Inelastic production of neutral pions in the 4He(γ,π0p)3H reaction

The 4He(γ,π0p)3H reaction yield was measured on a bremsstrahlung photon beam with the maximum energy of 450 MeV. The measurements were carried out at an experimental facility consisting of a Cherenkov total-absorption γ spectrometer and a helium streamer chamber. To study the mechanism of neutral pion inelastic photoproduction kinematic analysis of angular distributions of 4He nucleus disintegration products was performed. A rather high density of the distribution of events at small divergence angles of proton and triton can be explained by a quasielastic reaction mechanism when pion photoproduction is followed by 4He nucleus excitation