The first order optical potential evaluation for the elastic scattering of neutron on the bound system using the impulse approximation

Abstract. The method of impulse approximation is used to check the validity of the …rst order optical potential for the nucleon-bound system elastic scattering problem namely, C12(n:n)C12;Ca40(n; n)Ca40and Pb208(n; n)Pb208at neutron incident energies of 155 and 225 MeV. The optical potential is derived as the …rst order term within the spectator expansion of a non-relativistic multiple scattering theory using the Lippmann-Schwinger equation which is solved in momentum space. The two-body matrix elements show that in order to have a full description for the scattering problem using the impulse approx- imation the analytical dependence of the half shell of the two -body matrix elements on the momentum of the initial and …nal states of the projectile neutron and its den- sity momentum distribution are requiered .The modren realistic two-body potential the- ArgonneV18 was used as input in the Lippmann-Schwinger equation . The elastic di¤er- ential cross sections results are in good agreement with the experimental data for studied nuclei at neutron energy above 200 MeV. As the energy of the neutron decreases down to approximately155 MeV, the discripancies with experimental data appear, which is in accordance with the impulse approximation formalism.