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Sep 1957

Volume 28, Issue 9, pp. 677-727


Absolute Flux Measurement of Anisotropic Neutron Spectra with Proton Recoil Tracks in Nuclear Emulsions

J. H. Roberts

Rev. Sci. Instrum. 28, 677 (1957); http://dx.doi.org/10.1063/1.1715974 (4 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A technique for the measurement of neutron spectra which is independent of neutron direction has been studied. The technique consists of measuring all proton tracks in a known volume of type C2 Ilford emulsion, in which shrinkage has been reduced by treating the plates with rosin. By a suitable differentiation of the proton spectrum the absolute flux of neutrons as a function of energy is determined. Rotated plates were exposed to 0.8 and 1.3 Mev neutrons. 4000 tracks were measured, and two peaks with a width ∼150 kev at half‐maximum were obtained. The statistical accuracy of the neutron flux in the two peaks is about ten percent. The flux determination was checked by a fixed C2 plate in which the conventional proton recoil method was used. Good agreement was obtained.

Improved Low‐Level Alpha‐Scintillation Counter for Radon

Henry F. Lucas

Rev. Sci. Instrum. 28, 680 (1957); http://dx.doi.org/10.1063/1.1715975 (4 pages) | Cited 99 times

Online Publication Date: 29 December 2004

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A low counter background is obtained by use of steel for the shell and quartz for the counter window, while marked improvement in the stability is obtained by coating the window with an electrically conducting layer of tin oxide. The distribution of radon and its daughters within the counter under various conditions was determined by comparison of observed and calculated counting efficiencies. A stable counting efficiency of 5.58±0.05 cpm∕μμc radon and a background counting rate of 0.08 cpm is obtained. The usefulness of this counter is augmented by adsorbing the radon on charcoal. The radon is then easily transferred to the counter with a small volume of helium and a Sigmamotor pump. This system is suitable for the analysis of samples of radon as small as 10−14 c or concentrations in air smaller than 10−16 C radon∕liter.

Measurements of the Mobilities of the Negative Ions in Oxygen and in Mixtures of Oxygen with the Noble Gases, Hydrogen, Nitrogen, and Carbon Dioxide

E. W. McDaniel and H. R. Crane

Rev. Sci. Instrum. 28, 684 (1957); http://dx.doi.org/10.1063/1.1715976 (6 pages) | Cited 14 times

Online Publication Date: 29 December 2004

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The mobility constants for oxygen negative ions in He, Ne, A, Kr, Xe, H2, N2, and CO2, each containing various partial pressures of O2 were measured, and extrapolations to zero partial pressure of O2 were obtained. A measurement of the mobility of the negative ion in 100% oxygen was also made. The value found for the latter was 2.46±0.05 cm2∕v‐sec at STP. It was shown that the mobility values referred to a single species of oxygen ion, but the question as to whether it was O2− or O3− was not resolved. A time‐of‐flight method was used, in which the ions were made by the passage of alpha particles through the gas, and detected by a proportional counter.

Dipmeter Curve Comparator, an Optical Aid to the Interpretation of Dipmeter Data

Maurice Ferre and Richard Kinnaird

Rev. Sci. Instrum. 28, 690 (1957); http://dx.doi.org/10.1063/1.1715977 (4 pages)

Online Publication Date: 29 December 2004

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An optical instrument has been designed to eliminate the printing and shifting of dipmeter logs for dip calculations. The instrument comprises sliding and rotating mirrors and provides two differently colored images. Depth shift between curves thus can be determined easily and accurately.

Extended Range Thermal Conductivity Vacuum Gauge

Allen R. Hamilton

Rev. Sci. Instrum. 28, 693 (1957); http://dx.doi.org/10.1063/1.1715978 (3 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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Two magnetic amplifier circuits for automatically controlling a constant temperature hot wire vacuum gauge are described. The differential circuit senses temperature variations by means of voltage and current control coils which respond to the ratio of voltage to current in the hot wire. The bridge circuit senses temperature variations by unbalance in a Wheatstone bridge circuit. In either case, the sensing signal is amplified and fed back to the hot wire in such a direction as to very nearly restore the original temperature. Experimental data are given showing good gauge sensitivity up to 50 mm. Circuitry is simple and, since the magnetic amplifier is inherently a stable device with no perishable components, long trouble‐free life can be expected.

Automatic Temperature Control for an Adiabatic Calorimeter

W. W. Cleland and Richard S. Harding

Rev. Sci. Instrum. 28, 696 (1957); http://dx.doi.org/10.1063/1.1715979 (3 pages)

Online Publication Date: 29 December 2004

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An automatic temperature control device for an adiabatic oxygen bomb calorimeter has been developed which keeps the temperature of the outer water jacket equal to that of the inner bath. When the temperature of the inner bath is not changing rapidly, heat losses are negligible; however, the error due to lag when the inner bath temperature is rising rapidly is about two parts per thousand. This degree of precision permits the accurate analysis of samples of low caloric content such as lyophilized urine. Since the technician need not watch the calorimeter once the bomb has been fired, but instead can prepare a second bomb, the number of samples analyzed in a given time can be doubled if two bombs are available for use with the calorimeter.

Dielectric Rod Wave‐Guide Cells for Microwave Spectroscopy

Elizabeth B. Brackett, Paul H. Kasai, and Rollie J. Myers

Rev. Sci. Instrum. 28, 699 (1957); http://dx.doi.org/10.1063/1.1715980 (4 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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The distribution of microwave power around a quartz rod excited in the dipole mode has been calculated. On the basis of these data, quartz rod sizes have been selected for cells covering the region from 17 000 to 60 000 Mc∕sec. All‐quartz and Teflon‐window cells have been constructed, and the Teflon‐window type has been found to have good transmission and high sensitivity.

Fade‐Canceling Zero Beat Indicator for Reception of Standard Radio‐Frequencies

Richard J. Blume

Rev. Sci. Instrum. 28, 703 (1957); http://dx.doi.org/10.1063/1.1715981 (6 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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A simple circuit is described which enables a local secondary frequency standard to be set quickly to a definite zero beat with a received short‐wave standard frequency signal, without the usual uncertainty due to amplitude fading of the short‐wave signal. In principle, two identical receivers, both fed by the same antenna, are used. One receiver picks up WWV, for example, and a weak signal from the local standard. The other picks up WWV either alone or together with a second weak signal from the local standard which is 180° out of phase with the first. The outputs of the detectors of the two receivers are subtracted, leaving only the beat note, which is recorded on a strip chart. In practice, one unmodified AM receiver is used on a time‐sharing basis by means of a chopper. The band width of the device may be made much less than one cycle per second, and therefore, it is particularly useful when the WWV signal is reasonably stable in phase but far too weak for an audible zero beat to be achieved. Alternatively, the device may be regarded as a simple means of observing fast Doppler shifts of a received standard frequency signal. A schematic diagram and sample recorder charts are included.

Electron Probe X‐Ray Microanalyzer

L. S. Birks and E. J. Brooks

Rev. Sci. Instrum. 28, 709 (1957); http://dx.doi.org/10.1063/1.1715982 (4 pages) | Cited 20 times

Online Publication Date: 29 December 2004

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A 1–3 micron electron probe of simplified design has been constructed for x‐ray spectrochemical analysis of metallic and nonmetallic specimens. At operating conditions of 20–30 kv and less than 0.1 microampere beam current, counting rates of about 3000 counts per second are obtained from pure elements such as iron; thus compositions as low as a few tenths percent are detectable. At increased voltage and current and with a beam size of 10–20 micron, counting rates may be increased to 50 000 counts per second. Applications include analysis of inclusions in metals and minerals, mass transfer material from liquid‐metal cooling systems, phase composition, and intermetallic diffusion studies.

Extended Angular Range Direct Reading Phase Meter

S. Bigelow and J. Wuorinen

Rev. Sci. Instrum. 28, 713 (1957); http://dx.doi.org/10.1063/1.1715983 (5 pages)

Online Publication Date: 29 December 2004

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Most commercial phase meters have an inherent range of 0° to 360°. These instruments usually have a switching arrangement by means of which the range of angles from 360° lagging to 360° leading is covered in a number of sub‐ranges. In the development of a specialized computer, the complex plane scanner, a phase meter was required capable of measuring angles from 540° lagging to 540° leading in one continuous range without ambiguity of output. This paper describes a direct reading pulse position comparison instrument with an inherent range of from 720° lagging to 720° leading. The design is such that this range may be further extended, theoretically without limit. The accuracy of the instrument is ±1° for angles from 540° lagging to 540° leading and for input amplitudes from 0.1 to 100 v. While the phase meter described is designed for operation at a fixed frequency of 400 cps, modifications are suggested for adapting it to broad‐band applications.

Efficiencies and Photofractions for Sodium‐Iodide Crystals

W. F. Miller, John Reynolds, and William J. Snow

Rev. Sci. Instrum. 28, 717 (1957); http://dx.doi.org/10.1063/1.1715984 (3 pages) | Cited 22 times

Online Publication Date: 29 December 2004

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Efficiencies and photofractions for monoenergetic gamma rays, from a broad parallel beam, incident on sodium‐iodide crystals of various sizes have been calculated by the Monte Carlo method. The calculations were carried out for photon energies of 0.279, 0.661, 1.33, 2.62, and 4.45 Mev; the crystals considered were right circular cylinders with radii of 1.0, 2.0, 4.0, 8.0, 12.0, and 16.0 in. and, for each radius, crystals of heights 1.0, 2.0, 4.0, and 8.0 in. The effect of the escape of annihilation gammas from the crystal was taken into account in the Monte Carlo calculation; however no correction was made for escape of bremsstrahlung. This correction is important only at the largest energies and for the smallest crystals where it affects the photofraction by a few percent.
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Magnetic Stirring Technique

W. G. Pfann and D. Dorsi

Rev. Sci. Instrum. 28, 720 (1957); http://dx.doi.org/10.1063/1.1715985 (1 page) | Cited 5 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Preparation of Thin Single Crystals of Barium Titanate

J. T. Last

Rev. Sci. Instrum. 28, 720 (1957); http://dx.doi.org/10.1063/1.1715986 (2 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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Simplified Method of Measuring Peak Pressures

I. R. King and G. J. Gibbs

Rev. Sci. Instrum. 28, 721 (1957); http://dx.doi.org/10.1063/1.1715987 (2 pages)

Online Publication Date: 29 December 2004

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Apparatus for the Conductometric Determination of Solubility

Peter K. Weyl

Rev. Sci. Instrum. 28, 722 (1957); http://dx.doi.org/10.1063/1.1715988 (2 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Use of B2O3 as a Parting Layer for ``Direct'' Replicas in Electron Microscopy

F. W. C. Boswell

Rev. Sci. Instrum. 28, 723 (1957); http://dx.doi.org/10.1063/1.1715989 (2 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Conversion Processes Used in High‐Precision Gamma‐Ray Spectroscopy

D. B. Beard

Rev. Sci. Instrum. 28, 724 (1957); http://dx.doi.org/10.1063/1.1715990 (2 pages)

Online Publication Date: 29 December 2004

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Measurement of Tritium

C. Eaborn, E. Matsukawa, and R. Taylor

Rev. Sci. Instrum. 28, 725 (1957); http://dx.doi.org/10.1063/1.1715991 (2 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Step‐Type Demountable Metal Vacuum Joint

W. J. Lange and D. Alpert

Rev. Sci. Instrum. 28, 726 (1957); http://dx.doi.org/10.1063/1.1715992 (1 page) | Cited 6 times

Online Publication Date: 29 December 2004

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Observations of Nonlinear Maser Phenomena

Walter H. Higa

Rev. Sci. Instrum. 28, 726 (1957); http://dx.doi.org/10.1063/1.1715993 (2 pages) | Cited 9 times

Online Publication Date: 29 December 2004

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