NUCLEAR-STRUCTURE EFFECTS IN (PI(-13(),PI(0)) AND (P,N) REACTIONS ON C)

The role of 2p-shell admixture in the ground-state wave function of C- 13 is studied in the case of reactions such as C-13 (e,e) C-13, C-13(p i+,pi0)N-13g.s., and C-13(p,n) N-13g.s. A comparison is made between m icroscopic ground-state wave functions elaborated in the (0+2) homegaB AR basis and the phenomenological 1p-shell model. The best agreement w ith the data for electromagnetic form factors, cross sections, and asy mmetries is achieved using a combination of the microscopic and the ph enomenological description. At low pion energies a large suppression o f differential cross section is observed for the C-13(pi+,pi0)N-13g.s. reaction when 2hkomegaBAR configurations are taken into account.