FURTHER STUDY OF SEVERAL PHYSICAL EFFECTS ON THE CALCULATION OF ANGULAR DISTRIBUTION BASED ON EXCITON MODEL

In order to understand angular distribution deviation betweep the calculation based on conventional exciton model of the preequilibrium and equilibrium decays and the experimental data,especially the underestimate of angular distribution by the theory at backward angles, an exact closed form solution to the time-integrated master.equation of the exciton model by including the effects of the Fermi motion, the Pauli principle, the finite nuclear size and the refraction of the incident wave at the nuclear surface is applied to the calculation of the angular distribution, In this paper the neutron inelastic scattering cross sections.for 34 elements at 19.6 MeV have been calculated and compared with experimental data measured by Hermsdorf et al.The results show that because the influence of several: physical effects mentioned above has been taken into account the theory can explain the presently available experimental data and is especially suitable for solving the problem of the double differentia1; cross section for emitted neutrons with higher energy at backward angles.