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

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.