摘要:

Some properties of proportional counters using air at atmospheric pressure are described. It is shown that a variety of counter designs may be developed which are stable both with and without thin windows. A few counter designs which have applications in the detection of alpha‐radioactive contamination are discussed in detail.

ISSN:0034-6748    

DOI:10.1063/1.1741155

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The photo‐multiplier radiation detector consists of a commercial multiplier photo‐tube arranged to register the scintillations produced in a fluorescent screen by radiation quanta. The signal pulses thus obtained are large for alpha‐particles and other high velocity ions, much weaker for x‐rays, gamma‐rays, and high velocity electrons. The method is limited by the presence of noise pulses caused by electrons thermally emitted at the photo‐cathode; signal pulses can be discriminated from noise pulses only to the extent that their amplitudes are greater. Satisfactory detection of the weaker signal pulses has been accomplished by careful attention to (1) selection of photo‐tubes, (2) choice of fluorescent screen, (3) efficient collection of light, and (4) proper circuit design.The new detector is especially suited to narrow‐beam measurements where high counting rates are desired. However, it compares favorably with conventional detectors even when low counting rates and weak signal pulses are involved. The detector is rugged and fast, requires no special thin‐window technique, and shows high efficiency. The primary detecting medium, being a solid, has high absorption and is well defined in position.This article includes full construction details, an analysis of performance characteristics, particularly with weak signal pulses, and numerous suggestions for further improvement.

ISSN:0034-6748    

DOI:10.1063/1.1741156

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

For the measurement of beta‐ and gamma‐ray energies one requires a magnetic spectrometer of high resolution and large solid angle. One of the simplest instruments satisfying these specifications is the double‐focusing beta‐ray spectrometer. The design and construction of such an instrument is described. This particular spectrometer has a mean radius of curvature for the electrons of 24.33 cm and preliminary measurements show that its resolution is about ⅓ percent and that about 0.2 percent of all the electrons of given energy which leave the source are focused on the counter. Construction of such an instrument proved to be very easy.

ISSN:0034-6748    

DOI:10.1063/1.1741157

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Methods for construction of various types of quartz fiber structures by means of jigs also made from small quartz rod are described. It is shown that the advantages of jig construction are in obtaining a better product and particularly the ability to reproduce quite accurately a number of such quartz structures.Various practical aspects of quartz fiber manipulation and construction are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1741158

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Technique is described for the construction of uniform smooth quartz helix balances of any desired sensitivity or load capacity by mechanical means. Some of the less common but highly desirable uses of such balances are listed.

ISSN:0034-6748    

DOI:10.1063/1.1741159

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A neutron detector which utilizes the fission of bismuth and responds only to neutrons of energy greater than about 50 Mev is described. The efficiency is low (about 10−6), but the instrument is suitable for monitoring a high energy neutron beam and for beam attenuation measurements.

ISSN:0034-6748    

DOI:10.1063/1.1741160

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Data on several standard diffusion pumps indicate that the speed for hydrogen may be considerably less than 3.8 times the rated speed for air depending on the jet design, pump fluid, heater input, and speed of the fore pump. Evidence is presented that this reduction in speed is partly the result of diffusion of hydrogen back through the vapor jet from fore vacuum to high vacuum and partly the result of diffusion of hydrogen back out of the jet after entering from the high vacuum side. Measurements of the back diffusion of hydrogen, helium, and air in an experimental pump are correlated with the diffusion coefficient through an extension of the theories of Gaede and Matricon. The mechanism of jet breakdown has been observed with the aid of a glow discharge and a pilot dye.

ISSN:0034-6748    

DOI:10.1063/1.1741161

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A device is described which produces a reference light beam capable of being modulated at any desired frequency up to several thousand cycles per second. The light source can be mounted on the face of most oscilloscopes with slight alterations. It facilitates the introduction of a timing scale and fixed reference line when photographic recordings are made of oscilloscope traces by means of drum or continuously moving film cameras.

ISSN:0034-6748    

DOI:10.1063/1.1741162

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Various mechanical and electrical techniques have been used to record the spontaneous activity of animals during pharmacological and physiological studies. Most of them are in‐adequate in one way or another. An electronic integrating circuit is described which eliminates the principal faults inherent in other methods. An electromagnetic pick‐up is mounted on a small rigid cage which is supported on a viscous damping mount. The output of this pick‐up is amplified, rectified, and stored in a condenser. The voltage acquired by the condenser is applied as the plate voltage of a small thyratron. The bias on the thyratron controls the energy required to fire the circuit. When the circuit fires, a sensitive relay is closed and the unit represented is written on a moving tape and added to a counter. The results obtained by this method are in discrete units and can be treated by mathematical methods.

ISSN:0034-6748    

DOI:10.1063/1.1741163

出版商:AIP    

年代:1948

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1741164

出版商:AIP    

年代:1948

数据来源: AIP