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Dec 1949

Volume 20, Issue 12, pp. 849-972

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Direct Calorimetry by Means of the Gradient Principle

T. H. Benzinger and C. Kitzinger

Rev. Sci. Instrum. 20, 849 (1949); http://dx.doi.org/10.1063/1.1741416 (12 pages) | Cited 29 times

Online Publication Date: 20 December 2004

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A rapidly responding calorimeter for continuous recording of biological heat exchange has been described. The method is based on the enclosure of the subject in a shell completely lined with a uniform heat flow metering layer (``gradient layer'') while ventilatory and respiratory heat losses are determined in heat exchange meters based on the same technic. The measurement comprises in one thermoelectric potential the sum of all components of heat loss (radiant, convective, conductive, and evaporative fractions). Partitioning measurements of respiratory and evaporative heat losses are readily obtained. Environmental conditions can be closely controlled, and widely varied.
The gradient calorimeter with its rapid response (time lag 42 seconds) is specifically designed for studies of reflex mechanisms involved in temperature control. It is, however, suggested that the characteristics described will, in general, encourage wider application of direct calorimetry in experimental and clinical studies.

Production and Measurement of Ultra‐High Speed Impulses

R. C. Fletcher

Rev. Sci. Instrum. 20, 861 (1949); http://dx.doi.org/10.1063/1.1741417 (9 pages) | Cited 28 times

Online Publication Date: 20 December 2004

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The capabilities and limitations of several impulse generators and voltage dividers, and a micro‐oscillograph sweep circuit for dealing with kilovolt impulses in the millimicrosecond range, are described. The most successful combination produces and measures an impulse of a rise time equal to 4×10−10 sec.

Double Magnetic Lens Nuclear Spectrometer

Harold M. Agnew and Herbert L. Anderson

Rev. Sci. Instrum. 20, 869 (1949); http://dx.doi.org/10.1063/1.1741418 (5 pages) | Cited 15 times

Online Publication Date: 20 December 2004

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A large double magnetic lens spectrometer has been constructed for the study of gamma‐ and beta‐ray spectra. The magnetic field is produced by two identical coaxial water‐cooled coils, each 10.2 cm wide, 31.7 cm I.D., 73.7 cm O.D., and spaced 95.6 cm apart. The source is placed on the axis at the center of one coil and the detector is placed on the axis at the center of the other. The instrument is characterized by a large transmission with moderate resolution. Scattering is virtually absent because of the nature of the trajectories which are used, and because the large dimensions have made possible the removal of scattering material to a considerable distance from the source. The design has lent itself easily to the application of accelerating voltages at the detector admitting the detection of beta‐rays down to 1 kilovolt. The maximum energy conveniently studied with the present arrangement is 2.8 Mev. Beryllium‐coated Zapon films of thickness 0.01 mg/cm2 have been used to mount sources. Charge does not accumulate on these sources. Observations with a Cs137 source 4 mm in diameter have shown a transmission of 1.4 percent with a resolution of 1 percent. The appearance of the internal conversion and Auger electron lines testifies to the absence of appreciable scattering.

A Small Differential Analyzer with Ball Carriage Integrators and Selsyn Coupling

R. E. Meyerott and G. Breit

Rev. Sci. Instrum. 20, 874 (1949); http://dx.doi.org/10.1063/1.1741419 (3 pages)

Online Publication Date: 20 December 2004

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A small scale differential analyzer is described which uses ball carriage integrators instead of the usual Kelvin disk integrators, and selsyn angle transmission instead of mechanical coupling of the rotating parts. The machine is inexpensive, easily constructed and is moderately accurate.

A Slide Rule for Radiation Calculations

M. W. Makowski

Rev. Sci. Instrum. 20, 876 (1949); http://dx.doi.org/10.1063/1.1741420 (9 pages) | Cited 5 times

Online Publication Date: 20 December 2004

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See Also: Erratum

Show Abstract
A slide rule has been developed to facilitate rapid calculations based on the Planck radiation formula. Quantities such as the radiant flux density in a given wave‐length region, the spectral radiant flux density at a given wave‐length, or the corresponding quantities expressed in photon units, can be obtained readily for a black body over a range λT=2×102 to λT=4×106 micron degrees with an accuracy of about 1 percent. Simple extension rules can be used for larger values of λT.

Volumetric Respirometer for Aquatic Animals

P. F. Scholander

Rev. Sci. Instrum. 20, 885 (1949); http://dx.doi.org/10.1063/1.1741421 (3 pages) | Cited 13 times

Online Publication Date: 20 December 2004

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The oxygen consumption of fish and other aquatic animals can be determined in the gas phase of a closed system provided the water is thoroughly equilibrated with the gas phase. The present respirometer employs a simpler and more efficient equilibration system than the earlier described model [Scholander, Haugaard, and Irving, Rev. Sci. Inst. 14, 48 (1943).] and permits a continuous recording of the oxygen consumption over a considerable range. The apparatus is well suited to be set up in banks and has been used extensively in temperature studies on arctic and tropical fishes and crustaceans.

Operation of the 184‐In. Cyclotron

L. R. Henrich, D. C. Sewell, and J. Vale

Rev. Sci. Instrum. 20, 887 (1949); http://dx.doi.org/10.1063/1.1741422 (12 pages) | Cited 12 times

Online Publication Date: 20 December 2004

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The operation of the 184‐in. synchro‐cyclotron is reviewed in terms of the theory as developed by Bohm and Foldy. Certain relevant data on the properties of the magnet and rotating condenser are also presented.

A Fractional Microsecond X‐Ray Pulse Generator for Studying High Explosive Phenomena

H. I. Breidenbach

Rev. Sci. Instrum. 20, 899 (1949); http://dx.doi.org/10.1063/1.1741423 (5 pages) | Cited 1 time

Online Publication Date: 20 December 2004

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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.

An Air Ionization Chamber for Soft X‐Rays

Herman E. Seemann

Rev. Sci. Instrum. 20, 903 (1949); http://dx.doi.org/10.1063/1.1741424 (5 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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An ionization chamber is described which is nearly air‐equivalent from 0.5 to 2.5A, ``effective wave‐length.'' It has been made adaptable for use with the electrometer and charging system of the Victoreen Minometer. Its sensitivity is of the order of 0.15 roentgen per scale division. Suggestions are made for possible improvements.

Instrument for Measurement of X‐Ray Diffraction Patterns

John A. Bennett

Rev. Sci. Instrum. 20, 908 (1949); http://dx.doi.org/10.1063/1.1741425 (3 pages)

Online Publication Date: 20 December 2004

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An instrument is described for measuring x‐ray back reflection patterns for surface stress determinations. The chief feature of the apparatus is a curved slit in the optical system so that the beam of light which scans the diffraction ring is an arc having the same radius of curvature as the ring. This simple, inexpensive instrument has been found to be at least as precise as a microphotometer for these measurements and its use has resulted in a considerable saving of time. It is suggested that the instrument might appropriately be called a photomicrometer.

Circuit for Rapid Determination of Resolving Power and Other Characteristics of Coincidence‐Systems

H. de Waard

Rev. Sci. Instrum. 20, 911 (1949); http://dx.doi.org/10.1063/1.1741426 (5 pages) | Cited 1 time

Online Publication Date: 20 December 2004

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A simple device is described in which pairs of pulses are produced that are moved continuously with respect to each other (wobbled) by an a.c. voltage that also sweeps an oscilloscope spot horizontally. The pulses are applied to both inputs of a coincidence system. Vertical deflection of the c.r. scope spot is caused by the output pulses of the system. Thus various characteristics can be made visible and the resolution can be read from the scope screen at a glance. With the instrument resolving powers from 3.10−6−10−9 sec. approx. can be determined. The apparatus was calibrated by feeding the wobbling pulses into a radio receiver. The output of the receiver has a sharp minimum when the pulse distance (Δt) satisfies the condition Δt=(1+2n)/2ν where n is an integer, ν is the frequency to which the receiver is tuned.

Design Curves for 180° Magnetic Spectrometers

George E. Owen

Rev. Sci. Instrum. 20, 916 (1949); http://dx.doi.org/10.1063/1.1741427 (8 pages) | Cited 7 times

Online Publication Date: 20 December 2004

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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.

Apparatus for Isotope Separation by Thermal Diffusion

W. W. Watson, L. Onsager, and A. Zucker

Rev. Sci. Instrum. 20, 924 (1949); http://dx.doi.org/10.1063/1.1741428 (4 pages) | Cited 9 times

Online Publication Date: 20 December 2004

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A compact, all‐metal, multi‐stage thermal diffusion apparatus for the separation of isotopes in quantity in non‐corrosive gases at any pressure up to 175 lb/in.2 is described. For a particular gas the proper pressure may be well‐enough calculated in advance as that giving maximum separation factor in the last column only. Operating with neon at 3 atmos. pressure, and using 12 meters of column consuming 4.9 kw for 260 hours, 7 liters of gas with a Ne22 content of 93.4 percent were produced.

A Single Pulse Voltmeter

G. T. Rado, M. H. Johnson, and M. Maloof

Rev. Sci. Instrum. 20, 927 (1949); http://dx.doi.org/10.1063/1.1741429 (3 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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The voltmeter described herein is capable of measuring the average amplitude of a single pulse with a random error of 0.2 percent of full‐scale deflection. The instrument consists of a gated cathode follower bridge in conjunction with a ballistic indicator. In its present form the circuit responds to the average pulse amplitude over an arbitrarily selected interval of two milliseconds; thus, it measures the actual amplitude in the special case of a flat pulse of sufficient duration. The required input is 0.8 volt for full‐scale deflection. The nonlinearity is less than 1 percent of any given deflection throughout the major part of the range of the instrument.

Sliding Contacts to Transmit Small Signals

Billy M. Horton

Rev. Sci. Instrum. 20, 930 (1949); http://dx.doi.org/10.1063/1.1741430 (3 pages) | Cited 1 time

Online Publication Date: 20 December 2004

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Measurements have been made of root‐mean‐square noise voltage in the frequency range 0.5 to 200 c.p.s. generated by contacts sliding at low speeds using four arrangements of contacting bodies and various materials. Mercury with amalgamated probes gave the lowest noise levels. Some solid contacts operating with low friction on clean metal surfaces yielded values of generated noise below 1 microvolt at a sliding speed of 35 cm/sec. when two contacts were in parallel.
The noise increases with speed and varies with normal force. The r.m.s. generated noise voltage of a large number of independently mounted contacts in parallel is inversely proportional to the square root of the number of contacts.

The Gamma‐Ray Counting Efficiency for a Lead‐Cathode G‐M Counter

E. T. Jurney and Fred Maienschein

Rev. Sci. Instrum. 20, 932 (1949); http://dx.doi.org/10.1063/1.1741431 (3 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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The dependence of gamma‐ray counting efficiency on energy has been determined in the range 0.17 Mev to 2.76 Mev for a G‐M counter with a lead cathode. The efficiency for six energy values was found by coincidence measurements utilizing the disintegration of In111, Au198, Co60, and Na24. The result indicates a smooth increase in counting efficiency for increasing energy over the range of energies investigated.

A Secondary‐Emission Electron Multiplier Tube for the Detection of High Energy Particles

Robert P. Stone

Rev. Sci. Instrum. 20, 935 (1949); http://dx.doi.org/10.1063/1.1741432 (7 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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The requirements of high gain and low background current in an electron‐multiplier tube for the direct detection of high energy particles are considered. The design and construction of an experimental electron‐multiplier tube with a stable over‐all gain of at least 108 and a background at room temperature corresponding to three or four electrons per minute released at the input is described. An 0.0008‐inch thick nickel window is provided in the tube envelope to admit the high energy particles to the multiplier. The efficiency of this device is compared quantitatively with that of a Geiger tube as a detector of beta‐particles. It is found that the over‐all beta‐particle counting efficiency of the tube is of the order of 1.3 percent, and that the efficiency of the oxidized silver magnesium target surface is 4.9 percent for a uranium source and 6.0 percent for a strontium source.

A High Resolution Scale‐of‐Four

Val Fitch

Rev. Sci. Instrum. 20, 942 (1949); http://dx.doi.org/10.1063/1.1741433 (3 pages) | Cited 5 times

Online Publication Date: 20 December 2004

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A high resolution scale of four has been developed to be used in conjunction with the nuclear particle detection devices in applications where the counting rate is unusually high. Specifically, it is intended to precede the commercially available medium‐resolution scaling circuits and so decrease the resolving time of the counting system. The circuit will function reliably on continuously recurring pulses separated by less than 0.1 μsec. It will resolve two pulses (occurring at a moderate repetition rate) which are spaced at 0.04 μsec. A five‐volt input signal is sufficient to actuate the device.
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Erratum: A Wide Range Radiation Instrument

Leonard Reiffel and Glenn Burgwald

Rev. Sci. Instrum. 20, 944 (1949); http://dx.doi.org/10.1063/1.1741434 (1 page)

Online Publication Date: 20 December 2004

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Abstract Unavailable

A Sensitive Magnetometer for Very Small Areas

Daryl M. Chapin

Rev. Sci. Instrum. 20, 945 (1949); http://dx.doi.org/10.1063/1.1741435 (2 pages) | Cited 7 times

Online Publication Date: 20 December 2004

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A vibrating wire system for measuring weak magnetic fields is described for use in very small spaces. Quartz crystals are used for drivers to get sufficient velocity with very small displacements. To adjust the driving voltage to correspond exactly to the natural crystal frequency, the crystal is also used to regulate the oscillator.

Growing and Processing of Single Crystals of Magnetic Metals

J. G. Walker, H. J. Williams, and R. M. Bozorth

Rev. Sci. Instrum. 20, 947 (1949); http://dx.doi.org/10.1063/1.1741436 (4 pages) | Cited 23 times

Online Publication Date: 20 December 2004

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Single crystals of nickel, cobalt, and various alloys are grown by slow cooling of the melt. They are oriented by optical means and by x‐rays, and ground to the desired shape using the technique described.
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An Electromagnetic Blood Flow Meter

John W. Clark and James E. Randall

Rev. Sci. Instrum. 20, 951 (1949); http://dx.doi.org/10.1063/1.1741437 (4 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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This report describes the design of an instrument for electrically measuring the rate of flow of blood passing through a glass cannula which has been inserted within a vessel of an anesthetized animal.
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An Electromagnetic Focusing Device for the Electron Microscope

Harold T. Meryman

Rev. Sci. Instrum. 20, 955 (1949); http://dx.doi.org/10.1063/1.1741438 (1 page)

Online Publication Date: 20 December 2004

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Abstract Unavailable

Automatic Stabilization of the Overvoltage on a Geiger Counter

H. R. Crane

Rev. Sci. Instrum. 20, 955 (1949); http://dx.doi.org/10.1063/1.1741439 (2 pages)

Online Publication Date: 20 December 2004

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Abstract Unavailable

Long‐Lived Self‐Quenching Counter Filling

Lloyd G. Shore

Rev. Sci. Instrum. 20, 956 (1949); http://dx.doi.org/10.1063/1.1741440 (2 pages) | Cited 3 times

Online Publication Date: 20 December 2004

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Abstract Unavailable
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