High Transverse Momentum Hadron Spectra at $\sqrt{s_{NN}}=17.3$ GeV, in Pb+Pb and p+p Collisions, Measured by CERN-NA49

Transverse momentum spectra up to 4.5 GeV/c around midrapidity of $\pi^{\pm}, p, pbar, K^{\pm}$ in Pb+Pb reactions were measured at $\sqrt{s_{NN}}=17.3$ GeV by the CERN-NA49 experiment. The nuclear modification factors $R_{AA}$ 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. This indicates that the Cronin effect is the dominating effect in our energy range. The modification factor $R_{CP}$, in which the contribution of the Cronin effect is reduced, shows a saturation well below unity in the $\pi^{\pm}$ channel. The extracted $R_{CP}$ values follow the 200 GeV RHIC results closely in the available transverse momentum range, except for $\pi^{\pm}$ above 2.5 GeV/c transverse momentum. There the measured suppression is smaller than that observed at RHIC.