The Emission and Transmission of Rontgen Rays . e thus obtained, and show how the Rontgen rays from lead,platinum, silver, copper, nickel, iron, and aluminium, generated under a potentialdifference of about 28,000 volts, are dealt with by screens of aluminium, copper, and * Starke, . Aluminium Screens.—Consider fig. 3. As the thickness of aluminium screen isincreased, lead and silver increase their radiation values, and take places warrantedby their atomic weights. Thus the softest rays due to a lead or silver radiator aremore penetrating to aluminium than the softest rays from platinum. (00 q
The Emission and Transmission of Rontgen Rays . e thus obtained, and show how the Rontgen rays from lead,platinum, silver, copper, nickel, iron, and aluminium, generated under a potentialdifference of about 28,000 volts, are dealt with by screens of aluminium, copper, and * Starke, . Aluminium Screens.—Consider fig. 3. As the thickness of aluminium screen isincreased, lead and silver increase their radiation values, and take places warrantedby their atomic weights. Thus the softest rays due to a lead or silver radiator aremore penetrating to aluminium than the softest rays from platinum. (00 q: a Q:. * OS CM, THICKNESS or AL SCREEN Fig. 3. Aluminium screen, 28,000 volts. The metals of the iron group—copper, nickel, and iron—rapidly lose, with thickerscreens, their initially high radiation values. Together with aluminium they afterwardsshow weak maxima at a thickness of about 0*07 cm. of screen. Thus for the range003 to 0*07 cm. the rays from these metals are more penetrating to aluminium thanare the rays from platinum, and we thus have a region over which selectivetransmission is manifested. It will be noticed that for screens thicker than about 2 mms. an alteration in thethickness produces very little change in the relative amounts of radiation from the X «/ CD EMISSION AND TRANSMISSION OF RQNTGEN RAYS. 131 different metals. The inference is that all the beams are now similar in composition,and we should therefore be justified in expecting, at this stage, some evident relationbetween intensity and the atomic weight of the radiator. The point is gone into later(p. 135), but i
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