X rays / by G.W.C. Kaye.

  • Kaye, G. W. C. (George William Clarkson), 1880-1941.
Date:
1918
Catalogue details

Licence: In copyright

Credit: X rays / by G.W.C. Kaye. Source: Wellcome Collection.

    159/322 (page 129)
    owing to the absorption of the softer components. It is not until the radiation is reduced to about -g-J-g- of its initial value that the absorption curve becomes very nearly a straight line, at any rate with the higher voltages. This shows that the “ end-radiation ” is approximately homo¬ geneous. At the lowest voltages the main radiation proved to be the L characteristic radiation of tungsten, that being the material of the anticathode. At high voltages the radiation is mainly of the independent type. Thickness of Aluminium inmms. Fig. 66.—•Log-absorptiou carves, for A1 screens, of the X rays from a Coolidge tube with tungsten anticathode. The highest voltage used by Rutherford (P.M. 1917) was 196,000 volts. The rays were filtered through 1 cm. of lead, the reduction in intensity being over a million fold. The end rays had XA1 = 0 23 cm.-1, APb = 9 cm.-1, and a wave length of about 0-06 a.u. The relation between voltage and the hardest X ray is given by Einstein’s formula, Ve = hv (p. 245). Inserting Millikan’s values of these constants {P.M. 1917) we have: Wave length in a.u. = 12,400/voltage. The accuracy of this simple relation has been confirmed experimentally by Hull and Rice (p. 245). i