Central Pb+Pb collisions at 158 A GeV/c studied by $\pi^-\pi^-$ interferometry

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2000, Vol.16 (3), p.445-451
• Main Author: Aggarwal et al, M.M.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Phenomenology; Physics; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1007/s100520000413

Two-particle correlations have been measured for identified $\pi^-$ from central 158 A GeV Pb+Pb collisions and fitted radii of about 7 fm in all dimensions have been obtained. A multi-dimensional study of the radii as a function of kT is presented, including a full correction for the resolution effects of the apparatus. The cross term R2out-long of the standard fit in the Longitudinally CoMoving System (LCMS) and the vL parameter of the generalised Yano-Koonin fit are compatible with o, suggesting that the source undergoes a boost invariant expansion. The shapes of the correlation functions in Qinv and Qspace = √Q$2\atop{x}$ + Q$2\atop{y}$ + Q$2\atop{z}$ have been analyzed in detail. They are not Gaussian but better represented by exponentials. As a consequence fitting Gaussians to these correlation functions may produce different radii depending on the acceptance of the experimental setup used for the measurement.