摘要:

An experimental technique for obtaining the spatial size and velocity distributions for liquid or solid aerosols suspended in an air flow is described. The technique leaves the flow undisturbed and allows for a large range of particle sizes and velocities. The successful combination of a Q‐spoiled ruby laser and holography was employed to record the desired information. A helium‐neon laser was used to reconstruct the magnified image which was analyzed using closed circuit television.

ISSN:0034-6748    

DOI:10.1063/1.1683903

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

This article describes the equipment, techniques, and philosophy associated with experiments designed to anneal irradiated uranium in NaK to temperatures as high as 900°C and pressures as high as 1000 bars. Considerable attention is paid to the details of the experimental procedure owing to the inherent dangers connected with such tests.

ISSN:0034-6748    

DOI:10.1063/1.1683904

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The logarithmic properties of a photomultiplier are investigated. There is a logarithmic relationship between the voltage and gain of a group of three dynodes of a photomultiplier. An exponential current generator for the calibration of logarithmic amplifiers based on these principles is described. The dynamic range of the generator is about 4 decades with an output current of 250 mA. The exponent is constant within a few percent over the entire range. The calibration of a fast logarithmic amplifier is shown. The generator can also be used to simulate the wave shape of fast scintillators with exponents as fast as a few nanoseconds.

ISSN:0034-6748    

DOI:10.1063/1.1683905

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A device has been designed for the transfer and rotation of single crystals so that angular dependent ESR data can be obtained with a stationary magnet and rectangular cavity. The apparatus consists of a modified Donnay optical analyzer and a second goniometer which is rotated about a vertical axis in the ESR instrument. It has been possible to transfer crystals within ±0.5° of the desired orientation. Measurements of effectivegvalues on two systems yielded standard deviations of 0.001 or less.

ISSN:0034-6748    

DOI:10.1063/1.1683906

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We present a method of calculating proportional counter pulse shapes for both point and extended ionization tracks. The method is applicable to any counter gas for which the electron drift velocity as a function of the electric field is known. The mobility of the positive ions that are responsible for pulse formation is a parameter of the theory. If we assume there is only one species of positive charge carrier, we can identify it by measuring counter pulse shapes for point ionization tracks and comparing them to calculated pulse shapes. The theory is consistent with measurements of actual pulses in four counter gases: 90% Ar‐10% CH4, 90% Ar‐10% N2, 90% Kr‐10% CO2, and 90% Xe‐10% CO2.

ISSN:0034-6748    

DOI:10.1063/1.1683907

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A speed control has been designed for the Beckman model E analytical centrifuge which employs as the velocity transducer a photoelectric pickoff and a digital counter. The controller regularly gives a short term stability of one part in 20 000 and a long term stability (24 h) of one part in 10 000 at rotor speeds greater than 15 000 rpm. The speed controller can be used for any motor which can be controlled by changing the current in the field winding. Even further, the method of control can be used to control any quantity that can be measured by digital means if the relatively low sampling can be tolerated.

ISSN:0034-6748    

DOI:10.1063/1.1683908

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

This report describes the mechanical and electrical features of a mobile fluorescer‐photomultiplier cosmic ray telescope. The telescope has been used on frequent occasions to obtain cosmic ray equator points and to examine the vertical cosmic ray intensity at atmospheric depths of 200 to 250 g/cm2. Statistical errors in the total counting rates were less than 1% and over‐all experimental errors totaled less than 2%.

ISSN:0034-6748    

DOI:10.1063/1.1683909

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A simple scanning microscope has been built which uses a field emission electron gun alone, without the aid of auxiliary lenses. The design and operation of the microscope are described and the calculated performance is compared with experiment. Resolution of 100 Å has been obtained and is shown in transmission electron micrographs. The probe current is of the order of 10−10to 10−11A, a value which is high enough to allow micrographs to be taken with scan times of 10 sec.

ISSN:0034-6748    

DOI:10.1063/1.1683910

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A simple dc method has been developed for measuring conductance in fused salt systems using inexpensive equipment. The technique is particularly well suited to salts which are able to dissolve their own metal. Cell constants are obtained using a well studied fused salt as the reference material. Fused BiCl3and fused NaNO3were studied; the data are in excellent agreement with literature values. Conductance readings were made at or just above the decomposition potential for the melt being studied.

ISSN:0034-6748    

DOI:10.1063/1.1683911

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A new feature of the spectrometer is the monochromator unit, which contains two parallel reflecting copper crystals and delivers a beam of monoenergetic neutrons through a fixed collimator which is parallel to the incident beam from the reactor. About half the neutrons reflected by the first crystal are reflected by the second crystal, though the fraction declines at the upper end of our energy scale (about 60 meV). The beam from the monochromator is free from fast neutrons, and the background extremely low. The material, thickness, and mosaic width appropriate to efficient reflection in a monochromator crystal are discussed. The sample and analyzer form a compact separate unit on a stationary base. All the angles of the spectrometer (including those of the monochromator) are continuously variable over wide ranges, with either manual control or automatic control from a programming tape. Two spectrometers which are mirror images of one another are mounted side by side at the same reactor beam hole. They are mainly intended for measurements on phonons with comparatively high resolution. An example of the accuracy attained is given.

ISSN:0034-6748    

DOI:10.1063/1.1683912

出版商:AIP    

年代:1969

数据来源: AIP