Speaker
Dr
Marek Kowalski
(Institute of Nuclear Physics, Cracow, Poland)
Description
It is now generally accepted that heavy ion collisions at ultra relativistic
energies result in a fireball of matter with high density and temperature. Such
conditions prevail, when the incoming nucleons deposit enough of their kinetic
energy in the reaction zone. Little is known about this stopping process and
about possible differences between the stopping of the incident nucleons in
elementary nucleon-nucleon interactions and nucleus-nucleus collisions.
The longitudinal momentum of the net baryons after the collision is a suitable
observable to characterize the energy loss (stopping) of the incident nucleons.
In this contribution we present a systematic study of the rapidity
distributions of net protons and Lambda hyperons as function of centrality in
Pb+Pb collisions at 158 and 40 GeV per nucleon incident energy. The
experimental nuclear collision data are compared to data from elementary
nucleon-nucleon interactions, to results of microscopic transport model
calculations, and to expectations from a core-corona picture in which the
reaction zone consists of a hot and thermalized core (central fireball) and a
corona with characteristics given by elementary nucleon-nucleon interactions.
Primary author
Dr
Marek Kowalski
(Institute of Nuclear Physics, Cracow, Poland)
