R. Hakobyan

Maximum particle densities in rapidity space of π+ p, K+ p and pp collisions at 250 GeV/c

Abstract In a study of π + p, K + p and pp collisions at √ s =22GeV in the european hybrid spectrometer (EHS), the maximum charged particle density per given rapidity interval is found to rise linearly with charged particle multiplicity, independent of beam particle type and practically independent of energy between 22 and 900 GeV. An anomalous π + p event is found with ten particles within the very narrow rapidity interval Δy =0.098.

Higher-Order Bose-Einstein Correlations in Pi(+)P and K(+)P Collisions at 250-Gev/C

AbstractBose-Einstein correlations up to fourth order are presented at

Influence of multiplicity and kinematical cuts on Bose-Einstein correlation in Pi+ P-interactions at 250 Gev/C

\sqrt s = 22GeV

Factorial moments and correlations in meson-nucleus interactions at 250 GeV/c

. Genuine third-order correlations are observed. The experimental data are compared with predictions from a quantum statistical approach of radiation from a partially coherent source and with the FRITIOF model.

Erraticity of rapidity gaps in π+p and K+p collisions at 250 GeV/c

Abstract The erraticity behavior of multiparticle production is analyzed in π + p and K + p collisions at 250 GeV/ c . It is demonstrated that, for these low-multiplicity final states, the erraticity measure based on event-to-event fluctuation of factorial moments is dominated by statistical fluctuations.

Reactions with leading hadrons in meson-proton interactions at 250 GeV/c

The correlation of negative particles at small momentum difference and its dependence on multiplicity and on kinematical cuts is studied in π+p-interactions at 250 GeV/c. In terms of the Kopylov-Podgoretskiį parametrization, an average radius of the pion emitting region ofrK=1.59±0.14 fm and a life-time (or emission depth) τ=0.83±0.25 fm are found. The Lorentz invariant parametrization of Goldhaber givesrG=0.85±0.04 fm. Assuming two different sources of pions, their radii are estimated asr1=1.75±0.25 fm andr2=0.60±0.08 fm. An angular and multiplicity dependence of the space-time size of the source is observed. The source is elongated along the collision axis and has larger sizerK at higher multiplicities. The radiusrK decreases with increasing pion pair momentum. The size of the emitting region appears to be larger for low rapidity pions than for pions from the fragmentation region. No evidence is found for a unique reference frame, where the pion source is motionless for each π+p collision, i. e. where the space-time size of the source is definitely smaller than in any other frame.

Coherent inelastic interactions of pi(+) and K+-mesons on Al and Au nuclei at 250 GeV/c

Abstract Boost invariance and multiplicity dependence of the charge balance function are studied in π + p and K + p collisions at 250 GeV/ c incident beam momentum with full acceptance coverage. Charge balance, as well as charge fluctuations, are found to be boost invariant over the whole rapidity region, but both depend on the size of the rapidity window. It is also found that the balance function becomes narrower with increasing multiplicity, which is consistent with the narrowing of the balance function with increasing centrality and/or system size, as observed in current relativistic heavy ion experiments.

Study of Intranuclear Collision Effects in Interactions of K+/Pi+ Mesons with Al and Au Nuclei at 250 Gev/C

A sample of 8000 interactions of 250 GeV/c π+ andK+ mesons on Al and Au nuclei, is used to search for intermittency effects by calculating the normalized factorial moments of order two to four. No significant effect is observed in the higher moments. Two-body rapidity correlations and Bose-Einstein correlations in these interactions are presented.