The discovery of asymptotic freedom in the theory of the strong interaction has initiated the high-energy heavy-ion collisions program. It is expected such collisions to produce a deconfined phase of quarks and gluons. The prediction of the phase transition to occur in the vicinity of non-pQCD regime increase the challenges at the theoretical and experimental levels. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory was constructed to explore the QGP-hadronic matter phase transition.

This book covers various experimental and theoretical aspects of multiparticle production in high energy interactions from lepton-lepton, lepton-hadron, hadron-hadron, hadron-nucleus and heavy ion collisons. This is the first time that data from CERN LEP, FNAL, DESY, BNL AGS, CERN SPS and BNL RHIC have been collected in a single volume. Not only accelerator-induced reactions but also cosmic ray interactions of very high energy are discussed, and the up-to-date theoretical interpretations are summarized.

We report the first inclusive photon measurements about mid-rapidity (

The proceedings of the Joint International Lepton-Photon Symposium and Europhysics Conference on High Energy Physics cover the full range of frontline research in high energy particle physics. The latest results, both theoretical and experimental, are presented and reviews of recent developments in instrumentation and accelerator techniques are included.Volume one summarises the highly specialised topics presented in the parallel sessions while the second volume contains the review talks given by the invited speakers.

Inclusive transverse momentum spectra of photons and [pi]°s at mid-rapidity are studied as a function of collision centrality for 197Au+ 197Au collisions at √s{sub NN} = 130 GeV. Photon pair conversions have been reconstructed from charged tracks measured by the main Time Project Chamber of the STAR experiment at the RHIC heavy ion facility. The transverse momentum resolution of photons with this method is estimated to be [Delta]p{sub t}/p{sub t} = 2% at 0.125 GeV/c and 5% at 2.5 GeV/c. Photon spectra were measured up to a transverse momentum of 2.4 GeV/c between ± 0.5 units of rapidity. The dominant photon production mechanism, the [pi]° → [gamma][gamma] decay, was measured between 0.25-2.5 GeV/c and ± 1 units of rapidity. Spectra are reported for the top 11%, 11-34% and 34-85% centrality classes. It was observed that in mid-central and central collisions the relative contribution of the [pi]° → [gamma][gamma] decay to the inclusive photon spectrum decreases above a transverse momentum of 1.65 GeV/c. In central collisions the magnitude of the decrease from p{sub t} = 1.65 GeV/c to 2.4 GeV/c is 20%. It is unlikely that contributions from other [pi]° decay channels and other particle decays fully explain this decrease. The centrality dependence on the shapes of the [pi]° spectra was analyzed with Boltmann and Bose-Einstein functions. In the transverse momentum windows of the spectra, the extracted temperatures are near 0.295 GeV. These temperatures are substantially higher than those extracted from [pi]{sup {+-}} spectra in a lower range of transverse momentum. This is an indication that the shapes of the pion spectra deviate from purely exponential shapes.

The International Conference "Bologna 2000: Structure of the Nucleus at the Dawn of the Century" was devoted to a discipline which has seen a strong revival of research activities in the last decade. New experimental results and theoretical developments in nuclear physics will certainly make important contributions to our knowledge and understanding of Nature's fundamental building blocks. The interest aroused by the Conference among the scientific community was clearly reflected in the large number of participants. These represented the most important nuclear physics laboratories in the world. The Conference covered five major topics of modern nuclear physics: nuclear structure, nucleus-nucleus collisions, hadron dynamics, nuclear astrophysics, and transdisciplinary and peaceful applications of nuclear science. It reviewed recent progress in the field and provided a forum for the discussion of current and future research projects.