Sheffield Responsive RA for exploitation of ADMX, ATLAS, LZ, T2K

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This proposal is for 4 responsive RA positions to assist in the exploitation of the experiments we areinvolved in, ADMX, ATLAS, LZ and T2K, with full details given in the case for support attached. The goal is to recruit new postdoctoral researchers for a 2.5 years contract. The length of theposts is ideal for newly graduated PhD students to further their careers in particle physics and developas independent researchers. RAs will join the group activities and will be given the chance to join andorganise the group seminars and journal clubs, as well to work with research students both at the Mastersand PhD level.(1) Improving the measurement of Photon- Induced Processes in UPC collisions with the ATLAS detectorThis post is focused on extending the phase space accessible via electrons and photons with the ATLAS experiment and the exploitation of these new developments in measurements of photon-induced pro- cesses, building up on the significant expertise of Anastopoulos and Lohwasser. Specifically, the post will lead to a doubling of the accessible fiducial cross-section for the SM gg -> gg, process and will allow for extension to lower masses and improvement of the limits on BSM physics in photon-induced processes. This will be achieved by developing beyond the state-of-the-art electron and photon reconstruction, identification and calibration algorithms, an endeavour that requires significant expertise and prior involvement. (2) Exploitation of the gadolinium loading at the T2K far detector to improve sensitivity to CP violationThis post is focused on exploiting recent upgrades to the T2K far detector to maximise sensitivity to the Dirac-phase CP violation parameter, delta(CP). The main handle that T2K uses to achieve sensitivity to this parameter is to compare oscillation results from its neutrino mode ("Forward Horn Current") to those obtained from data in its antineutrino mode ("Reverse Horn Current"). At present, a major limiting factor in this sensitivity is that face that data collected in Reverse Horn Current (RHC) mode contain significant contamination (about 20%) from 'wrong-sign' neutrinos. Improving the physics reach of the T2K search for CP violation requires enhancing the ability to distinguish neutrino interactions from antineutrino interactions. (3) New techniques for reconstructing, identifying and measuring neutron-induced multiple scatter in LZThis post is focused on analysis of data from the LUX-ZEPLIN (LZ) experiment. A major concern in LZ is the level of irreducible nuclear recoil (NR) background to WIMP-induced NR signals generated by neutron scattering. This post will develop and apply transformative new techniques for reconstructing, identifying and measuring neutron-induced multiple scatter (MS) NR events. These events will be used in a profile-likelihood ratio (PLR) fit, implemented within the FlameNEST framework, to estimate the population of neutron-induced single scatter (SS) NR events in the WIMP search region of interest (ROI). This will, for the first time, enable a WIMP dark matter NR signal to be identified with confidence in LZ data. (4) ADMX Axion Search ExploitationNull results from accelerator and direct searches for WIMPs at ever-increasing sensitivity levels have led to rapidly increasing interest in axion dark matter. Daw is the sole UK member of the US Axion Dark Matter eXperiment (ADMX) collaboration, which leads the world in sensitivity for the QCD axion. A Sheffield PDRA focused on ADMX data analysis would allow Sheffield to lead the next phase of ADMX data analysis, further reinforce UK collaboration with ADMX, and facilitate the formation of a joint ADMX/QSHS analysis taskforce consisting of the proposed PDRA,