bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Speed Turbine-Driven Rotating Mirrors: Notes on Design, Construction, and Performance
Authors: Brixner Berlyn
Published: February 2005

Described in detail are the main features of design and fabrication which contribute to the production of the reliable long-lived drives of several styles of high-speed turbine-driven rotating mirrors. The subjects analyzed are steel mirror fabrication, which includes heat treatment; mirror balancing and surface finishing techniques; important bearing design features; construction of the turbine; and performance of selected models.
Fast Neutron Time-of-Flight Spectrometer
Authors: Neilson G. C. , Dawson W. K. , Johnson F. A.
Published: February 2005

A versatile neutron time-of-flight spectrometer suitable for use in the millimicrosecond region is described. Either the rf beam deflection method or the gamma coincidence method is used to provide the zero time indication. Details of these methods, along with spectra obtained for some (d,n) reactions, are given. The two systems are compatible and make use of the same simple time-to-pulse-height converter. The dependence of the decay time of a liquid scintillator on the specific ionization of the detected particle has been used to make the neutron detector insensitive to gamma-rays.
Techniques for Handling Metallic Whiskers
Authors: Fontanella Ethel L. , DeBlois R. W.
Published: February 2005

Detailed descriptive methods are presented for the selection, removal, and preparation for experimental use of both iron and copper whiskers. Techniques which minimize damage are emphasized.
Liquid Hydrogen Targets of Adhesive-Bonded Mylar Plastic
Authors: Hickman Roy S. , Kenney Robert W. , Mathewson Robert C. , Perkins Richard A.
Published: February 2005

Vacuum-tight cryogenic containers can easily be made from Mylar plastic sheet and metal, or from Mylar alone, for use in vacuum-insulated liquid hydrogen target assemblies. Mylar is bonded very firmly to metals or to itself by an Epon-Versamid mixture or by Armstrong A-4. These adhesives maintain strong vacuum-tight joints throughout the temperature range from 300 to 4°K. Mylar sheet has also proved satisfactory as vacuum-window material for beam ports. Fabrication of these structures is described in detail, and explosion safety measures are mentioned. Some examples are given of structures which have been used or tested, with data on the ultimate strength of each expressed as the internal pressure required to rupture it. Helium leak testing must be carried out at 77°K or below, because Mylar is relatively impermeable to helium only at low temperatures. The primary electron beams commonly obtained from electron linear accelerators are sufficiently intense to cause Mylar beam windows to fail under vacuum loading, probably because of radiation damage. However, the authors know of no case of radiation damage to Mylar sustained in exposure to secondary beams from high-energy accelerators.
Solid-State, High-Intensity Monochromatic Light Sources
Authors: Wieder Irwin
Published: February 2005

The extension of optical pumping techniques to solids has been hampered by the lack of suitable light sources. The utilization of photoluminescent effects is proposed as a method for obtaining light sources applicable to optical pumping experiments in some solids, and a ruby source which emits 0.1 w of light at 6934 A and 6920 A is described.
Equipment for ''Watching'' Propagating Stress Waves
Authors: Bfcker Herbert
Published: February 2005

The propagation of stress waves generated by impact may be ``watched'' photoelastically with the use of the simple experimental arrangement described herein. In addition to providing control over the observed progress of the wave, the apparatus makes possible photography of the wave with conventional cameras. The equipment not only is a scientific instrument, but also provides a useful demonstration for instructional purposes.
Transistorized Distributed Amplifier
Authors: McMullen Charles W.
Published: February 2005

Some analytical and experimental results are given for a transistorized distributed amplifier using the common emitter configuration. The characteristic impedances of the base and collector transmission lines are both 43.4Ω. A 4-section amplifier stage yields a mid-frequency gain of 5.1 db and an upper half-power frequency of 290 Mc. The low-frequency response is reasonably constant down to 10 cps.
Wagner-Earth and Other Null Instrument Capacity Neutralizing Circuits
Authors: Wolff Hanns H.
Published: February 2005

A simple but exact derivation of the conditions for ground potential on the null instrument input in nongrounded ac bridges is given. It is shown that not only the ``Wagner-earth,'' but also other networks and circuits between the power source and the ac bridge can easily fulfill these conditions. Advantages of such other networks and circuits are discussed. General considerations for optimum bridge details for measurements of highest obtainable accuracy are given. Practical supply circuits for ac bridges are described. Furthermore, it is shown how the adjustment of the earth capacity neutralizing system can be made in a minimum amount of time.
Magnetic Susceptibility Balance Using a Null Technique
Authors: Singer J. R.
Published: February 2005

A very sensitive magnetic susceptibility balance is described with the characteristic of providing a null reading over all field strengths whenever the sample is purely paramagnetic. The balance is used mainly for single crystal measurements of susceptibility at high and low temperatures. Any ferromagnetic impurity shows as a null deviation as the magnetic field strength is altered. The degree of unbalance obtained is readily used to subtract out the ferromagnetic impurity from the paramagnetic or antiferromagnetic components of the susceptibility.
Efficient Precision Current Regulator for High-Power Magnets
Authors: Garwin R. L. , Hutchinson D. , Penman S. , Shapiro G.
Published: February 2005

Using paralleled power transistors driven by a transistor and a chopper amplifier, supplemented by a coarse feedback loop to the generator field, we have regulated to <0.001% the field of an electromagnet requiring 80 amp at 200 v. The dissipation in the regulator is 250 w. The magnet current may be varied from zero to maximum by setting the reference potentiometer to the appropriate voltage, and sufficient protective measures are incorporated so that the circuit is not injured by misuse. The circuit is usable to perhaps a megawatt.
Construction and Characteristics of Teflon-Covered Polarographic Electrode for Intravascular Oxygen Determination
Authors: Krog John , Johansen Kjell
Published: February 2005

A Teflon-covered, combined silver silver-chloride platinum polarographic electrode mounted in a heart catheter is described. The advantage and characteristics of this particular construction are discussed.
High-Current Ion Source
Authors: Meyerand Russell G. , Brown Sanborn C.
Published: February 2005

A high-current ion source is described that is of simple design and construction. It is capable of producing an ion beam of ½ amp. The energy spread of the ions is large.
Refractory-Metal Thermocouples Containing Rhenium
Authors: Sims Chester T. , Gaines Gordon B. , Jaffee Robert I.
Published: February 2005

The thermoelectric force developed by the following junctions up to 2200°C has been measured: Re vs W, Re vs Mo, Re vs W-30Re, and Re vs Mo-50Re. The thermoelectric force for W vs W-30Re and Mo vs Mo-50Re has been calculated. The Re vs W junction develops about 15 mv at 1000°C and may be usable up to 2600°C. Re vs Mo develops about 17 mv at 1000°C; the thermoelectric power is low above 1600°C. The outputs of Re vs W-30Re and Re vs Mo-50Re couples are low and change signs at about 1200 and 1800°C, respectively. The calculated outputs of W vs W-30Re and Mo vs Mo-50Re are high; the W vs W-30Re output is nearly linear over a wide range in temperature, and the thermocouple should be useful to about 2600°C. All of these couples must be used in vacuum or in neutral or reducing atmospheres.
Adiabatic Calorimeter for Metals in the Range 50 to 1000°C
Authors: Stansbury E. E. , McElroy D. L. , Picklesimer M. L. , Elder G. E. , Pawel R. E.
Published: February 2005

An adiabatic calorimeter designed primarily for measurements on bulk metal samples is described. Details of the calorimeter design and operation are given. Experimental problems associated with precise high-temperature measurements are emphasized. Measurements from room temperature to 1000°C have been made and include determinations of specific heats, heats of transformation, and heats of solution. Representative data on pure nickel are shown with reported accuracy of ±0.5%.
Flow through Capillary Tubing with Eccentric Annular Sections
Authors: Bachman C. H. , Hottenrott H. G.
Published: February 2005

Gas flow through capillaries obstructed by wire inserts was investigated for ratios of core to capillary diameters (B/A's) of 0.08 to 0.9. For a given core-capillary combination, laminar and turbulent as well as an intermediate region are well defined. Deviations from Poiseuille flow for the range of B/A's are presented in a working curve, which will give flow rates for laminar flow correct to from 5 to 10%.

The pressure drop vs flow curves for the intermediate and turbulent flow regions are reasonably reproducible. The use of the cored capillary for very small leak rates looks especially attractive because, with large B/A's such that the maximum crescent clearance is less than 0.25 mm, the onset of turbulence is postponed to much higher pressure drops.
Use of Neon in Cryogenics
Authors: Dillon J. F. , Jaccarino V.
Published: February 2005

It is shown that the cost of using liquid neon as a coolant in the temperature range 20 to 30°K is not prohibitive. A simple method of condensing the gas is described, and an example of an experiment performed with liquid neon is given.
Vanguard I IGY Satellite (1958 Beta)
Authors: Easton R. L. , Votaw M. J.
Published: February 2005

The instrumentation used, the measurements obtained, and the uses of the Vanguard I satellite are described. This satellite contains two transmitters, one powered by batteries for about three weeks and one powered by solar cells (still operating). From the transmitted frequencies temperature information and rotation rates are obtained. The transmitted signals are also used to determine the satellite orbit. An approximate free orbital lifetime of 200 years is predicted.
Longitudinal Space Charge Effects in Particle Accelerators
Authors: Nielsen C. E. , Sessler A. M.
Published: February 2005

The modification of the single particle theory of particles subject to radio-frequency acceleration caused by electrostatic repulsion between particles is calculated. With the aid of an appropriate Hamiltonian the Boltzmann equation is reduced to a one-dimensional integral equation for the case of a uniform particle density in a limited region of phase space. For a range of parameters that includes most accelerators, this equation is approximated by an algebraic equation, and an analytic solution valid below the transition energy is obtained. Computations are given of the ``longitudinal space charge limit,'' as well as the effect of space charge on the azimuthal bunching of a beam by an accelerating cavity. Numerical examples of these two effects are given.
Single Crystal CdS as Soft X-Ray Detector
Authors: Henry Brother Brian , Cole H.
Published: February 2005

Photoconductivity in certain selected single crystals of CdS, by comparison with conventional Geiger-type counters, affords a fairly sensitive and inexpensive detector for simple x-ray spectrometry.
Transistorized Nuclear Resonance Magnetic Field Probe
Authors: Singer J. R. , Johnson S. D.
Published: February 2005

A transistorized marginal oscillator type of nuclear resonance probe is described. The main advantages of transistor use are in obtaining portability, eliminating external power sources, and low cost. The sensitivity and stability equaled that of a standard transition vacuum tube circuit when compared using protons in water.
Solution of Polynomials by Use of an Electromechanical Synthesizer
Authors: Schwetman Herbert D. , Burmeister Charles
Published: February 2005

The roots of polynomials of high degree are obtained with a stated accuracy in a time of ten to thirty minutes by use of an electromechanical harmonic synthesizer. The machine consists of sine-cosine potentiometers which are driven by meshed gears to produce sinusoidal potentials of frequency f, 2f, 3f, …. The algebraic polynomial is transformed into a trigonometric polynomial in which the terms are expressed in multiple angle form and applied to the machine. As the fundamental gear is rotated through 180°, the potentials are summed in a recording high impedance voltmeter in such a manner that when the curve f(θ)=0 passes through zero values, the angles are read from a large dial and the roots x=r cos θ are obtained.

Examples of the solutions are given, and the results of some twenty-five solutions reported to show an average accuracy of 1.19% and an average time of solution of 16 minutes. For higher accuracy a time of about 7 minutes is required for each additional substitution, until an accuracy of 0.30% may be obtained. Multiple or repeated roots are obtained by use of the factor theorem and repeated differentiation.
Modification of a Cone-Plate Viscometer for Direct Recording of Flow Curves
Authors: Bauer Walter H. , Finkelstein Alfred P. , Larom Charles A. , Wiberley Stephen E.
Published: February 2005

Using a concentric-cylinder rotational viscometer, Weltmann has shown that automatic recording of flow curves in accordance with a predetermined program is important in the study of materials whose flow properties are shear-dependent and time-dependent. When the flow of such materials as greases was studied using the Ferranti-Shirley cone-plate viscometer, advantages of small sample size, ease of loading with minimum deformation, and uniform shear rate across the sample were apparent. However, time-dependent properties of the grease could not be adequately described from data obtained in manual operation of the cone-plate viscometer.

An automatic control device for shear rate acceleration of the cone-plate viscometer has been designed so that flow curves can be obtained automatically using an X-Y recorder. Flow curves of typical greases and other materials exhibiting non-Newtonian and time-dependent properties have been successfully obtained using this automatic control device. The cone-plate viscometer as modified has distinct advantages for the study of non-Newtonian and time-dependent materials.
Greater Gain Band Width in Trigger Circuits
Authors: Brown Melvin
Published: February 2005

The relation between switching speed of a trigger circuit and the gain band width (GBW) of an amplifier is discussed. A special series connection of two tubes—referred to as a dynamic plate-load amplifier (DPL)—is then presented and analyzed. A dc analysis shows that the DPL investigated has 18% of the output impedance, and 2.75 times the dc gain of a conventional amplifier. A transient analysis shows that the DPL may have 3 times the advantage in GBW over a conventional amplifier. This GBW improvement recommends its utilization in fast trigger circuits.
Self-Excited 150-Kilovolt Resonant Cavity for Operation at 87 Megacycles
Authors: Jackson H. E. , Martin R. L. , Waggoner J.
Published: February 2005

A high-voltage, fixed frequency re-entrant cavity of moderate power requirements designed for use in the Cornell 1.5-Bev synchrotron is described. Design considerations and details of the cavity gap structure are presented. The problem of multipactoring is described. Advantages of coaxial gap construction using an internal insulator are given. In particular a dc bias to prevent multipactoring can easily be applied. A simplified analysis of the operation of the cavity in terms of equivalent circuits is also given.
Absorption Measurements and Irradiations in the Cary and Beckman Spectrophotometers, at Low and High Temperatures
Authors: Hirshberg Y. , Fischer E.
Published: February 2005

Attachments to the Cary recording spectrophotometer and the Beckman D.U. spectrophotometer are described, which make it possible to use all-quartz optical cells both for the measurement of absorption spectra and for irraditions of liquid or solid samples, in the temperature range between minus 170° and plus 200°. Gaseous heating and cooling agents are used throughout.
Ion Optics for the V-Type Surface Ionization Filament Used in Mass Spectrometry
Authors: Dietz Leonard A.
Published: February 2005

A field-plotting and ray-tracing technique based on electron-optical methods is developed for first-order ion optics of slit lenses and is applied to a Nier-type thick lens. A resistance paper analog gives the distribution of electrostatic potential. Maxwellian velocities of ions emitted from the filament and lens thickness affect ion trajectories, which are calculated to a few percent accuracy by a simple approximation technique. Paraxial ray paths are shown and the ion-focusing action of the single filament is described. Optimum detectability, 100 counts of the smallest isotope, is 5×10−15 g for uranium and 2×10−15 g for plutonium. Ionization at moderate temperatures improves transmission and avoids background impurities which appear at temperatures above 2000°C. Independent electrostatic focusing in the z direction improves transmission through the analyzer.
Lining-Up Nuclear Emulsion Stacks
Authors: Taylor S. , Harris G. , Orear J. , Baumel P. , Lee J.
Published: February 2005

A method has been devised for introducing reference marks in stacks of nuclear emulsion pellicles by the use of single-strand threads. The reference marks are then used for accurate lining-up of the stack after development. Details of the thread insertion and lining-up processes are described.
Solid Angle Calculation for a Circular Disk
Authors: Paxton F.
Published: February 2005

A general expression for the solid angle subtended by a circular disk is derived in terms of complete elliptic integrals of the first and third kind. The elliptic integral of the third kind is reduced in terms of Heuman's lambda function, which has been tabulated. By transformation of the double integral Ω = ∫ ∫ sinθdθdβ into a single line integral, the solid angle can be conveniently determined. Since the solution involves only tabulated functions, it is well suited for desk calculation.
Vacuum-Type Gas-Flow Calibrator
Authors: Strauss William A. , Edse Rudolph
Published: February 2005

A vacuum-type gas-flow calibrator was designed and constructed for making accurate calibrations of flowmeters needed for the investigation of high-pressure flames. This calibrator operates by automatically measuring the time required to pressurize a known volume from a near vacuum to 1 atmosphere pressure. The gas volume flow rate is obtained by dividing the calibration volume by the pressurization time and applying corrections from PVT data. This apparatus has been successfully used to calibrate flowmeters for use with hydrogen, oxygen, nitrogen, air, methane, nitric oxide, carbon monoxide, and various homogeneous nonexplosive gas mixtures.
Strong Focusing Ion Source for Mass Spectrometers
Authors: Giese Clayton F.
Published: February 2005

An ion source has been developed, using strong-focus principles, with a view toward obtaining high transmission through sector-shaped magnetic fields. The lens described, starting with an ion beam 0.375 in. square, produces a line focus 0.60 in. long and 0.025 in. wide, with a half-angle of divergence beyond the crossover of 0.034 rad.
Synthetic Mica as a Monochromator for Long Wavelength Neutrons
Authors: Goland A. N. , Sondericker J. H. , Antal J. J.
Published: February 2005

A comparison has been made between natural muscovite mica and synthetic fluor-phlogopite mica with regard to their usefulness as neutron monochromators. It has been found that a synthetic mica monochromator reflects a neutron beam which is from 2 to 6 times more intense than that from a natural mica monochromator, while requiring no appreciable sacrifice in resolution. The interplanar spacing of the synthetic material was found to be 9.963 A, which is slightly larger than that of the natural mineral.
Wide rf Level rf Unit for an NMR Spectrometer
Authors: Kapur K. N. , McGrath J. W.
Published: February 2005

An improved rf unit for a nuclear magnetic resonance spectrometer is described. It uses a crystal oscillator for frequency stability and positive feedback from a cathode follower to increase the effective Q of the sample rf coil. This unit provides an rf level range of 20 μv to 60 mv with little limitation on extending the range. This allows saturation studies. The circuit is well suited to direct relaxation time measurements.
Precision Integrator for Ion Beams
Authors: Lynch Frank J. , Langsdorf Alexander
Published: February 2005

The integrator consists of a circuit which operates relays to turn off data-storage devices, timers, etc., when the charge conducted by an ion beam reaches a specified quantity. A vibrating-reed electrometer (without feedback) senses when the potential drop across a capacitor into which the beam current flows becomes equal to the potential of several standard cells in series. Errors in sensing the potential are less than 0.001%, and the over-all time delay of the relay operation is about 15 msec. The major sources of error are associated with soakage and changes in capacitance with temperature, less than 0.05% and about −0.01% per °C, respectively. It should be feasible to attain a considerable reduction in all the errors of integration caused by these known sources of error.
Ten-Mc Pulse-Amplitude Discriminator
Authors: Mey Jacques
Published: February 2005

A pulse-height discriminator has been developed which is capable of operating at repetition rates up to 10 Mc. It accepts positive input pulses with a threshold adjustable from 1 to 11 v. The output signal is of constant shape and amplitude. The circuit is described and test results are given.
The Video Differential Planimeter
Authors: Tobin Michael
Published: February 2005

The video differential planimeter is an instrument which measures variations in the projected area of any remote object with the aid of a flying spot scanner or television camera system. The composite video signal, caused by the scanning of the object and its contrasting background, is shaped to yield a sequence of constant amplitude rectangular pulses that are negative going during a scan of the object, and positive going at all other times. The average of this sequence of pulses is obtained from a point on a bleeder resistance returned to the negative supply, and is fed into an integrator. The net integration voltage is read off and the integrator is returned to zero at the end of each field. If the object's projected area remains fixed, the sum of the positive and negative pulse areas entering the integrator will be constant. Hence, the change in integration voltage from field to field will be zero. If the object's projected area varies, the sum of the positive and negative pulses entering the integrator will change, and the readout voltage of the integrator will vary proportionately. The V.D.P. is applied here to the measurement of the vibration of a speaker cone, and to the measurement of the human respiration and plethysmogram.
Coaxial Displacement Dielectric Cell for Liquids Usable to 250 Mc
Authors: Lovell Stuart E. , Cole Robert H.
Published: February 2005

A dielectric plunger displaces liquid filling a short section of coaxial line, and dielectric constant and loss are determined from changes in measured capacitance and conductance with displacement. Corrections for imperfect plunger fit, lead capacitance, and inductance are small and well defined, and procedures for making them are given. Dielectric constants from 3 to 300 and high losses can be measured from −70 to 100°C with 3 cc or less of sample.
Ring Detection in a Thin-Lens Magnetic Spectrometer
Authors: Mann K. C. , Payne F. A.
Published: February 2005

Ring detection has been carried out in a thin-lens beta-ray spectrometer by locating anthracene crystals at the ring focus of the electron trajectories. The geometry of the electron focusing has been investigated for gathering powers of 1.6, 1.1, and 0.7% at mean emission angle tangents of 0.400, 0.385, and 0.352 and the resolutions obtained have been tabulated. At a gathering power of 1.6% a line width of better than 1.37% in momentum has been achieved. A comparison of this instrument with other helical spectrometers is made.
Resolution of Accelerator Magnetic Analyzing Systems
Authors: Cohen Bernard L.
Published: February 2005

In accelerator magnetic analyzing systems consisting of a beam analyzing system and a reaction product analyzing system, the total resolution of the system may be made, to first order, independent of target thickness or independent of the width of the beam on the target, by proper choice of target orientation angle. By proper choice of geometry, the two may be accomplished simultaneously for a given nuclear reaction, and suitable compromises give reasonably good results for a large variety of applications. In most cases, taking advantage of these effects allows an order of magnitude increase in intensity without affecting the resolution.
Use of Balanced Filters for Automatic Recording X-Ray Diffractometer
Authors: Tanaka Kenzo , Katayama Ken-ichi , Chikawa Jun-ichi , Suita Hiroshi
Published: February 2005

Using balanced filters with an automatic recording x-ray diffractometer, almost the same effect of monochromatization as with a crystal monochromator was achieved. The detection efficiency of the balanced filters method was about 30, taking the value as 100 when no filter was used. The effective resolving time of the system involving the electronic circuits was about 5 μsec using a NaI scintillation counter as a detector. The Cu-target x-ray tube was operated on full-wave rectified 60 cps 40 kvp. The comparison with the other monochromatization methods is discussed.
Millimicrosecond Light Source
Authors: Whetstone A.
Published: February 2005

A fast light pulse can be produced by pulsing reverse current through a suitable silicon p-n junction. The light covers a range of photon energies from 1 to 3 ev. The immediate application is the testing of photomultiplier tubes, and, since any number of the junctions can be pulsed simultaneously, a method is available for lining up experiments in which large numbers of scintillators and coincidence circuits are used.
Microscope Phase Fluorometer for Determining the Fluorescence Lifetimes of Fluorochromes
Authors: Venetta Benjamin D.
Published: February 2005

A microscope which can measure the mean fluorescence lifetimes of small fluorescent samples is described. Special emphasis is given to fluorochromes dissolved in biological solutions and bound to thin polymeric substances, such as the desoxyribonucleic acid complexes present in the nuclei of cells. Fundamentally, the method is similar to that described by physicists and physicochemists for solutions of fluorochrome only. A diffraction modulator is used to sinusoidally modulate the intensity of a high-pressure mercury-vapor lamp. The phase shift between the unabsorbed exciting light, passing through the microscopic sample, and the fluorescent light is related to the fluorescence lifetime by tanΔφ=ωτ. The phase shift Δφ is obtained differentially from the phase angles φ1 and φ2 of each microscopic light signal with respect to a third less noisy signal, the tracer signal. The principal effort has been directed toward studying the various sources of error in the fluorometer and variabilities in lifetime measurements. The data indicate that the mean fluorescence lifetime (2.7 msec) of proflavine, bound to nuclei of tumor cells and observed with a 130× oil immersion lens, can be determined with a precision of 4×10−10 sec.
Automatic Transistor Alpha Measuring Set
Authors: Thomas D. E. , Klein J. M.
Published: February 2005

This paper describes an automatic transistor alpha measuring set which was designed for alpha curve tracing and fast acquisition of directly read values of alpha at discrete operating points on research models of junction transistors at an early stage in their fabrication. The set operates on a true null basis. Its calibration is therefore independent of normal variations of the measuring signal level, amplifier gains, and meter calibrations. Although the set described was designed primarily as an applied research tool, it is readily adaptable to automatic card punching of large masses of data or for rapid automatic selection of production transistors which meet specified limits at a discrete operating point or over a wide and continuous operating range. The automatic selection and card punching features can be combined for production quality control studies.
Automatic Adiabatic Control for Calorimeter Shields
Authors: Todd Leslie J. , Dettre Robert H. , Andrews Donald H.
Published: February 2005

An automatic adiabatic shield control has been constructed for a calorimeter designed to measure heat capacities and heats of fusion, using a combination of partial on-off control coupled with an integrating device which keeps the on-cycle equal in length to the off-cycle. A difference thermocouple is the primary source of the control impulse. By calibrating the control with zero heat input, corrections can be made for variations from absolute adiabatic states. Measurements on test compounds indicate a reduction of error due to heat leak to less than 0.1% of the heat to the sample.
Unusually Highly Biased Gun on the Electron Microscope
Authors: Bishop F. W.
Published: February 2005

A self-biasing arrangement is described whereby the beam current of the electron microscope is decreased to less than 5 μa. This reduction of beam current reduces the contamination rate and the heating of the specimen and at the same time improves the illumination. A further combination wherein the bias can be adjusted from the control panel is described. The smaller aperture in the condenser system which is made possible by this system reduces the angular aperture of illumination and increases the depth of focus and resolution.
pH Measurements with a Glass Electrode Withstanding 1500 kg/cm2 Hydrostatic Pressure
Authors: Distèche A.
Published: February 2005

A glass electrode can be made to withstand high hydrostatic pressure, up to 1500 kg/cm2, by separating the inside fluid from the outside one with a layer of silicone oil acting as a liquid piston, enabling the inside and outside pressure to compensate continuously. Such a glass electrode, with two Ag–AgCl electrodes, maintains its hydrogen electrode function at high pressure. pH changes resulting from dissociation constant shifts caused by pressure in acid and buffer solutions have been measured in good agreement with theoretical expected values for HCl, acetic acid, carbonic acid, and acetate buffer. No agreement was found for bicarbonate buffer. Phosphate buffer and sea water have also been tested. An adapted version of the cell-assembly is planned to equip the French bathyscaphe for deep-sea investigations.
Transistor Circuitry for Radiation Counting
Authors: Gilland Jerry R.
Published: February 2005

The transistorized circuits described here have been developed to provide more reliable instrumentation for the experimental nuclear physicist. These devices are a pulse amplifier, a pulse-height analyzer, a scaler, and a linear count rate meter. The basic operating principles are discussed briefly. The electrical characteristics of these instruments compare favorably with their vacuum-tube counterparts and they have the additional advantages of improved reliability, small size, and low power consumption.
Simple Way of Measuring the Power of High-Intensity Light Beams
Authors: Flood W. F.
Published: February 2005

A simple way of measuring the absolute power of high-intensity light beams is described which requires only the measurement of the temperature of a known mass as a function of time. Measurements are shown to be accurate within a few percent.
Low-Noise Hydrophone Preamplifier
Authors: Macpherson J. D.
Published: February 2005

The design and performance of a low-noise hydrophone preamplifier is described. Transistors are used throughout the circuit and it is shown that, although the noise figure is slightly worse than the equivalent circuit using vacuum tubes and transformers, in practice the over-all performance is superior.
Preconversion of Oxide Cathodes
Authors: Haas George A. , Jensen John T.
Published: February 2005

It has been shown that the organic contaminants released during the carbonate and binder decomposition of conventional oxide cathodes can be eliminated if the cathode is preconverted in a separate envelope and is then transferred to the final tube as the alkaline-earth hydroxide. The technique used in accomplishing this lends itself readily to many laboratory applications where tube cleanliness is important. Specific applications to thermionic and secondary emission studies are described. The results indicate a definite reduction in the contamination of tube components and show improved cathode characteristics.
High-Precision Measurement of the Average Value of a Magnetic Field over an Extended Path in Space
Authors: Sherman Christopher
Published: February 2005

A nuclear magnetic resonance experiment which may be used to measure with high precision the average value of a magnetic field over an extended path in space is described. The nuclei, contained in a flowing liquid, are excited at one point and detected at another downstream from the point of excitation. Under proper conditions the average value of the magnetic field along the flow path between points of excitation and detection may be obtained therefrom. Some experimental criteria which must be met in order that this average be correctly obtained are discussed. The results of such an experiment are presented. Although the accuracy of the measurement may be somewhat less than this, line widths of 1 part in 107 have been obtained.
Anisotropic Field Plotting in the Electrolytic Tank
Authors: Jones D. A.
Published: February 2005

A method of solving anisotropic problems in the electrolytic tank has been devised. The resistance of the electrolyte along the two axes is caused to be different by means of a large number of vertical insulating strips.
Low-Temperature Thermal Noise Thermometer
Authors: Patronis Eugene T. , Marshak H. , Reynolds C. A. , Sailor V. L. , Shore F. J.
Published: February 2005

The design for a relatively simple noise thermometer for use at low temperatures is presented. This thermometer has been used to measure temperatures as low as the lambda point of liquid helium with a least accuracy of 10%. Some of the properties of thermal noise are discussed.
Current Noise and Nonlinearity in Pyrolytic Carbon Films
Authors: Williams Thomas R. , Thomas John B.
Published: February 2005

Measurements of the current noise and nonlinearity in the pyrolytic carbon films of 322 resistors are given. The resistances and the dimensions of the films both varied over a wide range. It is demonstrated that when the dimensions of the films are taken into account their noise and nonlinearity are highly correlated: the noise in a given film can therefore be used to estimate the nonlinearity, and conversely. In many groups of resistors of the same type the resistance change with a given applied voltage varied among resistors by a factor of more than 10, and the noise power for a given current through the resistors varied by a factor of more than 100.

In the measurements of nonlinearity the resistance changes were often very small, and, consequently, were easily masked by temperature effects. A measurement method was employed in which the resistors were placed in a balanced bridge, a short high-voltage pulse was applied to the bridge, and the resistance change was determined from the bridge output voltage. With this technique it was possible to measure resistance changes of the order of 20 ppm with an accuracy of ±3 ppm.
High-Accuracy X-Y Pulse Measuring System
Authors: Haas George A. , Harris Franklin H.
Published: February 2005

A method is described whereby a commercial oscilloscope such as the Tektronix Model 535 can be easily modified to give a pulsed X-Y presentation. The application to voltage-current plots is given in detail. For this case, a portion of the pulse voltage placed across the sample to be measured is applied to the horizontal sweep system of the oscilloscope superimposed on the regular time base while the pulse current information is applied to the normal vertical deflection system. By using the sweep delay circuits within the oscilloscope, any point of the pulse can be viewed as the start of the delayed sweep, the horizontal deflection of the starting point corresponding to the magnitude of the pulse voltage and the height corresponding to the pulse current. A family of such curves is obtained as the applied pulse voltage is changed, the locus of points of the start of the delayed sweep tracing out the desired V-I characteristics. This is recorded photographically and has resulted in rapid V-I plots having accuracies to within tenths of one percent.
Variable Permeability Transmission Dynamometers
Authors: Huey R. M.
Published: February 2005

The theory of variable permeability torque measuring devices, such as that described by Beth and Meeks in 1954, is developed. Certain design requirements and methods for such instruments are set down. Experimental results on an improved version of their instrument are given for torques up to about 75 in.-lb in a ½-in.-diam shaft, and indicate that accuracies between 1% and 5% may be expected.
Photoelectric Recording Interferometer for Gas Analysis
Authors: Namba Susumu
Published: February 2005

A photoelectric recording interferometer for gas analysis is reported. Central part of interference fringes is projected on the single slit of a photomultiplier through a polarizer P1 with its principal axis perpendicular to fringes and a field splitting polarizer P2 whose two Polaroid planes are split by a line parallel to fringes and oriented to ±45° to the principal axis of the polarizer P1 and a rotating Polaroid disk. When the center of a fringe is brought in line with the splitting line of polarizer P2, alternating photocurrent becomes zero. Any change of position of the center line of the fringe relative to the splitting line generates an alternating photocurrent with an amplitude which is a function of the fringe shift and a phase which is a function of the direction of the shift. The shift of fringes which is proportional to gas concentration is detected; this shift makes a servo-motor start to put the fringes back to their original position optically. The angle of rotation of the servo-motor is proportional to the shift of fringes indicating the variation of the refractive index, i.e., the variation of the content ratio of the mixed gas. The sensitivity of this apparatus is observed to be about 1×10−8 index unit, or in the case of CO2 gas in air, about 0.01% by volume.
Automatic Scanning Instrument for X-Ray Low-Angle Scatter
Authors: Beck B. L. , Gunn E. L.
Published: February 2005

An automatic scanning instrument for x-ray low-angle scatter measurements has been designed which provides high resolution and precision with relatively little effort in semiroutine operation. The apparatus employs Kratky optical geometry and a scintillation counter detector mounted on a variable speed scanning mechanism. The intensity of scattered radiation as a function of angle is plotted on a strip-chart recorder. The method of operation and examples of instrumental performance are presented.
Atomic-Beam Magnet-Stabilization System
Authors: Brink Gilbert O. , Braslau N.
Published: February 2005

A system is described which allows the magnetic field of the ``C'' magnet of an atomic-beam magnetic-resonance apparatus to be locked to a resonance in the beam. The construction of the system is discussed and representative performance data are presented.
Experimental Procedure for the Determination of Cavity Parameters
Authors: Yariv Amnon , Clapp Fred D.
Published: February 2005

A new experimental procedure for the determination of cavity parameters is described. The procedure follows the basic steps described by Slater. In this method one measures the frequencies at which the voltage standing wave ratio at the input to the cavity reaches a predetermined value. The knowledge of these frequencies coupled with a determination of the state of coupling to the cavity yields the necessary information. An exposition of some pertinent theoretical points is followed by a detailed description of the experimental procedure.
Considerations on the Design of a Molecular Frequency Standard Based on the Molecular Beam Electric Resonance Method
Authors: Hughes Vernon W.
Published: February 2005

The use of a rotational state transition as observed by the molecular beam electric resonance method is discussed as a possible frequency standard particularly in the millimeter wavelength range. As a promising example the 100 kMc transition between the J = 0 and J = 1 rotational states of Li6F19 is considered. The relative insensitivity of the transition frequency to external electric and magnetic fields and the low microwave power requirements appear favorable; the small fraction of the molecular beam that is in a single rotational state is a limiting factor.
Duo Plasmatron Ion Source for Use in Accelerators
Authors: Moak C. D. , Banta H. E. , Thurston J. N. , Johnson J. W. , King R. F.
Published: February 2005

Evaluations of various sources for accelerator use at proton currents above 10 ma indicate that a variation of Von Ardenne's Duo Plasmatron will give performance superior to that of any other source presently available. Operating characteristics for various sizes of the source have been examined for H1+, H2+, H3+, H1−, He+, and He++ ions and electrons. Experience with protons in the current range from 1 to 30 ma indicates that the Duo Plasmatron can deliver up to 100 amp/cm2 of exit aperture area. Current densities such as this cannot be maintained in the accelerator-extractor section because of space charge forces, even at the highest gradients normally available for well-polished electrodes in vacuum; thus it can be said that proton current densities will be space-charge-limited by the accelerator rather than emission-limited by the source. Operation for He+ ions and electrons is similar to proton operation. Currents of 11 μa of H1− ions and 5 μa of He++ ions were extracted directly from a source which had been designed for a proton current of several milliamperes. The most striking features of the Duo Plasmatron are its remarkably high brilliance, high gas efficiency, good power economy, and compactness.
Response of CsI(Tl) to p, d, and α Particles
Authors: Peck R. A. , Eubank H. P. , Lowe J.
Published: February 2005

The relation of pulse height in CsI(Tl) to particle energy for protons, deuterons, and alpha particles has been examined below 20 Mev under a variety of experimental conditions. Observed deviations from simple proportionality (both constant and quadratic terms in a power series representation) depend upon circuit parameters. For a given apparatus, the deviations vary monotonically with the energy interval represented by one spectrometer channel, and tend to zero in the limit of vanishing channel width. The observations suggest that the intrinsic response of CsI(Tl) in the limit of vanishing instrumental effects deviates from a straight line through the origin by less than 0.1% per Mev. Observed curvatures, for channel widths of order 0.3–0.6 Mev, are in the range 0.1–1%/Mev for both protons and deuterons. Pulse-height ratios for given energy are found to be d:p=1.04(+0.08, −0.02) and α:p=0.50(±0.03). Spectrometer peak positions are determined with a precision of 0.1 channel or better by a method of analytic interpolation.
Length Measurement by Fringe Counting
Authors: Hara Ko , Smith D. S.
Published: February 2005

A reversible fringe counter has been constructed and its performance examined. A counting rate of 100 fringes per second over a path difference exceeding 20 cm was obtained. The fringe excess fraction at zero path difference could be determined to 0.001 fringe, and a relative precision of about 1:108 was achieved at a path difference of 6.4 cm.
Strain Gauge Calibration Device for Extreme Temperatures
Authors: McClintock R. M.
Published: February 2005

A device is described for applying known static strains to strain gauges under extreme temperature environments. The essential part is a constant strength cantilever beam used in such a way that the mechanical properties of the component parts need not be accurately known. The location of the strain gauges on the beam is not critical since strain is constant along its length. Conditions are given for which errors caused by thermal expansion can be eliminated. Measurements of the strain sensitivity of constantan wire gauges are given at temperatures between 4 and 300°K.
Elimination of the α1α2 Doublet in X-Ray Patterns
Authors: Keating David T.
Published: February 2005

The characteristic K-radiation employed in x-ray diffraction consists of the bichromatic wavelengths λ(α1) and λ(α2). In practice the observed diffraction pattern is the superposition of the patterns of the two components. In many cases it is necessary to determine the diffraction pattern for a single wavelength. An analytical method for determining such a pattern from the observed superimposed pattern has been developed. The method can be applied to eliminate the doublet from the entire pattern or any particular section. The method can be used to correct diffraction patterns used in their entirety in radial distribution analysis, and is also very useful in line profile work and lattice parameter determinations.
Corona Counter for Thermal Neutrons
Authors: Peters C. W. , Jablonski F. E.
Published: February 2005

The characteristics of a double-plate, corona counter with a boron-coated cathode have been investigated with regard to variation of wire spacing, anode-to-cathode spacing, gas flow, and air pressure. A counter designed to detect a thin neutron beam of 0.0002 cm2 cross section is described. The sensitivity of each wire in this counter was investigated. This counter was life tested with a nitrogen filling for over 1500 hr or a total of 107 counts.
Highly Sensitive Recording Microspectrophotometer
Authors: Chance Britton , Perry Robert , Åkerman Lennart , Thorell Bo
Published: February 2005

This paper describes a sensitive, automatic recording microspectrophotometer capable of measuring the light absorption of substances present at ``enzyme'' concentrations in a single living cell. Modified dynode-feedback and measuring circuits have been especially adapted for measurement of small photocurrents at relatively high signal-to-noise ratios. The application of the instrument to observations of the mitochondrial aggregate (Nebenkern) of the grasshopper spermatid is discussed.
Bearing Dynamometer
Authors: Klint R. V. , Owens R. S.
Published: February 2005

A bearing dynamometer has been devised and built which enables ready evaluation of bearing materials. Coefficient of friction and shaft speed are presented on an X-Y recorder. By varying the load on the bearing a family of curves may be quickly obtained yielding the basic performance characteristics of the bearing materials under actual bearing conditions.

Prolonged tests can be performed during which observation of the bearing characteristics as a function of time can be studied.

At present, bearings of ½-in. diameter are being studied to speeds of 2000 rpm and coefficients of friction to 0.7. These ranges are easily extended.

The speed determination is made by a dc tachometer-generator. The essential element of the friction measuring system is a linear variable differential transformer acting as a transducer for the friction torque of the bearing.