Saad, A. M. E.Koçak, Fatma2024-07-022024-07-022020-01-010587-4254https://doi.org/10.5506/APhysPolB.51.2097https://www.actaphys.uj.edu.pl/index_n.php?I=R&V=51&N=11#2097https://hdl.handle.net/11452/42743In this paper, we investigate the effect on energy resolution from changing the angle and the position of incidence photon for a 5 x 5 crystal matrix built with (25 x 25 x 200) mm(3) LYSO scintillating crystals. Those crystals have been proposed for the electromagnetic calorimeter of the Turkish Accelerator Center-Particle Factory (TAC-PF) detector. The energy resolution was obtained as sigma(E)/E = 0.42%/ root E/GeV circle plus 1.60% at the center of the matrix in the energy range of 50 MeV to 2 GeV. When we examined the dependence of the energy resolution on the incidence angle of the photon, resolution began to deteriorate at angles greater than 2 degrees on the 5 x 5 crystal matrix. Moreover, energy resolution at the corners of the central crystal was worse than at the center of the central crystal by a factor of 1.3 at 50 MeV and 1.1 at 2 GeV.eninfo:eu-repo/semantics/openAccessCrystalSimulationScience & technologyPhysical sciencesPhysics, multidisciplinaryPhysicsArticle000591879200007511110.5506/APhysPolB.51.20971509-5770