bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Phase Measurements on the Birmingham Cyclotron
Authors: Konrad M.
Published: February 2005

The ion phase in the internal beam of the Birmingham cyclotron at distances from the ion source from 8 mm up to 69 cm has been determined by measurements of the target current waveform. The equipment consisted of a screened target and a specially built oscilloscope based on the sampling technique. The results obtained are discussed and compared with theory.

Ions are grouped in phase at early stages of acceleration over approximately 20 electrical degrees, which is about 5 times larger than predicted by the uniform electric field approximation. At later stages the measured phase changes are in good agreement with Rose's equation.
Theoretical Analysis of Ultrahigh Vacuum Condensers
Authors: Mickelsen William R. , Childs J. Howard
Published: February 2005

The analysis considers the condensation of high-velocity molecular beams on condenser surfaces having very low temperatures. The condenser surface area and volume necessary to maintain a given vacuum are derived theoretically from a highly idealized model.
Bridge Method for Microwave Dielectric Measurements
Authors: Glarum Sivert H.
Published: February 2005

A method for measuring complex dielectric constants of liquids is described. It involves the variation of the length of a short-circuited section of transmission line until its input admittance is solely resistive. A novel microwave bridge indicates when this condition is fulfilled and simultaneously measures the admittance. From a knowledge of this admittance and the length of the dielectric-filled section the complex dielectric constant may be readily calculated. Measurements at 1 and 3 kMc with several liquids of diverse dielectric character are in satisfactory agreement with values reported elsewhere.
Half-Megampere Magnetic-Energy-Storage Pulse Generator
Authors: Walker R. C. , Early H. C.
Published: February 2005

Energy is stored in the magnetic field of a large air-core transformer having a very low impedance, tightly coupled secondary winding. The energy can be effectively delivered in less than 5 msec to a noninductive load, having a resistance of less than 10−4 ohm.
Elastic Constant—Internal Friction Spectrometer
Authors: Thompson D. O. , Glass F. M.
Published: February 2005

An elastic constant-internal friction spectrometer has been developed which has proved to be very useful in measurements which must last over extended periods of time as well as in measurements which require a high degree of resolution. The essential feature of the spectrometer is the fact that it holds the sample in oscillation at its resonance frequency and at a preset strain amplitude, and measures the internal friction of the sample through a measurement of the driving force necessary to maintain the preset amplitude.
Second-Order Properties of Double-Focusing Spectrometer with Nonuniform Magnetic Field
Authors: Ikegami Hidetsugu
Published: February 2005

Second-order focusing properties are considered for a nonuniform magnetic field with arbitrary circular boundaries in the case of normal entry and exit. The formula obtained here agrees with that obtained by Hintenberger for the special case α=β=0. It is also shown that the double and second-order focusing can be achieved simultaneously. The numerical results are represented graphically for a symmetrical double-focusing spectrometer with an arbitrary deflection angle.
Alpha-Particle Irradiation Apparatus
Authors: Hart Edwin J. , Terandy John
Published: February 2005

An apparatus having up to four Po210 sources suitable for radiation chemistry studies in liquids is described. Each unit consists of a source and housing that supplies a collimated beam of α particles, a variable speed stirrer, and an irradiation cell holder. Energy output is measured with the ferrous sulfate dosimeter.
Alternate Current Apparatus for Measuring the Ordinary Hall Coefficient of Ferromagnetic Metals and Semiconductors
Authors: Lavine Jerome M.
Published: February 2005

An apparatus is described for measuring the ordinary Hall coefficient of ferromagnetic metals such as Ni and of ferrimagnetic semiconductors such as Fe3O4. An alternating electric field at 1000 cps is used with a static magnetic field. The apparatus has a sensitivity of 10−18 watt, a noise level of 10−9 volt, and a voltage resolution of one part in 105. The sensitivity is required by the small ordinary Hall coefficient of the metals and the ferrites, and the resolution is needed to separate the ordinary and extraordinary Hall effects. The apparatus may be used with sample impedances ranging from less than one ohm to several thousand ohms. The sample holders which are an important part of the apparatus are described. The measurement technique is detailed as is a method for ensuring the absence of spurious voltages. The system may also be used to measure changes in other second-order effects by bucking out all first-order effects.
Detection of Fast Neutrons by the Associated Particle Method
Authors: Okhuysen P. L. , Bennett E. W. , Ashe J. B. , Millett W. E.
Published: February 2005

The associated particle method of neutron detection has been used to reduce the background in measurements of the total cross section using neutrons from the D(d,n)He3 reaction and to measure the time-of-flight of the neutrons that are inelastically scattered when elements are bombarded with T(d,n)He4 neutrons. The techniques used are described.
Preparation of Thin Anthracene Single Crystals
Authors: Kallmann H. , Pope M.
Published: February 2005

Anthracene single crystals ranging in thickness from 4 to 80 μ and from 0.5 to 2 cm2 in area have been prepared by crystallization from a selected solution system. The method is general and employs a density and temperature gradient within the solution which permits the crystal to grow while suspended in the solvent.
Gamma-Ray Resolution of Larger NaI(Tl) Scintillators
Authors: Hickok R. L. , Draper J. E.
Published: February 2005

The various factors affecting the gamma-ray energy resolution of NaI(Tl) scintillation spectrometers have been investigated experimentally with commercially packaged 2.5- and 5-in. diam scintillators and routinely available 3- and 5-in. photomultipliers. The resolution contains contributions from the scintillator light yield, photocathode efficiency, intrinsic resolution due to the material NaI(Tl) and two terms involving the effects of various spatial inhomogeneities in the packaged scintillator and photomultiplier. Insofar as possible these contributions are experimentally separated. The poorer resolution of the 5-in. systems is in about equal measure caused by their smaller light yield, their larger spatial inhomogeneities and the lower efficiency of the 5-in. photomultipliers in producing and collecting cathode electrons.
Microwave Double-Sweep Method for Analysis of Time-Dependent Cavity Characteristics
Authors: Ruthberg Stanley
Published: February 2005

The impedance of a microwave cavity whose characteristics are time-dependent, as caused for example by a contained gaseous discharge afterglow, can be examined by means of a frequency-modulated search signal and a swept receiver. The intersection of the search-signal frequency and the acceptance frequency of the receiver results in a pulse whose shape is sensitive to cavity resonance. The time of occurrence of the pulse depends upon signal-to-receiver phase. This in combination with the measured receiver dispersion allows measurement of reflection coefficient and frequency shifts smaller than the readability of a precision wavemeter at 10 kMc. Problems of oscillator tuning are mitigated and special stabilization procedures are eliminated. Only standard components are used.
He3 Recirculation and Purification System for a Cyclotron Ion Source
Authors: Wegner H. E. , Hall W. S.
Published: February 2005

A He3 circulation system for a cyclotron has been built which will recover the gas and purify it continuously. This is accomplished by modifying a mechanical vacuum pump to meet the following special requirements: intake and exhaust sealed for both pressure and vacuum; small volume on the exhaust side; minimum oil volume. This pump, which is used instead of the cyclotron forevac pump during He3 operation, recovers the gas and forces it through a liquid nitrogen-cooled charcoal trap and on to the ion source. The system is completely interlocked to ensure He3 safety in the event of operator or electrical failure. With a flow rate of 6 cc per minute, the normal He3 loss over a period of 200 hours operation was less than 3 cc per hour after an initial charge of 1000 cc NTP. With trap reactivation periods of 50 hours, no change in ion yield was observed. External beams of approximately 100 μa of doubly charged particles were obtained.
Completely Nonmagnetic Alloy for Instrumentation in Magnetic Fields
Authors: Pugh Emerson W.
Published: February 2005

A high-purity copper-nickel alloy is described which has zero magnetic moment at room temperature and less than a tenth the moment of pure copper at all temperatures down to 2°K. The alloy has been used with considerable advantage in sample holders for magnetic force measurements, and other uses are anticipated. A method of preparing the alloy is discussed which requires limited metallurgical equipment.
Low-Level dc Amplifier with Whole-Loop Feedback
Authors: Hoell P. C.
Published: February 2005

The chopper amplifier described herein, using a 60-cps vibrating-contact modulator and whole-loop negative feedback, has a stabilized gain of 107 from dc to 10 cps. After the input circuits have reached thermal equilibrium, the zero drift is less than ±10−9 v per hour and less than 2×10−9 v per day.
Rapid-Quenching Hot Stage for Metallography
Authors: Speich G. R. , Cohen Morris
Published: February 2005

A microscope hot stage designed for use at temperatures up to 1100°C and for rapid quenching rates up to 500°C/sec is described. The stage is especially suited for the study of reactions in steels where it is often necessary to quench quickly from the austenitizing temperature to some lower transformation temperature. The sample is protected from oxidation by vacuum or an inert atmosphere.
Pulse Amplifier with Submillimicrosecond Rise Time
Authors: Sterzer Fred
Published: February 2005

A pulse amplifier having a rise time of approximately 0.7 millimicrosecond is described. In the amplifier the dc input pulses to be amplified modulate a 2750 megacycle carrier, producing pulses at the carrier frequency. The resulting rf pulses are amplified by a traveling-wave tube, and then demodulated to give amplified dc pulses. The amplifier works into a 120-ohm load and has a maximum power gain of 20 db; the maximum output voltage is 2.1 volts.
Cryostat for Reactor Irradiation
Authors: Sartain C. C. , Yockey H. P.
Published: February 2005

A cryostat for continuously bathing samples in liquid nitrogen or other heat transfer liquids during nuclear reactor irradiation has been constructed and successfully operated. The samples to be irradiated at low temperature are immersed in the heat transfer fluid which is high-purity liquified nitrogen circulating in a closed system at a pressure greater than that of the atmosphere. The liquid is kept below its boiling point throughout its cycle by use of a heat exchanger located outside the reactor shield. The heat exchanger is cooled by commercial liquid nitrogen boiling at atmospheric pressure. Since oxygen and water vapor from the air cannot enter the closed pressurized system, no chemical explosions inside the nuclear reactor have occurred. Baths at other temperatures may be obtained by substituting suitable liquids for the high-purity nitrogen heat transfer fluid and by keeping the heat exchanger at the desired temperature.
Iodine-Vapor-Filled Ultraviolet Photon Counter
Authors: Brackmann R. T. , Fite W. L. , Hagen K. E.
Published: February 2005

A device for the sensitive detection of ultraviolet radiation in the range 1080–1260 A is described. This device is a Geiger-Müller counter in which the counts are initiated by the photoionization of iodine vapor used in the tube's filling. The range of response is determined by the ionization potential of iodine and the short wavelength cutoff of LiF, through which radiation enters the counter. Because of iodine vapor in the filling, the electrical characteristics of the tube are those of a halogen-quenched counter.
Thermal Precipitator for Continuous Aerosol Sampling
Authors: Orr Clyde , Martin Roy A.
Published: February 2005

Thermal precipitation is attractive for airborne particle collection because of the high collection efficiencies which may be attained and the convenient examination of the deposit. Most thermal precipitators, however, have very low sampling capacities or flow rates. To take fullest advantage of the desirable features of thermal precipitation, a new precipitator was designed and constructed. It operated continuously, and deposited particles upon a moving tape or substrate. Complete collection of particles resolvable with an electron microscope was attained in a 3-in. diameter precipitating zone at a flow rate of 1 l/min.
Energy Stabilization of the Berkeley Proton Linear Accelerator
Authors: Knowles H. B.
Published: February 2005

A device is described which stabilizes the energy of the 32-Mev proton linear accelerator. The general system is similar to that developed for the Princeton cyclotron, with the exception of the control on the output energy. This control is obtained by slightly detuning the exit end of the rf cavity by means of a rotating paddle. Range is used to predetermine the proton energy. An auxiliary circuit is provided for direct control of the correcting paddle. Two ionization-chamber currents are compared by a difference amplifier which is quite sensitive but very stable and can be located at any distance from the ionization chamber. An energy stabilization of ±40 kev is achieved.
Pulsed Cyclotron Method for 2–25 Mev Neutron Spectroscopy
Authors: Draper James E.
Published: February 2005

A method is described for obtaining short intense bursts (5 mμsec and 10–20 ma) of 22 Mev deuterons at a repetition rate of 500 cps. The cyclotron arc is pulsed on for 1 μsec, and one of the approximately ten circulating phase-grouped beam bunches is selected for deflection onto the external cyclotron target by means of a 50 mμsec pulse on the cyclotron deflector. Using a 12.5 meter flight path the resulting radiations were analyzed. Investigations of backgrounds showed them to be less than one percent.
New Refraction Seismograph
Authors: Mooney Harold M. , Kaasa Robert A.
Published: February 2005

A transistorized refraction seismograph has been developed based on pulse systems techniques. This results in direct visual time indications, major reductions in operating complexity, size, and weight, and the elimination of the necessity for photographic processing and the use of explosives. A 4-kc crystal oscillator serves as the time base. The signal passes through a gate circuit to an electronic counter; the gate is opened at the time a sound wave enters the earth and is closed at the time the sound reaches a detector on the surface. The time-distance data can be interpreted in terms of depths to subsurface layers and the nature of subsurface materials.
Sensitive, Quantitative Recording X-Ray Spectrometer
Authors: Barstad Gotfred E. B. , Refsdal Ivar N.
Published: February 2005

A spectrometer has been developed with the object of achieving a high diffraction efficiency, low background, and stability and convenience in operation. A mechanism is used to position the detector and crystal in relation to the sample, for determining extended spectra by Johann's and Cauchois' methods. Sample-chambers with radiation shielding walls are used, and the outlet for fluorescent radiation is designed for reducing background. Microsamples can be used to simplify the evaluation of quantitative results. A vacuum-chamber has been designed for further reducing background. 4×7 cm crystal lamellae on glass supports are prepared from blocks of NaCl or LiF and bent cylindrically for line focusing, or double-curved for point-focusing to increase the intensity at particular wavelengths, the focusing always being aberration-free. The equipment has been calibrated for microquantitative determination of 30 elements, and an absolute sensitivity of 2×10−10 g has been achieved for the elements Co–Zn.
Electronic Computer for Mass Identification of Particles
Authors: Briscoe William L.
Published: February 2005

This paper describes a circuit for identifying protons, deuterons, and tritons. The identification is accomplished by obtaining the product of the energy and the initial space rate of energy loss. The product is modified so that each type of particle gives a unique result in the form of an output pulse having an amplitude nearly proportional to the mass of the particle. The circuit as given is capable of handling input pulses as narrow as 1 μsec, although shorter pulses may be used if some test features are eliminated. The multiplying operation is performed by QK-329 tubes, using the principle of difference of squares.
Photoproton Scintillation Spectrometer
Authors: Whetstone A. , Allison B. , Muirhead E. G. , Halpern J.
Published: February 2005

An apparatus is described for the measurement of the energy and angular distribution of protons from (γ, p) reactions. A method is presented for obtaining energy spread of 3% for protons of 3 to 15 Mev with a NaI scintillator of 1-in. diam aperture. Energy calibration of the detector with monoenergetic protons gives an energy vs pulse-height line having an intercept of 0.46±0.10 Mev. The ratio of α particle to proton energy for equal pulse heights is found to be 1.93±0.04 for 4.48-Mev α particles. A CsI scintillator, similarly mounted, yields an intercept of −0.17±0.15 Mev and an α-proton energy ratio of 1.66±0.07 for 5.3-Mev α particles. A modification of the phoswich to provide discrimination against electrons is described.
Gearing System for a Continually-Aligned Two-Crystal X-Ray Spectrometer
Authors: Hanson Harold P. , Economy Richard
Published: February 2005

A two crystal x-ray spectrometer which is able to scan continuously through Bragg angles of 10°–45° has been put into operation. The appropriate angular changes of the components, first pointed out by Allison, are effected through a planetary gear system. The unit in use is adapted to a Norelco goniometer.
Construction of Small Fixed Leaks of Predictable Throughput
Authors: Gordon Stuart A.
Published: February 2005

A method is described by which glass capillary leaks with extremely small flow rates can be easily and rapidly produced. The predictability of these leak rates is determined by the resolution of the optical system used in measurement of bore diameter. Data are given which will allow construction of such leaks. A manifold of leaks is described which will introduce gas into a high-vacuum system at several different fixed leak rates. It contains no moving parts or high vapor pressure material on the high-vacuum side, yet the leak rates can be manipulated over a wide range. The characteristic features of these leaks are shown to be reasonable in light of well established theory.
Method for the Rapid and Precise Determination of the Densities of Liquids
Authors: Gaines G. L. , Rutkowski C. P.
Published: February 2005

A device, based on Archimedes' Principle, and involving the use of a sensitive quartz spiral as a measuring element, has been constructed to permit the rapid measurement of the density of liquid samples. With n-butanol-n-heptane solutions which we have used for calibration, a precision of 1 in the fourth decimal place has been obtained.
He3 Cryostat for Measuring Specific Heat
Authors: Seidel G. , Keesom P. H.
Published: February 2005

An apparatus employing a bath of liquid He3 as a coolant has been developed for measuring specific heats below 1°K. Temperatures as low as 0.30°K can be maintained for long periods of time. A description of a simple thermal switch is also included.
Electronic Tracing of Oscilloscope Displays
Authors: Hertz C. H. , Möller E.
Published: February 2005

An electronic circuit is described which permits the direct recording of a repetitive high-frequency signal shown on the screen of a CRO by a common pen recorder. This is achieved by the intermittent connection of a condenser through a special type of gate to the Y-deflection plates of the CRO, the gate being opened only during a very short time at a delay time Δt after the X-sweep initiation. In this way the condenser is charged proportionally to the signal amplitude at the time Δt. If the voltage of this condenser is registered by a pen recorder, an exact copy of the signal displayed on the CRO screen will be obtained if Δt is slowly varied from zero to maximum sweep duration.
Suppressing Side-Band Interference in Superregenerative rf Spectrometers
Authors: Dean C. , Pollak M.
Published: February 2005

By slowly modulating the quench frequency, the side-band responses of a superregenerative spectrometer to a nuclear resonance can be prevented from appearing in a recorded spectrum. When searching for an unsplit Zeeman component in a nuclear quadrupole spectrum, an equivalent simplification of the recorded spectrum can be obtained by slowly modulating the magnetic field. Satisfactory spectrometers and the required modulation and compensation circuits are described.
Couette Viscometer for Structural Viscosity Studies
Authors: Baarli J. , Gussgard K.
Published: February 2005

A description is given of a rotational viscometer where the velocity gradient can be varied from 0.167 sec−1 to 250 sec−1 for liquids with viscosities around one centipoise. Measurements of the viscosity are made by using an electrostatic system. Discussion of the calibration of this instrument together with estimation of the error associated with each measurement are given. The total relative error as a function of the velocity gradient for water having a viscosity of one centipoise has been determined experimentally. The error at 0.167 sec−1 is 13% decreasing to 1.2% at a velocity gradient of 10 sec−1.
Modified Spin-Echo Method for Measuring Nuclear Relaxation Times
Authors: Meiboom S. , Gill D.
Published: February 2005

A spin echo method adapted to the measurement of long nuclear relaxation times (T2) in liquids is described. The pulse sequence is identical to the one proposed by Carr and Purcell, but the rf of the successive pulses is coherent, and a phase shift of 90° is introduced in the first pulse. Very long T2 values can be measured without appreciable effect of diffusion.
Induction Flowmeter
Authors: Cushing Vincent
Published: February 2005

According to Faraday's law of induction an electric field will be induced in a medium moving relative to a magnetic field. This induced electric field is proportional to the intensity of the magnetic field and to the relative velocity of the moving medium. When applied to media of arbitrary electrical conductivity and dielectric constant, it is seen that any potential difference that arises in connection with the induced electric field is attenuated by the shunting effect of the permittivity of free space. For most media this shunting effect is negligible; for media of extremely low conductivity, however, the effect is appreciable. Finally the effect of the electrical properties of the containing pipe is investigated.
Micromodulator—A Device for Measuring the Intensities of Microwave Absorption Lines
Authors: Mattuck R. D. , Strandberg M. W. P.
Published: February 2005

A simple device for rapid measurement of the intensities of microwave absorption lines has been constructed. It requires only a small electromagnet and power supply and utilizes a free electron resonance to provide a standard comparison line at any frequency from 0 to 40 kMc. Preliminary tests carried out on ammonia at K band indicate reproducible results with errors of less than ±30% in most cases. Suggestions are made for improving the accuracy of the measurements.
Modulation Pickup in Nuclear Magnetic Resonance rf Spectrometers
Authors: Robinson G. B. , Geiger F. E.
Published: February 2005

Radio-frequency oscillators used as detectors of nuclear paramagnetic resonance absorption employ an auxiliary source at audio frequency to modulate the static magnetic field. A small component of voltage at this frequency is usually induced into the tank coil of the oscillator. If this voltage is permitted to appear at the grid of the oscillator, mixing with the rf voltage will occur. This produces a false signal indistinguishable from the resonance signal. A simple LC filter put between tank circuit and oscillator tube is found to be extremely effective in removing false resonances. The response of the oscillator to signals generated by a Watkins calibrator is measured in the range from 5 to 25 Mc. Results of these and ``Q'' measurements show the oscillator sensitivity to be unimpaired by the addition of the LC network.
Linear Amplifier for Negative Pulses
Authors: Penfold A. S.
Published: February 2005

A two-tube, noninverting, linear amplifier is described. It has a gain of 100 and an inherent rise time of 50 mμsec for outputs up to 125 v. The amplifier recovers promptly from pulses which overload it a factor of 100.
Velocity Filter for Nuclear Spectroscopy
Authors: Rietjens L. H. Th. , Bilaniuk O. M. , Parkinson W. C.
Published: February 2005

The background resulting from nuclear reaction products of the same magnetic rigidity as the particles to be magnetically analyzed is eliminated by preceding the magnetic analyzer by a velocity filter of crossed electric and magnetic fields.
Method for Analyzing Vibration at a Surface Point
Authors: Arnold J. S. , Martner J. G.
Published: February 2005

The closed path (trajectory) traversed by a point on a vibrating surface is described in terms of two components normal to each other and contained in a plane perpendicular to the surface. For the analysis of this motion a biaxial vibration pickup (BVP), using acceleration-responsive piezoelectric transducers, has been developed. The signals for the BVP are combined by an X-Y oscilloscope to synthesize the amplified trajectory of the surface point to which the pickup is applied. Phase and amplitude of the component signals are measured with a double-beam oscilloscope so that a motion map of the vibrating surface can be made.
Simple Continuous He3 Refrigeration System
Authors: Reich H. A. , Garwin R. L.
Published: February 2005

A simple continuous He3 refrigerator which uses a minimal amount of gas (80 cc STP) has been built. Temperatures below 0.5°K may be attained for as long as He4 remains in the cryostat. Commercial components are used throughout.
Theory of the Cavity Microwave Spectrometer and Molecular Frequency Standard
Authors: Beers Yardley
Published: February 2005

A short section of a wave guide is considered as a nonresonant absorption cell and then as a resonant cavity. It is shown that the latter gives a better signal-to-noise ratio by a factor which depends upon the relative intensity of the various noise sources but which increases with the Q. It is shown that the voltage signal-to-noise ratio is proportional to the square root of the product of the volume and the Q and otherwise is independent of the shape. This result leads to the conclusion that it is possible in theory to build microwave spectrometers having signal-to-noise ratios some 50 db larger or capable of detecting absorption coefficients some 300 times smaller than spectrometers which are now widely used. However, practical considerations probably would prevent this advantage from being realized completely. These results are applied to a frequency standard using an absorption line. It is shown that it is possible to build a standard using the 3,3 line of NH3 with a fractional stability of about 4×10−12 over an extended interval of time. Some discussion of spectrometers with long nonresonant cells is also included.
Luminescent Effects in Photomultiplier Tube Faces and Plexiglas Čerenkov Detectors
Authors: Anderson Kinsey A.
Published: February 2005

By means of 20 and 35 Mev proton beams obtained from the University of Minnesota Linac, luminescent effects in Plexiglas Čerenkov detectors have been investigated. It was found that 1% of the protons entering the detector produced light pulses which overlapped the mu-meson Čerenkov light distribution. These light pulses correspond to energy losses in a sodium iodide crystal of mainly less than 20 kev. Luminescent effects in the glass face of the particular photomultiplier employed were also studied and found to be quite large.
Optimization of Frame Rates for High-Speed Photography
Authors: Rona Thomas P. , Feldman Charles L.
Published: February 2005

The numerical results obtained from high-speed photography are examined in order to determine the frame rate best suited to a given phenomenon. Procedures for optimum frame rate determination are shown for deterministic and random space-time functions with emphasis on error reduction in velocity measurements. Characteristics of the random errors of a typical high-speed camera are given.
New Device for Obtaining X-Ray Diffraction Patterns from Substances Exposed to High Pressure
Authors: Jamieson John C. , Lawson A. W. , Nachtrieb N. D.
Published: February 2005

A device is described for obtaining powder diffraction patterns of thin sheets pressed between opposing diamond pistons. The pressure, initially applied by a small auxiliary laboratory press, is clamped onto the sample by a lock-nut. The whole unit is designed to replace the sample mount of a standard x-ray diffraction unit. Sample patterns taken on two of the high pressure modifications of bismuth are exhibited.
High-Pressure Microwave Window
Authors: Lawson A. W. , Smith George E.
Published: February 2005

Two conically tapered single crystals of Al2O3, with small ends abutting, are used to simultaneously effect a high pressure seal and provide a matched transformation from a standard 1-cm circular wave guide at atmospheric pressure to a circular wave guide terminated by a high-Q cavity resonator with an internal hydrostatic pressure up to 104 bars.
Automatic Control and Programing System for Single Crystal Diffractometry
Authors: Langdon F. , Frazer B. C.
Published: February 2005

An automatic control and programing system for the collection of single crystal diffraction data is described. The system has been designed for a neutron diffractometer, but it could easily be adapted for use with x-rays.
Logarithmic Characteristic of Triode Electrometer Circuits
Authors: Chao Stanley K.
Published: February 2005

The triode-connected 5889 electrometer tube was found to be useful as a logarithmic element over a grid current range of 10−14 to 10−6 amp. The relationship of plate current to grid current was carefully studied over a span of three and one-half decades as a function of the plate supply potential, the plate circuit load resistance, and the filament voltage. A circuit was developed for use in an ionization chamber survey instrument. Most 5889 tubes will work in the circuit after a 150-hr aging period. Over-all accuracy of ±10% of the reading is feasible.
Mass Spectrometer Leak Detector with Improved Sensitivity
Authors: Peters John L.
Published: February 2005

A new type of mass spectrometer leak detector is described which has a sensitivity for helium of 10−13 standard cc/sec with a signal-to-noise ratio of unity. Operating pressure is in the 10−5 to 10−6 mm Hg range, time for ⅔ of final response is 2 sec or less, and operating characteristics are similar to present helium-sensitive mass spectrometer leak detectors.
Carbon-14 Respiration Pattern Analyzer for Clinical Studies
Authors: Tolbert Bert M. , Kirk Martha , Upham Frank
Published: February 2005

A description of an instrument for measuring C14, percent CO2, and C14 specific activity in the breath of human subjects is presented. Ionization chamber assay for the C14 is used. The design parameters of radioactivity sensitivity and response time are discussed. For simple carbon-14 metabolites some 1 to 10 μC are required for an eight-hour respiration analysis with this instrument.
Single-Line-Scan Television
Authors: Harris F. H. , Ainsworth J.
Published: February 2005

Equipment was constructed to demonstrate the practicability of using a Vidicon camera tube for measuring the space orientation of spin stabilized Aerobee-Hi research rockets. While ordinary television pictures are badly blurred by camera rotation, laboratory photographs which were obtained by means of a spinning, line-scan camera demonstrated that this method can be used to obtain pictures whose quality is similar to those of standard television.
Optimum Input Leads for Cryogenic Apparatus
Authors: McFee Richard
Published: February 2005

Electrical leads carrying currents into cryogenic apparatus also introduce heat. Even with an ideal Carnot cycle, the mechanical power needed to remove this heat can be one hundred or more times the heat flow itself. If the currents and hence the input leads are heavy, a very sizeable refrigerator may be required. In this article the configuration of the leads which minimizes the influx of heat is derived theoretically, taking variations in thermal and electrical conductivity into account. Graphs are given for the minimum heat flow and optimum cross section of a copper input lead carrying arbitrary current I. The optimum is found to be fairly sharp. If the diameter of the lead differs by a factor of two from the optimum, the influx of heat is increased by over 100%.
Vernier Chronotron
Authors: Lefevre Harlan W. , Russell James T.
Published: February 2005

The instrument described is a multichannel time interval analyzer with digital output for use in the millimicrosecond region. The analyzer consists of two circulating transmission lines with a single fast coincidence circuit between them and associated gating circuits. Each circulating line is a precisely trimmed coaxial cable with its ends joined by a two-stage noninverting saturating amplifier. A circulating pulse delivers time marks to the input of the coincidence circuit. By making the circulation periods of the two lines slightly different, the time marks are made to arrive at slightly different frequencies. The instrument is a true vernier. To measure an interval it is only necessary to count the number of circulations before coincidence and multiply by the difference in circulation period of the lines. A commercial 256-channel magnetic core memory is used for storage.

The circuit of the instrument is described. A method is described for predicting circulation threshold, growth to equilibrium, and equilibrium amplitude of a circulating pulse from the amplifier transfer characteristic. Data are presented which indicate the linearity, stability, and time resolution of the instrument.
High-Power Vacuum Spark Gap
Authors: Hagerman D. C. , Williams A. H.
Published: February 2005

The design and construction of a voltage graded vacuum spark gap is described. This gap is capable of switching currents as large as 106 amp at voltages up to 75 kv. The effect of the insulating walls of the gap is briefly discussed.
High-Q Stark Cavity Absorption Cell for Microwave Spectrometers
Authors: Dymanus A.
Published: February 2005

Design considerations, description, and some data on the performance are given of a large pillbox-shaped Stark cavity absorption cell for the 1.25-cm wavelength region. The cavity can be used in any TE0m1 mode with m ranging from about 5 to about 12 and its most prominent features are: high loaded Q factor (∼5×103−104), good electric insulation (at pressures below 4×10−2 mm Hg Stark voltages up to 3000 v can be applied), low Stark field inhomogeneity (diameter to length ratio 15–20), large band width (from about 18 to about 28 kMc), and low mode density. No cross-mode resonances occur and the only undesired modes excited appreciably are the TE2m1 ones. When used in transmission only the TE0m1 modes couple to the output.

The cavity can be used at the same time as a reference cavity of a Pound-type klystron frequency stabilizer. The klystron frequency will then automatically follow the resonance frequency of the cavity over a frequency interval up to 400 Mc.
Optical Method for Determining the C Axis of Ruby Boules
Authors: Mattuck R. D. , Strandberg M. W. P.
Published: February 2005

A simple method is described for locating the C axis of an uncut ruby crystal. The procedure involves measurement of the angular position of the ruby for zero light transmission when it is placed between crossed polarizer and analyzer. The precision is ±1°.
Cosmic-Ray Instrumentation in the First U. S. Earth Satellite
Authors: Ludwig George H.
Published: February 2005

The first U. S. satellite, 1958 Alpha (Explorer I) carried instrumentation to measure cosmic-ray intensity, micrometeorite impacts, and temperatures within the satellite. The instrumentation was designed with emphasis on conservation of electrical power, on stable and reliable operation, on operation over a wide range of temperatures, and on compactness and mechanical ruggedness.

The cosmic-ray instrumentation in 1958 Alpha operated according to expectations, providing several hundred recordings of data received during transits over ground stations. These data led to the discovery of a belt of high-intensity radiation around the earth.
Random Number Generator Using Subharmonic Oscillators
Authors: Sterzer Fred
Published: February 2005

A random number generator which uses two 2000-Mc subharmonic oscillators is described. This generator can produce random binary digits at a maximum rate of approximately 3×107 digits per second. Statistical tests performed on over a quarter-million digits produced by this generator indicate that they were at least as random as digits produced by other slower contemporary means.
Ion Focusing Properties of a Quadrupole Lens Pair
Authors: Enge H. A.
Published: February 2005

The focusing properties of a quadrupole lens pair have been studied, and the results of thick-lens calculations are presented in the form of graphs showing the field strength parameters and magnifications as functions of object and image distances.
Recording Optical Pyrometer
Authors: Blum Norman A.
Published: February 2005

A recording pyrometer which measures the brightness temperature at 0.65 μ of a small incandescent sample in the range 1300°C to above 3000°C with a time constant of a few milliseconds is described. The instrument, designed to be used in studies of materials exposed to the plasma jet of a high-intensity electric arc, is reliable to within ±20°C, and is suitable for measuring transient high-temperature fluctuations or for applications where use of a standard optical pyrometer might be hazardous to personnel.
Performance of a Piston-Expanded Bubble Chamber
Authors: Courant H. , Jensen J. E. , Louttit R. I. , Sanford J. R.
Published: February 2005

With liquid hydrogen as the track sensitive medium, electron tracks were observed from 26.1 to 28.9°K. Using liquid deuterium, the range was 30.5 to 32.6°K. The upper limits in both cases were imposed by the apparatus. Data on expansion pressures, sensitive times, and refrigerant consumption are presented.
22-Mev Electron Linear Accelerator
Authors: Austin N. A. , Fultz S. C.
Published: February 2005

This paper describes a 22-Mev electron linear accelerator of the traveling-wave type with several unique features. The features include the combination of an rf driven prebuncher cavity and a buncher of a new type in the first section of accelerator guide in order to obtain high-peak currents and minimum beam energy spread. A separately pulsed gun grid provides fast beam pulse rise time for use in neutron research. The accelerator and major electronics are housed in a single rf shielded rigid cabinet, which facilitates portability for field operations. The beam energy is continuously variable from 2 to 27 Mev; peak current for a one-μsec pulse is 380 ma; pulse rate is variable from 1 to 200 pulses per second; pulse length is variable from 0.2 to 2.4 μsec; and pulse rise time is adjustable from 0.2 to 0.4 μsec.
Recording Microwave Hygrometer
Authors: Sargent Jack
Published: February 2005

A description is given of a microwave refractometer designed to measure and record the water vapor pressure in a moving air stream, particularly at very low vapor pressures. The instrument has a sensitivity of 0.004 mm Hg with a four decade range extending to 71.3 mm Hg vapor pressure. By means of microwave techniques the difference in refractive index between dry and humid air is determined and then converted to vapor pressure by an empirical formula. The instrument can be readily calibrated by the use of pure gases whose dielectric constants are precisely known. Because of the automatic null-balancing technique used, the instrument has excellent calibration stability. Test results involving the measurement of known vapor pressures in the ranges of 0 to 0.15 mm Hg and 0 to 15 mm Hg are described. Possible applications of this instrument for the measurement of refractive index variation and its use for quality control are briefly discussed.
Permanent Magnet for Atomic Beam Focusing
Authors: Christensen R. L. , Hamilton D. R.
Published: February 2005

A compact six-pole permanent magnet useful for focusing of atomic beams is described, together with the equations of motion of atoms in its field as used in its design. The method of construction, magnetization, and measurement of its field are discussed.
Simplified Coincidence Circuits Using Transistors and Diodes
Authors: Miller R. H.
Published: February 2005

The fast semiconductor diodes and transistors now available make it possible to design counting circuits which are as fast as standard fast vacuum tube circuits. A simple coincidence circuit using these devices is described. The measured threshold and resolving time characteristics are given. The circuit is free from the difficulty present in some vacuum tube circuits wherein a coincidence count can be made with a pulse below the threshold at one input if a pulse considerably above the threshold is present at another input. The changes in counting arrangements which the simplicity of these circuits permits are discussed.
New Electron Diffraction Apparatus for Continuous Recording
Authors: Thun R.
Published: February 2005

A new electron diffraction device is described which is especially suited for the investigation of diffusion problems, phase transitions, and reactions of solids with gases or other solids. It is equipped with a continuously recording camera where a 4×10 in. photoplate passes underneath a narrow slit exposed to the diffraction cone. The resulting photograph shows parallel diffraction lines instead of the usual Debye-Scherrer rings and gives a gapless picture of the occurring structural changes which are easy to evaluate. If the sample is heated according to a known temperature-time function, the temperature-structure dependence may be recorded, and by moving the sample synchronously with the plate through the electron beam, one may record the geometrical distribution of different structures in an inhomogeneous sample. The latter method is especially suited for a rapid investigation of unknown binary or multicomponent phase diagrams. The device includes the following special features: deposition of the sample containing up to 3 different components by evaporation inside the specimen chamber, an attachment for monitoring the sample reflectance during runs, a rotating shutter producing wedge-shaped sample layers, and a heatable specimen holder for use in transmission as well as in reflection. Finally, a few examples are given showing some applications of the described electron diffraction unit.
Plateau Slopes and Pulse Characteristics of Large, High-Pressure BF3 Counters
Authors: Mendell R. B. , Korff S. A.
Published: February 2005

Factors affecting the flatness of plateaus of BF3 neutron counters of large radius and at high pressure were investigated. Counters prepared using special purification techniques showed improved characteristics. Counters of cathode radius from 1.91 to 5.06 cm were filled to pressures of BF3 from 40 to 64 cm Hg, and their pulse-height distributions were compared. Results are discussed in terms of electron attachment in BF3 and space charge effects.
Rotating-Anode X-Ray Generator
Authors: Davies D. A. , Mathieson A. McL. , Stiff G. M.
Published: February 2005

Construction of the rotating-anode x-ray generator was based on that of A. Taylor (1949), the main difference lying in the design of the anode and of the anode-cathode assembly. The anode is in the form of a flat disk, ⅞ in. thick and 6 in. in diameter, with the focus on the periphery. The cathode assembly is extended to partly cover the anode. This combined anode-cathode assembly not only greatly reduces wall-heating due to stray electrons but also improves the electron-optical system. With zero-bias conditions, it has been found possible with a silicated tungsten helix of outside diameter 0.065 in. to concentrate 200 ma into a line focus 0.020×0.40 in. with nominal spread outside the focal area. The cooling system is cyclic.
Use of Capacity-Controlled rf Energized Ionization Transducer for Balancing Rotors
Authors: Gross W. A.
Published: February 2005

A rotor-balancing technique is described in which conventional laboratory equipment may be used. The orbiting motion of a rotating shaft within its own fixed bearings is detected by capacitor probes. After passing through the transducer circuit, the signal is displayed on an oscilloscope. It is therefore possible to obtain the necessary balancing information at operating conditions.
Preparation of Diffusion Couples by Cathodic Sputtering
Authors: Weil Rolf , Rothman Steven J. , Lloyd Lowell T.
Published: February 2005

Apparatus and techniques are described for preparing metal diffusion couples by cleaning the sample surface and depositing an isotope layer by cathodic sputtering.
Single-Crystal Automatic Neutron Diffractometer
Authors: Prince E. , Abrahams S. C.
Published: February 2005

An automatic neutron diffraction system for measuring the intensities of all accessible reflections in a zone is described. Crystal and counter setting information is supplied to the instrument on five-channel punched paper tape. The angular settings are measured by means of analog-to-digital converters. All angle information is printed out digitally, together with the diffraction intensity information.
Volume and Index Measurements of Blood Cells with a Recording Diffractometer
Authors: Polanyi Michael L.
Published: February 2005

The measurement of the diameter and index of refraction of spheres whose diameter is larger than the wavelength of the light used and whose index, relative to the surround, is close to unity is described. The measurements are based on the angular position of the first dark ring and first bright ring in the Fraunhofer diffraction pattern.

The instrument is of novel design, its main advantages being that all the light scattered under a given angle is used in the measurement and that the peaks and valleys in the recorded graph are very prominent and easy to locate. The resolving power of the instrument is inversely proportional to the diffracting angle. The use of the Van de Hulst approximate diffraction theory for obtaining the diameter and the index of the diffracting spheres from the recorded diffraction pattern is described in detail. Application to the measurement of human blood cells, the main purpose of this work, is also completely worked out and experimental results are given. Very good agreement between the mean cell hemoglobin as measured with the standard procedures and the one described here has been found.
Comparison Study between a Microwave Interferometer and an Electrical Contact System for Following the Motion of High-Speed Projectile
Authors: Slawsky Z. I. , Seigel A. E. , Ho L. T. , Kopp H. J. , Vanderslice J. T.
Published: February 2005

A comparison study has been made between two different methods of tracking a high-speed missile in a barrel. This comparison between a microwave interferometer and an electrical contact system indicates that there are no systematic errors in either system in the velocity range from 250 m/sec to 425 m/sec. It is pointed out, however, that the microwave system must be used if reliable isentropic pressure vs density curves are to be obtained for the expanding gas behind the missile.