Sheffield physicists are searching for the missing 5/6 of the Universe’s matter—the invisible dark matter that holds galaxies together—while also trying to explain why the world is made of matter and not antimatter. These are two of the deepest open questions in fundamental science. The Standard Model of particle physics cannot account for dark matter, nor can it explain why the early Universe did not annihilate itself into pure energy. The team is attacking both problems simultaneously. At CERN’s Large Hadron Collider, they hunt for new particles in the debris of proton collisions. In a UK laboratory, they listen for dark matter bumping into xenon atoms. And in Japan, they study how ghostly neutrinos change identity—a process that may hold the key to matter’s survival. If successful, this work would rewrite the laws of physics. But the project also has immediate practical spin-offs. The group has already spun out a company, Geoptic, that uses cosmic-ray detectors to inspect railway tunnels and monitor carbon storage sites. Their machine-learning tools are improving irrigation in water-scarce regions, and their gamma-ray techniques are helping farmers measure soil health. This is fundamental science that quietly strengthens infrastructure, safety, and sustainability along the way.
View original technical description
"What is the Universe made of, and why?" Sheffield's HEP programme addresses this fundamental question. There are two problems here: about 5/6 of the matter in the Universe seems to be made of yet undiscovered particles (dark matter), and the remaining 1/6 is mostly matter, not the 50:50 matter-antimatter mix we produce in laboratories. We search for dark matter particles in two ways: at the energy frontier, by searching for particles created in high-energy proton-proton collisions of the LHC, and in direct searches, attempting to observe these particles in the Galaxy itself. Our ATLAS programme searches for new Higgs bosons, and for particles related to the SM quarks and gluons. We also study processes involving the force carriers of the weak interaction, probing our understanding of the Standard Model (SM), and measuring the properties of the SM Higgs boson. 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. In the LZ experiment, we search for evidence of dark matter colliding with Xenon atoms, and we are a world leader in the study of backgrounds originating from surrounding rocks, detector impurities and cosmic rays. The design of the next-generation Xenon detector (XLZD) is underway and it is proposed to host XLZD at the Boulby Underground laboratory in North Yorkshire. We are also constructing a detector based on quantum technology to be hosted in Sheffield to 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 lies in subtle differences between particles and antiparticles, an effect called CP violation. The CP-violating effects so far observed are not 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 made measurements of this and detected tantalising hints of CP violation. We plan to build on this work and study neutrino properties both in running experiments (T2K and SBND), and in designing the next generation of neutrino experiments (DUNE and HyperK). We have taken a leading role in developing tools to assist the neutrino community in processing and analysing data in the search for new physics and improving our understanding of how neutrinos interact. The group is committed to applying HEP technology to challenges in the industrial sector to maximise wider societal impact. We are a leader in the development and simulation of cosmic ray muon detectors for industrial applications. We recently established Geoptic, a company applying STFC know-how to improve safety in the UK rail sector and support carbon capture and storage in the international oil and gas sector. Our expertise in neutrons and machine learning is also being used to monitor and improve irrigation in water-scarce regions, and our experience in gamma-ray assay is being used to develop new methods to monitor soil health in sustainable farming practices. We are using techniques developed for ATLAS to contribute to the development of robotics with highly radioactive environments.
Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.
Is something wrong? Let us know