Nuclear Science and Techniques

Abstract:

The kinetic freeze-out temperatures, T₀, in nucleus–nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are extracted by four methods: (1) the Blast-Wave model with Boltzmann–Gibbs statistics (the BGBW model), (2) the Blast-Wave model with Tsallis statistics (the TBW model), (3) the Tsallis distribution with flow effect (the improved Tsallis distribution), and (4) the intercept in T =T₀ + am₀ (the alternative method), where m0 denotes the rest mass and T denotes the effective temperature which can be obtained by different distribution functions. It is found that the relative sizes of T₀ in central and peripheral collisions obtained by the conventional BGBW model which uses a zero or nearly zero transverse flow velocity, β_T, are contradictory in tendency with other methods. With a re-examination for β_T in the first method, in which β_T is taken to be ∽(0.40 ± 0.07) c, a recalculation presents a consistent result with others. Finally, our results show that the kinetic freeze-out temperature in central collisions is larger than that in peripheral collisions.

Key words: Kinetic freeze-out temperature, Methods for extraction, Central collisions, Peripheral collisions