The Phase 2 LHCb Upgrade, which is now being developed by the LHCb Collaboration, is supposed to make LHCb able to work at high luminosity, up to 2 ⋅ 1034/cm2/s. The plan is to collect ~300 fb−1 of data in a few years. The Phase 2 Upgrade will require a major revision of the LHCb Calorimeter system. The increased instantaneous and integrated luminosity will result in very high particle density and radiation doses in the areas close to the beam pipe. In these conditions, ECAL has to provide high quality energy and position measurements for electromagnetic showers, as well as separation of two nearby developing showers. Another requirement for the LHCb Phase 2 Upgrade ECAL is the ability to measure the time of arrival of the photon or electron with an accuracy of few tens of picoseconds. At high luminosity, such time measurement is a powerful tool helping to correctly assign electromagnetic showers to primary vertices. The choice for the central part of ECAL can be a sampling calorimeter with dense tungsten-based converter and radiation hard crystal scintillator. Concerning the particular structure type, it was found that the Spaghetti Calorimeter (SPACAL) concept meets all the requirements, including limits on radiation degradation, if its active elements are made of GAGG:Ce or YAG:Ce scintillators. The peripheral areas with moderate radiation doses can be instrumented with calorimeter modules based on plastic scintillator. A R&D campaign was started to optimize the Upgrade 2 ECAL structure. It includes studies of scintillating materials, beam test studies of the performance of various ECAL module prototypes, and simulation studies to find the optimal detector layout, longitudinal segmentation and granularity. In this paper we present the R&D results and the current status of the LHCb Calorimeter upgrade.

中文翻译：

---

LHCb热量计系统二期升级

LHCb Collaboration 目前正在开发的第二阶段 LHCb 升级旨在使 LHCb 能够在高达 2 ⋅ 1034/cm2/s 的高光度下工作。计划是在几年内收集约 300 fb-1 的数据。第 2 阶段升级将需要对 LHCb 热量计系统进行重大修改。瞬时光度和积分光度的增加将导致光束管附近区域的粒子密度和辐射剂量非常高。在这些条件下，ECAL 必须为电磁阵雨提供高质量的能量和位置测量，以及分离两个附近正在发展的阵雨。LHCb 第二阶段升级 ECAL 的另一个要求是能够以几十皮秒的精度测量光子或电子的到达时间。在高亮度下，这种时间测量是一种强大的工具，有助于将电磁簇射正确分配给主要顶点。ECAL 的中心部分可以选择带有致密钨基转换器和抗辐射晶体闪烁体的采样热量计。关于特定的结构类型，如果其活性元件由 GAGG:Ce 或 YAG:Ce 闪烁体制成，则发现意大利面热量计 (SPACAL) 概念满足所有要求，包括辐射降解限制。具有中等辐射剂量的外围区域可以配备基于塑料闪烁体的热量计模块。启动研发活动，优化升级2 ECAL结构。它包括闪烁材料的研究、各种 ECAL 模块原型性能的光束测试研究、和模拟研究，以找到最佳的探测器布局、纵向分割和粒度。在本文中，我们介绍了 LHCb 热量计升级的研发成果和现状。