Nuclear system size scan for freeze-out properties in relativistic heavy-ion collisions by using a multiphase transport model

摘要

A system size scan program was recently proposed for the STAR experiments at the Relativistic Heavy Ion Collider (RHIC). In this study, we employ a multiphase transport (AMPT) model for considering the bulk properties at the freeze-out stage for B-10 + B-10, C-12 + C-12, O-16+ O-16, Ne-20 Ne-20, Ca-40 Ca-40, Zr-96 + Zr-96, and Au-197 Au-197 collisions at RHIC energies root s(NN) of 200, 20, and 7.7 GeV. The results for Au-197 Au-197 collisions are comparable with those of previous experimental STAR data. The transverse momentum P T spectra of charged particles (pi(+/- ), K-+/-, p, and (p) over bar) at the kinetic freeze-out stage, based on a blast-wave model, are also discussed. In addition, we use a statistical thermal model to extract the parameters at the chemical freeze-out stage, which agree with those from other thermal model calculations. It was found that there is a competitive relationship between the kinetic freeze-out parameter T-kin and the radial expansion velocity beta(T), which also agrees with the STAR or ALICE results. We found that the chemical freeze-out strangeness potential mu(s) remains constant in all collision systems and that the fireball radius R is dominated by < N-part >, which can be well fitted by a function of a < N-part >(b) with b approximate to 1/3. In addition, we calculated the nuclear modification factors for different collision systems with respect to the B-10 + B-10 system, and found that they present a gradual suppression within a higher P T range from small to large systems.