Scintillator crystals like the tetragonal PbWO 4 (PWO) are largely used in calorimeters, for instance the CMS at CERN and in the PANDA calorimeter project. The performances of those calorimeters are directly linked to crystals homogeneity and quality, which can be assessed using indicators such as residual stress state condition. Since it is fundamental to develop and refine new mathematical models for the structural characterization and stress analysis of the crystalline materials, in this paper we present a novel approach aimed at the evaluation of stress or defect distribution and inhomogeneity, by analysing images obtained with photoelastic conoscopic system. A new model is proposed for the correct mathematical interpretation of the fringe pattern obtained by investigating the crystal in direction orthogonal to the uniaxial optical axis and parallel to the crystallographic a-axis. The model will be validated against experimentally acquir...

中文翻译：

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在垂直于晶体学a轴的平面上观察四边形PWO的边缘建模和光弹性应力测量方法

诸如四方PbWO 4（PWO）之类的闪烁体晶体大量用于量热仪，例如CERN的CMS和PAN​​DA量热仪项目。这些量热仪的性能直接关系到晶体的同质性和质量，可以使用诸如残余应力状态条件之类的指标进行评估。由于开发和完善用于结晶材料的结构表征和应力分析的新数学模型至关重要，因此本文中，我们提出了一种新方法，旨在通过分析由光弹性锥镜获得的图像来评估应力或缺陷分布和不均匀性系统。提出了一种新的模型，用于正确数学解释通过在垂直于单轴光轴且平行于晶体学a轴的方向上研究晶体而获得的条纹图案。该模型将通过实验获得验证。