Estimation of Hydrodynamical Model Parameters from the Invariant Spectrum and the Bose-einstein Correlations of Mesons

The invariant spectra of ? mesons produced in (+ =K +)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric nite systems. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity huti = 0:20 0:07, and is characterized by a large temperature inhomo-geneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140 3 MeV and 82 7 MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be = 1:36 0:02. Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of h f i = 1:4 0:1 fm/c and its transverse geometrical rms radius, R G (rms) = 1:2 0:2 fm.