CMS collaboration (2266 authors)Hollar, JonathanAlmeida, NunoBargassa, PedrameDavid Tinoco Mendes, AndreFaccioli, PietroFerreira Parracho, Pedro GuilhermeGallinaro, MicheleMusella, PasqualeNayak, ArunaPela, JoaoRibeiro, Pedro QuinazSeixas, JoaoVarela, JoaoVischia, PietroLloret Iglesias, LaraRodrigues Antunes, JoaoSilva, PedroLeonardo, Nuno2019-02-052019-02-052013-07-16http://dx.doi.org/10.1016/j.physletb.2012.02.077http://hdl.handle.net/10400.26/27734Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.engjournal article2019-02-05