Study of the Multiparticle Azimuthal Correlations of Pions in π~-(p, n, C) Collisions at Momentum of 40 GeV/c

摘要

Multiparticle azimuthal correlations of pions (π~- and π~+) were studied at the moment of 40 GeV/c for π~-(p, n) and π~-C collisions within the standard transverse momentum analysis technique of P. Danielewicz and G. Odyniec using different approach. In order to study the multiparticle azimuthal correlations (i. e. the "directed" and "elliptic" flows), definite direction was separated in the phase space and with respect to this axis the correlations of π~- and π~+ mesons were observed in π~-(p, n, C) interactions. The data were obtained from Propane Bubble Chamber (PBC-500) systems utilized at JINR (Joint Institute for Nuclear Research). Experiment was performed at the Serpukhov synchrophasotron. The π~-(p, n) systems are the lightest studied one, in which collective flow effects (directed and elliptic) haven ever been detected for pions (π~- and π~+). As shown, the pions exhibit directed flow in all colliding systems π~-(p, n, C) consistent with that for protons in nucleus-nucleus systems. On the other hand, the absolute value of the directed flow parameter F insignificantly changes and it is almost the same within errors for π~- and π~+ mesons in all interactions. It should be mentioned that, there is no change of the sign of the elliptic flow in these interactions. The absolute value of elliptic flow parameter a_2 increases with increasing of the mass number of target At nuclei in π~-(p, n, C) collisions for (π~- and π~+) and almost does not change with the change of the sign of pions. The obtained results provide important information on the mechanism of meson-nucleon and meson-nucleus interactions at 40 GeV/c, as well as on characteristics of the produced nuclear matter.