TOTAL CROSS-SECTIONS FOR THE A(PI+,PI+PI-) REACTION AT T-PI+ =280 MEV

The (pi+, Pi+ pi-) reaction on H-2, He-4, O-16 and Pb-208 has been measured in the reaction plane at T(pi+)=280 MeV and the cross sections determined. The out of plane behavior of the reaction has been accounted for by phase space and, by integration over it, total cross sections have been deduced. Data are compared with the results of model calculations that, based on different approaches and approximations, predict total cross sections largely discordant. Finally, the analogy between the processes of pion production and double charge exchange is discussed in terms of total cross sections.