$ \alpha$ -nucleus elastic scattering in the energy range 25-70 MeV/nucleon
Working within the framework of the Coulomb-modified Glauber model for nucleus-nucleus collisions, we analyse the elastic scattering of $ \alpha$ -particles on 4He at 25, 30, 35, 40, 50, and 70MeV/nucleon. Emphasis has been put on the parametrization of the basic (input) NN amplitude that preserves the low-q behavior at the desired energy, whereas the higher momentum transfer components are treated phenomenologically. The analysis also considers the medium modification of the NN amplitude due to Pauli blocking. Using the realistic form factors for colliding nuclei, it is found that the data are reproduced satisfactorily well up to the fairly large value of momentum transfer. We also discuss the suitability of the extracted NN amplitude for other target nuclei in the energy range under consideration. Our analysis suggests that the proper account of the higher momentum transfer components of the NN amplitude may push down the Glauber model to lower energies, and increase its validity in the region of relatively large momentum transfers.