Particle Ratio Fluctuations in NA49

The results of the NA49 energy scan program show a sharp maximum of the ratio of K + to !+ yields in central Pb+Pb collisions at beam energies of 20-30 AGeV. This observation has been interpreted as an indication of a phase transition at low SPS energies. We present results on energy dependence of event-by-event fluctuations of the kaon to pion and proton to pion ratios at beam energies close to this maximum and complement this study with preliminary data from the STAR collaboration in the RHIC energy range. A significant increase of the fluctuation signal of the kaon to pion ratio at 20 and 30 AGeV is observed while it stays constant from the highest SPS energies out to the RHIC energy range.