Abstract
Although the quasi-adiabatic calculations have led to an improved description of the measured observables, the theoretical justifications of the assumptions made in the model have not yet been studied. The first part of the work described in this thesis is therefore concerned with the clarification of these theoretical uncertainties by performing a rigorous investigation of the accuracy and the validity of the model. In addition, we reformulate the quasi-adiabatic theory to give a more general formalism, approaching the three-body problem in a different way. This alternative formulation provides a clear understanding of the assumptions made in the original quasi-adiabatic theory. Using the spirit of the new quasi-adiabatic formalism, we also develop alternative approximation schemes for the treatment of quantum mechanical three-body systems. The accuracy and the range of validity of the developments, together with the quasi-adiabatic theory, are investigated carefully and precisely by comparing their predictions with those essentially exact CDCC technique for the 66Zn (d,p)67Zn reaction at 88.2 MeV. It is found that the alternative models and quasi-adiabatic theory are reliable techniques for the treatment of deuteron breakup process at intermediate energies of interest. The remainder of this thesis is devoted to the investigation of the mechanism of (p,d*) reactions. As the treatment of the final state interactions in such reactions has not previously been studied consistently, we develop an adiabatic method and apply it to new data for the 13C(p,d)12C reaction with 35 MeV incident proton energy. Due to the weak coupling between spin channels of the continuum n-p system at the energies of interest, the singlet and triplet state pickup cross-sections for the final n-p system are analyzed separately. We find that the contribution from the singlet state is dominant for small relative energies while the triplet state dominates for large energies. This application clarifies the relationship between the three-body dynamics in the final state of (p,d) and (p,d*) reactions.