\ Isolated-photon purity (left) and efficiency (right) as a function of \ptg\ for peripheral \PbPb collisions in the 50--90\% centrality class for $R=0.2$ and $R=0.4$. The points are shown with systematic and statistical uncertainties discussed in Sect.~4 of Ref.~ The purity is calculated using Eq.~\eqref{eq:ABCDpurityMC}, and the uncertainties are calculated by adding in quadrature all the sources shown in Fig.~\ref{fig:pur_sys_2R_50-90Cen} but considering the fit variation discussed in Sect.~\ref{sec:purity_fit} The lines in the purity plot are the result of the fit with two sigmoid functions, Eq.~\eqref{eq:sigmoid}, for each cone radius The efficiency and its uncertainties are obtained as explained in Sect.~3.5 and Sect.~4 of Ref.~.