摘要:

A method has been developed for determining thermal conductivity by measuring temperatures at the center of the faces of a rectangular rod which is heated electrically. Radiation of energy causes a difference in the temperatures of the short and long faces, and this difference is related to the thermal conductivity. The emissivity of the surface must be known. The method has been applied successfully by Dr. Ralph Muller, of the Los Alamos Scientific Laboratory, to the measurement of the thermal conductivity of graphite at temperatures near 2500°K, when other standard methods failed.

ISSN:0034-6748    

DOI:10.1063/1.1715760

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

This paper describes a millimicrosecond timing apparatus for determining the arrival directions of extensive cosmic‐ray air showers. The apparatus consists of four plastic scintillation detectors in a square array and a fast oscillograph with which one can determine the relative arrival times of the first shower particles which reach the four detectors as indicated by the relative positions of pulses from the detectors on the oscillographic sweep. The uncertainty in determinations of the relative arrival times of the particles in a shower is about 3 millimicroseconds. The uncertainty in the determination of the arrival direction of a shower is about ±5°, and this uncertainty is caused primarily by the lack of coplanarity of the shower particles and not by instrumental limitations.

ISSN:0034-6748    

DOI:10.1063/1.1715761

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A device is proposed with which ions may be selected on account of their oscillating frequency in a static ``potential well'' whereby the ions pass several times across the same rf field tuned to the oscillation, thus gaining energy on each passage. No magnetic fields are used. As the initial velocity of the ions plays only a secondary role for the selection, the energy spread in the ion source is allowed to be much greater than with most types of mass spectrometers. Likewise, no high mechanical precision is required. The resolving power may be varied by electrical means. ``Harmonic masses'' (``ghost images'') are easily eliminated.

ISSN:0034-6748    

DOI:10.1063/1.1715762

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A sonic gas analyzer intended primarily for estimation of CO2in the physiological range of 0–10% is described. The instrument uses a resonant cavity maintained in oscillation by a transistor amplifier as the measuring device; the change in frequency caused by the presence of CO2in the cavity is linearly related to the amount of CO2present. As described the instrument is intended for continuous sampling at a rate of about 2 l/min. The time of response is about 0.5 sec for full deflection.

ISSN:0034-6748    

DOI:10.1063/1.1715763

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A single crystal goniometer intended both for x‐ray and neutron diffraction analysis has been used in neutron diffraction work at the Kjeller reactor. The unique feature of this goniometer is a macromodel of the unit cell designed for easy orienting of the crystal. A special arrangement is provided for setting any plane in reflecting position without previously calculating the angles, and a set of three‐dimensional data can be recorded on a counter moving in the horizontal plane.

ISSN:0034-6748    

DOI:10.1063/1.1715764

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Instrumentation for continuous, automatic recording of weight change in laboratory tests was constructed. Sensitivity and accuracy of the instrument permitted transcription of weight change rates from 3 to 70 mgs per min. Suggestions for instrument design for measurement of oxidation rates in the order of 0.1 mg per hour are presented.

ISSN:0034-6748    

DOI:10.1063/1.1715765

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A convenient electromechanical instrument has been developed to take the place of sets of sensitive hydrometers in measuring liquid densities. The range covered by the particular design is 0.8000 to 1.0000 and could be extended without impairing its accuracy. Temperature‐controlled liquid samples of 100 cc are used. The instrument derives its sensitivity from a miniature differential transformer and associated transistor electronics. One of the primary advantages of the device is positiveness of reading.

ISSN:0034-6748    

DOI:10.1063/1.1715766

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A circuit for the electrical simulation of transient diffusion and flow of material between two volumes is described. It allows such processes to be simulated even when forward and reverse transfer rates between the two volumes are unequal. When the reverse rate is zero, the circuit functions as a very‐high‐input‐impedance integrator of wide dynamic range and high accuracy. The circuit will integrate the current through a given resistor, even when this resistor is time varying or nonlinear. For voltage integration, it can have a minimum input impedance approaching 109ohms.

ISSN:0034-6748    

DOI:10.1063/1.1715767

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A rotation viscometer, directly measuring the ratio of the shearing stress to the rate of shear, is described in detail. The reading, for Newtonian liquids, is independent of the speed of rotation and, for non‐Newtonian liquids, gives a direct indication of the dependence of the apparent viscosity on the rate of shear. The principle of the measurement is as follows: A slit, the width of which is proportional to the shearing stress, rotates together with the rotating cylinder of the viscometer; a narrow beam of light passes through this slit and falls on a photoelectric cell; the time of illumination of the photoelectric cell is proportional to the viscosity. The instrument may be used over a wide range of viscosities and rates of shear.

ISSN:0034-6748    

DOI:10.1063/1.1715768

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A closed‐loop frequency‐control circuit is added to an rf spectrometer of the Pound‐Knight‐Watkins type. Frequency variations are detected by a discriminator circuit operating at a heterodyne frequency of 175 kc/sec. Correction signals affect a saturable reactor which is added to the spectrometer. Frequency variations are reduced by factors of 5 to 11. Larger factors can be obtained without instability. The objects are (a) to reduce frequency drift due to physical changes of the coil surrounding the sample; (b) to reduce distortion of absorption line shape, due to frequency modulation arising from the dispersion component in magnetic resonance.

ISSN:0034-6748    

DOI:10.1063/1.1715769

出版商:AIP    

年代:1957

数据来源: AIP