Author/Authors :
EHS-NA22 Collaboration، نويسنده , , N.M. Agababyan، نويسنده , , M.R. Atayan، نويسنده , , T. Cs?rg?، نويسنده , , E.A. De Wolf، نويسنده , , K. Dziunikowska، نويسنده , , A.M.F. Endler، نويسنده , , Z.Sh. Garutchava، نويسنده , , H.R. Gulkanyan، نويسنده , , R.Sh. Hakobyan، نويسنده , , J.K. Karamyan، نويسنده , , D. Kisielewska، نويسنده , , W. Kittel، نويسنده , , S.S. Mehrabyan، نويسنده , , Z.V. Metreveli، نويسنده , , K. Olkiewicz، نويسنده , , F.K. Rizatdinova، نويسنده , , E.K. Shabalina، نويسنده , , L.N. Smirnova، نويسنده , , M.D. Tabidze، نويسنده , , et al.، نويسنده ,
Abstract :
The invariant spectra of π− mesons produced in (π+/K+)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity 〈ut〉=0.20±0.07, and is characterized by a large temperature inhomogeneity 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 Δη=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 〈τf〉=1.4±0.1 fm/c and its transverse geometrical rms radius, RG(rms)=1.2±0.2 fm.
