Binary breakup: Onset of multifragmentation and vaporization in Ca-Ca collisions

The incomplete fusion, onset of multifragmentation and vaporization is studied in Ca-Ca collisions at bombarding energies between 20–1000 A MeV and at impact parameters between b=0 and b_max. The simulations of Ca-Ca are performed using the quantum molecular dynamics (QMD) model. We find incomplete fusion events at E/A=20–30 MeV. With an increase in the bombarding energy, the multiplicity of fragments first increases to a maximum value and then decreases for central and semi-central collisions. This peak in the multiplicity of fragments shifts towards higher energies for light mass fragments compared to intermediate mass fragments. The peak in the fragment production can be related to a critical point where onset of the fragmentation starts. The light mass fragment production at a given incident energy does not show any rise and fall in the multiplicity with a change in the impact parameter. The IMF production at higher energies (>~150A MeV), however, has a clear rise and fall in their multiplicity.