Two-step processes in the 116Sn(p,p')116Sn and 208Pb(p,t)206Pb reactions

In this thesis the role of two-step processes is investigated in (p,p') and (p,t) reactions. An analysis is presented of inelastic proton-scattering on 116Sn. In particular the transitions to the low lying 0+, 2+ and 4+ states have been studied. Next transitions to unnatural-parity states in the 208Pb(p,t)206Pb reaction, measured at Esub(p) = 20 and 50.5 MeV, are studied. It is demonstrated that the data of these transitions, which are strongly forbidden in direct transfer, could satisfactorily be described by sequential-transfer calculations only. These calculations have been performed in a zero-range approximation for the (p,d) and (d,t) projectile formfactors. It is investigated if the finite-range effects in (p,d) (d,t) processes can be approximated by a first order correction. A method is presented to calculate this correction with the zero-range Coupled-Reaction Channel code CHUCK and it is shown that, the finite-range effects, as calculated by Charlton and Hashimoto are nearly exactly reproduced. The natural-parity transitions in the 208Pb(p,t)206Pb reaction are studied at various bombarding energies with direct-transfer calculations alone as well as with combined direct- and sequential-transfer calculations. (Auth.)