The scattering of 4.2 MeV protons by protons

The methods described in a previous paper have been applied to an examination of the scattering of 4.2 MeV protons by protons. The angular distribution of the scattered protons is found to be isotropic, in the centre-of-mass co-ordinate system of the colliding particles, from 50 to 140° in the angle of scattering. A method of determining the absolute cross-section for proton-proton scattering at different energies, depending on the simultaneous recording of the protons scattered from hydrogen and from heavy nuclei is described, and the conditions necessary for its application at higher energies are discussed.