Angular distribution of the neutron-proton final-state interaction in the reaction d(α,αp)n at 28,2 MeV incident energy

The reaction d(α,p α)n was investigated in kinematically complete experiments in coplanar and noncoplanar geometry. The angular distribution for the production of n-p pairs with zero relative energy was measured at the bombarding energy Esub(α)=28.2 MeV. The experimental results have been compared with Faddeev calculations by Y.Koike and K.Hahn and in the region of np final state interaction (FSI) with the improved sequential decay model by K.Wick. At large production angles of the n-p pair the absolute cross sections are fairly well predicted by the sequential decay model, at smaller angles, however, the simple assumptions of the model result in major differences. The agreement of the data with the Faddeev calculations of Koike is generally good, especially the shape and position of the dominating FSI-structures is well reproduced. This is surprising because of the simple potentials, which are used. Some deviations occur in the intensity of the different effects. (orig.)