Nuclear Bubble Configuration in Heavy-Ion Collisions

We study the effects of a bubble configuration in a nucleus on heavy-ion collisions at a few tens and hundreds A MeV. We first investigate the bubble structure of Hg-206 using the relativistic continuum Hartree-Bogoliubov theory and then study the Hg-206 + Pb-208 and Hg-206+Hg-206 reactions using the DaeJeon-Boltzmann-Uehling-Uhlenbeck (DJBUU) transport model. To see the role of the bubble structure, we consider the maximum density of the produced nuclear matter, directed flow of neutrons and protons, and pi(-)/pi(+) ratio. We observe that the maximum density is smaller with a bubble nucleus, and the directed flow of nucleons and pi(-)/pi(+) ratio may depend on the bubble structure.