Isoscaling Parameter α as a Possible Probe of Medium Effect of Nucleon--Nucleon Cross Section

The medium effect of nucleon--nucleon cross section σ^med_NN(α_m) on the isoscaling parameter α is investigated for two central nuclear reactions ⁴⁰Ca+⁴⁰Ca, ⁶⁰Ca+⁶⁰Ca within isospin-dependent quantum molecular dynamics at beam energies from 40 to 50MeV/nucleon. It is found that there is the very obvious medium effects of nucleon--nucleon cross section σ^med_NN(α_m) on the isoscaling parameters α. In this case the isoscaling parameter α is a possible probe of the medium effect of nucleon--nucleon cross section σ^med_NN(α_m) in the heavy ion collisions. The mechanism of the above-mentioned properties is studied and discussed.