bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroheliometer for Continuously Monitoring Solar Radiation in Five Wavelength Bands
Authors: Sihvonen Y. T.
Published: February 2005

An instrument that quantitatively records and integrates solar radiation has been developed and put into operation. This instrument, called a spectroheliometer, records and integrates automatically from sunrise to sunset. Total radiation is measured in addition to sampling radiation in five distinct spectral regions: 3095–3260 A, 3410–3630 A, 3865–4150 A, 4420–4900 A, and 5385–6295 A. Solar power in these bands as low as 10−5 watt per cm2 has been quantitatively measured. The band widths intercepted are accurate to ±15 A with an estimated ±5 to 8% maximum error in determining absolute solar power and energy.
Low-Energy Meson Beam from Cyclotron
Authors: Koppel Donald , Bingham Robert , Booth E. T.
Published: February 2005

For experimental purposes an external meson beam of as low as 31±2.5 Mev kinetic energy has been obtained from the Nevis 385-Mev cyclotron by the use of a steel magnetic shield between the vacuum chamber and the concrete shielding. This has been achieved with comparatively little loss of intensity over that obtained at 63-Mev mean energy of mesons obtained through the same hole in the concrete shield without the use of the magnetic shielding.
Precision Integrator for Beam Current
Authors: Helmer R. J. , Hemmendinger A.
Published: February 2005

A current integrator has been built in which a servo is used to charge a capacitor in discrete amounts so as to match within certain limits the integral of an input current. By keeping the discrete charge small and the repetition rate for the incremental charge high, one can for practical purposes achieve continuous operation. An instrument accurate to better than 0.1% and with input impedance of 5×104 ohms for the current range 0.1 to 30 μa is described.
Measurements of the Mobilities of the Negative Ions in Oxygen and in Mixtures of Oxygen with the Noble Gases, Hydrogen, Nitrogen, and Carbon Dioxide
Authors: McDaniel E. W. , Crane H. R.
Published: February 2005

The mobility constants for oxygen negative ions in He, Ne, A, Kr, Xe, H2, N2, and CO2, each containing various partial pressures of O2 were measured, and extrapolations to zero partial pressure of O2 were obtained. A measurement of the mobility of the negative ion in 100% oxygen was also made. The value found for the latter was 2.46±0.05 cm2/v-sec at STP. It was shown that the mobility values referred to a single species of oxygen ion, but the question as to whether it was O2− or O3− was not resolved. A time-of-flight method was used, in which the ions were made by the passage of alpha particles through the gas, and detected by a proportional counter.
Extended Range Thermal Conductivity Vacuum Gauge
Authors: Hamilton Allen R.
Published: February 2005

Two magnetic amplifier circuits for automatically controlling a constant temperature hot wire vacuum gauge are described. The differential circuit senses temperature variations by means of voltage and current control coils which respond to the ratio of voltage to current in the hot wire. The bridge circuit senses temperature variations by unbalance in a Wheatstone bridge circuit. In either case, the sensing signal is amplified and fed back to the hot wire in such a direction as to very nearly restore the original temperature. Experimental data are given showing good gauge sensitivity up to 50 mm. Circuitry is simple and, since the magnetic amplifier is inherently a stable device with no perishable components, long trouble-free life can be expected.
Automatic Temperature Control for an Adiabatic Calorimeter
Authors: Cleland W. W. , Harding Richard S.
Published: February 2005

An automatic temperature control device for an adiabatic oxygen bomb calorimeter has been developed which keeps the temperature of the outer water jacket equal to that of the inner bath. When the temperature of the inner bath is not changing rapidly, heat losses are negligible; however, the error due to lag when the inner bath temperature is rising rapidly is about two parts per thousand. This degree of precision permits the accurate analysis of samples of low caloric content such as lyophilized urine. Since the technician need not watch the calorimeter once the bomb has been fired, but instead can prepare a second bomb, the number of samples analyzed in a given time can be doubled if two bombs are available for use with the calorimeter.
Dielectric Rod Wave-Guide Cells for Microwave Spectroscopy
Authors: Brackett Elizabeth B. , Kasai Paul H. , Myers Rollie J.
Published: February 2005

The distribution of microwave power around a quartz rod excited in the dipole mode has been calculated. On the basis of these data, quartz rod sizes have been selected for cells covering the region from 17 000 to 60 000 Mc/sec. All-quartz and Teflon-window cells have been constructed, and the Teflon-window type has been found to have good transmission and high sensitivity.
Efficiencies and Photofractions for Sodium-Iodide Crystals
Authors: Miller W. F. , Reynolds John , Snow William J.
Published: February 2005

Efficiencies and photofractions for monoenergetic gamma rays, from a broad parallel beam, incident on sodium-iodide crystals of various sizes have been calculated by the Monte Carlo method. The calculations were carried out for photon energies of 0.279, 0.661, 1.33, 2.62, and 4.45 Mev; the crystals considered were right circular cylinders with radii of 1.0, 2.0, 4.0, 8.0, 12.0, and 16.0 in. and, for each radius, crystals of heights 1.0, 2.0, 4.0, and 8.0 in. The effect of the escape of annihilation gammas from the crystal was taken into account in the Monte Carlo calculation; however no correction was made for escape of bremsstrahlung. This correction is important only at the largest energies and for the smallest crystals where it affects the photofraction by a few percent.
Description of a Sensitive Micromanometer
Authors: Eichhorn R. , Irvine T. F.
Published: February 2005

A micromanometer is described for the measurement of differential pressures greater than 10−4 in. of water with tolerable accuracy. The instrument uses concentric tubes to form the fluid passages and provides for remote indication of the level in the central tube by means of a mirrored float and telescope and scale arrangement. The highest instrument sensitivity obtained by the authors was 3.15×10−5in. of water applied pressure per mm of scale reading, but with suitable refinement in the optical system, it is felt that greater sensitivities are possible.
Self-Balancing Laboratory Differential Refractometer
Authors: Penther C. J. , Noller G. W.
Published: February 2005

This refractometer is used in conjunction with a light scattering apparatus to determine high molecular weights. The self-balancing feature relieves the operator of the tedium of making delicate visual observations while retaining high sensitivity and accuracy. Mounted on a shop surface plate it measures 15 in. wide by 18 in. long by 7 in. high exclusive of the light source transformer. A Brown Electronik amplifier and servo motor are used to position the photocells on the light beam with a repeatability of about 30 microinches. The beam deflection is read on a counter and vernier dial. The range of the instrument is 0.0175 RI unit and the stability and accuracy are within 5×10−7 RI units.

Differential refractometers are also useful in following fractionation by distillation or adsorption, in determining concentrations of colorless solutes in dilute solutions and in studying sedimentation equilibrium.
Apparatus for the Direct Measurement of Adsorption on Solid Surfaces from Liquids
Authors: Kafalas James A. , Gatos Harry C.
Published: February 2005

An apparatus is described for the measurement in situ of adsorption of solutes on solids and kinetics of film formation on solid surfaces. The technique is applicable only to very dilute solutions in which the solute can be tagged with a γ- or hard β-emitting isotope. The adsorbed radioactivity of the surface is determined through a continuously replenished thin layer of solution. The kinetics and equilibrium conditions of adsorption, desorption and exchange reactions can be determined conveniently; simultaneously, the electrochemical behavior of the surface can be studied. Some measurements are reported.
Nuclear Resonance Pulse Apparatus
Authors: Buchta J. C. , Gutowsky H. S. , Woessner D. E.
Published: February 2005

Radio-frequency pulse apparatus is described for nuclear magnetic and pure quadrupole spin-echo and free induction decay experiments in the 15 to 42 Mc frequency range. Nuclear spin relaxation times between 20 μsec and 50 sec have been measured with the apparatus. Simple cryostats provide temperatures from 100° to 500°K.
Response of a Large Sodium-Iodide Detector to High-Energy X-Rays
Authors: Hubbell J. H.
Published: February 2005

The response of a four-inch long by five-inch diameter sodium-iodide crystal to axially incident 0.01- to 8-Mev x-rays has been expressed as a 28 by 28 matrix. Measured pulse-height distributions were combined with Monte Carlo calculated distributions for the input data. The matrix was inverted on an automatic computer for ease of application to spectra. The mesh is uniform in the square root of energy, each interval including an entire photopeak. Such a coarse mesh makes the response matrix suitable for the unscrambling of continuous but not line spectra.
Cryostat for Electron Bombardment and Electron Diffraction Work
Authors: Hörl Erwin M. , Marton L.
Published: February 2005

A cryostat was constructed for the production of free radicals by electron bombardment of condensed gases at liquid helium and liquid hydrogen temperature. Provisions were made for simultaneous investigations of the bombardment products by electron diffraction and optical spectroscopy.
Magnetic Spectrometer for 450-Mev Protons
Authors: Crewe A. V.
Published: February 2005

A 60° wedge-focusing magnetic spectrometer has been built for use with the 450-Mev proton beam of the Chicago synchrocyclotron. It has curved pole edges to produce good focusing in one plane only. The minimum line width obtainable is ∼¼% with an available solid angle of ∼1/2000 sterad. The deflection is vertical, and angular distributions can be measured from 7° to 173° without allowing the primary beam to strike the magnet yoke.
Combined Magnetic Spectrograph and Spectrometer
Authors: Enge Harald A.
Published: February 2005

A combination instrument is proposed in which a broad-range magnetic spectrograph can be operated as such or in connection with a magnetic quadrupole lens to form a high-intensity spectrometer. A solid angle of approximately 10−2 steradian can be attained with this spectrometer without use of very large magnet gaps.
Magnetic Analyzer for Nuclear Reaction Products
Authors: Meier Otto , Fletcher N. R. , Wisseman W. R. , Williamson R. M.
Published: February 2005

A magnetic analyzer for nuclear reaction products has been built which employs a sector-shaped uniform magnetic field. The shaped sectors are inserted in the 8.5-in. gap of a C-shaped magnet with a 12×12 in. cross section. The iron core is 54×33 in., and 69 360 ampere-turns give 13 500 gauss across a total air gap of 1⅝ in. In the notation of W. G. Cross, [Rev. Sci. Instr. 22, 717, (1951)], the parameters were: ρ=15 in., φ=60°, useful gap=1.5 in., l′=22.5 in., l″=45 in., ε1=+46°38′, ε2=−18°21′, max usable α=±3°, max usable ω=±1.6°. The entrance boundary was straight, and the exit boundary had a convex curvature of 123.7 in. The boundaries of the sector and the locations of the object and image positions were corrected for the effect of the fringing field. The observed l″ was 46.5 in. Fringing field focusing in the direction perpendicular to the plane of deflection was not as strong as calculated; the maximum image height was 2 in. The magnet is capable of bending 12-Mev protons and has an energy resolution of 300 for the maximum useful solid angle of 1/2000 of 4π steradians. The observed maximum energy resolution was 400. The advantages of this magnet are simplicity of construction and ease of adaptation to other sector parameters.
Palladium Film Dosimeter
Authors: Childers H. M.
Published: February 2005

A PdO film electrical resistor, mounted on an insulating base and surrounded with a hydrogenous material, has been investigated for use as a neutron dosimeter. It was found that the resistance of such film was lowered from several thousand to a few ohms upon being irradiated either in a reactor or in a pure gamma-ray field. The cause of this resistance change was determined to be the evolution of hydrogen gas during irradiation, which reduced the PdO to Pd. The potential use of this device as a total dose dosimeter is discussed.
Convection Free Instrument for Measuring Infrared Radiation in the Atmosphere
Authors: Aagard Roger L.
Published: February 2005

The instrument described is a null type device which measures the equivalent blackbody radiation temperature in the atmosphere at night by supplying electrical power to the absorber surface to replace the net loss of energy by radiation and keep the surface at the ambient air temperature. Thus convection effects are eliminated. A thermopile is used to detect the absorber surface temperature difference from air and provide a signal to the high gain transistor dc amplifier of the servo system.

Apparatus is also described which was useful in the development of the instrument and in verifying its theoretical calibration.
Precision Current Regulator Using Transistors
Authors: Johnson S. D. , Singer J. R.
Published: February 2005

A current regulator for electromagnets is described in detail. The regulation over periods of an hour is precise to two parts in one hundred thousand. Feedback bandpass is a few thousand cycles wide in order to eliminate high-frequency fluctuations. An auxiliary current feedback loop is used to control a generator field.
Improved Magnetic Suspension System
Authors: McIlwraith C. G. , Breazeale J. B. , Dacus E. N.
Published: February 2005

A magnetic suspension apparatus is described which supports a ferromagnetic object free from contact with its surroundings and which is capable of maintaining this support for any attitude or orientation in space of the apparatus as a whole. The apparatus and circuits are described and the conditions for stable support given. Features of the system of potential use in instrumentation are described.
Review of High-Temperature Immersion Thermal Sensing Devices for In-Flight Engine Control
Authors: Sanders Victor D.
Published: February 2005

This paper is concerned with sensing devices that may be used for thermal monitoring and control of modern aircraft propulsion units. Performance and service requirements that transcend some aspects of present flight requirements for such devices are described. The possibility of exploiting the pneumatic probe and the high-temperature thermocouple to these ends is explored. Summaries are presented reviewing recent progress in the technical development of high-temperature measurement by these methods.

Typical performance and thermoelectric behavior of twenty metallic thermocouples that have been calibrated above the melting point of platinum are presented. Seven of these pairs have been taken above 4000°F, and nine additional combinations have been calibrated above 3500°F. A comparison is made of the calibration atmospheres, maximum outputs, estimated maximum errors, temperature ranges of calibration, and ultimate temperature ranges for all thermocouples reported herein.

A review of methods of, and properties of refractory oxides suitable for thermocouple protection at high temperatures are presented. A qualitative intercomparison of these materials is made by ranking them according to relative merit of features desirable for thermocouple protection and insulation in the subject application.
Determination of the Magnetic Anisotropy of Single Crystals from Magnetic Torques Measured with Quartz Fibers
Authors: Gordon Derck A.
Published: February 2005

The method of investigating the magnetic anisotropy of single crystals by observing the torque exerted on a crystal by a homogeneous magnetic field was found to be subject to several sources of error which were of particular importance when small differences of susceptibility were involved. Several changes in design of the equipment and in the experimental procedure have been introduced, resulting in a great improvement in the reproducibility of the measurements; these changes included the introduction of effective draft shielding, the use of high magnetic fields to saturate ferromagnetic impurities, and the use of a graphical method of data analysis. The method of determining the torsion constants of thin quartz fibers from the period of oscillation of a torsion pendulum has also been investigated; for accurate values it is necessary that the oscillating pendulum be under high vacuum and shielded from static electricity. A slight decrease in the torsion constants of quartz fibers left under tension for long periods of time has been observed. A systematic method of mounting and orienting the crystal specimens has also been devised.
Electron-Bombardment Detection of Noncondensable Molecular Beams
Authors: Quinn W. E. , Pery A. , Baker J. M. , Lewis H. R. , Ramsey N. F. , LaTourrette J. T.
Published: February 2005

An electron-bombardment detector developed for the detection of noncondensable as well as condensable molecular beams is described. The ionization efficiency for a hydrogen deuteride beam is in the range of 10−5 to 10−4. Auxiliary components include: vacuum buffer chambers for source background gas reduction; a mass spectrometer for ion mass selection; an electron multiplier, electrometer, and phase-sensitive detector combination for signal observation. Modulation techniques for beam and magnetic resonance detection are discussed. Efficiencies, background problems, and relevant noise sources are included in a discussion of operational characteristics. A resonance line trace produced by at most 3% of a total HD beam is presented to demonstrate the signal to noise ratio at low signal levels. The system has effectively detected beams of permanent gases such as HD, D2, and Ne.
Microscope Mechanical Object Stage for the Study of the Tracks of Charged Particles in Photographic Emulsions or Other Objects in Transparent Media
Authors: Slätis Hilding
Published: February 2005

A new microscope mechanical object stage is described. In addition to the usual arrangements for measurements of the x and y coordinates for nuclear tracks in photographic emulsions, the stage is rotatable about the optical axis of the microscope as well as about an axis perpendicular to the optical axis. The angles of rotation can be read off scales. Through these arrangements and by the use of an eyepiece micrometer the orientation and the length of nuclear tracks can be measured directly.
Grating Tangentimeter
Authors: Thompson T. E. , Oncley J. L. , Svensson H.
Published: February 2005

A tangentimeter for use with graphical data is described. Operation of the instrument is based on the production of multiple images by a coarse transmission grating. Under favorable conditions angular measurements may be made with a precision of ±0.1 degree.
Efficient Low-Level Counting System for C11
Authors: Cumming J. B. , Hoffmann R.
Published: February 2005

A low-level counting system used in absolute measurements of the C12(p,pn)C11 cross section is described. In this system small activities of C11 produced in polystyrene-based plastic scintillators by irradiation with high-energy protons are detected with high efficiency by 4π scintillation counting. Background reduction is achieved by counting in a shield consisting of 12 in. of iron and 1 in. of mercury and by the use of a ring of Geiger counters in anti-coincidence with the scintillation counter. A background of 8 counts per min was obtained for a 1.5-in. diam, 1-in. thick scintillator in which the over-all detection efficiency for C11 is 90%. Determination of the counting efficiency by a positron-annihilation coincidence method is described and the results of experiments to reduce the background still further are reported. Application of this system to monitoring fluxes of energetic protons and neutrons is discussed.
Automatic Recording Vacuum Microbalance
Authors: Cochran C. Norman
Published: February 2005

An automatic control and recording system for the null-type vacuum microbalance of Czanderna and Honig [Anal. Chem 29, 1206 (1957)] has been assembled from commercial components. A variable permeance transducer is employed to detect beam movement and to control a force to restore the beam to the null position. This force is recorded in a selection of ranges extending from 0–20 000 μg to 0–5 μg with accuracies ranging from 0.1% to 2% of full scale. On the most sensitive settings the balance can detect weight changes as small as 0.01 μg in loads up to 1 g. Stabilities of 0.1 μg have been observed for periods of many hours on the most sensitive ranges. The balance is undamped, and no corrections are made to the restoring force if beam oscillation is centered about the null point.
Mercury-Vapor Proportional Counters
Authors: McCutchen C. W.
Published: February 2005

A mercury-vapor filled proportional counter is described. Its behavior as a γ counter is investigated. The resolution is fair (7.5% energy spread at 60 kev); however, the various mercury x-ray fluorescence yields and absorption cross sections combine to make the output spectrum of the counter complex and difficult to interpret. It is found that the output pulses are slow, rising in about 30 μsec, though this can be reduced to about 8 μsec by addition of CO2 to the filling.
Calorimetric Assembly for the Measurement of Heats of Fusion of Inorganic Compounds
Authors: Goodkin J. , Solomons C. , Janz G. J.
Published: February 2005

The apparatus consists of a calorimeter of basically simple design, above which is a movable, vertical furnace for heating the specimen contained in a hermetically sealed platinum capsule. A complete series of measurements may thus be carried out on one sample. The capsule is dropped directly into a metal dry-chamber in the calorimeter in contact with a stirred liquid for measurement of heat content changes. A recommended procedure, based on experiments in pairs is described; one of each pair being a calibration drop, the other the specimen drop. The computation of heat content changes from the temperature changes observed is described. The limits of error of this and other calorimetric assemblies are critically discussed. Data to illustrate the results for the LiCl–KCl eutectic mixture (mp 354.1°C) and the reproducibility of the measurements are given. The calorimetric assembly is capable of measurements of heats of fusion of inorganic compounds to an accuracy of ±2%.
Device for Measuring Isotonic or Isometric Contractions of Heart Muscle
Authors: Whalen William J. , Weddle Orville
Published: February 2005

The device converts the motion of isotonic contraction into an electrical signal which can be recorded with the same equipment used to record the output of an isometric strain gauge. The isotonic gauge is essentially a straight wire potentiometer which moves freely through mercury contacts. The muscle is attached to one end of a lever and the resistance wire with a suitable weight (usually 0.5 g) attached to the other end. As shortening of the muscle occurs the resistance between the mercury contacts increases. Changes in length of about 0.1 mm can be quite accurately recorded. Turning a screw attached to a strain gauge down on the lever registers the isometric force in the conventional manner. The whole system is mounted on a movable stage.
Liquid Scintillators for Free Neutrino Detection
Authors: Ronzio A. R. , Cowan C. L. , Reines F.
Published: February 2005

The criteria by which liquid scintillators have been selected and developed for free neutrino detection experiments are described and a discussion is given of the preparation of the solutions. Triethylbenzene is a superior solvent and cadmium octoate is found to be the best cadmium compound known for these purposes.
Single Path Phase Measuring System for Three-Centimeter Radio Waves
Authors: Thompson M. C. , Vetter M. J.
Published: February 2005

A practical system is described for making single-path phase measurements at X-band over ranges up to about 20 miles with instrumental noise of the order of a fraction of one degree. The techniques for obtaining the necessary transmitter frequency stability of 1:109 are described. The use of such techniques to form a simple microwave repeater system with power gain of the order of 50 db is discussed.
Advances in the Standard Proportional Counter Method of Fast Neutron Dosimetry
Authors: Wagner E. B. , Hurst G. S.
Published: February 2005

The proportional counter method for measuring fast neutron dose in the presence of gamma radiation has been considerably improved through (1) redesign of the proportional counter, (2) a study of the behavior of the counter for various filling gases, and (3) development of a more convenient form of the electronics necessary for pulse integration and dose indication. The instrument is suitable for radiobiological research, neutron physics, and shielding research, as well as radiation protection. It will be shown that the response of the instrument is within ±5% of tissue absorbed dose over the energy range of 0.5 Mev to 14 Mev.
Electronic ac Mutual Inductance Bridge for Measuring Small Susceptibilities at Low Temperatures
Authors: Pillinger W. L. , Jastram P. S. , Daunt J. G.
Published: February 2005

An electronic ac mutual inductance bridge is described, in which a vacuum tube and a fixed mutual inductance are combined to form an accurately variable mutual inductance. The variation is obtained by means of decade resistors. The primary and secondary self-impedances are constant, independent of the mutual inductance setting, and can be made substantially lower than is possible with comparable conventional variable mutual inductances. The bridge is designed to be suitable for use in balancing multiturn mutual inductances to permit susceptibilities of samples of 1 cm3 volume to be measured at low temperatures with a precision of ±2×10−7 emu/cm3. Details are given of the bridge circuit and of a typical multiturn mutual inductance; an outline of some typical susceptibility measurement results is appended.
Carbon Arc Image Furnaces
Authors: Null M. R. , Lozier W. W.
Published: February 2005

Various optical systems are discussed with reference to their use with carbon arc image furnaces. A new optical system which employs two elliptical mirrors is described and shown to have numerous practical advantages. Using modifications of motion picture projection lamps, measurements have been made of carbon arc image furnaces ranging up to more than 26-kw power input, producing approximately 3000-watts radiant flux at the image within a circular area of 30 mm diameter, with a center of image irradiance as high as 15 watts per mm2, a flux density equivalent to the radiation from a blackbody at more than 4000°K. Furnaces of lower output and higher efficiency are also described. Comparison with available data indicates carbon arc image furnace performance is essentially equivalent to existing solar furnaces in the 60 to 100-in. diameter range. Possibilities for further improvement of carbon arc image furnaces are also considered.
Temperature Determination in Flames by X-Ray Absorption Using a Radioactive Source
Authors: Mullaney George J.
Published: February 2005

A radioactive source Fe55 was used to measure the density of high-temperature combustion products through a flame zone 6.5 cm long. Premixed propane-oxygen and argon were used for the experiments with a porous metal burner. Temperatures were determined downstream of the main reaction zone in the flame at one atmosphere. Temperature profiles were obtained through the preheat and main reaction zone using radioactive Fe55 coated on a small platinum wire as a line source.
Apparatus for Precision Flash Radiography of Shock and Detonation Waves in Gases
Authors: Knight Herbert T. , Venable Douglas
Published: February 2005

An apparatus is described which is based on the technique introduced by Kistiakowsky utilizing the absorption of soft x-rays to measure densities behind gaseous shock and detonation waves. Experimental conditions leading to the smallest absorption statistical uncertainty consistent with maximum sensitivity are defined. These may be approximated at reasonable pressures and tube diameters by adding a strongly absorbing rare gas diluent to the experimental gas mixture. Under such conditions measured densities are accurate to ±1%, as demonstrated by comparison of experimental and calculated densities for shock waves in krypton. At some sacrifice in accuracy, space resolution of 1 mm and time resolution of 1 μsec may be achieved.

A continuously pumped, laboratory-built, demountable, pulsed x-ray tube with an L-cathode and tungsten target is used at an accelerating voltage of 20–-30 kv to obtain currents up to 0.2 amp for durations of the order of 1 msec. Copper and chromium targets were also investigated.

For calibration purposes the tube is operated at a steady current of ≈0.2 ma and detector signals are measured potentiometrically to obtain transmission as a function of gas density.
Apparatus for Producing and Measuring High-Energy Electrical Discharges
Authors: Richeson W. E.
Published: February 2005

Circuitry is described that is capable of delivering sparks with current pulses adjustable from square through damped oscillatory form, energies up to 100 j, peak currents to 50 000 amp, and rise times less than 2 μsec.

To observe the spark current, a novel differential measurement scheme was developed. This scheme eliminates errors inherent in establishing reference grounds, provides a method of reducing high-frequency and high-peak current distortions inherent in current viewing shunts, and provides a method of determining the potential across a spark gap.

Electrical characteristics of spark discharges in a saturated NaCl–H2O solution, as well as the rate of growth of the luminous plasma of a spark in air, are described to illustrate the flexibility and general characteristics of the spark circuitry and the differential measurement scheme.
Two-Dimensional Pulse-Height Analyzer
Authors: Birk M. , Braid T. H. , Detenbeck R. W.
Published: February 2005

A two-dimensional analyzer classifies a coincidence event between two detectors according to both pulse amplitudes. The events are sorted into ``channels'' covering a plane instead of the linear array of a conventional analyzer. For coincidence measurements in which the amplitude spectrum from one detector is examined as a function of the pulse height from the other over a wide range, such a device provides maximum efficiency in recording the data. An analyzer is described, in which each coincidence is recorded on a punched paper tape memory as a pair of correlated numbers (the two pulse heights) in binary notation (1–127). In the subsequent read-out these two numbers specify a two-dimensional channel. To examine the information in a particular region of the plane, a circuit controlled by a mechanical tape reader determines those events for which one coordinate lies in a preselected range. The corresponding coordinates are then displayed as a spectrum on a conventional 100-channel analyzer by a digital-to-analog conversion system in such a way that each event appears in the channel whose number is punched on the tape. The maximum recording rate is 8/sec; read-out is at 10/sec. The maximum number of channels is (127)2. In experiments with low coincidence rates the time taken to record and analyze such data is very considerably less than by conventional methods. Examples are given of the application of the analyzer to a (p,p′γ) experiment and to the identification of energetic charged particles by measuring simultaneously their energy and differential energy loss.
Absolute Assay and Study of Short-Lived Radionuclides by a Recoil Technique
Authors: Rowland F. S. , Wolfgang R. L.
Published: February 2005

A new type of accelerator target has been used to determine the yield of He6 from high-energy nuclear reactions. In this target the nuclear recoil of the product isotope separates it from the target material and carries it into a ``catcher'' gas which is then swept into a counter. Because of the design principle employed in this target, the data can be translated directly into absolute cross sections without explicit knowledge of the recoil properties of the product. This type of system may also prove useful in the determination of (1) the relative stopping powers of gases, (2) the rate of thermal diffusion of product species through the target material, and (3) the chemical properties of short-lived species of large kinetic energy.
Method for Damping Phase Oscillations in a Synchrotron
Authors: Rogers Edwin J.
Published: February 2005

A phase oscillation damping system has been developed and successfully tested at the Brookhaven cosmotron. Phase differences between the induced voltage in the beam pickup plates and the rf accelerating voltage are detected and fed back to the frequency control system. The frequency of the rf accelerating voltage is thus adjusted to provide a phase restoring force. The usual 50% beam loss during the accelerating cycle is eliminated and tests indicate that the beam stability with respect to disturbances in field vs frequency characteristic is improved by a factor of five.
Spectral Effects in the Comparison of Scintillators and Photomultipliers
Authors: Swank Robert K. , Buck Warren L. , Hayes F. Newton , Ott Donald G.
Published: February 2005

Photomultiplier evaluation of scintillation performance is considered in the light of its marked dependence on spectral shape effects in the emission spectrum of the scintillator, in photon absorption of cell, reflector and photomultiplier window, and in the photoelectric conversion process. Relative pulse height data indicating gross differences in spectral sensitivity are presented for a group of 132 photomultipliers (types 6292 and 6342). A fluorescent converter for measuring the quantum output of liquid scintillators is described.

Six scintillator solutions with fairly evenly spaced mean emission wavelengths from 3360 to 4660 A are evaluated for relative pulse height and relative photon output.

Suggestions are presented for desirable methods for measuring the performance of scintillators.
Continuous Energy Monitor for the External Beam of a Cyclotron
Authors: Northrop J. A. , Stokes R. H.
Published: February 2005

A simple scintillation counter system is described which monitors the average energy of particles in the external beam of a cyclotron and simultaneously serves as a current integrator. Energy changes are continuously presented on a chart recorder, thus allowing the machine energy to be held constant to a high degree of accuracy over extended runs. In typical operation using 14-Mev deuterons, the average energy may be held constant to within 0.07%.
Cryoscopic Assembly for Precise Measurements under Controlled Atmospheres at Temperatures up to 500°C
Authors: Solomons C. , Janz G. J.
Published: February 2005

A cryoscope is described which was designed for the accurate measurement of freezing points of molten salts under controlled atmospheres. It possesses several advantages over apparatus in the published literature, especially when used with solutions which attack or embrittle the glass container.

The ancillary apparatus used with the cryoscope is also described, and the features of the apparatus are discussed. Examples are given to show how several problems of molten salt cryoscopy under controlled atmosphere have been satisfactorily overcome.
Apparatus for the Observation of Infrared Streaming Dichroism of Polymer Solutions
Authors: Bird G. R. , Parrish M. , Blout E. R.
Published: February 2005

A method and apparatus have been developed for the quantitative observation of infrared streaming dichroism of solutions of macromolecules. The design, construction, and operation of the apparatus are described in detail. The apparatus consists of a modified standard infrared liquid cell through which the solution is pumped by means of a pair of hypodermic syringes which are driven in opposition by a pair of cams that provide a constant rate of displacement. The resulting flow is constant except for a reversal in direction at the end of each stroke. The maximum value of the gradient in the cell may be calculated by means of a simple formula. The total volume of the pump and cell is 2.2 cc so that small samples may be measured. Several types of materials have been measured and a typical result is shown.
Field Desorption by Alternating Fields. An Improved Technique for Field Emission Microscopy
Authors: Cooper Earl C. , Müller Erwin W.
Published: February 2005

The inclusion of field desorption in field emission microscopy yields additional information on adsorption systems and easily produces clean surfaces of metal tips without the application of heat. An alternating field technique is described using a dc-biased ac power supply for providing the desorption field during the positive portion of the cycle and allowing the observation of the field electron image during the negative portion. Ion and electron current during one cycle are calculated for a tungsten tip. Patterns from clean nickel, iron, and copper are shown.
Temperature-Regulated Bismuth Resistor for Magnetic-Field Measurements
Authors: Dols Charles G. , Skiff Edson W. , Watson Peter G.
Published: February 2005

The magnetoresistance effect of the metal bismuth has been used in measuring magnetic induction for many years. This report describes significant features of the electrical and mechanical design of an electrically temperature-regulated resistor assembly and associated equipment. Commercial ductile bismuth wire was successfully used in a small probe. Useful resolution of 2 gauss in fields above 5000 gauss was readily attained. Limitations and advantages of bismuth resistors as devices for measuring magnetic induction are discussed briefly. Some data from the use of the first units are presented.
Electronic Ultra-High Vacuum Pump
Authors: Hall Lewis D.
Published: February 2005

An ultra-high vacuum pump has been developed based on the combined effects of ionization, excitation and sputtering. A cold-cathode discharge in magnetic field is employed with no hot filaments nor moving parts. The ultimate vacuum attainable is not yet known but is probably below 2×10−10 mm Hg. A pumping speed of about 10 liters/sec for air has been recorded at 1×10−7 mm Hg. The pump replaces liquid nitrogen-trapped oil diffusion pumps for pumping microwave tubes.
Low-Noise 30-Mc Amplifier
Authors: Verma J. K. D.
Published: February 2005

A low-noise 30-Mc amplifier with Western Electric Type 416B triodes used in a cascode circuit is described. The theoretical noise figure of the amplifier, with the optimum value of source resistance, is 1.06 or 0.26 db. The amplifier is being used to study noise in semiconductors.
Production of Beams of Polarized Protons by the Acceleration of Protons Derived from Polarized Hydrogen Molecules
Authors: Garwin R. L.
Published: February 2005

A conventional Stern-Gerlach separation of hydrogen molecules is proposed for the supplying of a radio-frequency or PIG ion source of standard type to produce microampere beams of polarized protons for acceleration in electrostatic accelerators, cyclotrons, etc. The long nuclear relaxation time of molecular hydrogen gas allows the accumulation of polarized protons (as molecules) for the production of microampere average beams by means of a pulsed ion source. The polarized protons after acceleration have the energy- and angular-spread characteristic of the machine with which they were accelerated. There is no apparent reason why polarized H− may not be produced in the same strong-field rf ion source, accelerated in a weak field to preserve polarization and stripped in a tandem machine, all without significant depolarization.
Improved Instrument for the Measurement of Linear Pyrolysis Rates of Solids
Authors: Barsh M. K. , Andersen W. H. , Bills K. W. , Moe G. , Schultz R. D.
Published: February 2005

An improved instrument has been designed and constructed for the measurement of the linear decomposition and sublimation rates of solid substances. This instrument, which is provided with automatic recording devices, eliminates many of the shortcomings of the earlier prototypes and makes possible the determination of linear rates with a precision of 1%. Important new features include (1) an integral heating element and thermocouple assembly; (2) stainless-steel and Plexiglas construction throughout; (3) heavy, solid-copper electrical-conductor supports for the heating element; and (4) a precision position-sensing potentiometer. The use of cut strands of Plexiglas 55 is recommended for periodic standardization and calibration of the instrument.
Vapor Pressure Apparatus
Authors: Cook Marshall W.
Published: February 2005

A vapor pressure apparatus has been developed which has certain manipulative and accuracy advantages over the well-known isoteniscope. A reliable criterion for complete degassing is inherent in the apparatus. Since degassing is required only once for a series of determinations at various temperatures, the apparatus is well adapted where the amount of sample is limited. The useful temperature range of this apparatus is between the freezing point of mercury (−38.9°C) and the temperature at which the vapor pressure of mercury becomes appreciable (∼0.1 mm at 80°C). The apparatus may not be used if the sample reacts chemically with mercury.
Range of 14-Mev Protons in Nuclear Emulsion
Authors: Gilbert F. C. , Heckman H. H. , Smith F. M.
Published: February 2005

Neutrons, produced by the reaction H3(d,n)He4, gave proton recoils in nuclear emulsion whose ranges were used to obtain a calibration point on the range-energy relation. The range for 13.94±0.10-Mev protons in emulsion of density 3.815 g/cm3 is 995.9±2.1 μ.
Efficiencies of Sodium Iodide Crystals
Authors: Stanford A. L. , Rivers W. K.
Published: February 2005

Efficiencies for monoenergetic gamma rays, emanating from an axial point source and incident on sodium iodide crystals of 1.5 in. diameter and of various heights, have been calculated by numerical integration methods. The crystals considered are right circular cylinders of heights 0.125, 0.25, 0.375, 0.50, 0.75, 1.5, 2.0, and 3.0 in. Seventeen photon energies in the range from 0.025 to 10.0 Mev were used. Fourteen distances from source to crystal face in the range 0.1 to 50.0 cm were used. Efficiencies for crystals of diameters other than 1.5 in. may be obtained from these results. Relative photoelectric efficiencies were not calculated.
Respirator Suitable for both Small and Large Laboratory Animals
Authors: Guttmann Henry E.
Published: February 2005

A respirator with cycling rates from 5 to 80 cycles per minute is described. The inspiration-expiration ratio is adjustable. Four animals may be respirated simultaneously. Operation is quiet, with only one moving part in the multiple valve assembly. Manual operation is possible in event of power failure.
Quartz Helix Magnetic Susceptibility Balance Using the Curie-Cheneveau Principle
Authors: Senftle F. E. , Lee M. D. , Monkewicz A. A. , Mayo J. W. , Pankey Titus
Published: February 2005

A quartz spring balance is described which can be used to measure the magnetic susceptibility of submilligram amounts of sample. The magnetic field is supplied by a moving permanent magnet, and the susceptibility is determined by the deflection of the spring observed in a measuring microscope. The apparatus is calibrated by a comparison standard (platinum) and results are shown for platinum, nickel aluminate, lead, manganese, and sucrose. A precision of better than 2% can be obtained on submilligram amounts of paramagnetic substances having a magnetic susceptibility of from 1 to 50×10−6 emu/g. On weakly paramagnetic or diamagnetic substances comparable precision can be obtained on less than 10 mg amounts of sample.
Stable Multichannel Positive Pion Detector
Authors: Imhof William , Kalibjian Ralph , Perez-Mendez Victor
Published: February 2005

A π-μ decay counter has been designed and used to count positive pions in several synchrotron and cyclotron experiments. Utilizing an improved gate generator and coincidence circuit, the detector possesses a very stable efficiency for counting pions in several energy intervals. The detector is readily adaptable to the addition of extra counters to permit the detection of pions in the presence of large backgrounds.
Design of Simple Resistance Thermometer Bridges for Wide-Range Control of Low Temperatures
Authors: Goodwin Robert D.
Published: February 2005

To achieve a precision of temperature control in the range 0.01 to 0.0001°K, it usually is necessary to utilize the greatest sensitivity which can be obtained from a simple resistance thermometer bridge. Over the temperature range of T from 1° to 300°K the resistance, R, of different thermometers may vary from one to thousands of ohms, and R may increase or decrease with T. Sensitivity, |dR/RdT|, may vary more than tenfold. As the dominant limitation upon useful sensitivity is thermal dissipation of thermometer power, design parameters are derived which afford optimum practical sensitivity at the amplifier output per unit thermometer power. Quite unsymmetrical bridges are preferable. Different conditions are preferable for the basically different thermometers, pure metals, and semiconductors.
Design and Construction of a Blackbody and its Use in the Calibration of a Grating Spectroradiometer
Authors: Lalos G. T. , Corruccini R. J. , Broida H. P.
Published: February 2005

A blackbody was constructed of graphite which could be inductively heated in an atmosphere of helium to a maximum temperature of 2700°K. This blackbody was used as a source of radiant energy in the calibration of a grating spectroradiometer. The calibration was made over the spectral range of 2600 to 3800 A in the second order, and of 3300 to 7550 A in the first order. The accuracy of the calibrations was estimated to be of the order of 9% in the regions 2600 to 2800 A in the second order, and 7000 to 7550 A in the first order, and of 5% in the regions 2800 to 3800 A in the second order, and 3300 to 7000 A in the first order.
Grid Current in Electron Tubes
Authors: Fairstein E.
Published: February 2005

The outcome of an experimental study of grid current in currently produced low-power receiving tubes indicates that if the plate dissipation is kept below 75% of the manufacturers' ratings, the grid current is not primarily due to ionized gas, but to photoelectric emission from the grid under the action of soft x-rays produced at the plate. A simple empirical formula is given for predicting the grid current from the operating conditions. Data are given for 11 tube types.
Sintering Method for Semiconductor Material
Authors: Gaulé Gerhart K. , Breslin James T. , Pastore John R.
Published: February 2005

A sintering process has been developed which makes it possible to utilize semiconductor material which comes in the form of small grains or small dendrite-like pieces. When pressure, alternating current, and an rf field are applied, this loose material is sintered into rods without using a binder. These rods are used as ``feed'' for a floating zone apparatus.