Nuclear modification at sqrt{s_{NN}}=17.3 GeV, measured at NA49

TL;DR

This study measures nuclear modification factors in Pb+Pb collisions at 17.3 GeV, revealing how particle spectra and suppression patterns compare to higher energy RHIC results, providing insights into the energy dependence of nuclear effects.

Contribution

First measurement of nuclear modification factors at SPS energies, comparing them directly with RHIC results to explore energy dependence of nuclear effects in heavy-ion collisions.

Findings

R_{AA} increases rapidly with transverse momentum.

R_{CP} saturates below unity, similar to RHIC results.

Suppression at SPS energies is less pronounced than at RHIC.

Abstract

Transverse momentum spectra up to 4.5 GeV/c were measured around midrapidity in Pb+Pb reactions at sqrt{s_{NN}}=17.3 GeV, for pi^{+/-}, p, pbar and K^{+/-}, by the NA49 experiment. The nuclear modification factors R_{AA}, R_{AA/pA} and R_{CP} were extracted and are compared to RHIC results at sqrt{s_{NN}}=200 GeV. The modification factor R_{AA} shows a rapid increase with transverse momentum in the covered region. The modification factor R_{CP} shows saturation well below unity in the pi^{+/-} channel. The extracted R_{CP} values follow the 200 GeV RHIC results closely in the available transverse momentum range for all particle species. For pi^{+/-} above 2.5 GeV/c transverse momentum, the measured suppression is smaller than that observed at RHIC. The nuclear modification factor R_{AA/pA} for pi^{+/-} stays well below unity.