bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linearly Biased Track Counting in Cross-Section Determinations
Authors: Crawford Frank S. 
Published: February 2005

In determining the average number n̄ of tracks per bubble chamber picture, for purposes of determining cross sections, one usually cannot count all tracks, but counts tracks in only some of the pictures, selected at random. An alternative procedure is described here in which the pictures are not selected at random, but are those which contain the ``interesting events.'' The average of 1/n over this ``linearly biased'' sample equals 1/n̄, where n̄ is the desired average over a random sample.
The linear-bias method has some advantages that are complementary to those of the usual random method.
Wire-Rod Spark Counters in Air
Authors: Daddi Lino , De Franceschi Luciano 
Published: February 2005

The operating characteristics of the Rosenblum type spark counters in air are examined. A qualitative interpretation of the experimental data is given.
The advantages of the device (no background, absence of walls, detection of heavily ionizing particles only) and its disadvantages (limited reproducibility for some incidence directions, small sensitive volume), which limit its practical utilization, are reported.
Compact Pulsed Generator of Fast Neutrons
Authors: Hawkins P. O. , Sutton R. W. 
Published: February 2005

A study of the factors influencing the design of pulsed neutron generators is made. By using the reaction between tritium and deuterium, peak rates of 1013/sec should be obtainable from quite small sources.
A method of keeping the pressure of deuterium gas substantially constant at the working pressure was evolved. This enabled a ``sealed-off'' and hence portable source to be made.
The development of a fast neutron generator or neutron tube based on these considerations is described. This was capable of producing neutrons at a rate of 5×1012/sec at a voltage of 100 kv. The tube was suitable for operation at pulse lengths of 20 μsec, and the neutron content of each pulse was 108. No difficulty was experienced in operating at 1 pulse/sec, and higher pulse repetition frequencies may be possible.
Scintillation Type Mass Spectrometer Ion Detector
Authors: Daly N. R. 
Published: February 2005

A new and relatively simple type of mass spectrometer ion detector is described. The positive ion is accelerated onto an aluminum surface releasing secondary electrons, and these in turn are accelerated onto an organic scintillator, viewed by a sealed-off photomultiplier. Counting methods are used to measure the ion beams. The detector has a low noise level, 4×10−20 amp, and the mass discrimination is small for ions in the high and low mass range.
Admission of air to the vacuum system does not affect the gain of the detector, since no activated surfaces are situated within the vacuum.
In the event of a fault occurring in the photomultiplier a new one can be substituted in a few minutes without letting air into the vacuum system.
High Temperature Microscope Stage
Authors: Sundquist B. E. 
Published: February 2005

A microscope stage has been designed and constructed that permits microscopic observation of small particle specimens in the temperature range from room temperature to about 1200°C. Higher temperatures can be obtained with minor changes.
The constructed stage contains four independent furnaces designed to permit accurate observation and control of specimen temperature even under conditions of rapid heating or cooling. Specimens are heated in easily inter-changeable quartz crucibles by a Nichrome foil resistance wrapped on a small Alundum refractory tube.
Operation of Cesium-Antimony Phototubes under High Light Level
Authors: Miyake Kiyoshi 
Published: February 2005

The fatigue phenomena of vacuum and gas-filled cesium-antimony photocathodes were studied. It is shown that the phototubes can be operated without fatigue at high photocurrent densities, about 90 μa cm−2, by reducing the temperature rise of the cathode due to high illumination and by lowering the anode voltage to be applied.
The photocathodes whose responses ranged from 30 to 60 μa/lu were used to study the changes of their sensitivities in the following experiments: (a) Effect of intense illumination on the sensitivity; (b) variation in the response by heating at elevated temperatures and (c) relation between the change in photoresponse and the positive potential applied to the anode. The results obtained were as follows: In red radiation the thermal effects dominated, and in blue-green radiation an effect on the photosensitivity due to the absorption in the cesium anti-monide film appears. The photoresponse was appreciably reduced when a positive potential above the ionization potential of the gas in the phototubes was applied to the anode. At a very high light level the fatigue phenomena of the cathodes may be caused mainly by the thermal decomposition of cesium antimonides.
An Automatic Arc-Current Regulator
Authors: Potter E. V. , Scott Arden 
Published: February 2005

The desirability of eliminating errors in spectrographic analyses, resulting from fluctuations in arc current normally present in uncontrolled or manually controlled d.c. arcs, led to the design and construction of an electronic type of automatic current regulator. This regulator operates from a 250-volt d.c. supply, handles currents from 4 to 8 amperes, and maintains them within 0.02 percent per volt variation in arc voltage over a range of from 30 to 70 volts in arc voltage or 40 volts variation in supply voltage.
Oscillograms of the arc current and voltage during a typical run show no detectable fluctuations in the current and less variation in voltage than is normally present.
Standard curves obtained using the regulator are much more regular and reliable, and the individual points can be reproduced more closely than those from the uncontrolled arc. Analyses made using the regulator can also be reproduced more closely, and the results are in better agreement with chemical analyses than those obtained with the uncontrolled arc. In addition, the use of the automatic regulator eliminates the necessity for having an operator to regulate the arc current and the results obtained with one operator are better than two men could obtain without the regulator.
Extended Applications of the Hot-Wire Anemometer
Authors: Corrsin Stanley 
Published: February 2005

The use of the hot-wire anemometer has been extended to include the measurement of temperature fluctuation level as well as temperature-velocity correlation, in a turbulent flow with heat transfer.
Secondly, the hot wire can be used for the determination of mean relative concentration in the mixing of two gases of different known thermal characteristics.
Finally, the instantaneous response of a hot wire in a turbulent flow with mixing of two gases of different thermal characteristics has been computed. This permits measurement of the concentration fluctuation level as well as the concentration-velocity correlation.
The Measurement of Ultra-Short Time Intervals
Authors: Neddermeyer S. H. , Althaus E. J. , Allison W. , Schatz E. R. 
Published: February 2005

An instrument is described which utilizes the superposition locus of transient pulses traveling in opposite directions on a transmission line for a determination of the interval between the times of generation of the pulses. For testing purposes pulses are generated by discharging a short segment of line through a matching network into a closed loop so that equal pulses start simultaneously in opposite directions around the line. Two systems for pulse detection are described, one requiring repetitive pulsing, in which a detector is coupled to the line at any desired position, yields an output which varies as a function of position, and shows a maximum at the superposition locus; and another, not requiring repetitive pulsing, in which the outputs from multiple fixed detectors are recorded simultaneously. In the latter system the superposition locus appears as a maximum in the output peaks, which are recorded in one-to-one correspondence with the positions of the detectors on the line.
A measurement of the refractive index of polystyrene for pulses of duration about 2×10−10 sec. gave 1.48 with the first instrument and 1.45 with the second. The latter value is less certain than the first because of poorer resolution, and both are subject to an upward revision from an undetermined correction in the line propagation rate.
Metaborate Compounds for Internal Cyclotron Targets
Authors: Weil A. S. , Reid A. F. , Dunning J. R. 
Published: February 2005

The use of NaBO2 as a target material for the preparation of radioactive Na24 through the deuteron bombardment reaction Na2311+1d2→11Na24+1p1is discussed. The general advantages of NaBO2 as a target material, compared to metallic sodium or other sodium containing compounds, are given, as well as the procedure for target preparation and the details of the chemical treatment used for the purification of the Na24.
The general use of metaborate targets is discussed briefly for other deuteron bombardment reactions in which an elementary target material is less practical to use.
A Note on the Theory of Corrugated Diaphragms for Pressure-Measuring Instruments
Authors: Pfeiffer Alfred 
Published: February 2005

A hypothetical model for the distribution of stress in diaphragms is discussed. It is constructed of members in series, with each consisting of one flexural and one tension spring acting in parallel. This hypothetical model lends to a correlation between pressure P acting on the diaphragm, corresponding deflection of the diaphragm h, effective diameter 2r, sheet thickness d, and ``plate modulus'' F, as a measure of elasticity, of the following form: FP·h2r=Σ lim k=1k=n1ck1·d2r+ck2(d2r)3,where the quotients F/p·h/2r and d/2r each are factors without dimensions.
This formula with only two terms (n=2) checks well with the data for our own test material as well as with other experimental results1 on diaphragms with pressure-proportional deflection. The probable relation of the separate terms of the formula to definite annular zones of the diaphragm as well as its applicability to diaphragms with other than pressure-proportional deflection are discussed.
A Frequency Characteristic Analyzer
Authors: Sampsell J. W. 
Published: February 2005

The frequency characteristics analyzer is a device for analyzing the frequency characteristics of filters, amplifiers, and other electronic elements whose pass bands are within the 500–50,000 cycle range.
While many frequency analyzers have been constructed, this is one of the first such analyzers in which (1) the width of the swept band and the rate of sweep can be varied independently, (2) the frequency is swept linearly, (3) the response of the pass band circuit can be positioned to appear at any point in the sweep, and (4) the oscillograph time base can be interlocked with the generator frequency.
Reproducible Construction of Quartz Fiber Devices
Authors: Kirk Paul L. , Craig Roderick 
Published: February 2005

Methods for construction of various types of quartz fiber structures by means of jigs also made from small quartz rod are described. It is shown that the advantages of jig construction are in obtaining a better product and particularly the ability to reproduce quite accurately a number of such quartz structures.
Various practical aspects of quartz fiber manipulation and construction are discussed.
A Technique for the Making and Mounting of Fine Mesh Screens
Authors: Law H. B. 
Published: February 2005

A new process has been developed for making fine mesh metal screens from glass masters. The master contains grooves corresponding to the screen wires. Metal is sputtered on the master, rubbed off the surface and the remaining metal in the grooves plated to form the screen. Screens from 200 to 1500 meshes per inch have been made with better than 50 percent transmission.
A method of mounting the screens on a ring and subsequent tightening by heat treatment is described.
The Properties of Some New Types of Counters
Authors: Curran S. C. , Reid J. M. 
Published: February 2005

It is generally assumed that it is essential to use a cylinder of circular section as the cathode if a good counter of the point or wire type is to be made. Investigation of various geometrical forms of cathode with a wire as anode shows that counters may be made in a large variety of shapes and yet operate satisfactorily. Thus a large rectangular vessel with a wire placed symmetrically within the volume or mounted close to one wall has been found to operate as a self-quenched counter.
The use of such shapes is shown to result in improved performance in several important respects, e.g., reduced operating voltages, shorter dead-times. By the use of several wires in the same vessel, coincidence arrangements are made easily possible. This can be applied successfully to the construction of a counter which has a reduced natural counting rate but still presents a large solid angle to an external source. Various other applications are considered.
Impulse Determinations of Rockets by Means of Rotating Systems
Authors: Penner S. S. , Whiteman R. C. 
Published: February 2005

Two simple rotating systems have been designed for the determination of the specific impulse of rocket propellants. The pin wheel consists of a bicycle wheel mounted horizontally in a steel frame. A small rocket motor containing the propellant which is to be tested is mounted on the wheel so that the thrust delivered by the rocket accelerates the speed of rotation of the wheel. A photographic record of the rotational speed is then used to calculate the impulse delivered as a function of the time. The rotating bar is operated in a manner similar to that of the pin wheel.
The rotating systems have been used for the determination of relative effective gas velocities of a number of double-base rocket powders. Impulse measurements of miniature rockets of the order of 1 pound-second were made. An investigation of the effect of expansion ratio of rocket nozzles on the reduced specific impulse showed good agreement with theoretical calculations.
A Field Instrument for Measuring Volume and Instantaneous Flow Rate of Inspired Air
Authors: Silverman Leslie , Plotkin Theodore , Lee George 
Published: February 2005

The object of this study was the development of a portable self-contained instrument which would record the rates of inspiratory air flow through protective canisters under actual field conditions. This instrument was developed so that observations made in the laboratory could be checked under actual field conditions. Measurements of air flow on subjects in tanks or parachute troops or men moving in industrial operations cannot be obtained without a portable instrument.
The essential requirements of this instrument are that it obtain records of air flow, air volume, and respiration rate while worn by or held closely to the individual under observation. The apparatus should be rugged and independent of positional effects or a reasonable amount of rough handling. Its operation should be automatic and not require attention by the subject.
Design Study for a Ten-Bev Magnetic Accelerator
Authors: Brobeck W. M. 
Published: February 2005

A ten-billion volt proton synchrotron design using injection from Van de Graaff generators and betatron starting to reduce the required oscillator frequency range is described. Factors affecting the design of the iron core magnet, its power supply, and associated apparatus are discussed. Cost is roughly estimated as fifteen- to twenty-million dollars.
The exposition [E. M. McMillan, ``The synchrotron—a proposed high energy particle accelerator,'' Phys. Rev. 68, 143 (1945); V. Veksler, ``Concerning some new methods of acceleration of relativistic particles,'' Phys. Rev. 69, 244 (1946)] and successful test [J. R. Richardson, K. R. MacKenzie, E. J. Lofgren, and B. T. Wright, ``Frequency-modulated cyclotron,'' Phys. Rev. 69, 669 (1946)] of the synchrotron principle of magnetic particle acceleration has removed one of the limits to the energy obtainable with magnetic accelerators. Radiation loss [E. M. McMillan, ``Radiation from a group of electrons moving in a circular orbit,'' Phys. Rev. 68, 144 (1945)] varying inversely as the rest energy of the particle, is negligible for protons even at ten-billion electron volts. The maximum obtainable energy therefore appears to be limited only by engineering feasibility and available funds. In order to gain some information on these factors a preliminary design of a proton accelerator has been worked out for what is believed to be the largest machine that could be made in the near future without departing from the techniques used on machines at present in operation. Ten-billion electron volts, which is in the range of energy of some primary cosmic-ray particles and the requirements for proton pair formation, appears to be attainable within the above restriction.
A Fractional Microsecond X-Ray Pulse Generator for Studying High Explosive Phenomena
Authors: Breidenbach H. I. 
Published: February 2005

An x-ray pulse generator capable of producing short bursts of x-rays not greater than 3×10−7 seconds in duration has been constructed. These short bursts are obtained by supplying a negative 50 kv, 12.5 Joule trigger pulse to the cathode shield of a standard Westinghouse W.L. 389 flash x-ray tube. This pulse generates a pre-discharge plasma in the tube which blocks the main 100 kv, 290 Joule pulse until the cathode to anode gap impedance is lowered by ionization.
An arrangement is also described whereby 3 separate, successive radiographs of a single detonation may be taken at predetermined time intervals.
Design Curves for 180° Magnetic Spectrometers
Authors: Owen George E. 
Published: February 2005

The image shapes resulting from 180° focusing of charged particles in a homogeneous magnetic field have been computed. General curves are presented in terms of three variables for variable ρ-spectrometers (as in the case of photographic detection) and in terms of four variables for constant ρ-spectrometers (as in the case of detection with a fixed counter). The variables are source and exit-slit height, source width, angular selection, and exit-slit width.
The advantages of using sources and exit-slits with a large dimension parallel to the magnetic field (i.e., height) are noted.
A Cloud Chamber of Light Weight for Balloon Flights
Authors: Shutt R. P. , Johnson A. L. , Thorndike A. M. 
Published: February 2005

Some constructional details of cloud chambers used for balloon flights are described. Details are given on the fabrication of transparent plastic front walls and cylinders for the cloud chambers. A relatively large number of bicycle spokes is used for holding the chamber together, thus distributing material stresses, enabling one to make the aluminum parts of the cloud chamber quite light.
The back and front walls of the cloud chambers are somewhat spherically curved, resulting in considerable reduction of material thicknesses. By the same means a piece of slightly curved metal gauze is sufficient to limit the motion of the rubber diaphragm in the compressed position.
A mechanism used for adjusting expansion ratios can be removed before a balloon flight. Gas and liquid can be inserted through bicycle valves.
The cloud chambers are 12 inches in diameter, 3½ inches deep, and weigh approximately 6 pounds.
Measurement of the Spin of a Projectile in Flight
Authors: Warshaw H. D. 
Published: February 2005

Projectile spin is measured by recording the voltage generated in a pick-up coil as the rotating field of a transversely magnetized projectile passes the coil.
A permanent magnet within a brass sleeve (for magnetic insulation) is inserted in a projectile of mild steel. Rotation of the projectile as it passes the pick-up coil generates a sinusoidal e.m.f. which is displayed on the screen of a cathode-ray tube and photographed for subsequent analysis.
Frequency Analyzer for Bioelectric Potentials in the Sub-Audio Range
Authors: Markey Charles , Schoenfeld Robert L. , Hoefer Paul F. A. 
Published: February 2005

An analyzer for sub-audio bioelectric potentials, particularly the human electroencephalogram, is described. The instrument is coupled to the output of a standard EEG amplifier and records twenty frequencies by means of individual filters each coupled to a two-inch cathode-ray oscilloscope. A 35-mm slow moving camera provides a time base while simultaneously photographing, the filter deflections, a cathode-ray trace of the unanalyzed slow wave and one-second time markers produced by a clock driven flashing light. The system employs amplitude modulation of a 1200 cycle carrier; the filters being selective to the lower sideband frequencies which are recorded as horizontal deflections of the oscilloscopes.
The present analyzer, in contrast to others, has a one-half-second time constant and is thus a low ``Q'' system responsive to activity of short duration. The frequency spectrum obtained is necessarily broad but detailed in the time domain, an aspect of physiological importance, hitherto neglected.
Vortex Thermometer for Measuring True Air Temperatures and True Air Speeds in Flight
Authors: Vonnegut Bernard 
Published: February 2005

The aerodynamic heating experienced by thermometers exposed from airplanes can be very nearly eliminated over a wide range of operating conditions by mounting the thermometer in the center of an air vortex created by a simple housing. This method has been found to simplify air temperature measurements over the operating range of a B-17 airplane. The instrument has promise for measuring temperatures in clouds.
True air speeds can be measured by the difference between the temperature of the vortex thermometer and a thermometer exposed in the usual manner. Designs and flight data are presented for several vortex thermometers and a simple true air speed indicator.
RaDEF Standard Sources for Beta-Disintegration Rate Determinations
Authors: Novey Theodore B. 
Published: February 2005

The preparation and use of calibrated RaDEF equilibrium sources for absolute beta-counting is described. The sources are essentially weightless and are mounted on a thin backing to reduce self-absorption and back-scattering correction problems. Calibration was done by determination of the alpha-disintegration rate of RaF in a parallel plate alpha-ionization chamber. No secondary standards are required and the sources can be recalibrated at any time.
As an example of the application of such standards, details of the calibration of a P32 solution distributed by the Bureau of Standards for intercalibration in February 1949 are given. The final result is 88.8 mrd/ml at 8 A.M. C.D.T. March 1, 1949. The precision of the measurement is 0.3 percent. The accuracy is estimated to be 1–2 percent.
A New Mechanical Autocorrelator
Authors: Seiwell H. R. 
Published: February 2005

A relatively simple and inexpensive machine for mechanical computation of the autocorrelation function is described. The original design resulted from a collaboration with Dr. George P. Wadsworth of the Massachusetts Institute of Technology.
The theoretical definition of the autocorrelation function is given. This is followed by an outline of the hand computational procedure as applied in this laboratory to observational (ocean wave) data of finite scope. The machine computation is next compared with the hand process.
A Vacuum Furnace for Use in the Temperature Range 1000–2000°C
Authors: Tomlinson J. W. , Bockris J. O'M. 
Published: February 2005

A laboratory vacuum furnace with a glass envelope has been developed, using as a heater a cylindrical grid of tungsten wire enclosed by radiation shields.
The furnace is suitable for physicochemical measurements in the range 1000–2000°C.