Approaching neutron-rich nuclei toward the r-process path in peripheral heavy-ion collisions at 15 MeVucleon

摘要

The production cross sections of projectilelike fragments from the interaction of 15 MeVucleon 86Krnwith 64Ni and 58Ni and with 124Sn and 112Sn were measured using a magnetic separator with emphasis onnthe neutron-rich isotopes. Neutron pickup isotopes (with up to six neutrons picked up from the target) werenobserved with large cross sections. Calculations involving the the deep-inelastic transfer model as well as thenmicroscopic constrained molecular dynamics model (CoMD) for the primary interaction stage coupled to thenstatistical deexcitation code GEMINI were used to describe the gross properties of the product distributions.nThe present results were also compared with our previous data of the same reactions at 25 MeVucleon. Thendata at 15 MeVucleon show enhanced production of neutron-rich isotopes very close to the projectile, relativento the corresponding data at 25 MeVucleon. This enhancement in the cross sections is possibly associated withnvery peripheral collisions and longer interaction times of the neutron-rich 86Kr projectile with the neutron-richntargets. The large cross sections of such reactions well above the Coulomb barrier, but below the Fermi energy,ninvolving peripheral nucleon exchange, suggest that both the N/Z of the projectile and the N/Z of the target maynproperly be exploited in the production of neutron-rich rare isotopes. These reactions offer a novel and attractivenroute to access extremely neutron-rich rare isotopes toward the the astrophysical r-process path and, possibly,nthe neutron drip-line.