Fiducial cross section measurements of top quark pair production in association with a photon at $\sqrt{s} = 13$ TeV with the ATLAS detector

Top quark pairs in association with final state particles are produced in large quantities at the LHC due to the high centre-of-mass energy available in proton-proton collisions. One such topology is that of a prompt photon radiated from the top quark in addition to the final state particles from the top-quark decay. Using 36.1 fb$^{-1}$ of data, this poster presents the neural networks for object and event level discriminators, as well as the fiducial cross section results at $\sqrt{s} = 13$ TeV in the single lepton and dilepton decay channels for the ATLAS experiment.