Bubble and ring formation in nuclear fragmentation

Nuclear transport theory predicts the formation of unstable bubbles and rings in the central collision between equal-mass heavy ions. This phenomenon occurs around a beam energy of E/A{}50 MeV/nucleon and is due to the compression of the nuclei in the early stage of the collision. As observable consequences, we predict a higher number of intermediate-mass fragments than expected from multifragmentation of a homogeneously filled sphere, and a different pattern of fragment Coulomb accelerations.