Pion absorption in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ above the delta resonance

The reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ (${\mathrm{\pi }}^{+}$,pp)pn was measured at ${\mathit{T}}_{\mathrm{\pi }}$=500 MeV. The angular distribution of quasifree two-body absorption which was obtained agrees in detail with the free πd→pp reaction and scales according to the number of T=0 pn pairs in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. Possible evidence for pd final-state interactions is discussed. The extrapolated total cross section for four-body absorption is 2.5±0.6 mb, which is substantially less than predicted from a model based on ΔΔ excitation.