Study of charm mixing with the LHCb experiment and development of a TORCH detector

Jennifer博士的研究将涉及两个主要方面：（i）通过分析CERN LHCb实验收集的数据来研究魅力混合，并为升级后的实验进行第三轮研究做准备; ㈡开发TORCH，一种新的飞行时间探测器，适合安装在LHCb或其他未来的实验。魅力混合是一种现象，只有在过去的~5年观察到，仍然需要更精确的研究。中性粲介子（D_0介子）的两体衰变中的粲混合一般已被分析。Jennifer将使用四体衰变模式D 0->Kpipipi进行研究，使用LHCb实验的组合运行1和运行2数据集。这种性质的多体研究是有价值的，因为它对衰变中的中间共振的影响很敏感。不仅分析将是第一次使用如此大的数据集，而且测量将首次在相空间的仓中执行，这将带来额外的灵敏度，并且还将提供测量CP破坏相伽马所需的信息。LHCb目前处于关闭状态，并正在进行大规模升级，为2021年恢复数据采集做准备。Jennifer将在CERN负责实验的这一重要阶段，并将协助操作和调试新实验。她将对收集的初始数据进行初步分析。这项研究的性质将在更接近时间的时候确定，但它不需要她的基线分析的复杂性，因此将及时完成。除了LHCb物理研究，Jennifer将从事TORCH飞行时间探测器的研究和开发。这项工作将涉及为今后对现有TORCH模块进行试验束测量做准备，该模块是一块125 x66 x1厘米的石英板，带有聚焦光学器件和11个光子探测器，并开发数据分析代码。她将通过分析现有的TORCH数据开始她的工作，该数据仅包括2个光子探测器，研究光子计数作为石英辐射器中光子路径长度的函数，并验证多光子反射的定时性能。然后将时序分辨率和光子产额与模拟性能进行比较。Jennifer的工作将导致TORCH作为LHCb实验的未来子探测器元件的验证，提供高达10 GeV/c的pi/K粒子识别能力。在这项工作的同时，Jennifer将与Photek公司（英国黑斯廷斯）合作，该公司开发了目前的TORCH MCP-PMT光子探测器。通过她的研究，可以实现未来MCP-PMT的改进，并为英国工业带来可能的营销机会。

Jennifer's DPhil research will involve two main aspects: (i) the study of charm mixing through the analysis of data collected at the LHCb experiment at CERN, and the preparation for run 3 studies with the upgraded experiment; (ii) the development of TORCH, a novel Time-of-Flight detector, suitable for installation at LHCb or other future experiment.Charm mixing is a phenomenon that has only been observed in the last ~5 years, and still warrants more precise study. Generally charm mixing has been analysed in two-body decays of neutral charm mesons (D0 mesons). Jennifer will perform a study using the four-body decay mode D0->Kpipipi using the combined run 1 and run 2 data sets of the LHCb experiment. A multibody study of this nature is valuable as it is sensitive to the effects of intermediate resonances in the decay. Not only will the analysis be the first of its kind with such a large data set, but the measurement will for the first time be performed in bins of phase space, which will bring additional sensitivity, and will also provide information that is necessary for the measurement of the CP-violating phase gamma. LHCb is currently in shutdown, and is undergoing extensive upgrade in preparation for the resumption of data taking in 2021. Jennifer will be based at CERN for this important phase of the experiment, and will assist in operating and commissioning the new experiment. It is intended she will perform a pilot analysis with the initial data that will be collected. The nature of this study will be determined closer to the time, but it will not require the sophistication of her baseline analysis, and therefore will be completed in a timely fashion.In addition to the LHCb physics studies, Jennifer will work on the research and development for the TORCH time of-flight-detector. The work will involve preparing for future test-beam measurements of an existing TORCH module, a quartz plate of 125 x 66 x 1 cm with focussing optics and 11 photon detectors, and developing code for the analysis of the data. She will start her work by analysing already existing TORCH data comprising only 2 photon detectors, studying photon counting as a function of photon path length in the quartz radiator, and also verifying the timing performance for multiple photon reflections. The timing resolution and photon yields will then be compared to simulated performance. Jennifer's work will result in the verification of TORCH as a future sub-detector element for the LHCb experiment, providing pi/K particle identification capabilities up to 10 GeV/c. In conjunction with this work, Jennifer will work in collaboration with the Photek Company (Hastings, UK), who have developed the current TORCH MCP-PMT photon detectors. Resulting from her studies, future improvements of the MCP-PMTs can be achieved, and lead to possible marketing opportunities for UK industry.