Neutron decay of the giant resonance region in 124Sn and especially of the giant monopole resonance

Abstract

The decay of the isoscalar giant monopole and quadrupole resonances and of the underlying continuum in 124Sn has been studied with the 124Sn(α, α'n) 123Sn reaction. The data are compared with calculations based on the statistical model to extract the non-statistical decay component. The giant monopole resonance (GMR) decay mode is predominantly statistical; non-statistical processes account for 15% of the decay. Possible evidence for a pre-equilibrium decay branch of the GMR between 5% and 10% was found. The non-statistical fraction of the decay of the GMR decreases with increasing excitation energy. The contribution of neutron knock-out was found to be in qualitative agreement with PWIA calculations.