bluuebunny/crossref_metadata_2025_split huggingface dataset:
Construction and Calibration of a Cylindrical Electrostatic Analyzer
Authors: Allison S. K. , Frankel S. P. , Hall T. A. , Montague J. H. , Morrish A. H. , Warshaw S. D. 
Published: February 2005

A cylindrical electrostatic deflector has been constructed with average radius 15 cm, spacing 0.5 cm and deflection 90°, in which the deflecting potential can be in the neighborhood of 50 kv. Thus protons up to 0.75 Mev can be focused. Movable slits have been incorporated in the design, and the geometry of the entrance and exit apertures of the deflecting channel is such that the stray field may be calculated analytically. This has been done for the case in which the deflecting plates are symmetrically charged above and below zero potential. The predictions have been compared with experiments on the focusing of electron beams by the instrument under controlled conditions. Agreement with the calculations is demonstrated within the accuracy of the experiments, which is about 0.3 percent.
Experiments with asymmetric charging of the electrodes are reported and shown to agree with a plausible extension of the theory. Further experiments investigated the effect of small displacements of the slits from the computed focal positions. A set of factors, or calibration constants, has been measured so that, given the coordinates of the centers of the entrance and exit slits, and the potentials applied to the deflecting plates, the kinetic energy of the focused ion beam, as it left its source at zero potential, can be calculated to within 0.3 percent.
A Microwave Secondary Electron Multiplier
Authors: Greenblatt M. H. 
Published: February 2005

The construction and operation of a dynamic electron multiplier, of the type sometimes called a multipactor, is described. Briefly, the multipactor consists of two parallel secondary emissive plates having an alternating voltage across them. The magnitude of the voltage is adjusted so that the transit time across the gap for electrons starting with zero velocity from one of the plates when the field is passing through zero shall be just one-half the period of the a.c. voltage. In this way, electrons and their secondary descendents can be made to bounce back and forth between the plates and multiplication takes place. The necessary phase relationships between the electrons and the field are discussed.
The multipactor described here uses 10 cm microwave power to get the a.c. voltage. It has been used as a gamma-ray detector in which case the cavity is ``broken down'' by the multiplication of a Compton electron ejected from the cavity wall by a gamma-ray. This breakdown gives rise to a microwave pulse several millivolts high at a crystal rectifier. The efficiency of this process is about 1.5×10−5 count/gamma-ray. The rise time of the pulse is calculated to be about 5×10−10 sec. and is measured to be less than 10−7 sec. The deadtime is presumed to be about 5 microseconds.
The Theoretical Background of the Multiple Pressure Tube Anemometer
Authors: Goudy Paul R. , Colvin Henry F. 
Published: February 2005

A recent investigation has resulted in the development of a multiple pressure tube anemometer, which measures both wind speed and direction without moving parts exposed to the wind.
From the expression for the air flow past a quadric surface, it is shown that, by the use of one system of suitably spaced impact holes, it is possible to measure the rectangular components of wind velocity in one quadrant. Another arrangement of holes is presented that takes advantage of the breakdown in flow pattern past 90° to measure wind components in all quadrants without ambiguity.
The components of wind velocity so measured are combined in an electromechanical system which provides indications of speed and direction.
Finally, the experimental instrument embodying these principles is evaluated and performance data taken from it are presented.
An Analog Computer
Authors: Bayly J. G. 
Published: February 2005

An integrator has been constructed which is capable of computing the yield of nuclear reactions produced by radiation of intensity that varies arbitrarily with time. By combining the appropriate number of such machines the yield resulting from a series of consecutive reactions may be found.
While the emphasis in this paper is on applications involving the yield of radioactive isotopes produced by a pile or other source of radiation, the instrument may be used to calculate temperatures in thermodynamic problems, voltages and currents in electrical networks, and so on, wherever the quantity (x) to be determined is governed by the differential equation dx/dt=−λx+f(t),f(t) being a given function of the time, and λ a known constant.
A Sector-Type Double-Focusing Magnetic Spectrometer
Authors: Rosenblum Earl S. 
Published: February 2005

An analysis is made of the focusing characteristics of a magnetic spectrometer having an annular magnetic field which varies approximately with 1/r½, thus permitting axial as well as radial focusing of particles of a given energy. By considering the field angle and source location as independently variable, the analysis provides for an instrument more flexible in use than similar existing types.
An optical analogy is developed from which a first approximation to the field shape is made, and from which the source and image location, magnification, dispersion and resolution can be readily obtained. Information thus obtained, combined with the results of an investigation into the image shape based on a series expansion, through second order, of expressions for the field strength and particle coordinates, yields more detailed information on the field shape which gives optimum focusing conditions and resolution for any chosen set of initial conditions.
Comparisons are made with the homogeneous field spectrometer and with the spectrometer of Svartholm and Siegbahn.
Molecular Diffraction Attachment for RCA Microscope
Authors: Heston B. O. , Cutter P. R. 
Published: February 2005

A new device for the distribution of vapors across an electron beam for molecular diffraction studies is described. The efficiency of the new method has made it possible to obtain molecular diffraction patterns with an electron microscope without need of alterations.
The vapors are ejected from a circular crest of a diffusion box immediately surrounding the beam to give a heavy concentration of vapors in contact with the beam while releasing a small amount of vapor. The method has been standardized with well known patterns of CCl4 and CBr4.
The Chalk River Single Crystal Neutron Spectrometer
Authors: Hurst D. G. , Pressesky A. J. , Tunnicliffe P. R. 
Published: February 2005

A single crystal neutron spectrometer has been constructed which shows improvement in resolution and intensity over previously described instruments. This has been made possible by the high flux available from the Chalk River heavy water reactor. The instrument can be operated automatically.
Mechanical design, crystals, resolution and the contamination of the spectrum by higher orders are discussed.
A High—Low Temperature Microscope Stage
Authors: Cech R. E. 
Published: February 2005

A microscope stage has been designed and constructed which permits microscopic observation of metal specimens from the temperature of liquid nitrogen to an upper temperature usually determined by the melting point of the specimen.
The stage consists of a vacuum-tight water or liquid nitrogen-cooled copper chamber in which a specimen is heated by passage of an electric current. A quartz window in the chamber permits ``at temperature'' observation of the specimen. Operation of this stage is described.
A Reflectionless Wave-Guide Termination
Authors: Grantham Rodney E. 
Published: February 2005

A reflectionless termination design is described which, in principle, can be adapted to wave-guide or coaxial transmission lines. Reflection coefficients of 0.001 were obtained experimentally with X-band wave-guide terminations. The termination comprises a section of transmission line into which is fitted a tunable sliding load. The sliding load is tuned to be reflectionless by means of the ``sliding load'' method of measuring reflection coefficients. The termination can be operated over a wide frequency range but must be retuned each time the frequency is changed.
The wave-guide circuit of the load is analyzed and design equations are derived.
The reflectionless wave-guide termination is primarily useful as a reference standard for microwave impedance bridges.
Spherical Electrostatic Analyzer for Measurement of Nuclear Reaction Energies
Authors: Browne C. P. , Craig D. S. , Williamson R. M. 
Published: February 2005

A spherical electrostatic analyzer was constructed for use with the Wisconsin cylindrical analyzer in accurate measurements of nuclear reaction energies. The focusing properties of such an instrument have been described by Purcell. It has the unique feature of providing a large solid angle and high resolution for a very small angular spread of the reaction products.
Only a portion of the entire sphere is used. This is 90° along the path of the particles with a 60° azimuthal opening. The mean radius of the gap is 18 inches and the gap spacing is 316 inch. One million volt protons may be focused with a gap voltage of 20.2 kv. The analyzer is designed to fit over the cylindrical analyzer and to accept particles at an angle of 135° from the bombarding beam.
Alignment, focus, and resolution tests show that the difficult machining of the plates has been done satisfactorily and that the analyzer is properly aligned. A shutter allows small sectors of the total gap to be tested individually. A sharp focus is obtained and all sectors focus particles of the same energy for a given gap voltage.
Resolution tests and calibration are made using monoenergetic protons scattered from thin targets of heavy elements. A plot of the number of particles entering the detector vs the voltage across the spherical gap gives the resolution. With 1-mm object and image apertures the measured energy resolution is 650. The measured effective solid angle with this source size and resolution is 3.2×10−3 steradian.
A Densitometer Which Records Directly in Units of Emulsion Exposure
Authors: Brown Walter N. , Birtley Willard B. 
Published: February 2005

The use of photographic emulsions to record the spatial distributions and the intensity of radiation in spectroscopy, x-ray diffraction, astronomy, and other fields is hampered by the sensitivity of the characteristic curve to development and exposure conditions. The deflection of a microphotometer or microdensitometer of conventional design cannot be made directly proportional to the intensity of radiation which is incident upon the element of area of the film or plate at the time of exposure.
The recording microdensitometer described herein incorporates a device, termed a function transformer, which automatically and continuously converts densitometer deflection values to exposure values, and two pen and ink recorders. One recorder produces a direct exposure trace, while the other records the usual densitometer trace. An integrator permits the integrated exposure to be evaluated for any desired portion of the plate or film.
The apparatus described can be used with any film or plate to which a suitable calibrating exposure has been applied and over the area of which the characteristic curve is sufficiently uniform.
A Phase-Shift Refractometer
Authors: Tolbert C. W. , Straiton A. W. 
Published: February 2005

This paper describes a refractometer for measuring small changes in the dielectric constant or index of refraction of atmospheric air. The method employed is that of measuring the change in phase of a 9375 megacycle per second radio wave along a path approximately three feet long caused by a change in the average dielectric constant of the air over the path.
The test path may be confined to a wave guide through which air is drawn, or it may be the space between two antenna systems. Because of the greater rigidity and the elimination of reflections, the wave guide system is able to measure short time changes in the index of refraction with an error of less than one part in a million. The antenna arrangement usually has somewhat larger error because of the flexibility of the supports and the external reflections.
Measurement of Low Level Radiocarbon
Authors: Anderson E. C. , Arnold J. R. , Libby W. F. 
Published: February 2005

Techniques are described for chemical purification and measurement of radiocarbon at natural levels (10−12 curie/g or less). The chemical cycle has the following steps: (1) conversion of the starting material to carbon dioxide, by combustion or hydrolysis, (2) precipitation as calcium carbonate, followed by evolution of the purified carbon dioxide, (3) reduction to elementary carbon with magnesium turnings, and (4) extraction with hydrochloric acid and water to remove magnesium and magnesium oxide. The over-all yield is about 85 percent, based on the carbon in the original sample.
The counting is done in a screen-wall counter, twenty-four inches long, with an eight-inch effective counting length. The sample (about 8.5 g) is mounted uniformly in an ``infinitely thick'' layer, on a split cylinder which can be shifted from ``sample'' to ``background'' position by sliding from end to end of the counter. An argon-ethylene filling is used. The background of the counter (about 400 cpm, unshielded) is reduced to 4.5 cpm by the use of an eight-inch thick iron shield and eleven anti-coincidence counters, eighteen inches long. The calibration of the counter on an absolute basis is described. Its efficiency for a 20 mg/cm2 layer of carbon, over a 400 cm2 area, is 5.46±0.03 percent.
An Improved dc Amplifier for Portable Ionization Chamber Instruments
Authors: Moody N. F. 
Published: February 2005

It is widely recognized that the zero stability of dc amplifiers for measuring currents in the micro-micro-ampere region can be enhanced by the application of negative feed-back. The promised advantages are often not fulfilled, however; and a design approach which emphasizes the economic exchange of amplifier gain for these benefits is outlined. In portable battery-operated ionization chamber instruments, which are the main concern of this paper, it is not easy to achieve the loop gain needed for optimum performance; and a subsidiary reflexing scheme is adopted to overcome the limitation.
In conclusion a practical instrument incorporating this improved circuit receives brief discussion and performance figures are given.
Delayed Coincidence Circuit for Scintillation Counters
Authors: Lundby Arne 
Published: February 2005

Using organic crystals or liquids as scintillators and 1P21 photomultipliers as detectors, a delayed coincidence circuit has been designed for measuring nuclear lifetimes in the region 10−10−10−7 sec. The pulses from the photomultipliers were amplified in distributed amplifiers and applied to a germanium diode bridge coincidence circuit.
The apparatus has been used for measuring scintillation decay times, the lifetimes of nuclear transitions, and the time of flight of light over distances of the order of one meter.
A Comprehensive Counting System for Nuclear Physics Research Part I. Basic System and Synthesis of Simple Instruments
Authors: Moody N. F. , Howell W. D. , Battell W. J. , Taplin R. H. 
Published: February 2005

A majority of nuclear measurements involve digital pulse counting so that the associated instruments have many common functions. Further investigation reveals that these counting systems fall into two broad classes: Those in which all pulses exceeding a certain threshold are summed, and a more complex analyzing procedure wherein pulses must be classified according to amplitude or temporal distribution.
In the former class are found the orthodox scalers, while the latter defines the pulse amplitude analyzers and other machines capable of yielding spectral distributions.
It is found that such instruments may be synthesized from a common group of sub units, and these are outlined and listed on a functional basis.
While the utility of the sub units is evidently determined by their versatility, they are in addition required to have high reliability in order that complex assemblies may give satisfactory service. Design for long life follows naturally from the latter consideration.
The next section of the paper shows the manner in which the simpler instruments can be synthesized according to the proposed scheme and outlines the more complex automatic counting and analyzing systems to follow in later parts of the paper. In particular the construction of a range of scalers is illustrated and their performance specifications and photographs are shown.
Regulated Low Voltage Supply for Electrolysis and Other Uses
Authors: Greenough M. L. , Williams W. E. , Taylor John Keenan 
Published: February 2005

An electronic power source for use in selective electrolysis or as a low voltage regulated supply is described. Its output is dc continuously controllable from zero to five volts at two amperes. Among its features are ripple content of 0.1 percent, and an output resistance of 0.01 ohm. The input impedance of the regulator circuit itself is in the order of 10 megohms, permitting control from high resistance electrodes.
The instrument uses a variable-amplitude two-kilocycle carrier which is amplified by a power stage and fed to a dry-disk rectifier. The output is then automatically controlled for equality to a self-contained adjustable reference voltage. With modifications in the high level stages, the circuit is adaptable to a wide range of output capabilities.
Rotor Temperature Measurement and Control in the Ultracentrifuge
Authors: Waugh David F. , Yphantis David A. 
Published: February 2005

Moving rotor temperatures may be measured with a precision of ±0.03°C and an accuracy of 0.1°C in a vacuum centrifuge. The method does not use physical contact with the rotor but utilizes the infrared radiation from the rotor. A reference temperature is maintained in a mass of metal (reference block) placed near and shielding the base of the rotor. A copper disk, shielded also by the reference block, assumes a temperature between rotor and reference block temperatures through radiation exchange. The various temperatures and temperature differentials are determined by copper-constantan thermocouples. Heat conduction through thermojunction leads and copper disk supports, and radiation exchange between copper disk and reference block have been minimized, the copper disk maintaining a temperature 0.72 of that between reference block and rotor.
On acceleration the rotor cools, the opposite effect occurring during deceleration. Such changes are shown to be due to the adiabatic changes concomitant with the production or release of stress in the rotor. At 60,000 rpm a change of −0.9°C is observed on acceleration. On correction for kinetic heating this becomes −1.0°C. Such changes have not generally been taken into account.
By installing a chamber heating coil in addition to refrigeration, the moving rotor temperature may be kept to within ±0.05°C of a chosen temperature for indefinite periods.
Apparatus for Zeeman Effect Measurements on Microwave Spectra
Authors: Eshbach J. R. , Strandberg M. W. P. 
Published: February 2005

Apparatus and experimental techniques for Zeeman-effect measurements on microwave spectra are described. The method uses a wave-guide type absorption cell and provides for either π- or σ-type observations. Molecular rotational and nuclear gyromagnetic ratios are found to be measurable to about 1 percent accuracy.
A method is presented for sign determination of these gyromagnetic ratios using circularly polarized microwaves. The microwave components used in setting up the circularly polarized waves are described.
The IMFL Anemoclinometer—An Instrument for the Investigation of a Fluctuating Velocity Vector
Authors: Martinot-Lagarde A. , Fauquet A. , Frenkiel F. N. 
Published: February 2005

The IMFL anemoclinometer is an instrument measuring the magnitude and direction of a fluctuating fluid velocity. As a result of a measurement, three pressure differences are obtained from which the vector velocity is found. Contrary to some similar instruments, the anemoclinometer is not moved during a test and can, therefore, be easily used to obtain recordings.
Three variants of the IMFL anemoclinometer are described and their application to experimental measurements is discussed.
Some Properties of Plastics and the Use of Plastic Apparatus at Low Temperatures
Authors: Giauque W. F. , Geballe T. H. , Lyon D. N. , Fritz J. J. 
Published: February 2005

Some properties of methyl methacrylate plastic have been investigated at low temperatures to supply design data needed for the construction of plastic apparatus. The diffusion rates for air and helium have been measured at temperatures from 260 to 300°K. The diffusion coefficient k (expressed as cm3 (N.T.P.) sec−1(cm Hg−1)) is given roughly by the following relation: log10k=[(−2.85×103)/T]−1.68 for airand log10k=[(−1.28×103)/T]−4.95 for helium.
The change in length of a 30-cm rod has been measured at 298.7°, 273.16°, 194.7°, 77.3°, and 20.4°K by comparison with quartz using a depth micrometer gage. The coefficient of expansion is tabulated as a function of temperature, increasing from 0.6×10−5 at 20°K to 8.0×10−5 at 300°K. Hysteresis and geometrical distortion accompanying cooling are shown to be very small. Complex apparatus containing many seals, including various sorts of electrical leads, has been shown to be vacuum tight when tested in liquid helium II. A method of connecting a vacuum line at room temperature and a plastic apparatus at low temperatures by means of a metal tube liner-diluted rubber cement seal is described. The adsorption of helium gas has been measured at 4.2 and 1.2°K and at pressures from 4×10−4 to 4×10−1 mm.
A Recording Device for Surface Temperature Measurements
Authors: Sasaki Nobuji , Kamada Akira 
Published: February 2005

By means of a small heating coil, the temperature of a thermocouple junction is made to oscillate regularly between two temperatures T1 and T2. Simultaneously the junction makes about one contact every two seconds with the surface being measured. A short-period galvanometer in the thermocouple circuit produces on a moving photographic film a serrated sine curve whose serrations vanish once for every half-oscillation at a point that corresponds to the surface temperature T3, provided T3 lies between T1 and T2. This mode of measurement minimizes disturbances due to air currents.
Alternatively, use of a thermocouple with two adjacent junctions is proposed. A simple but accurate portable thermostat for maintaining reference junctions temperatures somewhat higher than room temperature is also described.
THE DIMENSIONS OF LOW FREQUENCY QUARTZ OSCILLATORS
Authors: Hitchcock R. C. 
Published: February 2005

The frequencies of the Curie cut quartz oscillator plates from 60 to 320 kc/sec are shown to be discontinuous functions of the dimensions.
The K, ``meters per millimeter,'' is shown to vary from 90 to 145.
It is suggested that the use of relative power measurements will insure a single frequency crystal operating at minimum damping.