Mass dependence of the onset of multifragmentation in low energy heavy-ion collisions

Based on the quantum molecular dynamics (QMD) picture, we calculate the energy and mass dependence of fragment production. For the present study, we simulated the reactions of (20)Ne + (20)Ne, (40)Ar + (45)Sc, (58)Ni + (58)Ni, (86)Kr + (93)Nb, (129)Xe + (124)Sn and (197)Au + (197)Au at central geometry. Our findings clearly show a linear mass dependence for the peak center-of-mass energy at which the maximal IMF production occurs. Such a linear dependence for peak center-of-mass energy on the system size has also been observed in recent experimental studies. We also predict a similar behavior for the multiplicities of different kinds of fragments. Experiments are called for to verify this prediction.