发表机构
Università degli Studi di Milano-Bicocca; CERN; Peking University; INFN Sezione di Bologna; Karlsruhe Institute of Technology（米兰比可卡大学; 欧洲核子研究中心; 北京大学; 意大利国家核物理研究所博洛尼部分所; 卡尔斯鲁厄理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
HybridMC通过解耦簇射发展与光学输运，基于概率密度函数参数化光输运，实现光学量能器快速精细模拟，加速150-480倍，并保持与全光线追踪及测试束数据的一致性。
AI 中文摘要
光学量能器的精细蒙特卡洛模拟主要受闪烁光和切伦科夫光子的产生与追踪主导，在标准Geant4光线追踪中，与仅模拟能量沉积相比，每个电磁簇射的CPU时间增加多达三个数量级。在LHCb ECAL Upgrade II预期的亮度和粒度下，这一成本对探测器研发和大规模样本生产都变得难以承受。光学光子不能简单地被丢弃，因为升级旨在缓解堆积效应的几十皮秒时间分辨率是由光子在光电探测器上的到达时间分布决定的。本文介绍了HybridMC，一个用于光学量能器的快速精细模拟框架，它将簇射发展与光学输运解耦。能量沉积由标准Geant4模拟处理，不进行光学光子传播，而光输运则通过基于从一次性全光线追踪光学校准中提取的概率密度函数的参数化摘要蒙特卡洛步骤再现。蒙特卡洛到蒙特卡洛的验证表明，对于升级后的LHCb ECAL的所有模块类型，从单个光子到达时间到重建的能量和时间分辨率，与全光线追踪具有良好的统计一致性。CPU时间减少了两个数量级以上，模块相关的加速因子从150到480不等。与DESY II和CERN SPS的测试束数据比较表明，该框架再现了真实原型测量能量和时间分辨率的动量依赖性，直至一个小的残余常数项。HybridMC保留了基于生成模型的闪光模拟器无法访问的微观光学细节，其CPU成本与在标准计算基础设施上的大规模生产兼容。
英文摘要
The detailed Monte Carlo simulation of optical calorimeters is dominated by the generation and tracking of scintillation and Cherenkov photons, which in standard Geant4 ray-tracing increases the CPU time per electromagnetic shower by up to three orders of magnitude compared to simulating only the energy deposition. At the luminosity and granularity foreseen for the LHCb ECAL Upgrade II, this cost becomes prohibitive for both detector R&D and large-scale sample production. The optical photons cannot simply be discarded, because the time resolution of a few tens of picoseconds targeted by the upgrade to mitigate pile-up is driven by their arrival-time distribution at the photo-detectors. This paper presents HybridMC, a fast and detailed simulation framework for optical calorimeters that decouples shower development from optical transport. Energy deposition is handled by a standard Geant4 simulation without optical photon propagation, while light transport is reproduced by a parametrised summary Monte Carlo step based on probability density functions extracted from a one-time full ray-tracing optical calibration. A Monte Carlo-to-Monte Carlo validation shows good statistical agreement with full ray-tracing for all module types of the upgraded LHCb ECAL, from individual photon arrival times up to the reconstructed energy and time resolutions. The CPU time is reduced by more than two orders of magnitude, with module-dependent acceleration factors from 150 to 480. A comparison to test-beam data from DESY II and the CERN SPS shows that the framework reproduces the momentum dependence of the measured energy and time resolutions of a real prototype, up to a small residual constant term. HybridMC retains the microscopic optical detail not accessible to flash simulators based on generative models, at a CPU cost compatible with large-scale production on standard computing infrastructure.
