Figure 6

$\dedx$ spectra for secondary pions (top panel) and protons (bottom panel) identified via the reconstruction of the weak decay topology of ${\rm K_{S}^{0}}$ and $\Lambda$, respectively. A narrow invariant-mass cut reducing statistics was applied to select clean samples (but the pion sample still contains a small visible proton background). The curves are single Gaussian fits to the data and the reduced $\chi^2$ is calculated in the range indicated by the fit curves only.