bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave Separator for High Energy Particle Beams
Authors: Phillips P. R.
Published: February 2005

This paper describes the design and construction of a microwave separator for high energy particle beams, following the original ideas of Panofsky and Wenzel. We used a TM012 rectangular cavity with a Q of 15 000 and a maximum power dissipation of 1.3 Mw (megawatts). With this we could deflect electrons of 150 Mev/c momentum through ¾ in. at the final focus of our analyzing magnet. The available aperture is so small that the technique is not immediately useful, but we anticipate that it may become so at higher energies, when other methods of beam separation become unfeasible.
Measurement of Magnetic Susceptibility in Very High Pulsed Fields
Authors: Stevenson Richard
Published: February 2005

A technique has been developed for making Gouy type measurements of magnetic susceptibility in high transient magnetic fields. The magnetic force on the sample travels as a stress wave through the apparatus assembly and excites a voltage on two piezoelectric crystals which are the active elements of the transducer. The apparatus has a small risetime and high response. Typical experimental difficulties are described.
Homodyne Balanced Mixer Electron Spin Resonance Spectrometer
Authors: Henning J. C. M.
Published: February 2005

A simple electron spin resonance (ESR) spectrometer for the detection of organic free radicals is described. The salient features are: (1) homodyne balanced mixer detection, (2) improvement of the magnetic field homogeneity by means of two pairs of current shims, and (3) new tuning procedure independent of the resonance spectrum itself, making use of the klystron-stabilization error signal. At 3200 gauss the magnetic field homogeneity is better than 2:105 over a sample volume of 0.25 cm3. The sensitivity is such that 2×1013 spins of the free radical DPPH can be detected.
Sensitive Diaphragm Type Pressure Transducer
Authors: Lovejoy D. R.
Published: February 2005

A simple diaphragm type transducer for small differences in gas pressures is described together with a suitable electronic arrangement for using it as a control element. The sensitivity of the arrangement is limited by ambient temperature effects on the diaphragm. A zero stability of about 0.1 μ Hg has been achieved and this could probably be improved on by sufficiently good thermostating. An important feature of the diaphragm is that it may be subjected to large unbalanced pressures without damage, although such pressures will produce zero shifts equivalent to a few microns of mercury.
Thermocouples for Use in Carbon Atmospheres
Authors: Nadler M. R. , Kempter Charles P.
Published: February 2005

Criteria are discussed for using thermocouples in carbon atmospheres above 2000°C. Experimental data are given for W/Re, W/W-25 Re, Re/W-25 Re, graphite/Re, and graphite/Ir thermocouples in carbon atmospheres from room temperature to 2200°C. Reaction temperatures of carbon with thoria, urania, and yttria were measured to be below 1730°, 1620°, and 1590°C, respectively.
Variable Sensitivity Automatic Ionization Chamber
Authors: Neher H. V.
Published: February 2005

An all quartz electroscope system is described whose sensitivity may be varied over a wide range by changing one potential. Like other previously described systems, it accumulates a definite quantity of electric charge, for given potentials, and then automatically recharges itself. When this recharging occurs an electrical pulse may be taken off for recording purposes. It is possible to change the sensitivity by a factor of 500.
Zig-Zag Oscilloscope Presentation of Millimicrosecond Accuracy for Microsecond Time Intervals
Authors: Leger E. G. , Nyberg D. , Graf K. , Tardif L.
Published: February 2005

In the study of metal-high explosive detonation wave interaction, by the pin technique, it is desirable to obtain time measurements to an accuracy of less than 1 mμsec over a total time interval of 5 μsec. Commercial instruments capable of a high degree of time resolution were not available and a special instrument was developed for this purpose. A cathode-ray oscilloscope, displaying deflection type event pulses, is converted into a precise time-measuring instrument by a calibrated zig-zag sweep. The record is obtained by single-shot photography of the cathode-ray tube sweep which is triggered by the event to be measured. The calibrated zig-zag sweep is crystal controlled at 2 Mc and has superimposed deflection type time marks, 2 mμsec wide, at 50-mμsec interval, synchronized with the zig-zag frequency. The apparatus can drive six oscilloscopes simultaneously or in sequence from delayed triggers.
Low-Level Linear Microsecond Gate
Authors: Chagnon P. R.
Published: February 2005

A linear transmission gate for use in scintillation counter coincidence experiments is described. The gate is suitable for negative pulses of microsecond duration and is linear over a range of 0.01 to 5 v. The circuit is relatively simple, uses no vacuum tubes, and is reliable over long periods of use. The use of low-level gates can increase the usable counting rate of a multichannel coincidence system by an order of magnitude.
Specimen Tilting Device for Use in the Hitachi H. U. 10 Electron Microscope
Authors: Huffstutler M. C. , Thomas G.
Published: February 2005

A tilting specimen holder for the Hitachi H. U. 10 electron microscope is described. Its usefulness in transmission studies of the fine structure of metal foils is illustrated.
Tests and Comparisons of Carbon and Germanium Thermometers
Authors: Lindenfeld Peter
Published: February 2005

Two encapsulated germanium thermometers have been calibrated and tested between 1.4° and 4.2°K. Within the precision of the measurements (±0.4 millidegree) no change in their calibration was found after cycling to room temperature or after temporary removal from the measuring apparatus. In this respect, the germanium thermometers were considerably better than carbon thermometers. For comparison a carbon thermometer was encapsulated and found to undergo unpredictable changes corresponding to several millidegrees under similar circumstances.
A Beam Maser Spectrometer
Authors: Thaddeus Patrick , Krisher Lawrence C.
Published: February 2005

The construction and operation of a molecular beam maser spectrometer, similar to the ammonia maser, is described. The observed linewidths are of the order of 5 kc at microwave frequencies, thereby allowing high resolution hyperfine spectroscopy on a number of molecules. The major factors affecting the resolution and sensitivity are examined. A brief survey of possible experiments is given.
Fast Molecular Nitrogen Beam
Authors: Utterback Nyle G. , Miller Glenn H.
Published: February 2005

Apparatus has been developed for producing a molecular N2 beam covering the energy range 5–1000 ev. The technique includes ionization by electron impact, acceleration and focusing, and neutralization by charge transfer. Energy spread is 0.5 ev. The beam intensity ranges from 108 molecules per second at low energy to 1010 at high energy. The absolute beam intensity can be determined within 20%. Charge transfer efficiency, beam intensity monitoring, and adaptability of the apparatus to the studies of ionization cross sections and surface phenomena are discussed.
Radiation Resistant, Remotely Operated, High Capacity Spring Balance
Authors: Ayer J. E. , Pokorny G. J.
Published: February 2005

A balance with a weighing range between 9 and 24 kg has been tested. The use of radiation resistant sensing devices makes it acceptable for use in hot cell applications. With an unrefined read-out method the system sensitivity, including resolution of chart reading by eye, at 65% confidence limits is ±10 g in 2.5-kg intervals. Over the entire 9 to 24 kg range the linearity of the system is such that the sensitivity is reduced to ±17 g. It is predicted that digital indication of weight and use of a low inertia, low friction indicating system will double the system sensitivity.
High-Temperature Calorimeter for the Determination of Heats of Formation of Refractory Compounds
Authors: Lowell C. E. , Williams Wendell S.
Published: February 2005

A high-temperature calorimeter has been built to measure the heats of formation of certain refractory compounds (by direct reaction of the elements) at temperatures in excess of 1000°C. The standard heat of formation of TiB2 was found to be −50±5 kcal/mole. A known heat of formation, that of TiC, was also measured, yielding reasonable agreement with the literature value.
Instrument for Making Individual Spheres to a High Degree of Accuracy
Authors: Cross P. H.
Published: February 2005

This paper describes a mechanical method of producing polished spheres constant in radius to about one microinch. Spheres have been made to this accuracy in anisotropic materials such as yttrium iron garnet and also in steel, sapphire, quartz, and ceramic. The method has not been fully exploited; it may yield even further improved surfaces and also be found suitable for softer materials. The principle may also have application for finishing concave and convex mirror and lens surfaces of small radius. The instrument is also suited for the rapid production of spheres to a lesser degree of accuracy.
Production of Very Stable Magnetic Fields in the Range 0–50 Gauss
Authors: Schearer L. D.
Published: February 2005

An instrument is described which has the property of accurately measuring the magnitude of magnetic field to 0.05 μgauss at the center of a set of Helmholtz coils while simultaneously reducing by a factor of 600 stray fluctuations of the field caused by drift in the earth's magnetic field, power supply anomalies, and external magnetic noise generated by the motion of magnetic material. The device utilizes an optically pumped metastable helium magnetometer which senses the total magnetic field. The output signal of the magnetometer is used to control the current in the Helmholtz coils. The new features of this device are (a) its ability to discern and hence control magnetic field variations at the microgauss level and (b) its scalar character enabling the field control to be accomplished with a single set of coils
Avalanche Transistor Circuits
Authors: Henebry W. Michael
Published: February 2005

Avalanche transistor circuits offer several features which are desirable in fast counting systems; simplicity, versatility, fast response, and large charge gain. This paper describes the evolution of avalanche circuits which retain the desirable features but which do not suffer from the two defects of the basic avalanche circuit: low duty cycle, and a pulse propagation delay which is dependent upon input. Several transistor types which are suitable for fast avalanche circuits are compared and comments are made about the application of these transistors. Described also are several useful circuits which may be constructed with avalanche transistor techniques.
Fast-Acting Gas Valve
Authors: Wetstone David M.
Published: February 2005

The design and operation of an electrodynamically driven valve, which is employed to deliver rapidly a gas pulse (0.6 cc STP) with a sharp front to the annulus of a coaxial plasmoid source of small aspect ratio (2-mm annulus at 2-cm radius), is described. The spring loaded piston holds the plenum closed against pressures up to 2 atm. The piston is driven open by eddy currents induced by discharging a capacitor through a coil surrounding the plenum. A piston velocity of 5 cm/msec is achieved in less than 20 μsec and is maintained for 7 mm of travel. The arrival of a gas front (air) at the annulus was detected in 100 μsec after firing, employing hot-wire anemometry. The subsequent axial position and velocity of this front in the source annulus were determined as functions of time and position, respectively. It was found that the initial axial velocity of the front exceeded the stagnation sound speed (though not the vacuum escape speed) and remained constant until the displacement thickness from wall friction reached the half-annulus spacing.
Tunnel Diode Nanosecond Coincidence Circuit
Authors: Franzini Paolo
Published: February 2005

A fast coincidence circuit using tunnel diodes is described. In ideal conditions, resolving times as low as 0.5 nsec have been measured. But in a practical case of beam particles crossing scintillation counters, a typical resolving time is ≈1.5 nsec. The same circuit can also be used as an anticoincidence whose total dead time can be as low as 5 nsec.
Frequency Shift Magnetometer
Authors: Rogers R. M. , Kantor R. H.
Published: February 2005

A technique has been devised for measuring the saturation magnetization and anisotropy constants of ferrites and garnets. It uses a tiny sample of the ferromagnetic material in a dc magnetic field. The sample is surrounded by a small radio-frequency coil, which determines the frequency of an oscillating circuit. As the dc magnetic field is swept through a range of values, the frequency of the rf oscillator changes and becomes a measure of the magnetization. The technique makes possible a simple, versatile instrument that would be equal or superior in accuracy to any other technique now known. However, it is not suitable for metals because of their conductivity.
Coupling Resonances in Spiral Sector Accelerators
Authors: Laslett L. J. , Sessler A. M.
Published: February 2005

Theoretical and computational results are presented to illustrate the behavior of single particle motion in spiral sector FFAG accelerators of small flutter factor when operated in the neighborhood of vertical-radial coupling resonances. The theoretical analysis proceeds from the approximation in which the radial motion is determined without consideration of the vertical motion, and this solution is then inserted into the linearized equation for the vertical motion. The resulting generalized Hill equation is analyzed by a variational technique which yields both the bands of instability of the vertical motion and the exponential rate of growth within these zones. This mathematical analysis is confirmed by a computational study of the Hill equation used in the theoretical analysis. Extensive computational results are presented of the actual particle motion near coupling resonances for a choice of parameters characteristic of both full-scale accelerators and models. Attention is concentrated on defining the regions of instability and determining the rate of vertical growth, both of which are seen to be in semiquantitative agreement with the theoretical analysis.
Design of Retarding Field Energy Analyzers
Authors: Simpson J. Arol
Published: February 2005

Retarding field analyzers of the plane parallel plate, the spherical condenser, the Faraday cage, and the filter lens types are examined in some detail. The often neglected lens effect of the hole in the plane parallel plate through which the beam passes is shown to have significant effect on the energy resolution. The previous analysis of the spherical condenser is extended to the hemispherical case and the effect of the aperture in the inner sphere calculated. It is shown that for certain relations between the sphere sizes and the position of the source very high resolution may be obtained. The general restrictions on the performance of imaging retarding fields are considered and a design procedure based upon empirical knowledge of immersion lenses is given.
Automatic Vapor Pressure Measurements at Moderately High Pressures
Authors: Spauschus Hans O.
Published: February 2005

Apparatus has been devised for automatically measuring and recording vapor pressure (1 to 35 atm) and temperature (−40 to +100°C) of pure liquids or solutions. The measurements are performed on a dynamic system wherein P and T are changed at very slow rates. Many P-T data sets are recorded in a single run, providing the input for a computer program which correlates the two variables. Data for dichlorodifluoromethane are presented and compared with literature values. It is concluded that precise and accurate results are obtained with the automatic apparatus. Furthermore, the data processing program provides valuable information for analyzing the operation of the equipment.
A 300-Liter Heavy Liquid Bubble Chamber
Authors: Bloch M. , Lagarrigue A. , Rançon P. , Rousset A.
Published: February 2005

A heavy liquid bubble chamber with a useful volume of 100×50×50 cm operating in a magnetic field of 20 000 gauss is described. Engineering details are given. Lateral illumination of the liquid and scattering of light at 90° is used to photograph the tracks. Different mixtures of Freon (CF3Br) and propane have been used in the chamber allowing a choice of radiation length and stopping power particularly suitable to the experiment performed.
Technique for Studying Piezoelectricity under Transient High Stress Conditions
Authors: Graham R. A.
Published: February 2005

An experimental technique is described which is being successfully used to study the transient high stress piezoelectric behavior of synthetic alpha-quartz. Short, flat-faced cylinders of quartz are impacted upon each other at high velocity to produce the desired transient stress in the range from 5–70 kilobar. Precision is maintained in the alignment of the flat impact surfaces so that the Hugoniot conservation of momentum and the relationship governing the impact of flat cylinders may be used to compute the stress imparted to the target cylinders of quartz. Electric charge release data are taken in conjunction with the initial passage of the stress wave produced by impact.
Design and Sensitivity of a Photoconductive Recording System Applied to the Sucksmith Ring Balance
Authors: Shuttleworth Rose A.
Published: February 2005

This paper describes a photoconductive locator for continuous recording of physical displacement. The system is applied as an example to the optomechanics of the Sucksmith ring balance. It is shown that the sensitivity and accuracy are considerably higher than those obtained with optical instruments such as the traveling telemicroscope. Application to wave modulation is suggested.
Improved Gravimetric Vapor-Sorption Apparatus
Authors: Brooks C. S.
Published: February 2005

This improved gravimetric vapor-sorption apparatus was designed for vapor-sorption measurements at 20–50°C with condensable vapors, e.g., water and organic vapors on inorganic and organic adsorbents, such as minerals and resins. The apparatus can be readily adapted to low-temperature adsorption of noncondensable gases, e.g., N2, Kr, and Ar. The system consisted of a helical spring (quartz or tungsten) sorption balance. A Pirani gauge and a mercury manometer permitted the measurement of vapor pressures from several microns to more than 100 mm. Important considerations relevant to the design of helical springs (quartz or metal) were summarized, and a comparative evaluation was made of the advantages and limitations of tungsten and quartz helices. A practical high-vacuum Teflon seal for use in place of greases and waxes on ground glass joints was developed. This seal was designed for use with organic vapors. The aqueous vapor pressures at 20°C were measured for a wide range of concentrations of aqueous sulfuric acid solutions. These data were in excellent agreement (of the order of 1%) with the published data down to pressures of 1 mm of mercury, and they provided a reliable indication of the accuracy of the vapor pressures measured with this apparatus.
Scanning Microscope for Photoelectric Data Evaluation
Authors: Tove P.-A. , Brolin S. , Hellman B.
Published: February 2005

This paper describes a mechanical scanning device for evaluation of microscopic data over a large area and an electronic system for collecting and sorting information about the size of light and dark patches on a plate. Preliminary experiments for measuring the size distribution of the islets of Langerhans in histologic sections of the pancreas are described.
Nonobstructive Low Energy Electron Beam Monitor
Authors: Okabe S. , Tabata T. , Ito R.
Published: February 2005

A modified type of secondary electron monitor useful for the monitoring of low energy electron beams during irradiation is described. Using the window foil at the end of the accelerator as a part of the detector, it is designed to have minimum disturbance on the primary beam. The monitor output is independent of the primary beam energy and proportional to the primary beam current in the range over which the monitor was tested (1.0–1.7 Mev and up to 120 μa).
Apparatus for the Measurement of Stress in Vacuum Evaporated Films
Authors: Priest Joseph R.
Published: February 2005

An apparatus suitable for the measurement, in vacuum, of the residual stress in evaporated metal or dielectric films has been built and tested. The substrate on which the film is deposited is clamped at one end to form a cantilevered beam. When the substrate is bent as a result of the film stress, the force required to restore the beam to its initial position is measured. The stress is then calculated from a knowledge of the restoring force, the beam dimensions, and the film thickness. A stress of 5×107 d/cm2 can be easily detected and measured with this apparatus.
High Intensity Low Noise Rubidium Light Source
Authors: Brewer Richard G.
Published: February 2005

A 40-w electrodeless rubidium light source is described which emits a total of 13 w in the two D lines. The intensity is a factor of 50 larger than that of a previously reported electrodeless rubidium source. In addition, high stability, long life, minimum noise, and the absence of self-reversal make it attractive for optical pumping studies of alkali metal vapors.
Method of Measuring the Normal Velocity Distribution of Secondary Electrons at Low Primary Bombarding Energies
Authors: Evtuhov V. , Smith G. F. , Yaggy L. S.
Published: February 2005

Experimental apparatus designed to measure the secondary electron emission from solids at low primary electron energies is described. The design permits the determination of the normal velocity distribution of secondary electrons off insulating targets. Some of the usual difficulties associated with measurements of this kind are avoided through the use of an orthicon-type deflection system to separate primary and secondary beams. Measurements of the secondary emitting properties of molybdenum, some of which are performed under pulse conditions appropriate for insulating targets, are described and serve to demonstrate the performance of the apparatus.
Vacuum Measurements by Means of Alternating Gas Discharges
Authors: Hirsch E. H.
Published: February 2005

A pressure gauge for the range from several mm Hg down to the micron region is described. The new gauge, based on the properties of alternating gas discharges, measures pressure in terms of the frequency of a relaxation oscillator incorporating as the nonlinear element a glow discharge between electrodes immersed in the gas, the pressure of which is to be determined. A stability of 1% has been obtained; the robustness and simplicity of the instrument render it particularly suitable for rocket-borne measurements at high altitude.
Diffuse Reflection Coating for Use with Čerenkov Counters
Authors: Schnurmacher Gerald L.
Published: February 2005

A diffuse, highly reflecting coating for use with Čerenkov counters is described. This coating can be used to advantage inside inorganic-liquid Čerenkov counters, or can be used externally when bonded to the inside surface of the light-tight radiator cover.
Radio-Frequency Spectrometer with Bidirectional Square Wave Frequency Modulation
Authors: Verdieck J. F. , Cornwell C. D.
Published: February 2005

The use of a bidirectional square wave for frequency modulation of a radio-frequency spectrometer offers certain advantages, the principal one being that the background signal due to incidental amplitude modulation can be effectively eliminated by appropriate adjustment of the relative amplitudes of the positive- and negative-going excursions. A quadrupole resonance spectrometer employing this principle has given excellent sensitivity and faithful line shape presentation. The oscillator, of the regenerative type, is based on a circuit recently published by Knight. The frequency modulation method should be widely applicable to other types of spectrometers.
Interferometric Instrument for the Rapid Measurement of Small Diameters
Authors: Blackburn Douglas H.
Published: February 2005

An instrument was developed for the rapid and accurate measurement of small diameters. The operating procedure consists of placing the test fiber between two optically flat surfaces and, using the fiber as a fulcrum, adjusting the upper flat until the surfaces are parallel and utilizing the absence of interference fringes between the surfaces to indicate parallelism. Controlled tilting of the upper flat is obtained by adjusting, with a micrometer screw, a sliding wedge under a lever attached to the upper flat. Fiber diameter is a linear function of wedge position as indicated by micrometer screw setting.
Piezoelectric Probe for Plasma Research
Authors: Stern Martin O. , Dacus Edward N.
Published: February 2005

A piezoelectric probe has been devised for use in plasma work, where one wishes to measure phenomena of short time duration (microseconds) giving rise to moderately small pressures (fractions of an atmosphere). Some of the response characteristics of such a probe and a method for its calibration are also presented.
Four-Inch Shaped Pole Caps for Susceptibility Measurements by the Curie Method
Authors: Heyding R. D. , Taylor J. B. , Hair M. L.
Published: February 2005

Henry's profile for shaped pole caps has been adapted to a 4-in. magnet. The fields obtained at a pole cap separation of 2.6 cm have been examined in some detail. A region of constant ∂B2/∂x is obtained which is 1 cm in length at low fields and 1.4 cm at high fields. For excitation currents of 40×103 amp turns the value of B∂B/∂x is about 24×106 gauss2/cm.
An Operational Ruby Maser for Observations at 21 Centimeters with a 60-Foot Radio Telescope
Authors: Jelley J. V. , Cooper B. F. C.
Published: February 2005

A maser preamplifier designed for radiometry at a wavelength of 21 cm is described. The maser is mounted at the focus of the 60-ft reflector of the Harvard College Observatory and is being used principally for observations of hydrogen-line radiation from extra-galactic nebulae. An automatic gain stabilization system for the maser using a modulated-noise reference signal is described and an example of an observation made with this stabilization scheme is included. The total input noise temperature of the radiometer is 85°K, without the gain stabilization, and 148°K with the stabilization.
High Current Electronic Potentiostat
Authors: Staicopoulos D. N.
Published: February 2005

The design of a high current transistorized potentiostat capable of delivering currents of the order of 5 amp for anodic or cathodic polarization studies at controlled potentials is presented. The range of potentials possible is determined only by the characteristics of the test electrode/solution interface. The response of this instrument is such that switching from maximum cathodic to maximum anodic potentials and vice versa can be accomplished within 10−3 sec. Analysis indicates that it is possible to effect a tenfold increase in the current-carrying capacity of this potentiostat with only minor modifications. The combination of high speed, short rise time, and high current instantly available for either anodic or cathodic polarization is unique in this potentiostat and provides outstanding versatility.
Hodoscope for Low Level Output Particle Detectors
Authors: Heggie L. D. , Masek G. E.
Published: February 2005

A scheme of combining a large number of low level output particle detectors into a hodoscope is described. Features include economy of amplification equipment and a short resolving time against accidental events.
Statistics of Electron Multiplication
Authors: Lombard Francis J. , Martin Fred
Published: February 2005

The pulse-height distribution at the output of an electron multiplier structure for a single electron input has been calculated assuming a Poisson distribution at each stage. Graphs are given which illustrate the change in pulse-height distribution as a function of the number of stages. This has been done for interstage multiplications of 1.5, 2.0, 3.0, and 5.0.
Electrical Current Shims for Correcting Magnetic Fields
Authors: Anderson Weston A.
Published: February 2005

The design criteria of electrical current shims for high resolution nuclear magnetic resonance magnets are discussed. Specific current configurations are given for various corrections to magnetic field gradients of the first, second, third, and fourth orders.
Coherent Electromagnetic Effects in High Current Particle Accelerators: I. Interaction of a Particle Beam with an Externally Driven Radio-Frequency Cavity
Authors: Neil V. Kelvin , Sessler Andrew M.
Published: February 2005

A calculation is made of the interaction of a beam of particles in an accelerator with the radio-frequency cavity that provides the accelerating mechanism of the machine. A Hamiltonian for synchrotron motion is employed that makes possible the simultaneous solution of Maxwell's equations and the Vlasov equation, so that a self-consistent distribution of particles in synchrotron phase space is determined. The effective voltage on the cavity due to the beam of charged particles is of the order of magnitude of the product of the total circulating current in the accelerator and the shunt impedance of the rf cavity. It has the net effect of producing a total voltage on the cavity which is both less than the applied voltage, and shifted in phase with respect to it. The increase in the stable phase angle required so the particles will remain in phase with the accelerating radio frequency is calculated. The decrease in total voltage and increase in stable phase angle result in a decrease in stable phase space available for acceleration, and convenient expressions are given for these quantities in terms of parameters of the accelerator. It is shown that the consequences of the induced voltage may be alleviated by increasing the voltage applied to the cavity. Non-resonant interaction between the beam and cavity is not considered.
Coherent Electromagnetic Effects in High Current Particle Accelerators: II. Electromagnetic Fields and Resistive Losses
Authors: Neil V. Kelvin , Judd David L. , Laslett L. Jackson
Published: February 2005

Coherent electromagnetic fields arising from an azimuthally modulated beam are considered. The beam is completely enclosed in a toroidal vacuum tank of rectangular cross section and highly conducting walls. Expressions are given for the image currents arising from low harmonics of the beam circulation frequency. These expressions are then used to evaluate resistive losses in the walls of the chamber. Expressions are given for fields arising from harmonics of the revolution frequency high enough that the beam may be in resonance with a characteristic mode of the vacuum chamber. The results are generalized to provide a description of the electric field in the neighborhood of a resonance. Numerical examples of resistive losses are given, indicating that these effects will not be serious for circulating currents of the order of 1 amp. Some properties of high-order Bessel functions, required for a description of the resonant chamber modes and the energy lost in their excitation, are developed in an appendix.
Pulse Conduction in Decaying Plasma
Authors: Arunasalam V. , Trimmer John D.
Published: February 2005

Apparatus has been constructed in which plasma, ionized by 144-Mc radio-frequency excitation, is subjected to repeated submicrosecond voltage pulses immediately after excitation is removed. It is expected that observed variation of resulting current pulses may be correlated with quantitative aspects of the plasma decay.
Absorption Measurements on a Plastic Scintillator
Authors: Potter Robert J.
Published: February 2005

The absolute absorption coefficient of a commercial plastic scintillator was measured as a function of wavelength over the region of its luminescence. The absorption coefficient was found to be quite small (∼10−3 cm−1) through most of the visible spectrum with strong absorption beginning at about 4000 A. The details of the experimental apparatus and the procedure are described. Some interpretations of the absorption properties are offered.
Voltage-Tuned Swept-Frequency Receiver
Authors: Riihimaa J. J.
Published: February 2005

A voltage-tuned low frequency solar spectrum analyser has been developed. This analyser tunes over the range 15 to 30 Mc at rates up to 10/sec. A description is given of the voltage-controlled tuner device which employs silicon capacitors.
Instrument to Measure Density Profiles behind Shock Waves
Authors: Witteman W. J.
Published: February 2005

An optical method for the quantitative study of the density distribution behind shock waves has been developed. The method, which uses a photoelectric recording, is based upon the integrated schlieren method originally devised by Resler and Scheibe. A detailed theoretical analysis is given. Excellent agreement with predicted performance was found in measurements of the density profiles behind shock waves in CO2. The method is very accurate and retains its high sensitivity for weak shocks. The pictures obtained show a nearly exponential approach to equilibrium of the density behind shock waves.
High Pressure Electrical Resistance Cell, and Calibration Points above 100 Kilobars
Authors: Balchan A. S. , Drickamer H. G.
Published: February 2005

A high pressure electrical cell is described consisting of tapered Carboloy pistons supported by a pyrophyllite pellet. The pistons are heavily work hardened. A calibration is obtained based on the barium transition at 59 kb, the bismuth transition at 90 kb, and an extrapolation of Bridgman's data. The pressure range is to 500 kb under favorable circumstances. New fixed points include a discontinuous rise in resistance of lead at 161 kb, a discontinuous rise in resistance of barium at 147 kb, a discontinuous rise in the resistance of rubidium at 193 kb, a maximum in the resistance of calcium at 370–75 kb, and a maximum in the resistance of rubidium at 425 kb. In addition, there is a discontinuous rise in resistance of iron at 133 kb which is consistent with the shock wave pressure point found at 131 kb and 37°C.
Sampling Technique for Generating Gaussian Noise
Authors: Rainal A. J.
Published: February 2005

A sampling technique for generating Gaussian noise having a uniform power spectral density from approximately 0.1 cps to 5 kc is described. In principle one could extend the uniform power spectral density property at both ends of the spectrum. The only nonlinear circuit required to implement the technique is a simple high level sampling circuit. Random noise is periodically sampled in order to generate a pulse train having short pulse durations and statistically independent pulse amplitudes. The random pulse train is then applied to a low pass filter in order to produce a Gaussianly distributed output as is predicted by the central limit theorem of probability. The technique is also useful for studying periodic overlapping impulse noise.
Transducer for the Measurement of Thermal Power
Authors: Mattes B. L. , Perls T. A.
Published: February 2005

A transducer has been developed to measure intense, transient heat levels. This transducer was designed to operate at close range in the heat environment generated by the Polaris missile at launch, but its use is readily adaptable to other similar requirements. Its main features as a transducer for measurement of thermal power are: (1) broad spectral sensitivity, (2) fast transient response (less than 1 msec for 63% response for the transducer described, while the inherent response time of the material is less than 12 μsec), (3) ability to withstand intense heat levels for short periods (600 w/in.2 for 0.5 sec), (4) continued use for succeeding tests without need for recalibration, and (5) ease of installation, requiring a minimum in circuitry to record the heat levels. The transducer consists of a pyroelectric ceramic disk placed in a shock isolation mount. The ceramic disks used were either barium titanate or lead zirconate-titanate, depending upon the thermal power level.
Apparatus for Measuring Internal Friction and Modulus Changes of Metals at Low Frequencies
Authors: Swartz J. C.
Published: February 2005

A description is given of a torsion pendulum and associated apparatus which have been employed in measuring internal friction and modulus changes due to dislocations. The pendulum is contained in an evacuated chamber. One specimen chamber is used for temperatures between 80° and 400°K and another for the range 290° to 1000°K. Decrements above 4×10−5 have been observed at maximum strain amplitudes in the range 2×10−7 to 2×10−4. Modulus changes may be measured within 1 part in 104. The specimens may be plastically deformed in situ at temperature. A method is described for making measurements with an elastic torsional bias stress on the specimen.
Simple Wet-String Crystal Cutter
Authors: Fallier Charles N.
Published: February 2005

A simple, automatic wet-string cutter for rapid cutting of water soluble crystals is described. The instrument, assembled from commercially available components, is provided with a microscope stage and rotating vernier scale for accurately positioning the specimen to be sliced. Interchange of crystals is simple and rapid.
Molecular Beam Electron Bombardment Detector
Authors: Weiss Rainer
Published: February 2005

A molecular beam electron bombardment detector that detects approximately 1/40 of a neutral beam falling into an area of 3×10−2 cm2 is described. Molecular beams of sulfur dioxide and argon have been detected with signal-to-noise ratios of 2000/1 and 500/1, respectively. An improved design is discussed.
Vacuum Gauge Calibration System (10−2 to 101 mm Hg)
Authors: Flanick A. P. , Ainsworth J. E.
Published: February 2005

Accurately determined pressures can be produced in a vacuum gauge calibration chamber by means of repeated injections of small, precisely metered masses of air. The apparatus is simple and the pressures obtained are highly repeatable.
Preparation of Thin Metal Foils from Ordinary Tensile Specimens for Use in Transmission Electron Microscopy
Authors: Strutt P. R.
Published: February 2005

Methods are described to produce thin foils suitable for transmission electron microscopy from ordinary tensile specimens. The specimens were cylindrical single crystals of α-brass of diameter ¼ in. and gauge length ¾ in. All the procedures are electrolytic in order to avoid introduction of mechanical strains.
Coaxial Cylinder Viscometer for Non-Newtonian Fluids
Authors: Harper John C.
Published: February 2005

A complete description is given of a narrow-gapped coaxial cylinder viscometer, particularly designed for applicability to non-Newtonian fluids. Included are details of mechanical construction, torque and speed measuring systems, and operating characteristics.
M-H Loop Tracer for Circumferential Fields
Authors: Schrader George F.
Published: February 2005

An apparatus has been constructed to measure the M-H characteristics of thin magnetic films plated on a nonmagnetic wire substrate. The films were uniaxially anisotropic and the characteristics were to be measured in the circumferential direction. Cancellation of air coupling and spurious noises was accomplished by means of a bridge circuit which used magnetic coupling to provide the necessary isolation for the various signals. The characteristics of the bridge are derived.
Variable, Precision Regulated, Low Voltage High Current Supply for Large Electromagnets
Authors: Mobley R. C.
Published: February 2005

A hybrid combination of electronic and magnetic amplifiers has been successfully and reliably utilized over the past five years in a variable, precision regulated, low voltage high current supply for a charged particle deflection magnet. Controlled current range is from 5–200 amp at up to 40 v. Despite the nonlinear impedance presented by the magnet's shielded coils, appropriate feedback loops permit an essentially critically damped 0.01% control response throughout the entire current range. As crucially reflected in the magnet's field, regulation and ripple are <0.01%.
Electron Beam Analyzer Using a Piezoelectric Scanner
Authors: Fujii Tadakuni
Published: February 2005

The electron beam analyzer reported here is intended to investigate the current density distribution of a high current-density electron beam for use with a klystron or a traveling-wave tube. A pair of piezo-electric elements of barium titanate ceramic is used to drive a vibrating, pinholed target for the purpose of sampling the beam to be investigated. This enables direct observation of the current density distribution on a cathode ray oscilloscope screen at any part of the electron beam under investigation, including the part very close to the anode aperture of the electron gun. This is one of the most important parts in our present investigation and yet it is inherently impossible to observe the entire picture of the distribution in this vicinity when a conventional method as, for example, that described by Ashkin is used. Both PPI and A presentations are possible. Only qualitative measurements can be made by the former type of presentation which, however, is indispensable for the purpose of observing the entire picture of the distribution at a glance. The latter, on the other hand, is suitable for quantitative measurements of the distribution along a straight line on a cross section of the beam. The analyzer is so designed and built that either one of these two types of presentation can be selected simply by turning a switch for rapid and accurate measurements. Utmost care is paid in the design and construction of the vacuum and mechanical systems as well as of the associated electrical circuitry with the intention of assuring satisfactory over-all performance and for the convenience of the experimenters. As the result, for example, the pressure in the useful part of the vacuum chamber, with all the complications of the entire setup, could be made to as low as 10−6∼10−7 mm Hg under typical operating conditions. The merits and demerits of the new analyzer are fully discussed with particular reference to the resolving power of the observed pattern. Possible causes of errors which might be introduced to the observed results are also considered.
Development of the Spark Chamber: A Review
Authors: Roberts Arthur
Published: February 2005

A survey of the development of the spark chamber from the spark counter is given. An effort has been made to clarify the early history of the device. Some unpublished recent Russian work on spark chambers is summarized. A consistent terminology for the various times relevant to spark chamber operation is suggested.
A 14×14×7-in. Thin Plate Spark Chamber
Authors: Meyer Donald I. , Terwilliger Kent M.
Published: February 2005

A Lucite wall spark chamber with 0.012-in. aluminum electrodes, active dimensions 14×14×7 in., has been constructed and tested both with cosmic rays and a particle beam. The gap efficiency is nearly 100% and the time resolution ∼1 μsec. Construction methods and chamber characteristics are presented.
Kinematical Analysis of Interaction Vertices from Bubble Chamber Data
Authors: Berge J. Peter , Solmitz Frank T. , Taft Horace D.
Published: February 2005

A high speed computer program for the kinematical analysis of bubble chamber events is described. The program treats individual particle interaction or decay vertices, subjecting the measured variables to the equations of energy and momentum according to the least-squares criterion. This is done in four different cases in which the problem is overdetermined, and a fifth case is calculated in which the problem is just determined. The adjusted or computed variables corresponding to each particle are obtained in all cases as well as the first-order error matrices for each type of variable. A connected chain of vertices may be processed in sequence.
rf Gate with 109 Carrier Suppression
Authors: Blume R. J.
Published: February 2005

A 10.7-Mc cw reference oscillator drives the cathode of a planar triode grounded-grid amplifier, which is normally cut off by −20 v on its plate. The grounded planar grid forms a perforated region in the wall of a copper can which otherwise totally shields both the cw oscillator and the planar cathode. Radio-frequency energy, which leaks capacitively from that cathode through the grounded grid to the negative plate, is bypassed to ground at the plate through a conducting diode. A positive gate voltage applied to the plate switches off the bypass diode and causes the grounded grid stage to amplify the rf voltage on its cathode. The following power amplifier stage, whose input is dc coupled, develops about 100-v rf output during the positive gate. When the gate is off, the output of the power amplifier is ≤10−7 v. The carrier suppression ratio is therefore ≥109, or 180 db. The ungated cw signal is continuously available. Circuitry, leakage measurement, and shielding are described in detail.
Absorption Corrections for the Precession Method
Authors: Kennedy S. W. , Patterson J. H.
Published: February 2005

A means is presented of making absorption corrections graphically for the zero level in x-ray diffraction photography with the precession camera.
Induction Heated Pressure Vessel for Growing Oxide Single Crystals
Authors: Ferretti August , Wickham Donald G. , Wold Aaron
Published: February 2005

An induction-heated oxygen-pressure vessel was constructed to grow ferrite crystals under sufficient oxygen pressure to minimize their decomposition. The furnace is capable of operation at 1600°C and 75 atm pressure.
Theory for the Operation of a Magnetic Refrigerator at Temperatures below 1°K
Authors: Gordon J. E. , Silsbee H. B.
Published: February 2005

A theory for determining the optimum cycle of a magnetic refrigerator is developed. The refrigerator consists of a helium bath, a paramagnetic working substance, and an isothermal reservoir. The working substance is connected to the bath and to the reservoir via thermal valves. In the theory the valves are presumed to be superconducting wires, but no assumptions are made concerning the characteristics of the working substance. The expected behavior of a refrigerator utilizing both He4 and He3 baths is investigated. It is predicted that a magnetic refrigerator operating from a bath temperature of 0.3° or 0.4°K will be able to maintain an isothermal reservoir temperature of 0.05°K or lower with heat inputs of 10–20 ergs/sec, providing the effects of thermal contact resistance can be kept small. The effect of thermal resistance on refrigerator performance is investigated. The same theoretical techniques have been used to predict the behavior of a magnetic refrigerator utilizing a mechanical switch. In the paper the theoretical and experimental results are compared. Moderately good agreement is obtained.
High Current Positive Hydrogen Ion Source with Mass Analysis
Authors: Rose P. H. , Bastide R. P. , Wittkower A. B.
Published: February 2005

A high current positive ion source with an extraction electrode, focusing system and mass analysis is described. The results of experiments on the apparatus for different geometries are presented. The difficulties involved in extracting and containing ion beams under space-charge forces are explored and a practical method which reduced the space-charge effects is described. It is shown that when space-charge densities of ∼30 ma/in2. are reached the optimum Einzel lens geometry is a function of beam current and beam diameter at the position of measurement.
Liquid Pumping Apparatus for Use in Studying Fast Chemical Reactions
Authors: Weiss H. G. , Urmy C. W.
Published: February 2005

A versatile pump apparatus is described which is capable of rapidly pumping small quantities of two dissimilar liquids at volume ratios varying from one to one to about three to one. For the conditions described herein, pumping times of the order of milliseconds were obtained for delivery volumes varying between 1 and 3 ml of liquid per pump. The pentaborane-methanol reaction is used to demonstrate the reliability of this apparatus and to show an application to fast chemical reactions.