Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV 2°8Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered 2°8Pb + Pb collisions. An upgraded multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization. 35 refs., 15 figs., 5 tabs.

Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV 2°8Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered 2°8Pb + Pb collisions. An updated multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au + Au reaction, taken with full event characterization.

Written primarily for researchers and graduate students who are new in this emerging field, this book develops the necessary tools so that readers can follow the latest advances in this subject. Readers are first guided to examine the basic informations on nucleon-nucleon collisions and the use of the nucleus as an arena to study the interaction of one nucleon with another. A good survey of the relation between nucleon-nucleon and nucleus-nucleus collisions provides the proper comparison to study phenomena involving the more exotic quark-gluon plasma. Properties of the quark-gluon plasma and signatures for its detection are discussed to aid future searches and exploration for this exotic matter. Recent experimental findings are summarised.

Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from high-multiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE collaboration on charged pion and kaon pairs produced in pp collisions at s√=13 TeV from the LHC to study possible collectivity in pp collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jet-like events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in pp collisions for the multiplicity ranges studied.

Abstract: A few microseconds after the Big Bang, the universe is believed to have existed in the form of a plasma composed of strongly interacting particles known as quarks and gluons. Although the quarks and gluons behave as asymptotically free particles in a Quark Gluon Plasma (QGP), free quarks and gluons have never been discovered in the laboratory. Experiments at the Relativistic Heavy Ion Collider (RHIC) aim to create conditions similar to the early universe by colliding heavy ions at the highest energies possible in the hope of observing a phase transition from a QGP into hadronic degrees of freedom. The response of the space time structure of the hot reaction zone created in a heavy ion collision to a phase transition is one of the many observables being studied at RHIC. Making use of the techniques of two particle intensity interferometry, also known as the HBT effect, the RHIC experiments are studying the space-time structure and dynamical properties of the region from which particles are emitted. A large spatial size and long duration of particle emission are the predicted signals for a phase transition from a QGP to a hadronic phase. In this thesis we present results on the first measurement of one dimensional K0[subscript s] K0[subscript s] interferometry by the STAR experiment at RHIC in central (small impact parameter) Au-Au collisions at center of mass energy of 200 GeV per nucleon pair. The lambda parameter, which is a measure of the sources chaoticity, is found to be consistent with unity confirming the fact that the source is mostly chaotic as measured by STAR using three particle correlations. Without taking into account the effect of the strong interaction, the invariant radius R inv is found to be large for the mean transverse mass M [subscript t] of the pair, which is about 980 MeV/c, compared to expectations from charged pion correlations at the same M [subscript t]. Including the effect of the strong interactions makes the radius parameter for the K0[subscript s] K0[subscript s] system fall within the charged pion M [subscript t] systematics. Our result serves as a valuable cross-check of charged pion measurements which are mainly affected by contributions from resonance decays and final state interactions. This is also an important first step towards a full three dimensional analysis of neutral kaon correlations as high statistics data from RHIC will be available in the near future.

Both NA44 and EOS continue to publish high quality data on relativistic heavy ion collisions. The next leap in energy will be provided by BRAHMS at RHIC. Experiment NA44 has measured particle correlations of [pi]{sup {+-}}, K and protons and single particle distributions of [pi]{sup {+-}}, K{sup {+-}}, p, {anti p}, d and {anti d} for pA, SA and PbPb collisions at 450GeV/c, 200A·GeV and 158A·GeV for the p, S and Pb beams respectively. When the spectra are fitted to an exponential in m{sub T}, the inverse slopes increase as the system gets heavier and with increasing particle mass. For larger systems the baryon density at mid-rapidity increases implying more secondary collisions. These fuel a collective expansion and a boost in transverse momentum proportional to the mass as seen in the data. The EOS collaboration has continued to publish results from their large data set of heavy ion collisions at the BEVALAC. They plan to study the energy dependence of coalescence and flow by comparing results from NA44 and EOS.

This thesis contains the setup, analysis and results of experiment E684H Multi-Pion Correlations in Relativistic Heavy Ion Collisions''. The goals of the original proposal were: (1) To initiate the use of the HISS facility in the study of central Relativistic Heavy Ion Collisions (RHIC). (2) To perform a second generation experiment for the detailed study of the pion source in RHIC. The first generation experiments, implied by the second goal above, refer to pion correlation studies which the Riverside group had performed at the LBL streamer chamber. The major advantage offered by moving the pion correlation studies to HISS is that, being an electronic detector system, as opposed to the Streamer Chamber which is a visual detector, one can greatly increase the statistics for a study of this sort. An additional advantage is that once one has written the necessary detector and physics analysis code to do a particular type of study, the study may be extended to investigate the systematics, with much less effort and in a relatively short time. This paper discusses the Physics motivation for this experiment, the experimental setup and detectors used, the pion correlation analysis, the results, and the conclusions possible future directions for pion studies at HISS. If one is not interested in all the details of the experiment, I believe that by reading the sections on intensity interferometry, the section the fitting of the correlation function and the systematic corrections applied, and the results section, one will get a fairly complete synopsis of the experiment.