"What is the Universe made of, and why?" Sheffield's HEP programme aims to address this fundamental question. There are two problems here: about 5/6 of the matter in the Universe seems to be an as yet undiscovered particle (dark matter), and the remaining 1/6 is all matter - not the 50:50 matter-antimatter mix we make in laboratories. We search for the dark matter particle in two ways: at the energy frontier, by seeking to detect new particles created by the high-energy proton-proton collisions of the LHC at CERN, and in direct searches, attempting to observe these particles in the Galaxy itself. The theory of supersymmetry, which predicts a whole set of particles related to, but more massive than, the known particles of the Standard Model (SM), offers a candidate dark matter particle. If supersymmetric particles can be made at the LHC, they should be detected in ATLAS. Our programme searches specifically for new Higgs bosons and for particles related to the SM quarks and gluons. At ATLAS, we also study SM processes involving the force carriers of the weak interaction, probing our understanding of the SM. Looking to the future, we are contributing essential work to the upgrade of the ATLAS experiment required to take full advantage of higher event rates in future running of the LHC. Most of the matter in our Galaxy is dark matter. In the LZ experiment, we search for evidence of dark matter colliding with Xe atoms in the experiment and causing them to recoil. This experiment will be the most sensitive dark matter detector ever constructed. Understanding possible background - non-dark-matter - events is critical to this, and we have world leading expertise in this field. In addition, we are leading the development of directional dark matter detectors, which will be vital in proving that any candidate signal really does come from the Galaxy and not the Earth. We are also the only UK group involved in the search for axions: another possible type of dark matter particle which cannot be detected at the LHC or in standard dark matter experiments. Why is the matter in the Universe all matter, not antimatter? The answer to this question must lie in subtle differences between particles and antiparticles, an effect called CP violation. The CP violating effects so far observed are not nearly large enough to create the Universe we see. The most likely source for more CP violation is in the interactions of neutrinos. A key observation is that neutrinos have mass, and that different types of neutrinos can interchange their identities in flight. The T2K experiment has made measurements of this, and has detected tantalising hints of CP violation. We plan to build on this work, both in running experiments (T2K and SBND) and in designing the next generation of neutrino experiments which will have much greater sensitivity. We have developed tools to assist the neutrino community in comparing results and improving our understanding of how neutrinos interact. Our access to Boulby Mine provides an invaluable low-background laboratory for testing materials and detector prototypes. Last but not least, we seek to apply HEP technology to industry and to solving global problems. We are using techniques developed for ATLAS to contribute to the development of robotics and to deal with highly radioactive environments such as Chernobyl. We are designing muon detectors to search for nuclear contraband and monitor volcanoes. Our signal processing techniques are being applied to improving medical imaging for heart patients. Our expertise in water Cherenkov neutrino detection is being exploited in an experiment designed to monitor compliance with nuclear non-proliferation treaties. All of this work builds on our STFC core programme to benefit the wider world.

It is an exceptional time for discoveries in particle physics and particle astrophysics and the research we wish to conduct in this STFC consolidated grant programme at Sheffield is at the heart of this action. Foremost recently has been the discovery by ATLAS of a Higgs boson particle. Members of the group led and helped to develop the key 4-lepton analysis upon which the discovery was based. We will now use our expertise to measure carefully the properties of the new particle to establish whether it is the Higgs boson predicted by theory, or something else. We will also search for squark and gluino particles predicted by supersymmetry theory, which will be the main target of the next, higher energy, run of the LHC. Preparing for the future, we will expand our role in the ATLAS upgrade programme to build key components of a new ATLAS tracker. Our involvement in the T2K experiment in Japan also greatly benefited from confirmation of a non-zero third neutrino mixing angle, a result fundamental to our understanding of the neutrino. The group's respected work in neutrino analyses for T2K, particularly of so-called charge current and neutral current events, will continue along with international responsibilities for data management and for the critical light injection calibration system. However, bolstered by the exciting new results we will now also accelerate participation in next generation long baseline neutrino experiment for CP violation aimed to unravel the mystery of antimatter in the Universe, notably using LBNE/F in the US and Hyper-K in Japan. For these our particular focus will be on detector construction. For the precursor LAr1-ND experiment at Fermilab we plan to construct the central Anode Plane Array for the detector, while working also on our pioneering liquid argon R&D. We will also establish novel detector prototypes at the new CERN-based neutrino platform and for LBNE/F itself. Closely related here will be work on the MICE experiment towards a potential future neutrino factory, plus related R&D on high power particle beam targets for future neutrino beams and experiments. For particle astrophysics we plan to expand work on gravitation waves, through specialist noise analysis for Advanced Ligo, and develop new effort on dark matter, thought to comprise 90% of the Universe. There is strong motivation here because the US LUX experiment recently produced a step-change in sensitivity to dark matter particles. We will complete leading analysis for the EDELWEISS experiment and then lead key simulations for the upcoming LZ experiment in the US. Following our pioneering work on detectors with sensitivity to galactic signatures, the group will also lead analysis and construction tasks for the DRIFT direction sensitive experiment at Boulby and the new DM-ICE250 NaI experiment, which US collaborators recently agreed will be hosted at Boubly. DM-ICE will seek a new annual modulation signal for dark matter. These experiments are all searching WIMP particles, but we will also expand study of axions as a potential alternative. Meanwhile, our generic detector R&D and knowledge exchange programme is vital to underpinning the group's expertise and skills-base. It benefits from our historic links to the Boulby deep underground science laboratory but critically now involves multiple industrial and non-STFC projects. Noteworthy aims now will be to complete our DECC-funded programme on muon tomography for climate change, develop new instrumentation for radon assay, spin-out work on novel motor control electronics via a new patent and continue development of novel welding technology. It is interesting that our long-standing efforts to develop liquid argon technology for neutrino physics are also relevant to medical imaging requirements. We plan to complete a new prototype instrument, building on a recent MRC award. This all reflects the group's commitment to contributing to societal and impact agendas.