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Oct 1948

Volume 19, Issue 10, pp. 617-732

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Coincidence Circuit of Medium Resolution

H. L. Schultz and Ernest Pollard

Rev. Sci. Instrum. 19, 617 (1948); http://dx.doi.org/10.1063/1.1741063 (4 pages) | Cited 7 times

Online Publication Date: 20 December 2004

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A reliable coincidence circuit of medium resolution with resolving time adjustable between 0.4 and 0.01 microsecond is described. The circuit uses a biased‐diode pulse level selector in either channel, followed by a triggered blocking oscillator. Narrow and constant shape pulses so produced in the channels actuate a coincidence tube, output from which keys a rectangular pulse generator for turning on a power tube connected to a mechanical impulse recorder. Preliminary applications to the study of time fluctuations and delays in proportional counters and to proton time of flight measurements are described.

A Frequency Characteristic Analyzer

J. W. Sampsell

Rev. Sci. Instrum. 19, 620 (1948); http://dx.doi.org/10.1063/1.1741064 (8 pages)

Online Publication Date: 20 December 2004

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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.

An Improved Conductance Bridge

Walter L. Foy and Arthur E. Martell

Rev. Sci. Instrum. 19, 628 (1948); http://dx.doi.org/10.1063/1.1741065 (5 pages)

Online Publication Date: 20 December 2004

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The design and construction of a bridge for the determination of the conductance of electrolytic solutions is described. The best recommendations of other workers are incorporated into the apparatus, and a number of new features and improvements are included. An important characteristic of the bridge is the fact that it may be constructed from easily obtained parts. The instrument has considerable accuracy over a wide range of resistance and may be adapted to the measurement of capacitance.

Electrostatic Deflection of a Betatron or Synchrotron Beam

E. D. Courant and H. A. Bethe

Rev. Sci. Instrum. 19, 632 (1948); http://dx.doi.org/10.1063/1.1741066 (6 pages) | Cited 2 times

Online Publication Date: 20 December 2004

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An electrostatic deflection scheme for removing the electron beam from a betatron or synchrotron is considered. The deflection is accomplished in two stages: The first stage is an orbit expansion achieved by a sudden decrease of the magnetic field in the orbit region. The electrons move outwards in spirals of increasing pitch; if the orbit radius is 1 meter and the rate of decrease of the magnetic field is one percent per microsecond, the pitch of the spiral is 1.26 cm at the ``neutral position'' where Hr has its maximum value. The pitch is proportional to the ⅗ power of the rate of decrease of the field.
At the neutral position the beam enters a radial electric field which deflects it outward more sharply. If this field, and the magnetic field with it, extends a distance of about a tenth of the orbit radius beyond the orbit, the electrons will be collimated into a beam whose angular divergence is approximately proportional to (H/E)¾, where H is the magnetic field at the orbit and E the electric deflecting field. With H = 10 kilogauss and E = 60 kv/cm, the angular divergence will be of the order of ten degrees. Curves showing the dependence of the angular divergence on E/H and on the distance to which the fields extend are presented.

A Counter for Low Energy Ionizing Particles

H. C. Thomas and N. Underwood

Rev. Sci. Instrum. 19, 637 (1948); http://dx.doi.org/10.1063/1.1741067 (3 pages)

Online Publication Date: 20 December 2004

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A counter which combines large solid angle, low operating voltage, ease of changing source, and ability to detect particles of very low energy is described.
By means of a revolving plate a sample may be rotated to a position inside the counting chamber through which helium is slowly passing. A large solid angle with low operating voltage is achieved by placing side by side several semicylindrical cathodes whose central wires are electrically connected.
Fe55, which has a half‐life of four years, was used as a sample with which to examine the operational characteristics of the counter.

An Electrokinetic Transducer

Milton Williams

Rev. Sci. Instrum. 19, 640 (1948); http://dx.doi.org/10.1063/1.1741068 (7 pages) | Cited 2 times

Online Publication Date: 20 December 2004

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A description is given of a transducer which utilizes, for the transformation of sonic to electrical energy, the electrokinetic potential developed by the movement of a fluid through a porous solid. The construction and calibration of the transducer are discussed, and results of measurements of the pressure fluctuations in oil pipe lines are presented.

Automatic Plotting of Electrostatic Fields

Paul E. Green

Rev. Sci. Instrum. 19, 646 (1948); http://dx.doi.org/10.1063/1.1741069 (8 pages) | Cited 6 times

Online Publication Date: 20 December 2004

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An apparatus is described by means of which plots of the equipotentials of two‐dimensional fields may be made automatically from models of the electrodes. The usual electrolytic tank method has been extended by the addition of a servomechanism which causes the probe to traverse an equipotential automatically. A stepping relay operated by a limit switch effects automatic plotting of successive equipotentials and limits the plot to a desired area. A number of plots made with such an apparatus are reproduced.

An Instrument for Recording Ultra Low Frequency Ocean Waves

Walter H. Munk, Hector V. Iglesias, and T. R. Folsom

Rev. Sci. Instrum. 19, 654 (1948); http://dx.doi.org/10.1063/1.1741070 (5 pages) | Cited 8 times

Online Publication Date: 20 December 2004

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An instrument has been designed to measure low amplitude waves whose frequencies fall between those of the wind‐generated ocean swell and those of the astronomic tides. Its maximum sensitivity is to waves whose period is 15 minutes, and its pass band extends approximately from 2‐minute periods to 2 hours. The suppression of the ocean swell and tides (whose amplitudes are much greater than those of the waves to be studied) is accomplished by means of capillaries and air chambers which give the instrument a response characteristic analogous to that of an electrical R—C circuit. Records obtained show the continual presence of waves in this previously unexplored portion of the spectrum of gravity waves in the sea.

A Simple Temperature Controller

J. C. Mouzon

Rev. Sci. Instrum. 19, 659 (1948); http://dx.doi.org/10.1063/1.1741071 (4 pages) | Cited 4 times

Online Publication Date: 20 December 2004

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A simple electronic temperature controller has been developed which incorporates ``proportional'' control action. Utilizing a resistance thermometer element, its precision of operation is determined ultimately by the stability of the resistance element and the gain of the amplifier. Its operation is essentially independent of line voltage.

The Production of Thin Be Foils

Hugh Bradner

Rev. Sci. Instrum. 19, 662 (1948); http://dx.doi.org/10.1063/1.1741072 (3 pages) | Cited 7 times

Online Publication Date: 20 December 2004

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A procedure for making Be foils between 10−5‐cm and 10−3‐cm thick, and with diameters up to an inch and a half, is described, and methods of mounting these foils are indicated.

A Comparison of Mercury Diffusion Pumping Speeds for Five Gases

Donald Fluke

Rev. Sci. Instrum. 19, 665 (1948); http://dx.doi.org/10.1063/1.1741073 (2 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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Mercury diffusion pumping speeds for hydrogen, helium, air, argon, and Freon have been measured for a pump of small aperture and found to vary inversely as the square root of the molecular weight.

Routine Use of Ionization Chamber Method for C14 Assay

C. D. Janney and B. J. Moyer

Rev. Sci. Instrum. 19, 667 (1948); http://dx.doi.org/10.1063/1.1741074 (8 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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The design and routine use of apparatus for the measurement of amounts of C14 down to a specific activity of the order of 10−9 curie per gram is described. Use is made of an ionization chamber containing the sample to be analyzed (as CO2) and a Lindemann electrometer. The auxiliary electrometer circuits and the apparatus for handling the CO2 gas are also presented. The method is in regular use in the radiation laboratory for the routine analysis of samples obtained from biological tracer experiments. A comparison with other methods of C14 detection is included.
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Erratum: Cathode‐Ray Magnetization Curve Tracer

M. V. Scherb

Rev. Sci. Instrum. 19, 674 (1948); http://dx.doi.org/10.1063/1.1741075 (1 page)

Online Publication Date: 20 December 2004

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The Unbalance Squelcher

K. Tomiyasu

Rev. Sci. Instrum. 19, 675 (1948); http://dx.doi.org/10.1063/1.1741076 (3 pages) | Cited 2 times

Online Publication Date: 20 December 2004

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The transmission of unbalanced currents on shielded pair lines can be stopped by a double stub device called an unbalance squelcher. The unbalance squelcher, which is substantially a tandem bridge for unbalanced currents, reflects completely the unbalanced currents yet allows free passage of the balanced currents.

Dynamic Pressure Measurement by Optical Interference

Willard E. Buck and Walter H. Barkas

Rev. Sci. Instrum. 19, 678 (1948); http://dx.doi.org/10.1063/1.1741077 (7 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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A pressure gauge is described in which the displacement of a pressure diaphragm is measured by recording photographically the motion of interference fringes formed by light reflected from the diaphragm and from an adjacent stationary mirror. The instrument is simple and unusually accurate and stable. Typical observed performance: frequency range, zero to over ten thousand c.p.s.; pressure range, zero to five thousand p.s.i.; absolute error, less than one‐half percent. Calibration is carried out under static conditions and the response is linear. Presentation of the data is direct and the analysis of the records simple. Other broad fields of application of the new recording principle are indicated.

Improved Method for Measuring Hall Coefficients

I. Isenberg, B. R. Russell, and R. F. Greene

Rev. Sci. Instrum. 19, 685 (1948); http://dx.doi.org/10.1063/1.1741078 (4 pages) | Cited 77 times

Online Publication Date: 20 December 2004

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The influence of the current electrodes on measurements of the Hall coefficient is examined. Equations are given for the ratio of the measured voltage as a function of the geometry of the sample. Experiments verifying these results are described. The conditions for maximum sensitivity are given.

A Voltage Integrator

Anne Buzzell and Julian M. Sturtevant

Rev. Sci. Instrum. 19, 688 (1948); http://dx.doi.org/10.1063/1.1741079 (5 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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Integration, with respect to time, of a varying voltage is accomplished by counting the revolutions of the output shaft of a rate servomechanism. Accuracy of the order of ±0.1 percent over a 100‐fold range of input voltage is obtained, with speed of response ample for many purposes.

A D.C. Voltage Regulator for Moderately High Currents

J. M. McCrea and D. J. Le Roy

Rev. Sci. Instrum. 19, 692 (1948); http://dx.doi.org/10.1063/1.1741080 (6 pages) | Cited 2 times

Online Publication Date: 20 December 2004

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The theory and design is given for a voltage stabilizer capable of supplying a current of several amperes at voltages in the region of 100 volts d.c. The main power requirements are furnished by a 220‐volt d.c. line. The circuit incorporates two distinct methods of control, resulting in a large stabilization ratio and a low internal resistance.
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A New Pump

Louis W. Lewis

Rev. Sci. Instrum. 19, 698 (1948); http://dx.doi.org/10.1063/1.1741081 (3 pages)

Online Publication Date: 20 December 2004

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A new type of pump is described which has the unique property of being able to move a fluid without change in pressure, volume, or temperature. Against a small external resistance, it can be used for pressure, vacuum, or circulation of a gas, and with a simple attachment, liquids may be pumped.

A New Compact Tiselius Electrophoresis Apparatus

Dan H. Moore and John U. White

Rev. Sci. Instrum. 19, 700 (1948); http://dx.doi.org/10.1063/1.1741082 (7 pages) | Cited 9 times

Online Publication Date: 20 December 2004

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A compact Tiselius electrophoresis apparatus which incorporates the valuable features of the Tiselius method yet avoids its disadvantages of large size, costliness, and difficulty of operation is described. It incorporates a 2‐ml capacity Tiselius cell, and a highly precise optical system based on Longsworth's scanning modification of the Toepler schlieren method. Two schlieren lenses provide parallel light through the cell and reduce the optic path length. The over‐all dimensions of the self‐contained unit are 63″×14″×12″.

A Device for Measuring Physiologic Pressure Phenomena Using the Bonded Electrical Wire Resistance Strain Gauge

Howard R. Bierman

Rev. Sci. Instrum. 19, 707 (1948); http://dx.doi.org/10.1063/1.1741083 (4 pages) | Cited 6 times

Online Publication Date: 20 December 2004

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An electrical device for measuring physiological pressure phenomena, using a resistance wire strain gauge, is described. The gauge is bonded securely to a metal diaphragm, deformation of which changes the resistance of the gauge, and causes a flow of current through an appropriate circuit. Examples of the applications in physiology of this device are presented along with typical recordings.

An Apparatus and Method for the Continuous Measurement of Evaporative Water Loss from Human Subjects

Edward D. Palmes

Rev. Sci. Instrum. 19, 711 (1948); http://dx.doi.org/10.1063/1.1741094 (7 pages) | Cited 4 times

Online Publication Date: 20 December 2004

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The rate of evaporative water loss is measured by recording the difference in water vapor concentration in a stream of air before and after it passes over a man enclosed in a sealed chamber. An infra‐red gas analyzer is employed for measuring the difference in water vapor concentration. Construction and application of the apparatus are discussed.
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A Transfer Tube for the Collins Helium Cryostat

M. C. Desirant and W. J. Horvath

Rev. Sci. Instrum. 19, 718 (1948); http://dx.doi.org/10.1063/1.1741113 (2 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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Abstract Unavailable

A Simple Recording System for a Mass Spectrometer

V. H. Dibeler, R. B. Bernstein, and T. I. Taylor

Rev. Sci. Instrum. 19, 719 (1948); http://dx.doi.org/10.1063/1.1741133 (2 pages)

Online Publication Date: 20 December 2004

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Switch Interval Timer

Homer T. Gittings

Rev. Sci. Instrum. 19, 720 (1948); http://dx.doi.org/10.1063/1.1741148 (2 pages) | Cited 1 time

Online Publication Date: 20 December 2004

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