Effect Of Expansion And Gaussian Source Of HBT Parameters

In high energy heavy ion collision physics, extracted from high temperature andhigh density of particle source dynamic evolution process of information as well as thedetection time,the intensity interferometry is a kind of very effective analysis method.Source function includes information source of spatial distribution. Generally whencalculating the default correlation functions are gaussian for fitting arithmetic, and theexperiment, because the source and the decay of resonance is collective expansioneffects, such as the true source of gaussian distribution is not entirely. So in practicalapplications, the laboratory is the source and the ideal has the perfect shape of gaussiansource are different, the fitting of HBT radius parameter is not reflection of ideal sourceof space-time dimension size. Experimentally found, depend on HBT radius ofhorizontal momentum, in different collision energy region have the similar trend: withthe increase of transverse momentum,so HBT radius has a tendency to decrease.This paper using the Monte Carlo method (Monte Carlo), simulation of a gaussianheat source, does not contain the resonance state decay, the influence of spatialassociation or collective expansion momentum, then confronted the heart shock waveparametric model is adopted to200GeV energies of Au+Au to simulate the collisionevent.Then use blast-wave model to analyze HBT radius with frozen out of the particledistribution and the main affect its two factors: the source of collective expansion andresonance decay. Under the common effect of two factors, frozen out of the particles indifferent horizontal interval the radial and transverse radius distribution of momentumcan produce change, and the static source of gaussian shape has certain deviation.Resonance is the decay of pions produced mostly from at the centre of the source, makethe space of the source size become bigger, collective expansion has frozen the pionsHBT radius. These two factors jointly influence the result of the fitting HBT radius. Inthis paper, with different expansion rate and contains resonance is extracted from thesource of the decay of pions are discussed in this paper, the spatial distribution of imageand extract HBT radius were compared, the analysis of the expansion rate and thedistribution of resonance state decay of pions influence and affect HBT radius.