The pion optical potential in the nuclear surface

In the low and intermediate energies (pion kinetic energy Tsub(π)) ≤ 500 MeV), the basic microscopic approach to derive the pion-nucleus optical potential is formulated in terms of the sequences of the multiple scattering of the pion (π) from the nucleon of the target. Since in the pion-induced reactions dominate in the nuclear surface in the region of the Δ33 resonance it is essential to incorporate the effect of the nuclear surface and estimate the corrections to the impulse approximation (IA) in the calculation of the nucleus optical potential. The effect of the nuclear surface has been incorporated by calculating the (π)-nucleus optical potential for the semi-infinite nuclear matter (SINM). The correction to the IA has been estimated by expressing in terms of t and the difference between the pion propagator G in the nuclear medium and that in the free space denoted by Gsub(0). The effect of the nuclear binding, the nuclear Fermi motion, the Pauli blocking in the intermediate scattered states have been taken into account. A separable offshell model is used for the (π) N t-matrix. The offshell cutoff has been fixed by invoking the cloudy bag model for the nucleon. (author). 7 refs., 4 figs