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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:16 |
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Conference: Bucharest University Faculty of Physics 2006 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
Antiparticle to particle ratios in Au-Au collisions at 62.4 A GeV and their dynamical consequences
Authors:
R.F.Clarke
Affiliation:
Atomic and Nuclear Physics Chair, Faculty of Physics, University of
Bucharest, ROMANIA
*for the BRAHMS Collaboration
E-mail
Keywords:
relativistic nuclear collisions, collider, BRAHMS Experiment,
strangness content, chemical potential, antiparticle to particle ratios
Abstract:
It is believed that at high enough temperatures or densities normal hadronic matter will undergo a phase change and become a plasma of quarks and gluons called the Quark Gluon Plasma,(QGP). Experiments with relativistic heavy ion collisions can achieve the energy densities required to create this new phase of matter. The BRAHMS experiment is
one of four experiments designed to investigate this at the RHIC facility, in Brookhaven.
Capable of analysing charged particle production over a wide range of rapidity, we use charged particle yields and ratios to provide a measure of these Ultra-Relativistic reactions. Direct measurements of Kaon, Pion and Proton production as a function of pseudo-rapidity densities allow the dynamics of the expanding fireball to be investigated.
This talk will present the latest results for the work on the Au-Au 63 GeV CM collisions. This is work was has mainly been analysed jointly by the University Oslo and the University of Bucharest.
There will be some discussion of the challenges of the PID for this data set and then discussion of the latest results. This will include the charged particle multiplicity, which shows a large variation with rapidity and is consistent with the Landau hydrodynamical model.
Measurement of the kaon to pion ratio allows the strangeness content of the interaction to be measured and shows that, at mid-rapidity, strangeness production is greatly enhanced over what would be expected from normal hadronic interactions. This data can be compared with
strangeness enhancement data from the SPS experiment at lower beam energies, NA49 and the STAR and PHENIX experiment at RHIC. These data seems to show an increasing strangeness production and saturation with increasing beam energy.
The anti-proton to proton ratio allows the baryochemical potential of the interaction fireball to be measured as a function of baryon number in the mid rapidity region. Two scenarios are possible, full stopping, with a large bayochemical potential at mid rapidity, or transparency,
where the baryon number would be carried off down the beam line and found at higher rapidities. Both these scenarios are covered by the rapidity range of the BRAHMS detector and can be measured over various beam energies. This seems to show that stopping is increasing at the lower beam energy but the interaction region is still not fully transparent at the highest RHIC energies.
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