Molecular potential and elastic scattering of alpha particles by 28Si from 14 to 28 MeV

Abstract

The real part of the alpha- 28Si potential has been derived in the energy density formalism using the sudden approximation. The potential is found to be of the molecular type. The angular distributions at 14.47, 21.9, 24.0, 25.0, 26.0, 26.5, 27.0 and 28.0 MeV (lab) have been calculated using potentials, the real part of which are similar to the calculated one. The calculations using the molecular type of potentials can adequately account for such broad features as magnitudes, locations of maxima and minima and back-angle enhancement in angular distributions. In fact, in the energy region of 21.9 to 28.0 MeV (lab) the above observed features can be understood using an energy-independent real part. An analysis of the S-matrix using this potential does not reveal any obvious resonance, but implies that interference among partial waves determines the structure of the angular distributions. An alternative explanation for ALAS in 28Si might be that the potential between alpha particles and 28Si is of the molecular type, having a soft short-range repulsive core.