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

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