Large Hadron Collider at CERN

The past, present and future of particle physics - celebrating 70 years in partnership with CERN

The University of Liverpool has a distinguished legacy as a global leader in particle physics, a reputation that began in 1935 with the appointment of the eminent physicist Professor James Chadwick as the Lyon Jones Chair of Physics - the same year he received the Nobel Prize for his groundbreaking discovery of the neutron.

Chadwick’s decision to join Liverpool was driven by the commitment to build him a state-of-the-art particle accelerator, a promise fulfilled in 1951 with the construction of the Synchrocyclotron. This powerful machine was instrumental in shaping 20th-century physics and discovering some of the fundamental secrets of the universe.

Fun fact: The Synchrocyclotron was so large it couldn’t be housed on Liverpool’s campus and had to be built next to the crypt of the Metropolitan Catholic Cathedral.

tWorkers at the University of Liverpool’s Chadwick Lab sit on the synchrocyclotron’s massive single magnet

Workers at the University of Liverpool’s Chadwick Lab sit on the synchrocyclotron’s massive single magnet.

CERN, the European Organization for Nuclear Research, was founded in September 1954 in Geneva as an organisation to perform fundamental physics studies at an international level. Liverpool’s history has been closely entwined with CERN for 70 years.

Since the days of Professor Chadwick, Liverpool has built a world class reputation in discovery-driven science and the formation of CERN provided the scale and infrastructure needed to advance our capabilities. In fact, Liverpool were part of some of the very first experiments at CERN. In October 1954, one month after CERN was founded, Giuseppe Fidecaro, an experimental physicist, was awarded a CERN fellowship at the University of Liverpool and was part of the team that discovered the pion - electron decay.

In 1984, Professor Erwin Gabathuler was appointed Head of Physics at Liverpool after spending almost a decade at CERN where he led the European Muon Collaboration. Erwin guided the CERN programme during the critical era that led to the discovery of the W and Z for which Carlo Rubbia and Simon van de Meer were awarded the Nobel Pricze in 1984.

While at Liverpool. Professor Gabathuler successfully led the group’s regeneration, founding the CPLEAR experiment at CERN. He also laid the foundations for the group’s future experimental programme in the LHC era on the LHCb and ATLAS experiments.

Today, CERN’s science programme has delivered major advances in our understanding of the universe. Many of these discoveries wouldn’t have been possible without our unique capabilities. Not only do we conduct critical data analysis for some of the largest experiments globally, but we are also world leaders in constructing the essential components to carry them out.

Liverpool has a global reputation as a cornerstone for cutting-edge detector technology. Through a long-term programme of design, development, manufacture and integration of complex detector systems, we established The Detector Development Manufacturing Facility. This is a highly specialised workshop for the manufacture of precision-machined mechanical detector components. The Advanced Material Laboratory was also developed for the construction of low-mass carbon-fibre mechanical components. It was at these facilities where the high specification detectors were built for major experiments such as ATLAS, ALICE and LHCb at CERN’s Large Hadron Collider (LHC).

Liverpool and the Large Hadron Collider

The LHC, 100m below ground, is the most powerful particle accelerator ever built, and Liverpool's scientists are key to the global effort to build and upgrade three of the LHC’s main experiments - LHCb, ATLAS, and ALICE.

Our researchers are specialists in silicon particle detector technology and were instrumental in constructing the first detectors for LHCb and ATLAS, as well as the upgraded detectors now installed in ALICE and LHCb. Beyond data analysis from all three experiments, Liverpool scientists are also developing new detectors for ATLAS and prototyping future detectors for LHCb for the LHC's high-luminosity phase, which will significantly increase collision rates. These upgrades will enable the experiments to gather vastly larger and higher-quality datasets.

ATLAS is set to record more collisions during 'Run 3' than in the first two runs combined, LHCb will increase its data-taking rate tenfold, and ALICE aims to boost recorded collisions by a factor of 50. Furthermore, we have been able to exploit even more that LHC complex with the addition of other, smaller experiments such as the Forward Search Experiment, known as FASER, installed in 2021.

Professor Monica D’Onofrio, team leader for the ATLAS and FASER experiment groups at the University of Liverpool and UK deputy PI for ATLAS (UK PI for FASER) says: “At ATLAS, Run 3 and later HL-LHC will allow us to probe the nature of the Higgs boson with unprecedented precision, test whether it decays to new particles, for example those that could make up dark matter, and search for new physics at the highest energy ever reached by an accelerator. FASER will complement this fascinating quest, possibly uncovering light, weakly interacting new physics particles and detect subatomic neutrinos from the LHC.”

On the ATLAS experiment we were involved in one of the most important physics breakthroughs this century - the discovery of the Higgs boson in 2012 which won the Nobel Prize. On FASER, under Dr Carl Gwilliam’s leadership as Physics Coordinator, Liverpool published the first-ever FASER results in 2023, setting new constraints on new particles and achieving the first high-energy neutrino measurements from colliders.

Beyond the Large Hadron Collider

The activities of our teams at CERN go well beyond the LHC. In particle physics, Liverpool physicists are at the forefront of the exploitation of the Neutrino Platform Facility. Created in 2014, it supports major European participation in neutrino experiments. Among those, most prominent is ProtoDUNE, co-led by Professor Christos Touramanis, which aims to unlock the mysteries of neutrinos and the existence of matter. The project recently recorded its first signal as a cosmic particle travelled nearly four meters through liquid argon. In nuclear physics, ISOLDE, CERN’s longest-running facility, supports research in nuclear, medical, solid-state, and fundamental physics. Liverpool led the £4.2m construction of the ISOLDE Solenoidal Spectrometer and plays a major role in four of the facility’s 11 permanent experiments.

Our accelerator scientists are also very active, contributing and leading a suite of experiments including the AEGIS experiment, which studies fundamental symmetries in low-energy antimatter. Liverpool's SNAP project is developing slow beams of neutral antimatter atoms and Professor Carsten Welsch's team recently achieved a breakthrough by successfully demonstrating laser cooling Positronium for the first time – a goal for more than 35 years.

Future frontiers of particle physics

Our teams at Liverpool are also looking at the future. Several projects are in development which show great potential for next generation discoveries. This builds upon our long-standing contributions in developing cutting-edge technologies. For instance, the RD50 collaboration, focused on radiation-tolerant silicon sensors for the LHC, has been led by Professor Gianluigi Casse. We are now involved in forming eight new RD collaborations under the European technology R&D roadmap to address urgent needs for future experiments. Thanks to our world-wide expertise, we are actively engaged in their development.

The Future Circular Collider (FCC), a 100 km next-generation collider at CERN, is the flagship facility that CERN plans to pursue for the next decades. The FCC will initially support electron-positron collisions, followed by concurrent proton-proton and proton-electron collisions. Liverpool AS is studying the required technology and accelerator design, while our particle physicists are exploring novel detector technologies and AI-based simulations. This will enable us to evaluate the extent of precision and discovery potential of this facility. The Energy Recovery Linac, a green accelerator technology that recycles the kinetic energy of used beams, is also under development for the possible proton-electron option. Liverpool worked with CERN and other EU institutes on prototypes like PERLE, a collaboration which was led by Emeritus Professor Max Klein.

Beyond the FCC, CERN could host other facilities that could empower the potential for discovery. The proposed Forward Physics Facility at CERN could host experiments with unprecedented sensitivity to light, weakly coupling particles and high-energy neutrinos. Liverpool physicists are actively involved in designing and selecting detector technologies.

CERN is the world’s leading particle physics laboratory. It’s where you go if you want to test the furthest limits of our understanding, access amazing experiments, and work with fantastic people from all over the world. CERN is the place that brings talent, expertise, skills and ambition together to tackle the biggest questions in science.

Professor Tara Shears, team leader of the LHCb experiment, and LHCb-UK PI

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