bluuebunny/crossref_metadata_2025 huggingface dataset:
A Microcalorimeter Suitable for Study of Easily Absorbed Nuclear Radiations
Authors: Cannon C. V. , Jenks G. H.
Published: February 2005

A microcalorimeter suitable for measuring the energy of easily absorbed nuclear radiations is described. The calorimeter is an isothermal type operating at the temperature of liquid nitrogen and using the rate of vaporization of nitrogen under constant pressure as a measure of the heat input. The calorimeter is fairly simple to construct and to operate and has a short equilibration period. Heat inputs to the calorimeter as low as 7×10−6 cal./sec. can be measured with an accuracy of one percent.
Calcium and Cadmium Tungstate as Scintillation Counter Crystals for Gamma-Ray Detection
Authors: Gillette R. H.
Published: February 2005

The high density, transparency, and chemical inertness of calcium and cadmium tungstates, together with their reasonable luminescent efficiencies when stimulated with high energy radiation, strongly suggest their use as phosphors in scintillation counters for gamma-ray detection. Some of the properties of these crystals are reported and compared with anthracene. It is shown that with proper design, the total anode current produced by a given source is several times greater with the tungstates than with anthracene, although the latter has a more favorable pulse size distribution. Cadmium tungstate has a zero temperature coefficient of luminescence up to 40°C and shows no afterglow after exposure to intense radiation.
A Photo-Multiplier Gamma-Ray Detector
Authors: Graves J. D. , Koch G. E.
Published: February 2005

The sensitivity of the RCA 1P21 photo-multiplier to gamma-radiation has led to the investigation of the characteristics of this tube as a gamma-ray detector. The range, linearity, directional dependence, temperature dependence, applied voltage regulation requirements, and radiation energy dependence were determined for several tubes. Preliminary results concerning the ability of the tube to maintain a calibration are given. A basic circuit for such a detector is given.
A Dust Electricity Analyzer
Authors: Kunkel W. B. , Hansen J. W.
Published: February 2005

An apparatus is described by means of which the size and the charge of large numbers of microscopic particles can be simultaneously determined. The method is based on Hopper and Laby's work on the determination of the electronic charge, i.e., horizontal deflection of particles settling under gravity recorded photographically. The procedures involved are given in some detail, and the nature and limitations of the general results are discussed. Simplicity of operation and design are emphasized to render the instrument a workable tool in industrial research.
Spectral Sensitivity of Two Commercial X-Ray Films between 0.2 and 2.5 Angstroms
Authors: Seemann Herman E.
Published: February 2005

The spectral sensitivities of Kodak No-Screen and Kodak Industrial Type K X-Ray Films were determined in the region between 0.2 and 2.5A using the filtered K fluorescence of several irradiated elements as approximately homogeneous radiation. Exposures in roentgens were obtained with an air ionization chamber designed especially for the purpose. Curves are given showing the number of roentgens incident on the film which will give a developed photographic density of 1.0 above fog for the various wave-lengths. The K limits of silver and bromine are prominent. The maximum sensitivity in terms of roentgens occurs at about 0.4A, but the marked decrease found by other observers at shorter wave-lengths is probably obscured by inaccuracies. From the energy value of the roentgen, the sensitivity of the films is expressed as the incident ergs per square centimeter required to produce a density of 1.0 above fog. Computations from these results show that as the wave-length increases the films utilize the absorbed energy more efficiently. On the other hand, high energy quanta are more efficient than low energy quanta but not in proportion to their energy. In addition to the more or less gradual change with wave-length of efficiency of utilization of absorbed energy, there is evidence for sudden jumps at the K limits of Ag and Br. Qualitative explanations are given for the observed changes in efficiency.
A Monitor for Low Intensity Gamma-Rays
Authors: Kuper J. B. H. , Chase R. L.
Published: February 2005

A recording monitor for low intensity gamma-radiation has been developed, using a simple and inexpensive form of dynamic condenser electrometer in connection with an ionization chamber and a commercial recording potentiometer. Use of a rate of drift method at relatively low voltage sensitivity eliminates difficulties with contact potentials and grounding key kicks. The instrument gives an indication and recycles when 5 microroentgens have been received. Normal gamma-background current is 4 to 5×10−15 amperes and at this sensitivity the instrument is extremely rugged and operates outdoors in all weather.
Some Properties of the Parallel Plate Spark Counter II
Authors: Madansky Leon , Pidd R. W.
Published: February 2005

The delay error distribution of the parallel plate spark counter has been measured and the average delay is found to be 6×10−9 sec. The counters are, therefore, applicable to the measurement of lifetimes as short as 10−9 sec. Auxiliary circuits, including a fast synchroscope, for short time interval measurements are described, and the resolution limitations of the counters and circuits are discussed.
A Trigonometric Computer with Electrocardiographic Applications
Authors: McFee Richard
Published: February 2005

An analog computer has been built which determines (e12+e22)½ and Arc Tane2/e1 two thousand times a second with an accuracy of about five percent. Using amplified electrocardiographic voltages proportional to three perpendicular components of the dipole moment of the hearts electric field, a pair of computers of this type will be able to produce other voltages proportional to the magnitude and two directional angles of the dipole. This may simplify considerably the study of fluctuations in the direction of the dipole and the neutralization of the effects of abnormal heart positions.
An 80-Mev Model of a 300-Mev Betatron
Authors: Kerst D. W. , Adams G. D. , Koch H. W. , Robinson C. S.
Published: February 2005

The construction and operation of a flux-biased 80-Mev betatron is described. This betatron was built as a model to test design features later to be incorporated in a 300-Mev betatron. Particular attention is paid to factors influencing design and to considerations of magnetic problems which are common to betatrons and synchrotrons such as the construction of field magnets which are uniform, the testing of fields at injection time, the mechanism of electron capture, and the influence of field inhomogeneities. The dimensions and operating characteristics are included together with many comparisons with the 300-Mev betatron.
A High Intensity Ultraviolet Continuum Source for Use in Spectrophotometry
Authors: Finkelstein Nisson Ascher
Published: February 2005

A high intensity ultraviolet continuous spectrum d.c. source emitting between 50 and 100 times as much light as comparable commercial sources has been designed and constructed. Transitions between two molecular energy states of hydrogen are induced to produce a continuum from 1850A to 6000A. The arc is run at approximately 14 amperes and 90 volts from a 220-volt d.c. line. A hydrogen pressure of 3 mm of mercury is used. Lifetimes greater than 40 hours have been obtained.
A Rotary McLeod Gauge
Authors: Axelbank M.
Published: February 2005

The use of the sensitive McLeod gauge is limited by its fragility, bulk, and lack of portability. A new type of McLeod gauge is described which greatly reduces these difficulties. A helix of several turns of glass tubing provides the volume through which the gas is compressed by a small quantity of mercury as the gauge is rotated upon its rotary seal. A model has been constructed which is 16×16×21 cm in over-all dimensions and weighs less than 1 kg. Its gauge constant with a 0.8 mm capillary is 1.4×10−6 mm−1.
A Method of Measuring Spurious Counts in Geiger-Müller Counters
Authors: Willard D. , Montgomery C. G.
Published: February 2005

A counter was excited by a series of x-ray pulses of short duration occurring at regular intervals. Spurious counts were then easily recognized since they occur between the x-ray pulses. The counter pulses were displayed on an oscilloscope screen with a synchronized sweep and the counter deadtime, recovery time, and number of spurious counts determined by inspection. More quantitative information of the time distribution was obtained with an electronic circuit that recorded counts in a small arbitrarily chosen interval. It was found that the interval distribution shows at least two maxima. A mechanism is suggested for the appearance of the second maximum in terms of negative ions formed at the cathode by positive-ion bombardment.
Balloon-Borne Instrumentation for Neutron Detection
Authors: Pavalow Melvin , Davis William O. , Staker William P.
Published: February 2005

A description is given of balloon-borne proportional counters and circuitry for telemetering and recording cosmic-ray neutron intensities. The preamplifier, amplifier, scaler, and trigger circuit described all use low drain directly heated battery-type tubes. Methods and reasons for pressurization of high voltage circuits are discussed. Included is a description of a multiple-level flight technique using single large plastic balloons for long time intervals at pre-set altitudes.
A Transfer Device for Low Boiling Liquids
Authors: Wexler Aaron , Corak William S.
Published: February 2005

The principles involved in the transfer of low boiling liquids under their own vapor pressures are indicated and calculations are presented for the specific case of the transfer of liquid nitrogen. A convenient device for transferring liquid nitrogen by this procedure is described and its operating characteristics are compared with the calculations.
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.
A New Vacuum Gauge
Authors: Havens R. , Koll R. , LaGow H.
Published: February 2005

A new vacuum gauge has been developed that is capable of measuring pressures from one atmosphere down to less than 10−5 mm Hg. The principle and construction of the gauge and experimental results are given.
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.
Solution of Simultaneous Equations through Use of the A.C. Network Calculator
Authors: Haupt L. M.
Published: February 2005

Kirchhoff's law equations may be written for any electrical network. Conversely, it is usually possible to find an electrical network whose Kirchhoff law equations are similar to the given set of simultaneous equations. The solution to the equations may then be found by measuring the corresponding quantities in this analogous network. The a.c. network calculator is adaptable to this method of solving equations. Presented here are the fundamentals of finding the correct electrical network for a given set of simultaneous equations.
High Pressure Ionization Chamber Counters and Their Use
Authors: Wilson R. , Beghian L. , Collie C. H. , Halban H. , Bishop G. R.
Published: February 2005

Certain new developments in ionization chamber technique are described. Ionization chamber counters have been designed to operate with fillings of H2, D2, or CH4 to pressures of 35 atoms. with simple filling techniques. The design, characteristics, and uses of these counters are described.
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.
Lens Tester for Photographic Lenses
Authors: Back F. G.
Published: February 2005

Testing lenses, particularly photographic lenses, in a simple, fast, and accurate manner is quite a difficult problem. One of the solutions to this problem is a lens tester which is basically a modified autocollimator with a built-in color filter arranged in conjunction with an assembly unit consisting of an adjustable microscreen and a lens holder. This latter unit may be rotated about an axis perpendicular to the optical axis of the instrument, giving an immediate reading of the tangential and sagittal foci. By means of this instrument it is possible to determine: (1) the flange focal distance, (2) the shift of axial focus with respect to the lens aperture, (3) longitudinal chromatic aberration, (4) tangential and sagittal foci for any angular distance from the axis and for any aperture, and (5) all these readings for various color bands. This new instrument makes possible the immediate reading of the results without further computation. The determination of the nodal point and the focal length for extra-axial aberrations is unnecessary. Built-in color filters allow testing for chromatic aberrations. Because of a special microscreen and reflection-free beam splitter arrangement, this instrument gives satisfactory readings also for small apertures.
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.
Random Coincidence Rates with Unsteady Sources
Authors: Littauer R. M.
Published: February 2005

The random coincidence rate between two sets of pulses can be measured by delaying one of the sets through a time greater than twice the resolving time of the coincidence detector, thus destroying all true coincidences. A circuit using this principle for supervising the random rate continuously is described.
A Machine for Synthesizing Two-Dimensional Fourier Series in the Determination of Crystal Structures
Authors: Shimizu H. , Elsey P. J. , McLachlan D.
Published: February 2005

An electromechanical analog machine is described which performs a two-dimensional Fourier synthesis for use primarily in x-ray crystal structure calculations, ρ(xy)=Σ lim hΣ lim kFhkocos2π(hx+ky).The analog to a term in this summation is obtained through the use of a pair of selsyns as a synchro-variable transformer somewhat similar to its use in servomechanisms. ρ(xy)hk is represented by the output voltage, Fhko by the input voltage, and 2πhx and 2πky are the angles of rotation of the primary and secondary rotors respectively. A system of crossed shaft and cascading gear trains turns the rotors to the appropriate angles for each selection of point (x, y) in the unit cell. The present machine handles h and k values up through 8, but provision is made for future extension through 16. Computations are shown for two known structures to indicate the results obtainable with the machine.
The Scintillation Efficiency of Anthracene for Low Energy Electrons
Authors: Ramler W. J. , Freedman M. S.
Published: February 2005

The efficiency of an anthracene scintillation counter used as the detector in a double magnetic lens beta-ray spectrometer for electrons in the range 0–20 kev has been determined. Monoenergetic electrons generated by an electron gun were focused on the anthracene crystal, the beam being concurrently monitored by an electron collector and electrometer. The results are shown in Fig. 4.
A 500-Kilovolt Linear Accelerator Using Selenium Rectifiers
Authors: Arnold Wayne R.
Published: February 2005

A 500-kilovolt generator for use on a linear accelerator is described. This voltage is obtained by using selenium rectifiers and one microfarad condensers in 22 stages of voltage doublers. The maximum input is nine kilovolts r.m.s. at 750 cycles, and the maximum peak inverse voltage across each rectifier and each condenser is 25 kilovolts. The measured regulation is 25 kv/ma, the measured ripple (peak to peak voltage) is less than 1200 volts/ma; both independent of output voltage. The maximum load is 2.5 ma.
Wide Range, Continuously Variable High Current Generator Control
Authors: Wolff Jay R. , Freedman Melvin S.
Published: February 2005

A circuit is described for controlling the output current of a high current (100 amp) dc generator driving a low impedance (2.5 ohm, 40 mh) load. The circuit features precise continuous control of the load current by a single dial potentiometer over the range from zero to full output, with 0.03 percent linearity of current vs potentiometer setting. A method is presented for reduction of current ripple from the generator in the low impedance load.
Precise Solutions of Linear Simultaneous Equations Using a Low Cost Analog
Authors: Ackerman Sumner
Published: February 2005

The device described in this paper reflects a general philosophy for the fuller utilization of analog computing devices which has been promoted at Watertown Arsenal Laboratory. When solutions of analog computers are used as tools in conjunction with techniques readily handled by standard desk calculators rather than as direct solutions, any desired accuracy of the final solution can be usually obtained. The emphasis is placed upon obtaining the equivalent of a large scale digital device by combining solutions from analog computers with techniques readily handled by very small digital devices.
Microformer Dilatometer
Authors: Vanderman E. J.
Published: February 2005

The construction, calibration, and use of a dilatometer that is ideally suited for use with radioactive materials is described. Expansion measurements are made electrically with a linear variable transformer.
Production of High Specific Activities with a 22-Mev Betatron
Authors: Becker Robert A.
Published: February 2005

An internal probe technique of producing strong gamma-n and gamma-p activities with a betatron is described. Sources approaching 1 millicurie in strength of Cu62 have been realized. A typical specific activity of Cu62 produced in a piece of half-mil copper 2 mm×24 mm is 7 mc/g.
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.
A Liquid Hydrogen Target
Authors: Cook Leslie
Published: February 2005

A description is given of a target in which liquid hydrogen was bombarded with x-rays from the Berkeley synchrotron. The liquid hydrogen, in a stainless steel flask, was surrounded by an evacuated jacket containing a heat shield maintained at the temperature of liquid nitrogen. The liquid level was indicated by a counterweighted float system.
A Narrow Passband Polarization Interference Filter for Hydrogen Alpha
Authors: Billings Bruce H. , Sage S. , Draisin W.
Published: February 2005

This paper discusses the construction and testing of a Lyot-Öhman type polarization interference filter. This filter has a band width of approximately 1A peaked at H alpha. Previous filters have been fabricated, mainly of quartz. For a 1A passband filter a quartz thickness of approximately 24 cm would be needed for the thickest plate. This filter has been constructed using ammonium dihydrogen phosphate. Because the birefringence of this material is much higher than that of quartz, the tolerances associated with its construction are severe. By the use of mica corrector plates or optical shims, the tolerances can be made less critical. The final filter is equipped with a Senarmont compensator at each end so that the passband can be adjusted over a range of about 3A.
A Microspectrophotometer Equipped with Photomultipliers
Authors: Lange Paul W. , Stenius Åke S :son
Published: February 2005

A spectrophotometer, equipped with photomultiplier tubes, is described for the wavelength range 2500–7000A. The apparatus is intended for the determination of light absorption in microscopic objects and is especially useful for studies of biological material. The guiding principle of the construction is that the object in the course of the measurement should have a fixed position. Some applications concerning studies of small parts of cellulose and wood fibers are given. The weight of the examined samples has been between 10−10−10−12g.
An X-Ray Spectrometer for Polymer Studies
Authors: Krimm Samuel , Stein Richard S.
Published: February 2005

A Geiger counter x-ray spectrometer has been designed and constructed suitable for the quantitative study of crystallinity and orientation in polymers and of relaxation phenomena associated with these properties. The instrument is designed for use with crystal monochromatized or filtered radiation, and has such features as Soller slit collimation, means of studying the materials above room temperature, and a Geiger counter monitor on the x-ray beam. The spectrometer, pertinent techniques, and typical results are described.
The Panradiometer: An Absolute Measuring Instrument for Environmental Radiation
Authors: Richards Charles H. , Stoll Alice M. , Hardy James D.
Published: February 2005

The instrument consists of four hollow, silver spheres 6 mm in diameter, of identical construction; one sphere is painted black, one white, and the remaining two are highly polished. Each is provided with a thermocouple for measuring its temperature, and an internal heating coil for adjusting its temperature. Total environmental thermal radiation intensity is obtained by measuring the heat input to the two spheres of lower temperature to bring the black, white, and one polished sphere to the same temperature when the instrument is exposed in a given environment. The second polished sphere provides for wind velocity measurements after the manner of a sphere anemometer. Measurement of direct solar radiation exclusive of reflected and scattered solar radiation is made by comparing the total radiation in sunlight with that obtained when the spheres are shaded from the sun. The radiant temperature of the environment is obtained by correcting the measured value of total radiation for the effect of solar radiation. A precision of ±4 percent can be realized for the measurement of solar radiation and of ±1.8°C for the measurement of the radiant temperature of the surroundings.
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.
An Induction Flowmeter Design Suitable for Radioactive Liquids
Authors: James W. G.
Published: February 2005

A brief discussion of the principle of the induction flowmeter has been presented, as has a discussion of the considerations necessary for applying the induction flowmeter to the measurement of radioactive liquid flow rates of the order of 50 milliliters per minute. These considerations have been applied to the design of a zero-to-fifty milliliter-per-minute flowmeter. Linearity of response of ± 1 percent of full scale has been obtained in this instrument; stability from hour to hour is also ± 1 percent of full scale. Liquids having conductivity at least as great as that of tap water can be measured without change of calibration.
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.
Magnetically Suspended Vacuum-Type Ultracentrifuge
Authors: Beams J. W. , Ross J. D. , Dillon J. F.
Published: February 2005

A centrifuge rotor constructed of steel and Duralumin ST-14 weighing 4.93 kilograms and having a radius of 65 mm to the center of the standard centrifuge cell, which contains the material to be centrifuged, is suspended magnetically in a high vacuum (pressure less than 10−5 mm Hg). The rotor is driven to running speed by an air turbine below the vacuum chamber. The turbine is connected to the rotor by a small steel shaft along the axis of rotation and passing through vacuum-tight oil glands into the vacuum chamber. When the rotor reaches operating speed, the shaft is disconnected and the rotor is allowed to coast freely during the sedimentation experiment. This is possible because of the very small deceleration of the rotor (less than a 0.1 revolution per sec per hour). As a result the temperature and rotor speed not only can be measured accurately, but can be maintained very nearly constant. The ultracentrifuge has been used both for rates of sedimentation measurements and for sedimentation equilibrium measurements, but is especially suited for the latter.
Design of Variable Resonant Frequency Crystal Transducers
Authors: Hall Wayne L. , Fry William J.
Published: February 2005

Design considerations involved in the development of low loss continuously variable resonant frequency crystal transducers are discussed. A description of such a system employing liquid mercury as a backing of continuously variable dimensions is presented. The important aspects; tight coupling of the crystal and mercury backing, and decoupling of the crystal and mercury from the supporting structure are considered in detail. Construction procedure on a unit to cover the frequency range 40 to 80 kc is indicated. Experimental results on the magnitude of the electrical input impedance as a function of frequency and mercury column length are given. A comparison of the variable resonant frequency unit used as a transducer with a series of fixed resonant frequency transducers is presented.
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.
Graphical Determination of Transmission Curves for Certain Magnetic Lens Beta-Ray Spectrometers
Authors: Perkins J. F. , Solbrig A. W.
Published: February 2005

A graphical method is described for determining the transmission curve of a point source on the axis of a thick magnetic lens beta-ray spectrometer with ring-focusing baffles. The method is applicable to spectrometers in which the magnetic field in the region between the ring-focus position and the detector is weak compared with the maximum field in the instrument. It requires the computation of only a few electron paths because the plot of the radial coordinate against the axial coordinate is very nearly linear beyond the ring-focus position. Transmission curves are drawn for two different baffle systems in a particular instrument, and it is shown that the low energy side of the curve may be steepened considerably by the use of two outer baffles and a properly located counter aperture.
A Flux-Forced Field-Biased Betatron
Authors: Gregg E. C.
Published: February 2005

The design, construction, and operational performance of a flux-forced field-biased betatron at Case Institute of Technology are described. Limitations due to flux forcing and its effect on the time variation of the equilibrium orbit are also discussed.
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.
A Wide Range Mechano-Electronic Transducer for Physiological Applications
Authors: Talbot S. A. , Lilienthal J. L. , Beser J. , Reynolds L. W.
Published: February 2005

Physiological applications and technical limitations of the RCA 5734 mechano-electronic transducer tube are discussed. A variable protecting mount adapts this tube to full-scale ranges of force from 5 g to 2.5 kg or more with a 5 volt swing on all ranges. Fundamental resonance frequency varies linearly with the range, from 40 to 300 cps. Amplitude distortion is small and restricted to small deflections. Frequency and phase distortion depend on the driving tissue but are small for myographic phenomena whose highest harmonic is generally around 15 cps. Adaptation of the 5734 tube to ballistocardiography (1μ to 10μ swing) is also shown.
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 Methane, Proportional Counting Method for the Assay of Tritium
Authors: Robinson C. V.
Published: February 2005

A new method for the assay of tritium is described. Radioactive water is reacted with methyl Grignard reagent to give radioactive methane which is then admitted into a proportional counting chamber to be counted. Advantages of the method are convenience, absence of memory effects, linearity, and a precision with a standard deviation less than 1 percent.
Millimicroampere Current Integrator for a Cyclotron
Authors: Watts Richard J.
Published: February 2005

A low current integrator is described that successfully avoids the problem of current leakage by the use of electrometer tubes. In connection with the circuit an electronic master switch is described which permits the turning on and off of associated equipment with the beginning of the charging cycle of the integrator.
The Yale Linear Electron Accelerator
Authors: Schultz H. L. , Wadey W. G.
Published: February 2005

The Yale linear accelerator has been designed to produce large currents of 10-Mev electrons by the use of independent resonant cavities driven by 500-kw triode power amplifiers. The design principles and construction methods used for this recently completed machine and data on its performance are presented.
Auxiliary Equipment to be Used with a Beta-Ray Spectrometer for the Study of Radioactive Gases
Authors: Ter-Pogossian Michel , Porter Fred T. , Cook C. Sharp
Published: February 2005

A system is described whereby a gas may be circulated continuously between the cyclotron and the 14-cm radius of curvature magnetic spectrometer. This apparatus does not modify the spectrometer itself but considerably increases its usefulness. Detailed descriptions are given of the chamber which is attached to the cyclotron for bombardment and of both beta- and gamma-ray source holders in addition to an over-all picture of the entire system.
A Method for Annealing Metal Powders without Sintering
Authors: Von Batchelder F. W. , Stauss H. E.
Published: February 2005

A method is described for maintaining the separation of the component particles during the annealing of a metallic powder. The technique consists of mixing the metal powder with a larger quantity of a second powder that is inactive chemically relative to the metal, annealing the mixed powders, and separating the metal by dissolving the inert powder after annealing. In this way gold, silver, and iron powders have been annealed in sodium chloride without sintering.
Operation of a Six-Mev Linear Electron Accelerator
Authors: Becker G. E. , Caswell D. A.
Published: February 2005

The operation of a 6-Mev linear electron accelerator is described. It is of the traveling-wave type, 14 feet in length. A single magnetron is used as a power source, operating at a wavelength of 10.5 cm, with a peak power output of 0.9 megawatt. Electrons are injected at a velocity v=c/2. Approximately 1/20 of the injected electrons reach the target end of the accelerator, with energies falling in a 1-Mev range near 6 Mev. The average current obtained is 0.05 μa. With an electron pulse length of 0.8 μsec and a pulse repetition rate of 60 per sec, this corresponds to a peak current of the order of 1 ma.
A Multiple Projector for the Huggins Masks
Authors: McLachlan Dan , Woolley Roscoe H.
Published: February 2005

The usual procedure for making two-dimensional fourier projections of crystal structures by means of the Huggins masks requires the expenditure of time in the photographic darkroom during which errors may be made. These errors can be corrected only by a repetition of the entire laborious procedure of successive exposures of the plate. An apparatus is described whereby 144 Huggins masks are projected simultaneously on a screen and the result photographed. The projection is accomplished without lenses and the cost of production is thereby reduced considerably. Grooves are provided for changing the signs of the fourier coefficients at will. Rheostats on the projection lamps are provided for controlling the lumination in proportion to the magnitude of the fourier coefficients.
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.
A Cobalt Gamma-Ray Source Used for Studies in Radiation Chemistry
Authors: Ghormley J. A. , Hochanadel C. J.
Published: February 2005

A high intensity cobalt gamma-ray source for use in radiation chemistry studies is described. The lead shield was designed to provide safety, convenience, and reproducibility in irradiating samples under a variety of conditions.
A Bar-Magnet Velocity Meter
Authors: Perls Thomas A. , Buchmann Erich
Published: February 2005

A bar-magnet velocity meter for vibratory and shock motions has been investigated both theoretically and experimentally. There has resulted a set of characteristics which constitute a marked improvement over the characteristics of previous velocity meters, in important respects. The instrument consists of a long bar magnet which moves relative to a long coil. It is shown that Alnico V combines all the best features required of the magnet material, when compared experimentally with a magnet made of hardened tool steel and theoretically with other grades of Alnico, Cunife, and tungsten steel. Different methods are discussed for installing the velocity meter.
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.
The Calculation of the Geometrical Efficiency of End-Window Geiger-Müller Tubes
Authors: Berne E.
Published: February 2005

Integrals for the calculation of the solid angle of a plane disk in respect to the window of an end-window Geiger-Müller tube have been derived. Numerical values for a window diameter of 30 mm have been computed.
A New Method for Precision Measurement of the Hall and Magneto-Resistive Coefficients
Authors: Donoghue J. J. , Eatherly W. P.
Published: February 2005

A circuit capable of measuring alternating current potentials up to 1000 microvolts with a precision of 0.01 microvolt has been devised and applied to the measurement of the galvanomagnetic coefficients of semiconductors and metals. The circuit consists essentially of a peaked amplifier applied to the out-of-balance signal between an alternating current potentiometer and the potential being measured. The galvanomagnetic coefficients are so related to the potentials that the entire measurement becomes independent of the current. As an example of the results obtainable, data are given to show the variations of the Hall and magneto-resistivity coefficients during the high temperature graphitization of index rod. The precision of the final data is of the order of one-quarter percent.
Lorentz and Polarization Correction for the Buerger Precession Method
Authors: Waser Jürg
Published: February 2005

The reciprocal of the product of the Lorentz factor and the polarization factor is calculated for the zero level and μ̄=30∘.
An Automatic Plate Counter
Authors: Lerner Jerome L. , Uecker Donald F.
Published: February 2005

A versatile counter that automatically sorts sample plates into several groups according to the radioactivity of the plates is described. Details are given for a counter specifically intended to minimize the tedious job of counting decontaminated plates for background.
A Microphotometric Area Determinator
Authors: Walker Harvey , Van Winkle Quentin
Published: February 2005

The Knorr-Albers microphotometer has been modified to permit the application of the trapezoidal rule to the measurement of the true areas of photographically recorded figures of irregular shape. These modifications include a vertical plate-elevating mechanism and a timer controlled by a cam and roller microswitch.
Rapid and Sensitive Spectrophotometry. I. The Accelerated and Stopped-Flow Methods for the Measurement of the Reaction Kinetics and Spectra of Unstable Compounds in the Visible Region of the Spectrum
Authors: Chance Britton
Published: February 2005

The present form of the accelerated and stopped flow methods for the measurement of the reaction kinetics and spectra of intermediate compounds in biochemical reactions is described. This apparatus gives satisfactory records with only a few tenths of a cubic centimeter of 2×10−7M iron enzyme solution and covers a time range from a few milliseconds to several minutes. The wavelength range is 370 to 600 mμ, and the spectral interval is 7.5 mμ. The error in optical density measurement is about 1×10−5 corresponding to a signal-to-noise ratio of 5×104 for a response time of 1 sec over the wavelength range of 380–580 mμ. The present performance and range of usefulness considerably exceed that reported previously.
Vibrating Plate Transducers for Frequency Studies of the Breakdown Rate of Biological Cells
Authors: Ackerman Eugene
Published: February 2005

Transducers are described giving audio outputs greater than 0.1 watt/cm2, sufficient for cellular disruption. A method of measuring the spatial average of the transducer velocity amplitude is discussed. The apparatus is suitable for studies of the effect of frequency and velocity amplitude on the breakdown rate of biological cells.