Study on the homogeneity of large-size LYSO:Ce crystals for the HEPD-02 electromagnetic calorimeter

LYSO:Ce crystals are known for their high light output, good energy resolution, compact size and radiation hardness, making them ideal for high-energy physics experiments and medical imaging. These properties also make LYSO:Ce crystals suitable for space-based astroparticle physics experiments. Therefore, the LIMADOU collaboration selected this material to develop a compact electromagnetic calorimeter with 9 LYSO:Ce crystals of 5 × 5 × 4cm3 for the High Energy Physics Detector HEPD-01 mounted on the CSES satellite about 5 five years ago. Now, a second payload HEPD-02 is being constructed with 6 LYSO:Ce samples of 15×5×2.5cm3 fabricated by Filar OptoMaterials, enabling the development of a calorimeter with LYSO:Ce crystals two times larger in volume than the previous one. Since the growing process of crystals of this size requires new techniques for the company, an extensive experimental campaign is necessary to determine the properties of the samples. To this end, the INFN-TIFPA group, involved in the LIMADOU collaboration, has conducted a thorough study of 16 crystals. This paper summarises the main results of this characterization.