Two-nucleon pion absorption in 4He at 1 GeV/c

Abstract The first measurement of two-nucleon pion absorption in 4 He at 1 GeV/ c has been performed at the KEK 12 GeV proton synchroton. Both the (π + , pp) and (π + , pn) modes were measured and clearly identified, even at this energy. An isospin dependence was obtained which was different from that in the Δ-energy region.