Open AccessOn some close collisions of fast β-particles with electrons, photographed by the expansion method
Author(s) -
F. C. Champion
Publication year - 1932
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1932.0108
Subject(s) - electron , physics , collision , scattering , momentum (technical analysis) , particle (ecology) , classical mechanics , elastic collision , energy–momentum relation , subatomic particle , relativistic mechanics , atomic physics , computational physics , mechanics , elementary particle , theory of relativity , quantum mechanics , oceanography , computer security , finance , computer science , economics , geology
The present paper gives an account of measurements on some close collisions of fast β-particles with electrons, photographed by the Wilson cloud method. These measurements afford a direct test of the applicability of the principles of the conservation of momentum and energy and the principles of relativistic mechanics to individual atomic phenomena. On the basis of Newtonian mechanics, if one particle collides with another which is initially at rest and the two particles are of equal mass, the angle between the directions of motion of the two particles after collision is equal to 90° for all angles of scattering of the incident particle. On relativistic mechanics, however, this angle becomes a function of the angle of scattering and the velocity of the incident particle, and in particular, it becomes smaller and smaller as this velocity approaches that of light. Qualitative evidence has already been given by Wilson, Bothe and others that this angle is less than 90° for the collisions of fast β-particles with electrons, but up to the present no quantitative study has been made of the general relation between the whole angle after collision, the angle of scattering, and the velocity of the incident particle. Assuming that momentum and energy are conserved in the collision the following calculation may be made.