Damped reactions in medium mass nuclei

Abstract The distributions in mass, energy and angle of fully damped fragments from the A ≈80 system produced in the symmetric 40 Ca+ 40 Ca reaction at 197 and 231 MeV and in the asymmetric 28 Si+ 50 Cr reaction at 150 MeV have been studied. The mass distributions show a strong entrance channel dependence. A discussion in terms of barriers calculated using the finite-range liquid drop model suggests a fast-fission mechanism previously only ascribed to much heavier systems.