Alignment and Calibration of the Belle II Detector
Alignment and Calibration of the Belle II Detector
复制标题
Belle II 探测器的对准和校准
DOI：
10.1051/epjconf/201921401040
复制
发表时间：
2019
影响因子：
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通讯作者：
M. Sevior
中科院分区：
文献类型：
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作者：
T. Bilka;K. Chilikin;D. Dossett;Y. Guan;J. Kandra;C. Kleinwort;M. Sevior
2018年春季，高能加速器研究组织（KEK，筑波，日本）的SuperKEKB电子-正电子对撞机将为贝儿II实验提供首次碰撞。贝儿II的目标是收集比上一代BFactories大50倍的数据样本，利用前所未有的SuperKEKB设计光度8× 1035 cm-2s-1。贝儿II探测器将允许在恶劣的对撞机环境中进行精确测量，在精确前沿探测超出标准模型的物理学迹象。
为了提供适合物理分析的数据，探测器必须定期进行适当校准。在其他校准中，探测器对准起着关键作用。例如，依赖于时间的CP破坏的精确测量依赖于新顶点检测器的精确对准，以及依赖于束斑位置和大小的确定。为了自动化校准程序并管理检测器校准所需的大量数据和处理能力，已经开发了一个软件框架，该框架允许定义完整的工作流程并在计算集群上执行。该框架集成了Millepede II算法，以解决大的最小化问题出现在基于跟踪的对齐和校准的像素和条带探测器，中央漂移室，和μ子系统。
第一次碰撞数据将允许测试并进一步改进和调整对准和校准程序。尽管由于只安装了一小部分全顶点探测器，顶点能力将受到限制，但调试阶段将允许测试大部分对准程序功能，并为全面运行做好准备。我们将介绍在第一次数据采集过程中取得的结果，获得的经验和第一次物理运行的计划与完整的探测器。
In spring 2018 the SuperKEKB electron-positron collider at High Energy Accelerator Research Organization (KEK, Tsukuba, Japan) will deliver its first collisions to the Belle II experiment. The aim of Belle II is to collect a data sample 50 times larger than the previous generation of BFactories taking advantage of the unprecedented SuperKEKB design luminosity of 8×1035cm-2s-1. The Belle II detector will allow to conduct precise measurements in the harsh collider environment, probing for signs of physics beyond the standard model at the precision frontier.
In order to deliver data suitable for physics analysis, the detector has to be properly calibrated on a regular basis. Among other calibrations the detector alignment plays a key role. For example, precise measurements of time dependent CP-violation rely on the accurate alignment of the new vertex detector, as well as on the determination of the beamspot position and size. To automate the calibration procedures and manage the large amount of data and processing power needed for detector calibration, a software framework has been developed which allows to define the complete workflow and to execute it on a computing cluster. The framework integrates the Millepede II algorithm to solve the large minimization problem emerging in the track-based alignment and calibration of the pixel and strip detector, the central drift chamber, and the muon system.
The first collision data will allow to test and to further improve and tune the alignment and calibration procedures. Although the vertexing capabilities will be limited due to the installation of only a small slice of the full vertex detector, the commissioning phase will allow to test most of the alignment procedure features and to prepare for the full operation. We will present the results achieved during the first data taking, the experience gained and the plans for the first physics run with the full detector.