Distribution of $(m^{2} - m^{2}_{\rm d})$ measured with the TOF detector for tracks with 2.6 GeV/$c <  \pt\ < 2.8$ GeV/$c$ from central Pb-Pb collisions showing the peak corresponding to the deuteron mass $m_{\rm d}$ and the background from mismatched tracks (black dotted line) which is subtracted to obtain the raw yields (see text for details).