摘要:

Details are given of the construction of an electromagnet, cloud chamber and accessory apparatus for use in cosmic‐ray studies. The magnet has 9100 kg of steel, 1000 kg of copper, and has pole faces 30.5 cm diameter, normally used at an air‐gap of 19.2 cm. The magnet is oil cooled and is usually operated at from 35 to 125 kw, the power being supplied by a motor‐generator with variable field. Under these conditions the field increases from about 12,400 oersteds at the lower power to 16,000 oersteds at the higher power. The cloud chamber is of the diaphragm type, 30 cm diameter by 4.2 cm deep, and is filled with argon and ethyl alcohol vapor to 88 cm Hg pressure. The photographs are taken with the help of a 45° mirror placed against the front glass of the chamber. For illumination a Sperry carbon arc or a capillary mercury arc is used, the latter proving on the whole more satisfactory. With the lower magnetizing currents the temperature of the magnet and chamber can be maintained so close to that of the outside air that convection currents are small, and the tracks show little distortion. Errors in measuring the energy of cosmic‐ray tracks are caused chiefly by distortions of the tracks. The probable error is 6 percent for a track of 109ev, and about equal to the energy itself when this is 1.6×1010ev.

ISSN:0034-6748    

DOI:10.1063/1.1751655

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751656

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

A shutter for an x‐ray beam consists principally of a rotary disk with alternate open and opaque sectors, and a suitable control mechanism operated by an electromagnet. Several exposures may be made for one winding, a feature of convenience when remote control is desired. The motion of the disk is the same for opening and closing so that each part of the beam is turned on for the same length of time. The shutter will accommodate an x‐ray beam directed anywhere between the vertical and the horizontal.

ISSN:0034-6748    

DOI:10.1063/1.1751657

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

An apparatus has been developed in which orientations of single crystals, and the crystals in polycrystalline materials, can be studied with x‐rays by rotating the specimen and moving a photographic film at the same time. The apparatus combines the best features of both the Weissenberg goniometer and that of Dawson by having the x‐ray beam incident along the axis of a cylindrical film and thus recording a Debye‐Scherrer circle instead of a layer line. The motion of the film and rotation of the specimen may be continuous or in steps. For motion in steps an automatic mechanism is used which exposes the film for a length of time controlled by an electric clock, and then moves the film and rotates the specimen an amount controlled by a revolution counter geared to the motor. When the cylindrical film is flattened the Debye‐Scherrer circles become straight lines and a transparent net with rectangular coordinates is used to measure the angles. The data are then easily plotted in stereographic projection.

ISSN:0034-6748    

DOI:10.1063/1.1751658

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751659

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

An ion source has been built in which the ionization efficiency of the electrons is increased without making the gas pressure excessive. This is accomplished by making the electrons oscillate through the region occupied by the gas with energies corresponding to the maximum ionization probability. The electronic space charge is used to withdraw the ion beam and hold the beam together. Hydrogen ion beams of 150 milliamperes have been obtained.

ISSN:0034-6748    

DOI:10.1063/1.1751660

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

A thermopile consisting of Chromelp‐constantan junctions is described. Since the thermoelectric power of this couple is relatively high (over 60 microvolts per degree C) and since the metals have a low thermal conductivity and are easily worked, a sensitive, rugged thermopile may be constructed to meet individual needs in a short time without previous experience. A very simple technique of construction is described and the characteristics of a finished instrument are given.

ISSN:0034-6748    

DOI:10.1063/1.1751661

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751648

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751649

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

A cylindrical condenser has been so designed that it may be filled to a variable height with a liquid whose dielectric constant is desired. From the variation of the capacitance with the height, and a knowledge of the dimensions of the cylinders, one can make a determination of the constant that is free from errors due to stray capacitances. An analysis of the apparatus seems to indicate the method is capable of high precision.

ISSN:0034-6748    

DOI:10.1063/1.1751650

出版商:AIP    

年代:1940

数据来源: AIP