Powering discovery: the force behind experiments at the world’s largest particle accelerator
The Large Hadron Collider (LHC) located at CERN, in Geneva, is where the world’s most ambitious particle physics experiments are conducted. It’s a place where the very best physicists are pushing the frontiers of particle physics as they search for answers to the deepest secrets of the universe.
Three of the most significant experiments conducted at the Large Hadron Collider, LHCb, ATLAS and ALICE, are enabled by the pioneering vision and leadership of researchers from the Particle Physics group at Liverpool.
These experiments push the boundaries of our knowledge about the fundamental building blocks of life as we know it. We wouldn’t be any closer to answering these questions without Liverpool’s world-leading expertise in instrumentation has been key to developing the precise detectors these experiments rely on. In addition, our unique capabilities in data analysis enable us to extract groundbreaking insights, driving important discoveries in particle physics.
We are now constructing new detectors for ATLAS and prototype future detectors for LHCb for the High Luminosity phase of LHC (where luminosity measures how many collisions are happening in the accelerator). These upgrades allow the experiments to collect significantly larger and higher quality data sets than was possible previously.
Our leadership is shaping all aspects of these experiments at CERN.
“But what are we trying to discover?”
Physics holds endless possibilities for groundbreaking discoveries. Through our esteemed partnership with CERN, we are at the forefront of some of the most exciting breakthroughs in history, shaping our understanding of the universe.
Discovering the God particle and understanding the Mystery of dark matter
Professor Monica D’Onofrio, Director of Research of the Department of Physics, and Dr Helen Hayward, Research Physicist, are both members of the ATLAS experiment and part of the most significant scientific breakthroughs of this century – the discovery of the elusive Higgs Boson particle in 2012. Since then, understanding the Higgs Boson, sometimes referred to as the ‘God Particle’ due to its fundamental role in shaping the universe, has been a foundational aspect of the ATLAS experiment.
This year, Professor D’Onofrio, Liverpool group leader for seven years until 2024, will be the incoming UK Spokesperson for the ATLAS experiment (deputy since 2023). She will continue to play a key role in leading areas of the physics programme, with her work primary focus being on the search for new physics and understanding the nature of dark matter.
Dark matter is something that we know exists, but we are yet to uncover its secrets. In our efforts to understand what dark matter is, ATLAS, with Liverpool at the forefront, is delivering major results in our quest for what might lie beyond the standard model of particle physics, using cutting-edge analysis techniques and the fantastic capabilities of the detector.
Fun fact: ATLAS is the largest volume particle detector ever constructed.
Professor D’Onofrio is joined by Dr Helen Hayward, research physicist on ATLAS for almost two decades. Having played key roles in commissioning the current ATLAS tracking detector and leading its international software team, she now leads the ATLAS upgrade team at Liverpool. The team designs and builds modules and carbon fibre structures for the new silicon strip and pixel tracking detectors for the upgrade the ATLAS detector for the High Luminosity LHC. Dr Hayward is the co-ordinator for the UK pixel endcap detector which is being assembled at the unique Liverpool Semiconductor Detector Centre, situated in the Oliver Lodge building on campus.
Interestingly, unused components of the ATLAS tracking detector - specifically, SCT modules, a subsystem built with significant contributions from the Liverpool team - were repurposed to construct FASER, a small experiment installed in the LHC tunnel less than five years ago. Liverpool continues to play a key role in FASER, with Professor D’Onofrio serving as the elected chair of its international collaboration board. The experiment has already delivered remarkable results in the search for new physics, particularly within the dark sector, providing valuable insights that are highly complementary to ATLAS.
Investigating the beauty quark
Liverpool’s team at the LHCb experiment is led by Professor Tara Shears, who is the UK spokesperson for this experiment. LHCb is designed to investigate a type of elementary particle called the beauty quark, whose behaviour lets us understand various questions in fundamental physics, such as the mysteries of matter and antimatter which is responsible for the evolution of the universe.
Forensic investigation of beauty quark behaviour allows us to deduce how closely they follow the predicted theory of particle physics. Any deviation could signal the influence of new physics mechanisms that can be found in other experiments like ATLAS. However, we need exquisitely precise particle detectors to do this job well.
Dr Eva Vilella-Figueras is a UKRI Future Leaders fellow. Eva’s expertise lies in developing silicon sensors for fundamental physics experiments and she leads work to develop new detectors for LHCb within the collaboration. An essential part of physics experiments is particle tracking, which essentially consists of measuring the trajectories of the particles as they interact with the sensors. This is challenging because there are billions of collisions that produce hundreds of billions of particles per second and these particles need to be measured. The technology Dr Viella-Figueras is developing enables greater capability for reconstructing these particles and studying their behaviour.
Investigating the Quark-Gluon Plasma with high energy heavy-ion collisions
Liverpool’s contribution to the ALICE experiment is led by Professor Marielle Chartier, whose research at the LHC involves investigating the interactions of heavy ions at the highest energies possible. Lead-lead heavy-ion collisions at ultra-relativistic energies produce partonic matter and the thermodynamics of the medium formed by these strongly interacting particles (the quark-gluon plasma - a state of matter thought to have existed just after the Big Bang) can be investigated.
Professor Chartier developed and built, in the Liverpool Semiconductor Detector Centre and in collaboration with STFC Daresbury Laboratory, a significant part of the Outer Layers of the silicon Inner Tracking System upgrade for the ALICE experiment. She is also chair of the ALICE Collaboration board , the main decision-making body of the international experiment.
Advancing scientific discovery
CERN is truly unique: its large experiments like ATLAS, ALICE and LHCb serve as vast scientific facilities, where a multitude of independent analyses address a wide range of key science questions simultaneously. Those are complemented by smaller dedicated experiments, like FASER, and thrive thanks to the advancements in technology that serve to build more powerful detectors.
There is nowhere else in the world that can perform this type of research. The innovation, expertise and skills that our researchers provide is what really enables the experiments and facilities at CERN to reach their full potential.
Discover more about how we’re pushing the frontiers of Particle Physics at Liverpool.