Stopping and collective effects at SPS energies

We discuss preliminary data on stopping for central Pb + Pb collisions at 158 GeV/nucleon. The (net) proton rapidity density measured by the NA49 Time Projection Chambers, NA49 Time of Flight and the NA44 spectrometer is presented. Slightly higher stopping is observed relative to S + S at 200 GeV/nucleon. The rapidity density exhibits a plateau around mid-rapidity which is qualitatively different from results at the AGS and BEVALAC/SIS energies. The second part of the paper discusses the azimuthal correlation of the energy flow. Preliminary results reveal that the ‘fireball’ preserves the information of the collision geometry even at SPS energies.