Odd–even and nonequilibrium effects in multifragmentation of 56Fe on C, Al targets at 471 A MeV

With the aid of our recent experiment, the fragmentation of 56Fe at 471 A MeV interacting with C and Al targets has been systematically studied by the improved quantum molecular dynamics model together with the statistical GEMINI model. The fragment distributions in heavy-ion collisions at intermediate energies can be well reproduced by using this combination of the two models. It is found that the odd–even effect of the partial cross sections observed in experiments appears in the de-excitation process of the excited primary fragments as a result of pairing effect and is mainly formed in the grazing collisions. The peaked angular distributions of primary ions and their fragments are dominantly due to the heavier fragments produced in the grazing collisions and reveal the nonequilibrium property of collisions and the memory effects of outgoing fragments on the entrance channel.