Spacetime Characteristics of the Fireball from HBT Interferometry.pdf

TPR-96-24 Space-time Characteristics of the Fireball from HBT 7 Interferometry† 9 9 1 y a B. Tom´aˇsika,b , U. Heinza,c , U.A. Wiedemanna and Wu Y.-F.a,d M 1 3 2 a Institut f¨ur Theoretische Physik, Universit¨at Regensburg, v D-93040 Regensburg, Germany 1 b Faculty of Mathematics and Physics, Comenius University, 5 0 Mlynsk´a Dolina, SK-84215 Bratislava, Slovakia 4 c CERN, Theory Division, CH-1211 Geneve, Switzerland 0 d Institute of Particle Physics, Hua-Zhong Normal University, 7 9 Wuhan, China / h t - l c u November 28, 1996 n : v i X r a Abstract We present the Yano-Koonin-Podgoretski˘ı parametrisation of the correlation function. Compared to the conventionally used Cartesian parametrisation, this one provides more straightforward measurement of the duration of the emission process in the fireball and a clearer signal of the longitudinal expansion, which is expected in ulrarelativistic heavy ion collisions. † Talk presented at the Workshop on Heavy Ion Collisions, Sept. 2.–5., 1996, Bratislava, Slovakia 1 Introduction The study of ultrarelativistic heavy ion collisions is motivated by the prediction of QCD lattice gauge theory that hadronic matter undergoes at energy density of 1 GeV/fm a phase transition into the quark-gluon plasma (QGP). To determine the energy density obtained in heavy ion collisions, a measurement of