Cross‐section for the double charge exchange reaction π+ +4He→π−+4p at pion energies of 98, 135, 145 and 156 MeV

Cross‐sections for the double charge exchange of positive pions on 4He at various energies are presented. For measurements a high‐pressure helium streamer chamber has been used. The experimental results are compared with theoretical model calculations based on pair correlations or meson exchange currents.