Anisotropic Distributions Of Final-state Products In AA Collisions At GeV And Mev Energies

The pseudorapidity distributions of final-state charged particles produced in Cu-Cu collisions with centralities0-6%and6-15%at22.4A,62.4A, and200A GeV are calculated by using the multi-source thermal model. Meanwhile, the azimuthal distributions and the dependences of elliptic flows on transverse momentum for nuclear fragments produced in Kr-Sn collisions at25Me V/N are calculated by the model. It is shown that the model with a few simple parameters is successful in the descriptions of longitudinal pseudorapidity distributions, transverse azimuthal distributions, and the dependences of elliptic flows on transverse momentum. Our results calculated by the model are in agreement with the experimental data or other modeling results. The main results obtained in the present work can be summarized as two parts given in the following.(1) From the pseudorapidity distributions of final-state particles in Cu-Cu collisions at the RHIC energies, one can see that the distribution width and density increase with increasing the impact energy. These situations are the same for the two centralities. However, the density for centrality6-16%is slightly lower than that for centrality0-6%. The final-state pseudorapidity distribution is described by a sum of four Gaussian-like functions. A single Gaussian function does not describe the two-peak structure of pseudorapidity distribution. As representations of longitudinal flow effect and secondary collisions, the width of pseudorapidity distribution becomes wider.(2) From the azimuthal distributions of nuclear fragments produced in25MeV/N Kr-Sn collisions, one can see that the emission of fragments is anisotropic. There are fluctuations in the azimuthal range. The heavy fragments have large fluctuation and anisotropy. From the dependences of elliptic flows on transverse momentum, one can see that the fragments distribute in a ellipse in the space of transverse momentum. A large transverse momentum corresponds to a large elliptic flow. On the other hand, the heavy fragments have large elliptic flow.