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HK: Hadronen und Kerne
HK 23: Plenar
HK 23.2: Group Report
Tuesday, March 17, 1998, 12:00–12:30, P
Probing The Final And Initial State In Ultrarelativistic Heavy-Ion Collisions – Results From The WA98 Experiment∗ — •T. Peitzmann1 and WA982 — 1University of Münster, D-48149 Münster, Germany — 2
The WA98 experiment consists of large acceptance hadron and photon spectrometers. It is capable to study a variety of experimental observables in heavy-ion reactions via inclusive distributions and also event-by-event. Photons and neutral mesons are measured using a large acceptance Pbglass spectrometer. Momenta of both positive and negative hadrons are measured in a two-arm magnetic spectrometer with time-of-flight for particle identification. WA98 also obtains thorough event characterization with large acceptance photon and charged-particle multiplicity measurements, together with calorimeter measurements of the total transverse energy in the forward hemisphere and of the forward energy near zero degrees. In addition, the details of the target fragmentation are characterized using the Plastic Ball Detector, which allows an event-by-event determination of the reaction plane. In addition to a large data set of central collisions of 158 A GeV Pb-ions on Pb, WA98 has also taken minimum bias data for Pb-ions on targets of Pb, Nb, and Ni to provide information on nuclear dependences.
The WA98 experiment has several unique capabilities including:
measurement of photons and neutral mesons to large transverse momenta -
which allows to search for
thermal photon emission to provide information on the temperature
of the initial state and for hard or semi-hard scattering processes;
a low-background search for isospin fluctuations
as a signal for formation of a disoriented chiral condensate - which would
indicate chiral symmetry restoration; detailed measurement of momentum
spectra and correlations (HBT parameters) of various species as a
function of centrality and event characteristics, such as the
event-plane, to extract information on the volume, lifetime,
temperature, and collective motion of the heated nuclear matter.
A summary of the most recent WA98 results will be presented.
∗Supported in part by the
german BMBF
and by GSI.