Çetin, Serkant Ali2020-06-122020-06-122019-09-101873-24450370-2693https://hdl.handle.net/11411/2209https://doi.org/10.1016/j.physletb.2019.07.031The inclusive production rates of isolated, prompt photons in p Pb collisions at root s(NN) = 8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb(-1) recorded in 2016. The cross-section and nuclear modification factor R-p pb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon-nucleon centre-of-mass pseudorapidity regions, (-2.83, -2.02), (-1.84, 0.91), and (1.09, 1.90). The cross-section and R-p pb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei. (C) 2019 The Author. Published by Elsevier B.V.eninfo:eu-repo/semantics/openAccessArticle2-s2.0-8506988121810.1016/j.physletb.2019.07.031Q2WOS:000483426200031