Evaluation of Energy Resolution by Changing Angle and Position of Incident Photon in a LYSO Calorimeter

TL;DR

This study evaluates how the energy resolution of a LYSO crystal calorimeter varies with photon incident angle and position, revealing deterioration beyond 2 degrees and at the corners, for energies between 50 MeV and 2 GeV.

Contribution

It provides a detailed analysis of how incident angle and position affect energy resolution in a LYSO calorimeter for the first time.

Findings

Energy resolution at the center is 0.42%/√E + 1.60%.

Resolution worsens at angles > 2°.

Corner crystals have 1.1 to 1.3 times worse resolution.

Abstract

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 $\sigma_{E}/E = 0.42 \% / \sqrt{E/GeV} \oplus 1.60 \%$ 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.