Dipolar degrees of freedom and isospin equilibration processes in heavy ion collisions

The dipolar degrees of freedom on the Ca48+Al27 system at 40 MeV/nucleon have been investigated for the first time with the 4π multidetector CHIMERA. The global variable (Dz) was measured for well-reconstructed events in binary dissipative processes. Both the close link with isospin equilibration processes and its insensitivity to later statistical hot source decays have been discussed. This latter feature provides the opportunity to investigate globally and exclusively the dynamics of the equilibration processes. At this first level of investigation the experimental evidence, supported by the study of the reference system Al27+Ca40 and the auxiliary one Ca27+Ca48, substantially agree with the CoMD-III calculations by describing the isovectorial forces through stiffness parameter values γ≈0.8-1.2. © 2015 American Physical Society