Smithsonian Report. 1931.- Compton 



PLATE 1 



1, Tracks of alpha particles (helium atoms) made visible by eondeiisiuK clomls aloiiK Heir paths {W ilson); 

 2, helium atoms ejected from radium (Wilson) ; 3, counting atoms. Each peak marks the entrance of one 

 helium atom into the counting chamber (Qeiger and Rutherford); 4, trails of alpha and beta particles 

 (Wilson); 5, beta particles ejected from air by X rays (Wilson) 



