The Transverse Momentum Dependence Of HBT Radii In A Model With Blast-Wave Parameterization

The HBT effect (intensity interferometry) is widely used to detect the space-time size and extract the kinetic information of the formed matter with high temperature and density in high energy physics field. In the heavy ion collision experiments a decrease of the HBT radii with an increase of the transverse momentum (or transverse mass) is observed, and this dependence is similar for all energies. Generally, the space-momentum correlation and the collective expansion are thought to be the reason behind this. In this thesis we will discuss this issue using a model with blast-wave parameterization. We simulate a Gaussian source which does not contain expansion and space-momentum correlation by using the Monte Carlo method, and then we show the way to calculate two-particle correlations and the computer procedure used in this thesis briefly, and analyze the Gaussian source to know the meaning of HBT radii and how they change in order to compare with latter results from THERMINATOR. We find that the precondition to use HBT effect is that the particles freeze out in a close time, and the HBT radii of a Gaussian source don't show obvious transverse momentum dependence. Then we analyze the correlation between transverse momentum and the HBT parameters such as HBT radii from space-momentum correlation and collective expansion separately. The space and momentum do not keep independent when the source contains blast-wave, the particles of different places are more likely to leave the source, and those with higher transverse momentum are more close to the surface; by compare the data with and without flow, as well as different flow velocities, we find that the existence of flow will put the particles with lower transverse momentum to a larger space. At last we compare the similarities and differences of transverse momentum dependence of HBT parameters between heavier kaons and lighter pions. All those are supposed to give help in understanding the physics behind the relations between the HBT parameters such as HBT radii and the transverse momentum.