Anisotropic emission of charged mesons and structure characteristic of emission source in heavy ion collisions at 1--2A GeV

Angular distributions of pions and kaons produced in heavy ion collisions at the low-energy end of high energies (1--2 A GeV) have been investigated by using a multisource ideal gas model. The model covers the expansions and movements of the emission sources, and it is related to the collective flows. By using the analytic expression and the Monte Carlo method, the azimuthal and polar angle distributions of mesons are calculated by the model and compared with the experimental data of the KaoS Collaboration.