\WERS {Evaluation of Energy Resolution by Changing Angle and Position of Incident Photon in a LYSO Calorimeter}

In this paper, we investigate the effect on energy resolution from changing the angle and the position of incidence photon for a \(5 \times 5\) crystal matrix built with (\(25 \times 25 \times 200\)) 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 \(\sigma _{E}/E = 0.42\% / \sqrt {E/{\mathrm {GeV}}} \oplus 1.60\%\) 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 \(2^{\circ }\) on the \(5 \times 5\) 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.