Figure 17

Particle ratios of nuclei as measured in 0-10% most central Pb-Pb collisions compared to the THERMUS [54] model(solid lines) and the GSI-Heidelberg model [1] (dashed lines) as a function of the chemical freeze-out temperature $T_{\rm chem}$. The $\rm ^3He$ yield is scaled to 0-10%. Horizontal error bars indicate the temperature range obtained by a projection of the total error of the ratio on the temperature axis.