Space-Time Evolution of Hot Hadronic Matter Studied in PHENIX

点击翻译按钮获取中文摘要

In order to investigate non-perturbative QCD phenomenon of multiple quarks at high temperature, we have carried out this study in cooperation with the PHENIX collaboration at BNL-RHIC. Very high-statistic data of more than 100 million events in gold on gold-nuclear collisions were successfully taken in 2000 to 2002. Spatial and temporal evolution of the hot and dense nuclear matter created during the collisions was studied through three-dimensional two-particle correlation functions of charged pion-pairs and kaon-pairs. We found very clear dependences of the source size parameters both on the impact parameter of primary nuclear collisions and on the momentum of observed pairs. It is concluded that a hydro-dynamical expansion is created inside the colliding section and the strong radial flow affects the momentum correlation of secondary particles at freeze-out, as we have seen in studies at the CERN-SPS energies. Long duration time of particle emission was not observed in the measurements of pions, and this fact turns out to exclude several models predicting longer duration time as the pair momentum increases. A new theoretical scenario is demanded to understand what's going on.An electro-magnetic calorimeter prototype composed of a 3 by 3 tower of lead-tungstate crystal (PWO) produced by Furukawa, was studied with photon beams at LNS, Tohoku University. It achieved the energy resolution of 32MeV for GeV photons. To develop a new photon detection system being replaced with aphotomultiplier tube, a readout system of an avalanche-photo-diode with a newly designed pre-amplifier was studied. We are now ready to build a proof model.As an extension of this study, we have submitted a new plan supposed by a Grants-in-Aid entitled "QCD matter at High-Temperature" starting in H15.