Probing the medium effect and isospin dependence of the in-medium nucleon--nucleon cross section in heavy ion collisions

Probing in-medium nucleon--nucleon (NN) cross section$sigma^{1}_{rm NN}(alpha)$ in heavy ion collisions has beeninvestigated by means of the isospin-dependent quantum moleculardynamics (IQMD) with the isospin- and momentum-dependent interaction(IMDI$(tau)$). It is found that there are the very obvious mediumeffect and the sensitive isospin-dependence of nuclear stopping $R$on the in-medium NN cross section $sigma^{1}_{rm NN}(alpha)$ inthe nuclear reactions induced by halo-neutron projectile and thesame-mass stable projectile. However, $R$ induced by the neutron-haloprojectile is obviously lower than that induced by the correspondingstable projectile. In particular, there is a very obvious dependenceof $R$ on the medium effect of $sigma^{1}_{rm NN}(alpha)$ in thewhole beam energy region for the above two kinds of projectiles.Therefore, the comparison between the results of $R$'s in thereactions induced by the neutron-halo projectile and thecorresponding same-mass stable projectile is a more favourable probefor extracting the information of $sigma^{1}_{rm NN}(alpha)$because of adding a new judgement.