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Apr 1954

Volume 25, Issue 4, pp. 311-402

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Simple Equipment and Techniques for a Small Cryogenics Laboratory

N. S. Rasor

Rev. Sci. Instrum. 25, 311 (1954); http://dx.doi.org/10.1063/1.1771053 (8 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Simple techniques and easily constructed equipment are described for a small cryogenics laboratory utilizing a commercial helium liquefier. Emphasis is placed on simplicity and availability rather than on high accuracy and efficiency in low‐temperature work. Accessories for a Collins liquefier and a commercial liquid‐helium storage container are described. Techniques used for reaching and measuring intermediate temperatures are outlined, along with a description of two portable cryostats. A small mica and Pyrex platinum resistance thermometer has been developed, and its relatively simple fabrication is described.

A Method for the Estimation of the Relative Intensities of Microwave Absorption Lines

Donald H. Baird and George R. Bird

Rev. Sci. Instrum. 25, 319 (1954); http://dx.doi.org/10.1063/1.1771054 (5 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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An examination of the theoretical relationship between absorption and crystal response in a Stark‐effect microwave spectrograph indicates that a direct proportionality exists between the absorption coefficient and the component of crystal current at the modulation frequency, provided that certain reasonable conditions are fulfilled.
An experimental method is described which utilizes this principle to obtain measurements of the ratio of one absorption coefficient to another. This method involves a matching of the modulation frequency component of crystal current against an adjustable reference signal. These measurements may be used to determine the energy separation of the lower states of the lines observed, thus yielding microwave data on vibrational or torsional energy levels. Line breadth and saturation can be measured equally well with minor modifications in method.
This experimental method was tested by measuring the known ratios of absorption coefficients of the carbonyl sulfide lines near 24 000 mc which are assigned to various isotopic species. The range of deviation of measured ratio from known ratio was 25 percent, and this discrepancy is attributed to reflections in the microwave transmission line, particularly at the ends of the Stark electrode. The determination of molecular vibrational or torsional energy levels is discussed.

Note on the Estimation of Absolute Absorption Intensities with a Stark‐Modulated Microwave Spectrograph

George R. Bird

Rev. Sci. Instrum. 25, 324 (1954); http://dx.doi.org/10.1063/1.1771055 (3 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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The method developed by Baird and Bird for the measurement of relative absorption intensities has been extended to the estimation of absolute absorption intensities. The estimation of absolute intensity is based on the measurement of the ratio of modulation‐frequency component to direct component of crystal current at low microwave power levels.
A preliminary test of the method has been conducted by making measurements on the intensity of the line CH3Cl35, J=0→1, F = math→math over a range of crystal currents. Measured intensities less than the calculated intensity by 15 percent to 25 percent were observed over a range of nine in crystal current, indicating that the method is at least feasible for the estimation of intensities. Even crude estimates can be extremely useful in the identification of spectral lines, and it seems likely that the method admits of much refinement in accuracy.

Measurements of the Effects of Moisture in Nuclear Track Emulsion

Albert J. Oliver

Rev. Sci. Instrum. 25, 326 (1954); http://dx.doi.org/10.1063/1.1771056 (5 pages) | Cited 13 times

Online Publication Date: 29 December 2004

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In order to answer a number of specific questions, thickness and density measurements were made on Ilford nuclear track emulsions before and after processing. Measurements were made as equilibrium was approached under various conditions of ambient relative humidity. Thickness measurements were made with a modified dial micrometer. Volume measurements were made by weighing plates immersed in carbon tetrachloride. A special study of plates stored in a vacuum was carried out. The washing time was found to have an important effect on the shrinkage factor. The data obtained are presented in a number of tables and graphs. The theory of water diffusion in emulsion has been appended by W. H. Barkas, and the emulsion constants evaluated from the experimental data. Attention is directed to the very long characteristic diffusion times implied for thick emulsions.

Floating Zone Recrystallization of Silicon

P. H. Keck, W. Van Horn, J. Soled, and A. MacDonald

Rev. Sci. Instrum. 25, 331 (1954); http://dx.doi.org/10.1063/1.1771057 (4 pages) | Cited 7 times

Online Publication Date: 29 December 2004

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Equipment to carry out recrystallization and zone melting of silicon from a floating liquid zone is described. In the first design, silicon was melted by a tungsten ring. In an improved apparatus, no heater element inside the melting chamber is necessary, since the silicon is melted by induction heating. The system is capable of producing crystals of extreme purity. Silicon single crystals of resistivities up to several hundred ohm cm have been grown with the described equipment.

Response of the Long Counter

R. A. Nobles, R. B. Day, R. L. Henkel, G. A. Jarvis, R. P. Kutarnia, J. L. McKibben, J. E. Perry, and R. K. Smith

Rev. Sci. Instrum. 25, 334 (1954); http://dx.doi.org/10.1063/1.1771058 (2 pages) | Cited 15 times

Online Publication Date: 29 December 2004

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The response of the long counter has been investigated with calibrated neutron sources having average energies up to 5 Mev and has been found to be flat down to a low energy limit that is determined by the construction of the counter. A closer examination reveals fluctuations in the sensitivity of about 5 percent which occur at resonances for neutron scattering by carbon. One can account qualitatively for these fluctuations in terms of the scattering properties of the carbon present in the paraffin moderator of the counter.

A Device for Determining Relative Stopping Powers for Natural Alpha Particles

R. Hobart Ellis

Rev. Sci. Instrum. 25, 336 (1954); http://dx.doi.org/10.1063/1.1771059 (5 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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A device is described by which the stopping power for polonium alpha particles of thin solid or liquid films can be compared with that of gases. An optical system measures film thickness, and the relative stopping power is inferred from the decrease of range which results when a thin film is inserted across a beam of alpha particles.
The device has been used with polystyrene and acetylene and a relative stopping power of 0.99±0.02 is observed.

Techniques for Processing Thick Nuclear Emulsions

Bertram Stiller, Maurice M. Shapiro, and Francis W. O'Dell

Rev. Sci. Instrum. 25, 340 (1954); http://dx.doi.org/10.1063/1.1771060 (9 pages) | Cited 12 times

Online Publication Date: 29 December 2004

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Techniques are described for the ``eradication'' and processing of thick electron‐sensitive nuclear emulsions, and for handling ``pellicles.'' 400‐micron and 600‐micron emulsions, eradicated by a method which preserves their sensitivity to minimum‐ionization particles, exhibit marked reduction in track distortion, as well as in background. A modified procedure for uniform development of thick emulsions by the temperature‐cycling method gives a favorable ratio of grain density to background. Countermeasures against stripping of thick emulsions from their glass base have proved efficacious over a 3‐year period.
A stack of emulsions without glass support (``pellicles'') provides a large sensitive volume in which tracks can be readily followed from one layer to the next. The lateral swelling (∼25 percent) during processing, which discouraged the application of this technique, was overcome by the authors [Phys. Rev. 85, 712 (1952)] in 1951. They evolved a successful method for mounting thick, stripped emulsions onto glass after exposure, but prior to processing, so that the pellicles can be developed as ordinary plates. Since then, additional experience has been gained in the application of pellicle stacks to high‐energy physics. Our procedures lead to emulsions free from lateral swelling, free from blistering, and characterized by a level of distortion sufficiently low to permit multiple scattering measurement even on fairly ``stiff'' tracks. The advantages and limitations of this technique, its possible applications, details of the mounting procedure, and methods of following tracks from layer to layer are discussed.

Solid Angle Subtended by a Circular Aperture at Point and Spread Sources: Formulas and Some Tables

Arthur H. Jaffey

Rev. Sci. Instrum. 25, 349 (1954); http://dx.doi.org/10.1063/1.1771061 (6 pages) | Cited 45 times

Online Publication Date: 29 December 2004

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Some formulas for the calculation of the solid angle subtended by a circular aperture at an isotropically emitting point or spread source are presented as well as three tables of solid‐angle values.

The Type 6218 Beam Deflection Tube as a Complex Pulse Generator

Kurt Enslein

Rev. Sci. Instrum. 25, 355 (1954); http://dx.doi.org/10.1063/1.1771062 (4 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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The type 6218 tube provides a simple means of obtaining pulses with very fast rise time, unlimited, as heretofore, to 150 pps as in mercury‐switch pulsers. It also provides a means of generating double or n pulses of variable separation at repetition rates limited only by the separation of the pulses. Circuits permitting the use of the tube, as well as wave forms produced are given.

Thermoregulator for a Liquid Helium Bath

Willard S. Boyle and James B. Brown

Rev. Sci. Instrum. 25, 359 (1954); http://dx.doi.org/10.1063/1.1771063 (2 pages) | Cited 19 times

Online Publication Date: 29 December 2004

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A simple device is described for holding the temperature of any part of a liquid helium bath constant to within ±3×10−5°K under normal conditions.

Determination of Interfacial Area in Unstable Emulsions by Light Transmission

Gordon E. Langlois, Jonas E. Gullberg, and Theodore Vermeulen

Rev. Sci. Instrum. 25, 360 (1954); http://dx.doi.org/10.1063/1.1771064 (4 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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Total interfacial area can be determined in agitated mixtures of transparent immiscible liquids by calculation from photoelectric measurements of their light transmission relative to clear fluids, with a probe of new design which is inserted into the emulsion. The probe is compact and rugged, and can be assembled from a simply constructed housing together with commercially available parts. A calibration obtained by high‐speed photography of the emulsions is presented. The drop diameters measured were in the range of 0.01 to 0.10 cm, and, in this range, the specific area is found to depend only upon the light transmission and the ratio of refractive indexes of the dispersed and continuous phases.

Concentration of a Cyclotron Beam by Strong Focusing Lenses

F. B. Shull, C. E. MacFarland, and M. M. Bretscher

Rev. Sci. Instrum. 25, 364 (1954); http://dx.doi.org/10.1063/1.1771065 (4 pages) | Cited 6 times

Online Publication Date: 29 December 2004

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A pair of strong focusing magnetic lenses has been used to concentrate a part of the external beam from the Washington University cyclotron. The lenses focus the beam at distances up to more than four meters beyond the end of the cyclotron. This produces approximately an eightfold improvement in beam intensity.

Cyclotron Beam Energy Determination by a Time‐of‐Flight Method

J. H. Manley and M. J. Jakobson

Rev. Sci. Instrum. 25, 368 (1954); http://dx.doi.org/10.1063/1.1771066 (2 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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A simple time‐of‐flight method has been employed as a means of measuring cyclotron beam energy. Through use of a movable and a fixed stilbene scintillation detector, a phase delay measured in terms of the cyclotron frequency is introduced by the flight time of the beam particles. Results good to 2 percent in energy have been obtained. These have less precision than the direct errors of the method, largely because of cyclotron instabilities.
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A Calorimeter for Rapid Determination of Heat Loss and Heat Production in Laboratory Animals

Richard W. Lawton, Lawrence R. Prouty, and James D. Hardy

Rev. Sci. Instrum. 25, 370 (1954); http://dx.doi.org/10.1063/1.1771067 (8 pages) | Cited 6 times

Online Publication Date: 29 December 2004

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A rapid calorimeter of the gradient type, suitable for laboratory animals, has been built and tested. A thin gradient layer (0.015‐inch woven glass tape) of relatively high thermal conductivity is used to line the walls of the calorimeter. The heat flow rate across the gradient layer is measured by means of 2152 copper‐constantan thermal junctions wired in series. With an input of 1 kcal∕hour, 83.26 μv output is obtained. Total response time of the instrument together with the animal holder and metabolic equipment in place is of the order of 10–12 minutes. Heat loss by vaporization is measured by electric hygrometer sensing elements. Heat production is determined by a continual analysis of oxygen consumption using a Pauling analyzer. Heat loss, heat production, and rectal, skin, air, and wall temperatures are continuously recorded. Electric and alcohol calibrations and preliminary observations on monkeys are presented. The calorimeter should make possible critical experiments on thermoregulatory mechanisms of animals.

An Electronic Cardiac Defibrillator and Pacemaker

Rollin K. McCombs, Chester E. Herrod, and R. Stuart Mackay

Rev. Sci. Instrum. 25, 378 (1954); http://dx.doi.org/10.1063/1.1771068 (2 pages)

Online Publication Date: 29 December 2004

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There is described an instrument which has been devised to stop ventricular fibrillation and to restore rhythmical beating of the heart in standstill. The instrument provides 60‐cycle sinusoidal pulses continuously variable from 0 to 3 amperes in intensity and from 0.01 to 1.0 second in duration. A single pulse may be delivered for defibrillation, or regularly repeating pulses, from 20 to 120 per minute, may be delivered for instituting rhythmical beating of the arrested heart. The time intervals produced are quite independent of line voltage and tube changes. Suitable provision is made for the protection of the operator from accidental short circuit to ground. Clinical use of the instrument has been restricted to defibrillation, where it has proven successful.
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Influence of the Variation of the Conditions in a Cloud Chamber during the Sensitive Time on the Accuracy of Cross‐Section Measurements

Sam Barile and Rayjor Webeler

Rev. Sci. Instrum. 25, 389 (1954); http://dx.doi.org/10.1063/1.1771069 (1 page) | Cited 8 times

Online Publication Date: 29 December 2004

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Abstract Unavailable

Ionic Pump

A. M. Gurewitsch and W. F. Westendorp

Rev. Sci. Instrum. 25, 389 (1954); http://dx.doi.org/10.1063/1.1771070 (2 pages)

Online Publication Date: 29 December 2004

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Abstract Unavailable

RF Phase‐Sensitive Detector for Nuclear Magnetic Resonance Signals

Edward B. Baker

Rev. Sci. Instrum. 25, 390 (1954); http://dx.doi.org/10.1063/1.1771071 (2 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Intensity Corrections for Iodine X‐Rays Escaping from Sodium Iodide Scintillation Crystals

Peter Axel

Rev. Sci. Instrum. 25, 391 (1954); http://dx.doi.org/10.1063/1.1771073 (1 page) | Cited 29 times

Online Publication Date: 29 December 2004

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Vacuum Evaporation of Aluminum

R. L. Kelly and P. J. Rice

Rev. Sci. Instrum. 25, 391 (1954); http://dx.doi.org/10.1063/1.1771074 (2 pages)

Online Publication Date: 29 December 2004

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Application of Thermocouples to Target Temperature Measurement in the Internal Beam of a Cyclotron

William J. Sturm and Royce J. Jones

Rev. Sci. Instrum. 25, 392 (1954); http://dx.doi.org/10.1063/1.1771075 (2 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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Mechanical ``Differentiating'' Circuit for Impulse Analyzers and Other Similar Purposes

H. Glättli, P. Stoll, and H. Widmer

Rev. Sci. Instrum. 25, 393 (1954); http://dx.doi.org/10.1063/1.1771076 (1 page) | Cited 1 time

Online Publication Date: 29 December 2004

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Pressure Gauge for the CM Range

J. B. Johnson and N. T. Williams

Rev. Sci. Instrum. 25, 393 (1954); http://dx.doi.org/10.1063/1.1771077 (2 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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The Cockcroft‐Walton Voltage Multiplying Circuit

Edgar Everhart and Paul Lorrain

Rev. Sci. Instrum. 25, 394 (1954); http://dx.doi.org/10.1063/1.1771078 (1 page) | Cited 2 times

Online Publication Date: 29 December 2004

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Abstract Unavailable
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