The unified description of direct and resonant processes in the inelastic scattering of medium-energy projectiles on 40Ca

Abstract

In the framework of the unified theory of direct and resonant reactions we investigate the excitation of the nucleus 40Ca by medium-energy projectiles. We calculate the inelastic scattering spectra of electrons and α-particles as well as the corresponding coincidence spectra with an ejected nucleon in the final channel. The continuum shell-model applied in the 1p1h approximation turns out to be capable of describing the gross features of the experimental spectra. A considerable part of the smooth background is supposed to be produced by resonance transitions. We demonstrate the importance of high-lying single-particle resonances with large angular momentum for the explanation of the excitation spectrum around 30 MeV measured in reactions with a momentum transfer q ≳ 1 fm −1. The giant quadrupole resonance at 18 MeV is described by a dominant g 9 2 1 d 5 2 −1 component which is in agreement with the decay channels observed experimentally. We show that coincidence spectra are suitable for suppressing the background.