermopile having adjustable compensation can be utilized which, theoretically, will give almost no drifts due to changes in temperature of the optical parts of the spectrometer or of the surroundings.

A convenient technique of construction is described.
EXACT COMPENSATION FOR THE EFFECT OF A AND B BATTERY CHANGES WHEN USING THE VACUUM TUBE AS A DC AMPLIFIER
Authors: Dearle Raymond C. , Matheson Lorne A.
Published: February 2005

With the recent advances in photoelectric cell technique a number of experimenters have endeavored to devise a method of using vacuum tube amplification for the measurement of weak currents and small emf's. Among these may be mentioned Wynn-Williams1 and Eglin2 who have developed a balanced bridge amplifier of high sensitivity; also Razek and Mulder3 4 who have devised two single-tube circuits. The single tube circuit does not possess the sensitivity of the balanced bridge circuit but has certain advantages in the way of simplicity of operation and control. Under proper conditions it may be used in a multi-stage amplifier, using the principle of resistance-coupling.
STABILIZED OSCILLOSCOPE WITH AMPLIFIED STABILIZATION
Authors: Bedell Frederick , Kuhn Jackson G.
Published: February 2005

One stage of amplification included in the stabilizing circuit of the Bedell-Reich oscilloscope, which comprises a cathode-ray tube with linear time-axis for observation of periodically varying quantities, extends the frequency range of the instrument and permits stabilization without disturbance to the circuit under test. Although not primarily intended for use beyond the audio range, the instrument has in this way been stabilized above 100,000 cycles. Curves are given showing the use of the instrument for the study of non-electrical quantities (as sound and light) as well as of electrical quantities (as in the study of modulation and rectification).
AN X-RAY CAMERA FOR POWDER DIAGRAMS AT ANY TEMPERATURE
Authors: Taylor Nelson W.
Published: February 2005

A cylindrical x-ray camera of about 57 mm diameter has been designed which may be used for powder photographs (Hull-Debye-Scherrer method) up to 1000°C or down to liquid air temperatures. Convenience in use is obtained by placing the film on the outside rather than the inside. Using a Siegbahn type x-ray tube with Cu or Fe anticathode and 15 to 20 milliamperes tubes current, good diagrams may be obtained in ten minutes to two hours depending on the substance being investigated. The method permits the study of those crystal modifications which are stable at high or low temperatures but unstable at room temperature. Lattice constants may be determined to an accuracy of 0.2 percent.
A RECORDING DUST CONCENTRATION METER AND ITS APPLICATION TO THE BLAST FURNACE
Authors: Simon A. W. , Kron L. C. , Watson C. H. , Raymond H.
Published: February 2005

The law connecting the transmission of light and the concentration of a suspended material in a gas is deduced. It is pointed out that the Ringelmann method of measuring smoke density, as well as the so-called recording ``smoke densimeters'' do not measure the true concentration of the suspended material. The amount of light transmitted is shown to be an exponential function of the concentration. A recording instantaneous dust concentration meter making use of a thermopile as the light-sensitive element is described. Charts obtained on blast furnace gas are given.
VOLTAGE-REGULATING AUTO-TRANSFORMER
Authors: Bedell Frederick , Kuhn Jackson
Published: February 2005

A transformer is compounded by connecting some or all of the primary windings differentially in series with the secondary so that load voltage is constant through a wide range irrespective of changes in primary line voltage.
A PENTA COMPARISON PRISM FOR SPECTROSCOPES
Authors: Bryden Samuel D.
Published: February 2005

A penta prism placed before the slit of a spectroscope eliminates the objections to this method of simultaneously observing the comparison and unknown spectra.

The penta comparison prism is preferably mounted on a vertical slide before the slit instead of on the usual hinged bracket.
THE MERCURY ARC AS AN ACTINIC STROBOSCOPIC LIGHT SOURCE
Authors: Edgerton Harold E. , Germeshausen Kenneth J.
Published: February 2005

Stroboscopic light sources capable of producing sufficient actinic light to take a photograph with a single flash are described in this paper. The duration of the main flash is of the order of 10−5 seconds, depending upon the circuit arrangement and the temperature of the light-pulse tube. The light has been very useful for obtaining stroboscopic motion pictures of the hunting of synchronous motors, the surges of gasoline-engine valve springs, vibrations of mechanisms, etc. Also, motion pictures have been taken upon continuously-moving film at a rate of 480 pictures a second with a camera which has neither a shutter nor an intermittent motion. (Recently the speed has been increased to 4200 pictures per second.) The fundamental idea is to discharge considerable electrical energy into a mercury-arc tube by means of an electrical transient, which is usually obtained from a condenser discharge. The gaseous discharge is capable of giving a flash of very short duration of high instantaneous intensity. Several methods of actuating the flash are described.
DESIGN OF PRESSURE IONIZATION CHAMBERS
Authors: Williams John H.
Published: February 2005

Two ionization chambers are described which are suitable for the measurement of hard x-rays and γ-rays. One of them is designed to be used at 30 atmospheres and the other from 60 to 100 atmospheres. The method of assembling and testing the chambers is described.