Proton-proton bremsstrahlung at 42 MeV: Measurement of cross sections and comparison with a theoretical calculation

Proton-proton bremsstrahlung cross sections have been measured at 42 MeV incident beam energy using a wire chamber spectrometer developed for the study of nuclear reactions with three-body final states. Proton-proton bremsstrahlung events from a 22 cm long gaseous target were detected concurrently over polar angle ranges from 16° to 40° and all kinematically allowed values of event noncoplanarity. The data have been analyzed and compared in two different ways to a theoretical calculation based on the Hamada-Johnston potential. In a conventional analysis, the data were divided into eighteen independent polar angle regions and the $\frac{d^3\sigma }{d{\Omega }_{1}d{\Omega }_{2}d{\psi }_{\gamma }}$, $\frac{d^2\sigma }{d{\Omega }_{1}d{\Omega }_2}$, and $\frac{d^2\sigma }{d{\theta }_{1}d{\theta }_2}$ cross sections were determined and compared with the theoretical calculations. In a "global" analysis, the data were compared directly with a theoretically weighted, simulated set of events. The latter comparison was made in terms of a wide range of variables, both in the laboratory and in the center of mass systems. A significant discrepancy between experiment and theory was found in certain parts of the observed phase space.