T. Kobayashi

Identified pion interferometry in heavy-ion collisions at CERN

Abstract π + π + correlations from S + Pb collisions at 200 GeV/ c per nucleon, measured by the focusing spectrometer of the NA44 experiment at CERN, are presented. The large data set, particularly at small values of Q inv , allows determination of the detailed shape of the correlation function. We construct the background by event mixing, and correct for resolution, Coulomb interaction, and distortion of single-particle spectra which produce effects large compared to the statistical errors at small Q inv . An exponential, rather than gaussian, source distribution is slightly favoured, but both are statistically acceptable.

Three Pion Correlations in Sulphur Lead Collisions at the CERN SPS

Abstract π + π + π + correlations from sulphur-lead collisions at 200 GeV/c per nucleon are presented as measured by the focusing spectrometer of experiment NA44 at CERN. We have investigated the three-pion correlation function at mid-rapidity and found that a genuine three-body correlation is suppressed. A possible interpretation of this result is that the emission of particles is partially coherent.

Directional dependence of the pion source in high-energy heavy-ion collisions

Abstract π + π + and π − π − correlations from 200 GeV per nucleon S + Pb collisions and π + π + correlations from 450 GeV p + Pb collisions measured by the focussing spectrometer of CERN experiment NA44 are presented. The large data set which emphasizes small values of momentum difference allows multi-dimensional analysis along with the more traditional one-dimensional parameterization to characterize the pion emission source. It is found that the three radius parameters are similar and large compared to the projectile radius. This can be explained by pion scattering in the final state hadronic system.

Kaon interferometry in heavy ion collisions at the CERN SPS

K+K+ and K−K− correlations from S+Pb collisions at 200 GeV/c per nucleon and K+K+ correlations from p+Pb collisions at 450 GeV/c per nucleon, are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. Multidimensional fits are performed in order to characterize the kaon-emission volume, which is found to be smaller than the pion-emission volume.

Results from CERN experiment NA44

A preliminary analysis is presented, of proton-nucleus collisions at projectile energy 450 GeV and sulphur-lead interactions at projectile energy 200 A·GeV. The focussing spectrometer is designed to measure single and double-particle cross sections with high statistics, at central and forward rapidities. Inclusive spectra for π±, K±, p and p emitted from p + Be, p + Pb, S + S, and S + Pb collisions are presented, as well as the two-particle correlation function for minimum bias S + Pb → 2π+ + X collisions.

Identified particle interferometry in heavy-ion collisons: Results from the CERN NA44 experiment

Abstract A large sample of π and K pairs, produced in S-Pb and p-Pb collisions has been studied. Results of a 3-dimensional correlation function analysis are presented. We observe significant differences between radii measured with pion and kaon pairs.

Single particle spectra from NA44

Abstract We have measured π ± , K ± , P and P spectra from proton and sulfur collisions with nuclear targets at the at beam energies of 450 Gev and 200 Gev per nucleon respectively. For central SA collisions we see that kaons and (anti)protons have large transverse energies. Protons are moved into central rapidity by rescattering where they annhilate antiprotons. The RQMD event generator qualitatively reproduces these trends while Fritjof does not.