The elastic scattering of protons by protons at 925 MeV

Ilford G5 emulsions have been exposed to a 925 mev beam from the Birmingham proton synchroton. Sixty-five examples of the elastic scattering of protons by free protons in the emulsion have been found in 1539 metres of track. After removal of events having azimuthal angles ψ>45° where ψ is the angle between the plane of the two secondary particles and the plane of the emulsion, the remaining 44 events yielded a total elastic cross section of 17±3mb. The angular distribution of all the events shows a strong forward peak in the centre of mass system. The shape of this distribution has been compared with the predictions of a simple optical model and a value of (0·9±0·1) × 10−13 cm has been found for the interaction radius of the proton. The results are compared with other experimental work.