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Dec 1954

Volume 25, Issue 12, pp. 1151-1227

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Diffusion of Gases through Nickel and Design of a Convenient Leak for Hydrogen and Deuterium

K. Landecker and A. J. Gray

Rev. Sci. Instrum. 25, 1151 (1954); http://dx.doi.org/10.1063/1.1770969 (3 pages) | Cited 12 times

Online Publication Date: 29 December 2004

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The diffusion of gases through thin‐walled nickel tubing (cathode tubing) has been investigated in the temperature range 200–1000°C. It was found that at the most thoroughly examined temperature of 500°C and at a pressure difference of 1 atmos, hydrogen and deuterium diffuse through this tubing about 2000 times faster than any of the other gases tried. The design of a hydrogen and deuterium leak is described which is easy to construct and to operate. The tubing does not appear to deteriorate because of crystallization as is experienced with palladium tubing.

Electron‐Bombardment Ion Source for Mass Spectrometry of Solids

A. E. Cameron

Rev. Sci. Instrum. 25, 1154 (1954); http://dx.doi.org/10.1063/1.1770970 (3 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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An ion source structure is described which is specifically designed for slow electron ionization of vapors of salts. This may be used up to 550°C. The ion chambers are rapidly interchangeable and memory effects between samples are undetectable over moderate changes in concentration. Some of the characteristics of this source are discussed and its advantages indicated.

Moving‐Strip Fourier Analyzer

H. J. Grenville‐Wells

Rev. Sci. Instrum. 25, 1156 (1954); http://dx.doi.org/10.1063/1.1770971 (6 pages)

Online Publication Date: 29 December 2004

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A device embodying Robertson's principle of movable strips is described for performing two‐dimensional Fourier summations of the type ΣHΣKF(hk)[cos2π(hX+kY)] without first rearranging them in the form ΣHΣKF(hk)[cos2πhX⋅cos2πkY−sin2πhX⋅sin2πkY]. The same strips can be used to evaluate sine summations and some three‐dimensional summations directly. The electron density can be readily calculated at selected individual points in the projection. Summations can also be completed by means of masks. The operation of the device, which can accomodate values of F(hk) = ± (1 to 99), h= −15 to +15, k=0 to 15 for X, Y = 1∕36 of the repeat distance, is described, and illustrated by an example.

Airborne Infrared Spectrograph

C. W. Hargens

Rev. Sci. Instrum. 25, 1162 (1954); http://dx.doi.org/10.1063/1.1770972 (5 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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An airborne infrared spectrograph has recently been completed in which electronic techniques are used in novel ways to record 10 spectral samples and the total radiation signal for the wavelengths between 1 and 25 microns. The rapid operation of the sensing and recording systems makes it possible to obtain the complete analysis each 0.08 second together with other pertinent data.

Two New Electronic Analog Multipliers

Maurice A. Meyer and Harrison W. Fuller

Rev. Sci. Instrum. 25, 1166 (1954); http://dx.doi.org/10.1063/1.1770973 (7 pages)

Online Publication Date: 29 December 2004

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This paper describes two new four‐quadrant analog multipliers which have some advantages over other designs which have been reported earlier. A satisfactory balanced modulator which is necessary for both designs is described in some detail. The first multiplier uses a modified double amplitude modulation scheme applying the recent work of Sternberg and Kaufman on the two‐frequency modulation product problem. The test multiplier has a frequency response from dc to 30 kc for either input. The accuracy is ±0.5 percent of full scale at full‐scale output, and ±0.2 percent of full scale at one‐tenth of full‐scale output. The dc drift stability of the output is ±0.15 percent of full scale, and the scale factor stability is ±1 percent of full scale over a period of several hours. The second multiplier uses successive phase modulation and amplitude modulation of a carrier. A description of the method and a discussion of error sources are given. The performance of this multiplier is in general inferior to that of the first.

Isothermal Jacket Microcalorimeter for Heat Effects of Long Duration

Paul Gordon

Rev. Sci. Instrum. 25, 1173 (1954); http://dx.doi.org/10.1063/1.1770974 (5 pages) | Cited 7 times

Online Publication Date: 29 December 2004

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A Borelius type isothermal jacket microcalorimeter has been designed and constructed. It consists essentially of a vapor thermostat providing a constant temperature environment about a chamber containing the specimen and measuring device, the latter being a high‐sensitivity differential thermopile. With one set of thermopile junctions kept at constant temperature by contact with the environment, and the other set arranged to vary in temperature with the specimen, a heat effect in the specimen is measured by following the difference in temperature across the thermopile as a function of time. Calibration of the apparatus is carried out by using the Peltier heat developed at the junction of a thermocouple located in an axial hole in the specimen. With an argon atmosphere in the specimen chamber, the limit of detection is a heat flow of 0.003 gram‐calories per hour. The absolute accuracy of the determinations depends upon the particular conditions of a given run, but is usually in the vicinity of 2 to 5 percent.

Mutual Inductance Bridge and Cryostat for Low‐Temperature Magnetic Measurements

R. A. Erickson, L. D. Roberts, and J. W. T. Dabbs

Rev. Sci. Instrum. 25, 1178 (1954); http://dx.doi.org/10.1063/1.1770975 (5 pages) | Cited 11 times

Online Publication Date: 29 December 2004

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A mutual inductance bridge and cryostat are described which may be used to measure susceptibilities from 77°K, with liquid nitrogen, down to adiabatic demagnetization temperatures. In addition to the sensitivity necessary for measurements over such a temperature interval, the apparatus provides the following features: a usable frequency range of 5 kc, for the study of paramagnetic relaxation and paramagnetic specific heat; measurement of longitudinal susceptibilities in fields up to 3000 oersted, and transverse susceptibilities in fields up to 13 000 oersted; a simple method for changing samples with a minimum dismantling of the equipment.

Diffusion Cloud Chamber of Unusually Large Dimensions

Kenneth E. Relf and Wilson M. Powell

Rev. Sci. Instrum. 25, 1182 (1954); http://dx.doi.org/10.1063/1.1770977 (6 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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A diffusion cloud chamber 8 ft long, 4 ft wide, and 5 in. deep has been built and operated successfully for 540 hrs out of a continuous 720‐hr run. Though the actual area is 32 sq ft, the area photographed was 21 sq ft or approximately 2 sq m. A sensitive layer of good quality extending 2☒ to 3 in. above the floor was easily maintained. The coolant temperature was held near −67°C and the air above the glass sheet forming the top was held at 30°C. A clearing field of 30 v (top negative) was found desirable to keep the chamber free from general rain. The chamber contained an air and methyl‐alcohol mixture operated at 1 atmos pressure. Tracks in the sensitive region were photographed through the top with the aid of several mirrors. The chamber was used to study the structure of the cores of cosmic‐ray air showers. It is now being used for studies with the bevatron.

Apparatus for Measuring the Elastic Moduli and Internal Friction of Solids from 1.7 to above 77°K and Some Values for α‐Quartz

M. E. Fine

Rev. Sci. Instrum. 25, 1188 (1954); http://dx.doi.org/10.1063/1.1770978 (3 pages) | Cited 9 times

Online Publication Date: 29 December 2004

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Apparatus for measuring the moduli and internal friction of solids at temperatures from 1.7 to above 77°K is described. The resonant piezoelectric method with quartz transducers is used. The frequency range is 30 to 450 kc∕sec. For calibration variously oriented quartz crystals were measured over this temperature range and the values are given.

New Automatic Sharpener for Microtome Blades

Francis W. Bishop

Rev. Sci. Instrum. 25, 1190 (1954); http://dx.doi.org/10.1063/1.1770979 (3 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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A new compact microtome knife sharpener has been developed which, in its simplest form, provides a semi‐manual method of sharpening blades for standard and ultra‐thin sectioning. Fully mechanized, however, it eliminates the manual element and requires little attention except to see that the grinding powder and its vehicle are maintained. The knife is caused to move back and forth across an oscillating glass plate by means of a motor drive, and a simple mechanism periodically turns the blade over. It rapidly sharpens a blade capable of cutting ultra‐thin sections for electron microscopy while such an edge is unusually fine for paraffin sections. No stropping or other treatment is required.

Design and Operation of Evapor‐ion Pumps

Robert H. Davis and Ajay S. Divatia

Rev. Sci. Instrum. 25, 1193 (1954); http://dx.doi.org/10.1063/1.1770980 (5 pages) | Cited 15 times

Online Publication Date: 29 December 2004

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A new type of high vacuum pump has been developed which makes possible the elimination of organic vapors and high vapor pressure materials from vacuum systems, without using coolant traps or baffles. This pump utilizes the gettering action of continuously evaporated titanium in conjunction with ion pumping. Some pumping speeds achieved are: 7000–8000 liters∕sec at 3×10−6 mm of Hg for hydrogen, 6500–7500 liters∕sec at 1.5×10−6 mm for nitrogen and oxygen, approximately 9 liters∕sec at 4×10−6 mm for argon, and approximately 4 liters∕sec at 3×10−5 mm for helium. The lowest pressure obtainable is about 2×10−7 mm of Hg. Dependence of pumping speeds on the temperature of the gettering surface, the pressure and the rate of evaporation of titanium is given.

High Noise Cable as a Sensing Element

H. T. Meryman and H. W. Shirer

Rev. Sci. Instrum. 25, 1198 (1954); http://dx.doi.org/10.1063/1.1770981 (2 pages)

Online Publication Date: 29 December 2004

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The problem of devising a sensing element of the ``burglar alarm'' type which would be highly sensitive, portable, battery operated, and adaptable to any type of terrain was solved by using a shielded cable of high noise characteristics as an extended transducer. By this means, a device of extreme simplicity was developed with sensitivity sufficient to detect almost indiscernible physical deflection.

High‐Intensity Ion Source

C. B. Mills and C. F. Barnett

Rev. Sci. Instrum. 25, 1200 (1954); http://dx.doi.org/10.1063/1.1770982 (3 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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An ion source that does not require a filament has been developed for use in the cyclotron. Positive ions, from an oscillatory region within a hollow anode, bombard the cathodes at the ends and maintain them at emission temperatures. The source aperture is a lateral slit, math×2¼in., in the wall of the anode. With a 10 kv (dc) accelerating potential, stable hydrogen ion beams of 330 ma (82 percent protons) have been obtained. Ion output increases as hydrogen gas feed is increased from 1 to 12 cc∕min (N.T.P.). The average proton production efficiency has been 20 percent.

Programming a Digital Computer for Cell Counting and Sizing

Walter Welkowitz

Rev. Sci. Instrum. 25, 1202 (1954); http://dx.doi.org/10.1063/1.1770983 (3 pages)

Online Publication Date: 29 December 2004

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A method is presented for programming a digital computer, used in conjunction with a television scanning system, to count and size solidly and contrastingly stained cells of different shapes and sizes as found on slides prepared for histological study. When the operating times of the program are considered, it is found that machine counting and sizing is very much faster than a manual performance of the same operations. A program prepared in accordance with the method presented operated satisfactorily on the Illiac digital computer.

Variable‐Frequency Microwave Cavity Spectrometer

Robert J. Collier

Rev. Sci. Instrum. 25, 1205 (1954); http://dx.doi.org/10.1063/1.1770984 (3 pages) | Cited 6 times

Online Publication Date: 29 December 2004

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A variable‐frequency, resonant cavity spectrometer was developed for the investigation of molecular gases in the 10‐cm spectral region. Either Stark or Zeeman modulation could be applied. A single coaxial cavity, operated in the TEM mode, served as the Stark or Zeeman modulation cell and as the frequency tuning and stabilizing mechanism. The rf power transmitted through the cavity was detected by a bolometer and the signal component at the fundamental modulation frequency amplified and passed to a phase sensitive detector. The minimum detectable absorption coefficient for the spectrometer was determined to be αmin = 1×10−10 cm−1.

Solid Angle Subtended by a Circular Aperture

Milan Wayne Garrett

Rev. Sci. Instrum. 25, 1208 (1954); http://dx.doi.org/10.1063/1.1770985 (4 pages) | Cited 13 times

Online Publication Date: 29 December 2004

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Methods for calculating the solid angle subtended by a circle at an off‐axis point are correlated and the rates of convergence of available series are compared. Averages over a plane surface or a cylindrical volume are derived from an analogy that permits the use of existing tables of mutual inductances. Rates of variation, for displacement or rotation of the source, and the technique of computing from the zonal harmonic series are briefly discussed.
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Recording Dielectric Hygrometer for Expired Air

Paul Webb and M. Kenith Neugebauer

Rev. Sci. Instrum. 25, 1212 (1954); http://dx.doi.org/10.1063/1.1770986 (6 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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A method for rapid continuous measurement of water vapor in expired air was needed for studies of subjects under cold ambient conditions. The method chosen senses water vapor content by measuring the air dielectric constant. Air passes between the plates of a small capacitor so that changes in the air dielectric constant, which depend on water vapor concentration, cause capacitance changes. These small changes cause resonant frequency shifts in a 2‐Mc oscillator. Design features which insure stability in the element and oscillator are presented. The frequency changes are detected by the beat frequency method, converted to proportional linear dc voltage, and used to drive the pen of a magnetic ink‐writing oscillograph. The system detects changes in absolute humidity of 1.0‐mgm water vapor per liter, but the sensitivity could be increased or decreased for different applications. Precautions regarding the need for simultaneous temperature measurement are pointed out, a sample tracing is shown, and the calibration procedure is mentioned. There is a brief discussion of previous developments along similar lines, followed by a listing of some of the advantages of the method.
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``Cosmic‐Ray'' Effect in Photomultiplier Tubes

Elton M. Baker and B. M. Tolbert

Rev. Sci. Instrum. 25, 1218 (1954); http://dx.doi.org/10.1063/1.1770987 (1 page) | Cited 3 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Fast Detector for Fission Counting

Grenfell P. Boicourt and John E. Brolley

Rev. Sci. Instrum. 25, 1218 (1954); http://dx.doi.org/10.1063/1.1770988 (2 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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Effect of Feedback on Noise in a Pulse Amplifier

Robert L. Chase

Rev. Sci. Instrum. 25, 1219 (1954); http://dx.doi.org/10.1063/1.1770989 (1 page) | Cited 12 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

New Point‐Focusing Monochromator

Dwight W. Berreman, Jesse W. M. DuMond, and Pierre E. Marmier

Rev. Sci. Instrum. 25, 1219 (1954); http://dx.doi.org/10.1063/1.1770990 (2 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Improvement in Rubber Diaphragm Cloud‐Chamber Technique

H. Blumenfeld, E. T. Booth, and L. M. Lederman

Rev. Sci. Instrum. 25, 1220 (1954); http://dx.doi.org/10.1063/1.1770991 (1 page) | Cited 3 times

Online Publication Date: 29 December 2004

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See Also: Erratum

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Glass Ball Valves

C. W. McCutchen

Rev. Sci. Instrum. 25, 1220 (1954); http://dx.doi.org/10.1063/1.1770992 (2 pages)

Online Publication Date: 29 December 2004

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Inexpensive Method of Measuring Surface Finish

M. Matsunaga and S. Yamasaki

Rev. Sci. Instrum. 25, 1221 (1954); http://dx.doi.org/10.1063/1.1770993 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Abstract Unavailable

Apparatus for Measurement of Sensitivity of Electrical Resistance of Wires to Strains

G. C. Kuczynski and P. F. Stablein

Rev. Sci. Instrum. 25, 1222 (1954); http://dx.doi.org/10.1063/1.1770994 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable
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