524 Table 638 



RADIOACTIVITY 



H PARTICLES 



Marsden first observed the long-range particles due to the impact of a particles on matter, 

 now known to be H particles, i.e., hydrogen nuclei or protons set in motion by a rays. 

 Rutherford made a thorough study of this phenomenon, measured the ranges in H 2 of 

 H particles due to a particles of various speeds, counted the relative number of a and 

 H particles by the scintillation method ; measured the magnetic and electrostatic deflection 

 of the H particles and proved them to be hydrogen nuclei (protons) in motion. He was 

 able to produce them by bombardment of substances rich in H 2 . When the a particles 

 have a 7 cm air range, the H particles have a maximum air range of 29 cm. 



H Particles from Atomic Nuclei Bombarded by a Particles from RaC 



(Taken from Kovarik, McKeehan, Nat. Res. Council Bull. 51, 1925.) 

 Ranges in Cm in Air at 15° C in Directions Inclined to the a Rays 



1 Kirsch-Pettersson, 1924. 2 Rutherford-Chadwick, 1924. 3 Rutherford-Chadwick, 1922. 

 4 Rutherford-Chadwick, 1921. 



Smithsonian Tables 



