摘要:

A narrow, well‐collimated beam of soft x‐rays has been used for the purpose of measuring distortion in cloud chambers. The path of the x‐ray beam in the cloud chamber is made visible by the ionization of the short‐range photoelectrons. The main advantage of this method is that it can be used in the presence of a magnetic field. A limitation of the method is the finite width of the track. In argon it was not difficult to get a track 0.06 cm wide, allowing measurement to 0.004 cm. The appearance of the beam in both a diffusion and an expansion chamber is described. In addition to its use in measuring distortion, its applications to measuring rates of droplet growth and length of cloud chamber sensitive times are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1771146

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A simple and inexpensive radiation detection device has been constructed sensitive to gamma fluxes in the range from a few to a few hundred roentgen per hour. Thus one can distinguish between dangerous and relatively safe radiation levels such as one might expect from radiological warfare, low level atomic blasts, or from ``rigged'' hydrogen bomb explosions.A typical device consists of two gamma‐activated crystals in a light‐tight container which can be held close to one eye to exclude external light. A radium‐activated phosphorescent material is included for light intensity comparison purposes. The more sensitive crystal can be discerned in a gamma radiation of a few R/hr, and its light output matches that of the fluorescent material at levels of 20 to 30 R/hr. The light from the less sensitive crystal matches that of the phosphorescent material at about 100 R/hr.

ISSN:0034-6748    

DOI:10.1063/1.1771147

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A automatic system, employing a metal bellows, was designed and constructed for the purpose of studying the catalytic combination of hydrogen and oxygen on a submerged catalyst in a stirred solution. The reaction was carried out under conditions of constant temperature, pressure, and volume. This system can be used to study the reaction for unlimited lengths of time; it is completely automatic, and can be used to study reaction rates quantitatively. It can be modified for the study of other reactions.

ISSN:0034-6748    

DOI:10.1063/1.1771148

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A description is given of an instrument to determine the temperatures of rapidly varying flames. This instrument uses a photoelectric modification of the line‐reversal method, wherein the light beam from a temperature‐variable incandescent source is split into two monochromatic beams by means of mirrors and filters to impinge upon 931A multiplier phototubes. The phototube signals are sent to a mu‐bridge null detector, whose output is fed to an oscilloscope for photography of results. The instrument can detect 25°K temperature differences between about 1540° and 3100°K and three millisecond time differences. Typical time‐temperature results are given, along with the analytical procedures used.

ISSN:0034-6748    

DOI:10.1063/1.1771149

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A double‐focusing mass spectrograph for the analysis of low concentrations of impurities in solids has been developed. The instrument is of the Mattauch type and is designed for either photographic or electrical ion detection. The construction and performance of the instrument are discussed. Bulk concentrations below 0.1 part per million, and surface contaminants of less than 0.1 monolayer, can be detected in short exposures using a photographic plate.

ISSN:0034-6748    

DOI:10.1063/1.1771150

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

This paper describes a method for presenting on a fluorescent screen the time varying velocity and density modulation of an electron beam, modulated at a frequency of 3000 Mc, as it emerges from the cavities of a klystron, the wave guide in a traveling wave tube, or similar structures.In order to deflect an electron beam at this frequency, each pair of the usual deflection plates is replaced by a two‐wire transmission line, resonant at the beam modulating frequency. Under proper phase conditions a circular trace is obtained, where one complete revolution of the beam corresponds to exactly one complete cycle of events on the beam at the point of its deflection. Since electrons having different velocities will be deflected differently, a complete velocity and density picture of the beam at a given point of interest is obtained.This is demonstrated by observing the bunching action in the drift region of a velocity modulated electron beam.

ISSN:0034-6748    

DOI:10.1063/1.1771151

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A high‐speed two‐bladed shutter was built to deliver square‐wave pulses of energy from a converging light beam with an average intensity of about 5 cal/cm2/sec, and a diameter of 3 in., in the plane of the shutter. The blades open or close in less than 0.01 sec. They move in the same direction, so that all parts of the target are exposed for very nearly the same length of time. The shutter makes use of a new type of air cylinder which is suitable for driving high‐speed mechanisms, and has a dynamic shock absorbing system to stop the moving parts in a short distance with little rebound. It is electrically controlled and fully automatic. Exposure times may be varied from 0.07 to 5 sec by setting an electronic interval timer. Longer exposures are controlled manually. To date it has been used more than 15 000 times and has required only two overhauls.

ISSN:0034-6748    

DOI:10.1063/1.1771152

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Modifications of an electron impact ion source for a 60° mass spectrometer are described. The changes consist of (1) an almost completely enclosed ionization region which greatly reduces the contribution of ions from thermal decomposition products on the filament and reduces the contribution of background peaks and (2) a built‐in aligned and stronger magnetic field which eliminates source magnet adjustment, collimates the electron beam better and permits the use of a higher repeller voltage thereby increasing the collection efficiency for ions with initial kinetic energy. The performance of the source is described.

ISSN:0034-6748    

DOI:10.1063/1.1771153

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An energy‐analyzing detector of the pair‐spectrometer type has been used to observe the angular distribution of bremsstrahlung produced by 17‐Mev monokinetic electrons in molybdenum betatron targets. Distributions were measured for gamma‐ray energies of 7, 11, and 15 Mev, for each of three targets whose thicknesses were approximately 2, 5, and 21 mils. Reproducible variations of spectrum with angle were found, the variations becoming more pronounced with increasing target thickness. The experimental distributions are compared here with the theoretical distributions of Schiff and Lawson, the former being significantly narrower. Axial relative spectra are also presented.

ISSN:0034-6748    

DOI:10.1063/1.1771154

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A null instrument for the measurement of intense beams of radiant energy (from about 5 to 300 cal cm−2sec−1) is described. The instrument utilizes two identical hollow blackbody receivers whose walls are provided with coils carrying a stream of cooling water. The inflowing water divides equally between each chamber. The temperature difference between the two outflows is determined by a differential thermopile. One of the chambers is exposed to the radiant energy beam, while the other chamber is heated electrically until a null is obtained on a galvanometer connected to the differential thermopile. It is shown that measurements of the electrical power dissipated in the chambers under null conditions and a measurement of the aperture areas of the chambers is sufficient to give the radiant flux density.

ISSN:0034-6748    

DOI:10.1063/1.1771155

出版商:AIP    

年代:1954

数据来源: AIP