Proton-proton bremsstrahlung at T/sub p/=730 MeV with photon energies up to 300 MeV

The results of new proton-proton bremsstrahlung differential cross section measurements at T/sub p/=730 MeV are presented. The experiment was designed to measure photons of 40-300 MeV at forward angles in coincidence with the scattered and recoil protons. The cross sections rise rapidly when E/sub ..gamma../>100 MeV, in sharp disagreement with external-emission dominance calculations which predict a smooth and nearly flat spectrum. The model calculations of Tiator et al., which consider the ..delta..(1232) resonance in the intermediate state, agree with our results, as does an adjusted soft-photon approximation calculation.