标题： 基于取向钨酸铅晶体的高度紧凑且超快速的均匀电磁量能器 显示英文标题

标题： A highly-compact and ultra-fast homogeneous electromagnetic calorimeter based on oriented lead tungstate crystals

摘要： 高能物理的进步一直与高性能电磁量能器的发展密切相关。最近的实验表明，当入射束与晶体学轴对齐至几毫弧度以内时，通常用于均质量能器的闪烁晶体中的电磁簇射发展可以显著加速。特别是，当超相对论电子和光子束沿着高Z闪烁晶体的主要轴之一入射时，已经测量到辐射长度的减少。在这里，我们提出利用这种物理效应来设计一种新型紧凑型电磁量能器，基于取向的超快铅钨酸盐（PWO-UF）晶体，与当前最先进的技术相比，能够显著减少容纳高能粒子产生的电磁簇射所需的深度。我们报告了通过高分辨率X射线衍射和光弹性分析测试PWO-UF样品的晶体质量的结果。然后，我们描述了一个包含取向晶体中簇射发展的Geant4模型定义的概念验证量能器几何结构。最后，我们讨论了实现沿特定晶体学方向取向的闪烁晶体矩阵所需的实验技术。由于电磁簇射加速的角接受度对粒子能量依赖较小，而在极高能量下簇射长度的减少仍然明显，取向晶体量能器将为当前和未来实验所能达到的最大能量应用开辟道路。这些应用包括前向量能器、用于寻找轻暗物质的紧凑束流挡块，以及源指向的空间载荷{\gamma }-射线望远镜。 显示英文摘要

摘要： Progress in high-energy physics has been closely tied to the development of highperformance electromagnetic calorimeters. Recent experiments have demonstrated the possibility to significantly accelerate the development of electromagnetic showers inside scintillating crystals typically used in homogeneous calorimeters based on scintillating crystals when the incident beam is aligned with a crystallographic axis to within a few mrad. In particular, a reduction of the radiation length has been measured when ultrarelativistic electron and photon beams were incident on a high-Z scintillator crystal along one of its main axes. Here, we propose the possibility to exploit this physical effect for the design of a new type of compact e.m. calorimeter, based on oriented ultrafast lead tungstate (PWO-UF) crystals, with a significant reduction in the depth needed to contain electromagnetic showers produced by high-energy particles with respect to the state-of-the-art. We report results from tests of the crystallographic quality of PWO-UF samples via high-resolution X-ray diffraction and photoelastic analysis. We then describe a proof-of-concept calorimeter geometry defined with a Geant4 model including the shower development in oriented crystals. Finally, we discuss the experimental techniques needed for the realization of a matrix of scintillator crystals oriented along a specific crystallographic direction. Since the angular acceptance for e.m. shower acceleration depends little on the particle energy, while the decrease of the shower length remains pronounced at very high energy, an oriented crystal calorimeter will open the way for applications at the maximum energies achievable in current and future experiments. Such applications span from forward calorimeters, to compact beam dumps for the search for light dark matter, to source-pointing space-borne {\gamma}-ray telescopes.