FROM DIRAC PHENOMENOLOGY TO DEUTERON-NUCLEUS ELASTIC-SCATTERING AT INTERMEDIATE ENERGIES

A discussion of relativistic microscopic models of deuteron-nucleus scattering at intermediate energies is presented. Calculations based on various relativistic models, which take into account explicitly the deuteron internal structure, and on the nonrelativistic folding model are compared with elastic-scattering data from Ca-40 and Ni-58 at 400 and 700 MeV. The same global nucleon-nucleus Dirac optical potentials were used throughout. We find that the direct impulse approximation, where the deuteron-nucleus T matrix is the expectation value of the sum of the nucleon-nucleus T matrices in the deuteron, gives a reasonable description of the data. However, the fact that the best agreement is provided by the nonrelativistic folding model indicates the need for a more realistic treatment of multiple scattering and off-shell effects in the relativistic microscopic models.