Measurement of the Range of Alpha-Particles from Thorium with the Wilson Chamber

Abstract

The range of the $\ensuremath{\alpha}$-particles from thorium has been measured by the methods used by one of the authors previously. At 0\ifmmode^\circ\else\textdegree\fi{}C and 760 mm the extrapolated numberdistance range is 2.72\ifmmode\pm\else\textpm\fi{}0.03 cm. This range is derived from 300 tracks. It is pointed out that the great deviation of this range from that of Henderson and Nickerson is partially due to these authors' treatment of their data. The Geiger-Nuttall law is shown in the form indicated by Gamow's theory, and the latest data for the uranium and thorium series pertaining to it are given.