Neutral Strange Particle-Production in K+ and Pi+ Collisions with Al and Au Nuclei at 250 Gev/C

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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

Factorial moments and correlations in traverse momentum in \pi+p and K+p collisions at 250 GeV/c

: We have measured the factorial moments up to fifth order, as well as the secondorder normalized differential factorial moments, both as a function of the difference of transverse momentum (\Deltap T ) in ß + p and K + p collisions at 250 GeV/c. The second-order differential factorial moments for like-charged pairs reveal a strong increase with decreasing \Deltap T . In a small central rapidity window, this increase is described by a simple power law. If interpreted as originating from Bose-Einstein correlations, such a behavior indicates a power-law structure of the transverse spatial distribution of the particle source. a University of Nijmegen fellow, now at the Jagellonian University, Krakow, Poland; fellow of the Polish Science Foundation (FNP) scholarship for the year 1996 b Onderzoeksdirecteur NFWO, Belgium c Supported by the Polish State Committee for Scientific Research 1 Introduction Power-law scaling of multiparticle correlations [1] has become a central issue i..