Our research with the particle physics rolling grant at Sheffield attempts to progress understanding of some of the most important questions concerning the origins and make-up of the Universe. One of these big questions is to understand what gives fundamental particles their mass. Part of our work on the huge ATLAS experiment at the Large Hadron Collider (LHC) at CERN in Geneva is aimed at this question, in particular to see if the famous Higgs Boson particle exists. The best theories we have to explain particle mass predict that it should be there. We will play a key role in analysing the vast amount of data soon expected to make this exciting discovery. Another search at ATLAS will be to determine if the so-called supersymmetry (SUSY) theory is correct. This is our best prospect for understanding how particles interact at high energy and itself predicts a new class of particles. The concept states that for every known fundamental particle there exists a super-partner particle. We worked for many years developing the key silicon technology now installed in ATLAS to search for these particles. Now we are ready with our software to play a key role in analysing the data that will hopefully discover that they exist. One of the implications of SUSY theory is the likelihood that the most stable new particle, the so-called lightest supersymmetric particle (LSP), probably is very abundant throughout the Universe, making up about 25% of its mass. This would easily explain one of the big mysteries in physics, the so-called Dark Matter seen by astronomers from its gravitational effects on stars and galaxies. Our group has pioneered techniques to search directly for dark matter particles in the laboratory and is participating in a new multi-national venture, EURECA. This will build a tonne-sized device using low temperature superconductors to perform a new search. We will contribute to the key aspect of how to shield the experiment from natural background particles, like muons. Another mystery in the Universe are the strange properties of its most abundant particle, the neutrino. This has only recently been found to have a small mass and to readily change form between three different 'flavours' while propagating through space. Details of this are not fully understood but it is known that if properly unravelled it might answer another big question, why there is so little anti-matter in the Universe. We are working on these questions through participation in the big international T2K neutrino beam experiments in Japan. We are building a key component of the detectors and will, within two years, start to analyse the data to unravel these issues. T2K probably will not do a full job, so we have instigated in the UK work on a new neutrino detector concept, based on liquid argon, contributing to the FJNE programme. We plan to build test devices to enable the next generation of neutrino experiments to follow T2K. This is linked also to our work on accelerator technology, MICE, where we are building test beam targets. This is a vital step towards the ultimate facility, a neutrino factory. We are working on key technology for this within the UKNF project. Finally, much of the hardware and computer code developed for these fundamental studies have great relevance well outside our main research. There are many examples, involving projects with a dozen UK companies. For instance, our work with Corus Ltd. on new techniques for neutron detection, has allowed development of new monitors to detect illicit transport of nuclear materials at ports. This will continue now and broaden into medical applications. Our dark matter work has produced a new national facility for underground science, the Boulby laboratory. Here we have started a new project on climate change, SKY, to explore the effect of comic rays on cloud formation.

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.

The University of York (UoY) nuclear applications group is presently running a one-year GCRF project called NuTRAIN with University of Western Cape (UWC) and University of Zululand (UZ) in South Africa. They are transferring expertise in working with scintillators and silicon photomultipliers which can be applied to applications in environmental monitoring, experimental nuclear physics and medicine. Six South African students have visited York to receive training and funds have been provided to establish small detector development laboratories at UWC and UZ. The present MANDELA project intends to build on this initial training in the form of a genuine distributed project to develop the components for a new and inexpensive type of positron emission tomography (PET) scanner for medical imaging. This will be based on plastic scintillator and make use of a newly developed UK-based supply chain for plastic scintillator established by LabLogic, a company based in Sheffield close by to UoY. Students in South Africa will be trained to carry out GEANT4 simulations - a method that allows the response of radiation detectors to be studied and hence, novel detectors can be designed. Importantly, UoY will provide these simulations "in the cloud" avoiding the need for high performance computers based locally. The simulations could even be run on a web browser or on a smartphone. Based on the simulations, prototype detectors will be fabricated. Based on training received at York, the SA students will evaluate these and determine the best silicon photomultipliers and fibre optic configurations for scintillation light detection. The MANDELA project will provide funding to upgrade their detector laboratory so they can undertake the necessary work. The project will lead to a solid design for the basic components of a novel PET scanner which can be pursued through a further collaborative R&D phase or move rapidly to commercialisation.

Organic ion exchange resins are utilised in many different areas of the civil nuclear fuel cycle, from uranium ore concentration and refinement and chemical control of coolant water composition in light water reactors and spent fuel storage ponds, to decontamination of radioactive element-containing effluents arising from fuel reprocessing and nuclear decommissioning operations. These materials are effective "sponges" for a wide range of radioactive elements, hence their widespread use. The UK has stockpiled approximately 600 m3 of spent (i.e., used) ion exchange resins (SIERs), which require disposal, and continues to produce between 2.5 to 13 m3 per year. The disposal of SIERs is problematic; there are several key issues, which include: 1. The 14C inventory of the materials. This isotope has a half life of 5,730 years and is incorporated as 14CO32- and H14CO3-, which, if allowed to enter the environment are extremely mobile and biologically available. Release of 14C gas in a disposal environment provides a rapid 14C migration pathway to the biosphere; 2. The degradation of SIERs in a disposal environment through radioactive decay processes produces organic complexant molecules, which may facilitate rapid transport of radioactive elements from SIERs to the biosphere; 3. The degradation of SIERs in a storage environment may also yield chemically toxic gases such as benzene, phenol and ammonia, which make storage extremely problematic. These issues require the SIERs to be treated so as to meet waste acceptance criteria for disposal. This is typically achieved by destruction using thermal or chemical processes. In this proposal, we aim to develop a promising chemical treatment route for the destruction of SIERs, known as wet oxidation. Wet oxidation has been successfully trialled elsewhere for the destruction of non-radioactive surrogates for SIERs, however, the specific methods previously utilised do not give rise to by-product residues that are amenable to immobilisation in a material suitable for disposal in the UK. We propose two novel approaches to wet oxidation processes that will not only generate by-products more suitable for immobilisation, but that also have a greater destruction efficiency than those previously trialled. Furthermore, we will develop and optimise tailored cement, ceramic and glass waste forms for the immobilisation of SIER degradation. We will provide a robust scientific underpinning of the chemical speciation and local distribution of radionuclides in SIERs and the immobilisation matrices we develop, and understand their behaviour in disposal environments, to support the safe and timely disposal of SIER wastes. A significant novelty of this research is the verification of our new treatment and immobilisation methods for SIERs using real radioactive materials. After optimisation of the processes described above using inactive SIERs, we will apply them to real radioactive SIER from the UK decommissioning programme. If successful, this work will be a significant step towards demonstrating an effective treatment option for the resin, allowing early site termination of a significant hazard.

"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.