Modelling and analysis of large data sets for LUX and LZ experiments

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The Particle Physics and Particle Astrophysics group at the University of Sheffield has been involved in dark matter searches for more than 20 years. The supervisor of this PhD project is leading the Work Package on the UK Data Centre and Simulations within the UK part of the LUX-ZEPLIN (LZ) construction project, funded by STFC. This is the project to build and operate the world most sensitive dark matter experiment with 7 tonnes of liquid xenon target to detect WIMPs. LZ is expected to store about 1 PB of data per year of operation and the LZ Collaboration is currently developing software tools for Monte Carlo modelling and data analysis. The first mock data challenge with simulated data processing chain has been successfully completed in 2017. Further mock data challenges involving databases with detector parameters, fully implemented detector response and full event reconstruction are scheduled for 2018 and 2019 in preparation for data taking in 2020. The Sheffield group is responsible for a large number of tasks linked to event generators, Monte Carlo simulations and development of analysis software. UK will also host one of the two data centres based on GridPP resources including Sheffield HEP cluster. In addition to the involvement in the LZ experiment, the Sheffield group is working on simulations and data analysis for the predecessor of LZ - the LUX experiment. The detector operation has stopped 2 years ago but large data sets, in particular data from various calibration runs with different sources, carried out to help designing the LZ experiment, still need to be analysed. This analysis should be complemented by the full Monte Carlo of the detector effects. The PhD student will play key role in the simulation and analysis of data from the LUX experiment (years 1-2). They are also expected to contribute to the design and implementation of software for modelling and analysis of future LZ data (years 1-3) and take part in the data analysis when the LZ experiment will start calibration and science runs (years 3-4). The student is expected to spend 6-12 months on LTA at the Sanford Underground Research Facility where the LZ detector will be operating. This will happen in year 3 of the PhD project when the main detector commissioning, preparation to operations, engineering and calibration runs will take place. He will also see and analyse the first data coming from the LZ experiment with a special emphasis on validating the background model using coincident events. Large-scale simulations and analysis of data sets from LUX and LZ detectors will give the student an opportunity to learn software tools and computer infrastructure used in these experiments. The student is expected to spend 6 months at LBNL (Berkeley Lab, USA) that will host the US data centre, or in some other facility linked to large data set processing (Fermilab or BNL). LBNL hosts the National Energy Research Computing Center's supercomputing facility that includes a powerful High Performance Computing system Cori based on Cray XC40 that will be used for LZ data analysis and simulations together with the UK GridPP resources. The student will learn the software and procedures used in data transfer between the experiment and the US data centre, as well as between the two data centres in the US and the UK. They will participate in the developing the software for data management and control.