摘要:

To perform the double function of diffracting and focusing a monochromatic beam of x‐rays, multiple monomolecular layers of barium‐copper‐stearate were deposited upon an accurately ground concave spherical surface of glass. With a spherical crystal of radius of 218 cm, grating space of about 50.5A, preliminary photographs of the AlK&agr;,&bgr; region, component lines not resolved, were obtained in 30 minutes at 3 kv and 15 ma. It is believed that the intensity and resolving power from such a spherical grating are adequate for measurements with an ionization chamber of absorption coefficients at wave‐lengths above 8A.

ISSN:0034-6748    

DOI:10.1063/1.1751662

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

The specimen, in the form of a circular loop of wire, is fastened at one point to a rigid support. At the diametrically opposite point a magnetic field is applied. The frequency of an alternating current in the loop is adjusted until flexural vibrations occur in the plane of the loop. Then the resonance frequencyf,the radius of the loopr,the linear densitym,and the radius of the wireaare related to Young's modulus by the equationE=18.395mf2(r/a)4(1−g) in which (1−g) is a gap correction factor.

ISSN:0034-6748    

DOI:10.1063/1.1751663

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

The windings of the magnet are made of continuous lengths of copper tubing with cross section shown in Fig. 1. Water at high pressure is sent through the hollow center for cooling. The conductor is wound about the core in such a way that the resistance to the flow of the water is reduced to about half what would prevail in a magnet of conventional design. These features make possible a high effective current density. The disposition of the coils and the shape of the iron core were based on the experiences with the big magnets in Upsala and in Paris. A model gave the results indicated in Fig. 5. When the pole faces 2.5 cm in diameter were separated by 7 mm the field obtained was 33,200 gauss using 16 kw. The model was constructed to employ water at considerably higher pressures than were actually tried. A higher current density would then be permitted without risk of serious electrolytic corrosion.

ISSN:0034-6748    

DOI:10.1063/1.1751664

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751665

出版商:AIP    

年代:1940

数据来源: AIP

摘要:

A thermometer is described which detects temperature changes of the order of 10−4°C and quantities of heat of the order of 10−4g cal. It is essentially a gas or vapor thermometer in which the shift of the top of the meniscus of an indicating liquid is observed through a microscope. The shift isdue to changes of the shape of the meniscus while the circumference remains stationary.Hence the sensitivity depends upon the surface tension of the indicating liquid but not on the friction between the liquid and the glass.

ISSN:0034-6748    

DOI:10.1063/1.1751666

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751667

出版商:AIP    

年代:1940

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751669

出版商:AIP    

年代:1940

数据来源: AIP