Extraction Of Thermal Temperature And Expanding Velocity In Emitting Source Of Heavy-Ion Collisions At Relativistic Energy

The object of relativistic energy heavy-ion collision is to produce the matter with extemely high temperature and high density in interacting region and study temperature, expansion velocity and spatial size of the source. However, these imformation can not be detected directly with present experiment conditions. How to extract these parameters from final freeze-out particles effectly is the issue people concern. In prensent work, the methods to extracting temperature and expasion velocity of emitting source produced in collisons are discussed. Also, the temperature and expasion velocity of source at RHIC energy and LHC energy are extracted.In general, people use Boltzmann equation to fit single-particle transverse mass spectra and get apparent temperature of source, which based on the assumption that different particles have the same freeze-out temperature and expansion velocity. This method depends on the linear relation between the apparent temperature and rest mass of particle which in fact is not consistent. Thus, this method give results with large error. In addition, we usually use the Blast-Wave parameterization to fit simultaneously the transverse mass spectra ofπ±, K±, p and p to get the temperature and expansion velocity. Also, this method needs the assumption as last one. In this paper, we discuss the way that combine single-particle transverse mass spectra and the pair transverse mass dependence of HBT radius Rs to extract the thermal freeze-out temperature and expansion velocity of source. In the mean while, we use the method to extract these information for Au+Au collisions at s NN=200GeV measured by the STAR Collaboration at RHIC. Finally, after comparing the results to those obtained by simultaneous fitting the transverse mass spectra of six species, we find that they are consistent in central collisions but with large diversity in peripheral collisions. This means this methd of combing the single-particle transverse mass spectra and HBT radius Rs ( MT) to extract the temperature and expansion velocity is feasible and the assumption that different particles have the same freeze-out conditions is not reasonable.The AMPT model with string melting is used to produce transverse mass spectra ofπ? for 0-5% centrality in Pb-Pb collisions at s NN=2.76TeV of LHC. Also, we combine this spectra and the data of the pair transverse mass dependence of HBT radius Rs published by ALICE to extract the temperature and the surface radial flow rapidity. The results of these two parameters are smaller than those extracted from STAR which may be explained by the reason that the spectra obtained from AMPT model is different with the experiment. However, the ratio Tρ0 is smaller in LHC than that in RHIC which means the source produced in LHC expands more strongly and final state freeze-out particles tend to collective motion.