Investigation of the freeze-out parameters in B-B, O-O, Ca-Ca and Au-Au collisions at 39 GeV

TL;DR

This study investigates how freeze-out parameters like temperature, flow velocity, and volume vary with particle mass, system size, and collision centrality in high-energy nuclear collisions at 39 GeV, using a blast wave model with Tsallis statistics.

Contribution

It provides a systematic analysis of freeze-out parameters across different collision systems and centralities, revealing their dependence on system size, particle mass, and centrality at 39 GeV.

Findings

Kinetic freeze-out temperature increases with particle rest mass.

Transverse flow velocity and freeze-out volume decrease with particle mass.

Parameters depend on system size and collision centrality, decreasing from central to peripheral collisions.

Abstract

We analyzed the transverse momentum spectra of proton, deuteron and triton in Boron-Boron (B-B), Oxygen-Oxygen (O-O), and Calcium-Calcium (Ca-Ca) central collisions, as well as in several centrality bins in Gold-Gold (Au-Au) collisions at 39 GeV by using the blast wave model with Tsallis statistics. The bulk properties in terms of kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume are extracted from the model by the least square method. We observed that with increasing the rest mass of the particle, the kinetic freeze-out temperature becomes larger, while transverse flow velocity and the kinetic freeze-out volume reduces. These parameters are also found to depend on the size of the system. Larger the size of the system, the larger they are. Furthermore, the kinetic freeze-out temperature in peripheral Au-Au collisions is close to the central O-O collisions. We also observed that the above parameters depend on the centrality, and they decrease from central to peripheral collisions. Besides, we also extracted the entropy-index parameter $q$, and the parameter $N_0$ which shows the multiplicity. Both of them depend on the size of interacting the system, rest mass of the particle and centrality. Both $q$ and $N_0$ are larger for lighter particles, and the former is smaller for large systems while the latter is larger, and the former decrease with increasing centrality while the latter increase.