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Jan 1958

Volume 29, Issue 1, pp. 1-74


Gas‐Recoil Fast Neutron Spectrometer

R. E. Benenson and M. B. Shurman

Rev. Sci. Instrum. 29, 1 (1958); http://dx.doi.org/10.1063/1.1715996 (9 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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A gas‐recoil fast neutron spectrometer based on the collimation scheme of R. Giles has been constructed and its behavior analyzed. The principal effort has been directed to improving peak‐to‐valley ratio of the instrument. Electron capture has been minimized and anticoincidence end‐effect counters included in the present design. A graphical analysis has been made of the collimation scheme and the results predicted by the analysis compared with experiment. Li7(p,n)Be7 and D(d,n)He3 neutron groups have been observed using, in turn, palladium‐filtered hydrogen and pure propane as spectrometer fillings. Energy spreads of 10% and under with efficiencies exceeding 10−4 have been obtained with peak‐to‐valley ratios of 10 to 1. Neutron groups from the Be9(d,n)B10, C12(d,n)N13, O16(d,n)F17, and A40(d,n)K41 reactions have been observed.

Large Scintillator for Observation of Cosmic Rays

John R. Green

Rev. Sci. Instrum. 29, 10 (1958); http://dx.doi.org/10.1063/1.1715994 (5 pages) | Cited 6 times

Online Publication Date: 29 December 2004

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A liquid scintillator having an area of five square meters has been developed for the observation of the extensive air showers in cosmic rays. The scintillating liquid, in the form of a disk 10 ft in diameter and 6 in. deep, is viewed by a single 14‐in. Dumont type K1328 photomultiplier tube. The associated circuitry provides a gate whose length is proportional to the logarithm of the scintillator pulse height over a range in pulse height of 2000:1. The length of this gate can be either measured and recorded on a Berkeley EPUT timing meter or converted linearly to a pulse height and analyzed by a multichannel discriminator.

Extending Transducer Transient Response by Electronic Compensation for High‐Speed Physical Measurements

F. F. Liu and T. W. Berwin

Rev. Sci. Instrum. 29, 14 (1958); http://dx.doi.org/10.1063/1.1715995 (9 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Systems are described which automatically and continuously correct for dynamic errors of transducers during transient and steady‐state measurements. They enable high‐speed measurement to be made with improved accuracy even in regions beyond a transducer's natural frequency. Transient phenomena with rise time of a fraction of a microsecond can be measured directly with a minimum of amplitude and phase distortion. High‐speed electronic analog circuits form an integral part of the transducer system to obtain the wave forms of the unknown physical phenomena, and to enable quantitative determination to be made with simple static calibration procedure. Post‐measurement amplitude and phase corrections are made virtually unnecessary.

Description of a Sensitive Micromanometer

R. Eichhorn and T. F. Irvine

Rev. Sci. Instrum. 29, 23 (1958); http://dx.doi.org/10.1063/1.1715997 (5 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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A micromanometer is described for the measurement of differential pressures greater than 10−4 in. of water with tolerable accuracy. The instrument uses concentric tubes to form the fluid passages and provides for remote indication of the level in the central tube by means of a mirrored float and telescope and scale arrangement. The highest instrument sensitivity obtained by the authors was 3.15×10−5in. of water applied pressure per mm of scale reading, but with suitable refinement in the optical system, it is felt that greater sensitivities are possible.

Scintillation Camera

Hal O. Anger

Rev. Sci. Instrum. 29, 27 (1958); http://dx.doi.org/10.1063/1.1715998 (7 pages) | Cited 143 times

Online Publication Date: 29 December 2004

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A new and more sensitive gamma‐ray camera for visualizing sources of radioactivity is described. It consists of a lead shield with a pinhole aperture, a scintillating crystal within the shield viewed by a bank of seven photomultiplier tubes, a signal matrix circuit, a pulse‐height selector, and a cathode‐ray oscilloscope. Scintillations that fall in a certain range of brightness, such as the photopeak scintillations from a gamma‐ray‐emitting isotope, are reproduced as point flashes of light on the cathode‐ray tube screen in approximately the same relative positions as the original scintillations in the crystal. A time exposure of the screen is taken with an oscilloscope camera, during which time a gamma‐ray image of the subject is formed from the flashes that occur. One of many medical and industrial uses is described, namely the visualization of the thyroid gland with I131.

Film Thickness Determination from Substrate X‐Ray Reflections

D. T. Keating and O. F. Kammerer

Rev. Sci. Instrum. 29, 34 (1958); http://dx.doi.org/10.1063/1.1715999 (3 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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A method is given for the determination of the thickness of films using x‐rays diffracted from the substrate. The x‐rays pass through the film and are diffracted by the substrate back to the counter, the intensity being reduced by absorption due to the double transmission through the film. No assumptions need be made about the substrate reflection. Unknown conditions of the substrate are eliminated by measurement of the intensity of two orders of a reflection, or measurement of the intensity of a reflection using two different incident radiations. The method is suitable for all types of film, and is particularly useful in measurements of films containing elements of the substrate for which cases x‐ray fluorescence techniques are of little value. The procedure is illustrated with a measurement of the thickness of zirconium nitride on a zirconium substrate.

Improved Infrared Absorption Spectra Hygrometer

Rex C. Wood

Rev. Sci. Instrum. 29, 36 (1958); http://dx.doi.org/10.1063/1.1716000 (7 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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An infrared hygrometer is described which utilizes a light beam as the principal sensing element. Composed of two narrow bands of infrared radiation, this beam traverses a 12‐in. path through a sample atmosphere containing the humidity concentration to be measured. Wavelength isolation is by means of germanium narrow band‐pass interference filters. One band, centered near a wavelength of 2.60 μ, is subject to attenuation by water vapor, the other located near 2.45 μ is not. Thus the ratio of transmitted band energies is sensitive to the concentration of water vapor in the path. This ratio is effectively maintained at unity through use of a servo‐operated glass wedge which moves to compensate for energy unbalance caused by changes in absorbing vapor. Wedge position is given electrical significance through use of an appropriate transducer, calibrated in terms of vapor density, grams per cubic meter. Included in the design is a dry‐gas purge standardization system whereby periodic checks of the zero point enable compensation for drift factors. Because of the potential use of the method in airborne applications, the instrument was used in tests to determine the character of pressure effects. These showed that vapor concentration (W), total pressure (P), and partial pressure (p) of water vapor, may be related to fractional absorption (A):
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Conditions under which other, simpler relations may be used are discussed.

Self‐Balancing Laboratory Differential Refractometer

C. J. Penther and G. W. Noller

Rev. Sci. Instrum. 29, 43 (1958); http://dx.doi.org/10.1063/1.1716001 (4 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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This refractometer is used in conjunction with a light scattering apparatus to determine high molecular weights. The self‐balancing feature relieves the operator of the tedium of making delicate visual observations while retaining high sensitivity and accuracy. Mounted on a shop surface plate it measures 15 in. wide by 18 in. long by 7 in. high exclusive of the light source transformer. A Brown Electronik amplifier and servo motor are used to position the photocells on the light beam with a repeatability of about 30 microinches. The beam deflection is read on a counter and vernier dial. The range of the instrument is 0.0175 RI unit and the stability and accuracy are within 5×10−7 RI units.
Differential refractometers are also useful in following fractionation by distillation or adsorption, in determining concentrations of colorless solutes in dilute solutions and in studying sedimentation equilibrium.

Apparatus for the Direct Measurement of Adsorption on Solid Surfaces from Liquids

James A. Kafalas and Harry C. Gatos

Rev. Sci. Instrum. 29, 47 (1958); http://dx.doi.org/10.1063/1.1716002 (4 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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An apparatus is described for the measurement in situ of adsorption of solutes on solids and kinetics of film formation on solid surfaces. The technique is applicable only to very dilute solutions in which the solute can be tagged with a γ‐ or hard β‐emitting isotope. The adsorbed radioactivity of the surface is determined through a continuously replenished thin layer of solution. The kinetics and equilibrium conditions of adsorption, desorption and exchange reactions can be determined conveniently; simultaneously, the electrochemical behavior of the surface can be studied. Some measurements are reported.

Recording Microwave Hygrometer

J. B. Magee and C. M. Crain

Rev. Sci. Instrum. 29, 51 (1958); http://dx.doi.org/10.1063/1.1716003 (4 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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This paper describes a rapid response microwave hygrometer for continuously recording the water vapor pressure of atmospheric air over a wide ambient range. The principle employed involves the measurement by means of a cavity resonator of the contribution of water vapor to the refractive index of atmospheric air. The device described also has potential application to the continuous measurement of the degree of contamination of one gas (or of gas mixtures) by another gas (or gases).

Nuclear Resonance Pulse Apparatus

J. C. Buchta, H. S. Gutowsky, and D. E. Woessner

Rev. Sci. Instrum. 29, 55 (1958); http://dx.doi.org/10.1063/1.1716004 (6 pages) | Cited 53 times

Online Publication Date: 29 December 2004

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Radio‐frequency pulse apparatus is described for nuclear magnetic and pure quadrupole spin‐echo and free induction decay experiments in the 15 to 42 Mc frequency range. Nuclear spin relaxation times between 20 μsec and 50 sec have been measured with the apparatus. Simple cryostats provide temperatures from 100° to 500°K.

Apparatus for Measuring the Energy Spectra of Mass‐Selected Particles in Coincidence with Fission

R. H. Stokes, John A. Northrop, and Keith Boyer

Rev. Sci. Instrum. 29, 61 (1958); http://dx.doi.org/10.1063/1.1716005 (4 pages) | Cited 18 times

Online Publication Date: 29 December 2004

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An apparatus used to observe the energy spectrum of protons in coincidence with 14‐Mev deuteron‐induced fission is described. One feature is a mass identifier which operates over a range of 5 to 25 Mev and gives good separation of protons, deuterons, and tritons. Its operation depends on measuring the particle energy loss, ΔE, in a transmission counter and the residual energy, E, in a separate counter. The E and ΔE pulses are introduced into an electronic computer which in 1 μsec produces a pulse whose height is closely proportional to mass. The accuracy of mass separation is illustrated by a representative case in which less than 0.1% of the elastically scattered deuterons appear in the proton energy spectrum. In the presence of the complicating effects of cyclotron beam modulation, the chance coincidence correction to the proton‐fission coincidence spectrum is made by simultaneously measuring the delayed and undelayed spectra.

Response of a Large Sodium‐Iodide Detector to High‐Energy X‐Rays

J. H. Hubbell

Rev. Sci. Instrum. 29, 65 (1958); http://dx.doi.org/10.1063/1.1716006 (4 pages) | Cited 11 times

Online Publication Date: 29 December 2004

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The response of a four‐inch long by five‐inch diameter sodium‐iodide crystal to axially incident 0.01‐ to 8‐Mev x‐rays has been expressed as a 28 by 28 matrix. Measured pulse‐height distributions were combined with Monte Carlo calculated distributions for the input data. The matrix was inverted on an automatic computer for ease of application to spectra. The mesh is uniform in the square root of energy, each interval including an entire photopeak. Such a coarse mesh makes the response matrix suitable for the unscrambling of continuous but not line spectra.
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Hydrogen‐Sensitive McLeod Gauge

C. Norman Cochran

Rev. Sci. Instrum. 29, 69 (1958); http://dx.doi.org/10.1063/1.1716007 (2 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Differential Expansion Diffusion Couple Welding Device

Dilip K. Das

Rev. Sci. Instrum. 29, 70 (1958); http://dx.doi.org/10.1063/1.1716008 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable

Method of Continuous Measurement of Heart Diameter Utilizing Sonic Energy

L. S. Higgins, W. H. Mowbray, and D. P. Ward

Rev. Sci. Instrum. 29, 71 (1958); http://dx.doi.org/10.1063/1.1716009 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable

Constant‐Pressure Leak‐Rate Gauge

K. W. Ehlers

Rev. Sci. Instrum. 29, 72 (1958); http://dx.doi.org/10.1063/1.1716010 (1 page) | Cited 1 time

Online Publication Date: 29 December 2004

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Abstract Unavailable

Precision Phase Measurement

Max Hoberman

Rev. Sci. Instrum. 29, 72 (1958); http://dx.doi.org/10.1063/1.1716011 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable

Elimination of Cold‐Junction Error in Thermocouple Measurements in Electron Tubes

I. S. Solet

Rev. Sci. Instrum. 29, 73 (1958); http://dx.doi.org/10.1063/1.1716012 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable
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Preferred Frequencies of Tuning Forks

Rev. Sci. Instrum. 29, 74 (1958); http://dx.doi.org/10.1063/1.1716013 (1 page)

Online Publication Date: 29 December 2004

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