Investigation of the Light Yield Distribution in LYSO Crystals by the Optical Spectroscopy Method for the Electromagnetic Calorimeters of the COMET Experiment

Abstract

The distribution of the light yield and luminescence intensity along LYSO:Ce crystal length is investigated. These distributions, determined by different defects and emission centers of the dopant in the crystalline structure and its distribution along the length, is measured by two methods: the gamma spectroscopy using radiation sources and the optical spectroscopy using ultraviolet sources. It is shown that crystals have considerable variation of the light yield and luminescence intensity both over the length of an individual crystal (in the growing direction) and for different crystals. It is established that the correction factors for the segmented calorimeter of the COMET experiment can be obtained using optical spectroscopy methods. Consideration of the correction factors will significantly reduce an error of energy measurement in a segmented calorimeter during data handling.