Isospin Dependence of the Balance Energy

The energy at which collective transverse flow in the reaction plane disappears, the balance energy E{sub bal}, is found to depend on the isospin of the system using the reactions {sup 58}Fe+{sup 58}Fe and {sup 58}Ni+{sup 58}Ni. The more neutron-rich system exhibits higher balance energies for all measured impact parameters, in agreement with the predictions of a transport model which incorporates an isospin dependent mean field and isospin dependent in-medium nucleon-nucleon cross sections. {copyright} {ital 1997} {ital The American Physical Society}