Related paper One-dimensional pion, kaon, and proton femtoscopy in Pb-Pb collisions at $\sqrt{s_{\rm {NN}}}$ =2.76 TeV Single $\rm K^{\pm}$ purity (a) and $\rm K^{\pm}$ pair purity (b) for different centralities. In (b) the $k_{\rm T}$ values for different centrality intervals are slightly offset for clarity.[png] [pdf] [png] [pdf]