The CMS Electromagnetic Calorimeter (ECAL), is a high granularity lead tungstate (PbWO4) crystal calorimeter operating at the CERN LHC. The ECAL performance has been crucial in the discovery and subsequent characterization of the Higgs boson. The original ECAL design considerations, and the improvements to the energy reconstruction and energy calibration algorithms to cope with the LHC Run II are described. For the High-Luminosity LHC (HL-LHC) upgrades to ECAL are necessary. The crystals in the barrel region will be retained, defining the HL-LHC CMS barrel electromagnetic calorimeter ECAL. The readout electronics will be upgraded and operating at lower temperatures, to maintain the required performance of ECAL from 2027 onwards. The new readout electronics, the timing resolution and the electron and photon reconstruction efficiencies and energy resolution expected for HL-LHC are presented. The performance relevant to a number of key Higgs decay channels is reported.

中文翻译：

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优化 CMS 电磁热量计的性能，以测量 LHC 第一阶段和第二阶段的希格斯特性

CMS 电磁量热仪 (ECAL) 是一种高粒度钨酸铅 (PbWO4) 在 CERN LHC 运行的晶体热量计。ECAL 性能对于希格斯玻色子的发现和随后的表征至关重要。描述了最初的 ECAL 设计考虑，以及对能量重建和能量校准算法的改进，以应对 LHC Run II。对于高亮度 LHC (HL-LHC)，需要升级到 ECAL。筒体区域的晶体将被保留，从而定义了 HL-LHC CMS 筒体电磁热量计 ECAL。读出电子设备将升级并在较低温度下运行，以从 2027 年起保持 ECAL 所需的性能。介绍了 HL-LHC 预期的新读出电子设备、时间分辨率以及电子和光子重建效率和能量分辨率。