Experimental Particle Physics at the University of Edinburgh

The Edinburgh Experimental Particle Physics group is currently working in three different running experiments and we are also working on several future projects.

The ATLAS experiment at the Large Hadron Collider (LHC): ATLAS is one of two detectors able to study a wide variety of particles created from the collision of protons at the highest energies ever created, and it addresses fundamental questions. The most well known is that of the origin of mass. The beautiful symmetry which underlies our understanding of particle interactions inherently demands that all particles are massless. This cannot be the case, and the elegant solution put forward is now known as the Higgs mechanism. The discovery of the Higgs boson has verified this, and now we must measure its properties in great detail. Another area addressed by ATLAS is the search for new heavy particles such as new heavy Higgs like particles or supersymmetric particles, which are predicted in models trying to address shortcomings of the Standard Model, such as why their is dark matter.

The LHCb experiment at the LHC. Prior to the 1960s, it had been thought that matter and anti-matter would behave in the same way. However, it was discovered that this symmetry was violated, and that matter does not behave in an identical way to anti-matter. This is embodied in the phenomenon of CP violation and is essential to the understanding of the early universe. Shortly after the big bang there were equal amounts of matter and anti-matter. During expansion and cooling, matter and anti-matter would have annihilated into photons to leave a universe full of radiation, but no stars and galaxies. It was shown in 1967 by Sakarov that if three conditions, including CP violation, were met, then it would be possible for a small imbalance of matter over anti-matter to accrue, which would be sufficient to explain the existence of the universe. LHCb measures differences (CP violation) in behaviour of particles and antiparticle with at least one b or anti-b quark and searches for very rare decays of these particles, which could be affected by heavy unobserved particles.

The LUX experiment, which is the current world-leading apparatus searching for dark matter. It is well known that some 27% of the Universe is comprised of Dark Matter - that is matter of some form which does not interact in a way which produces radiation, or other easy to observe signatures. There are many theoretical candidates and resolution of this mystery must include the direct detection of our own galactic dark matter. Thermal production of Weakly Interacting Massive Particles in the early universe naturally results in the correct dark matter abundance today, and most supersymmetry models mentioned earlier contain such particles. Many other well-motivated theories also invoke particles that may be searched for.

We are also working hard on the design, development and construction of the upgraded detectors at the LHC for around 2020. The intensity of the beams will be increased and the data rates recorded by the detectors will increase by orders of magnitude. This requires building new detectors for precisely measuring trajectories of longlived particles, for measuring Cherenkov photons to deterimene their speed, and faster and more powerful simulation, and new ways to handle the massive data rates. We are also constructing the LUX-ZEPLIN project, expected to dominate direct searches for dark matter in the next decade. We work on simulations, control systems for the 10 tonnes of liquid xenon, and analysis.

We have recently started an activity neutrino physics by joining the Hyper-K experiment to be constructed in Japan. One of the most interesting fact of nature is that there are only three species of neutrinos, which until recently were thought to be massless. It is important to measure precisely the "mixing" between the species and to search for CP violation in neutrinos.

Society will benefit from the wider implications of the work, for advancement in all areas of science is fertilised by advances which originate in unlikely areas. This work will constrain some of the major outstanding questions about the Universe. The direct discovery of new particles will further define our universe. The origin of CP violation will provide valuable input to models used to explain the matter anti-matter asymmetry in the early universe needed to understand why we exist. The search for now particles appearing in quantum loops will provide insight and the possible discovery of super-symmetry could help understand dark matter.

We will continue our programme to engage, enthuse and educate the general public, pupils in secondary school education and physics teachers, in science and in fundamental physics. Due to our position as Peter Higgs' Institute and as one of only two LHC groups in Scotland, with its own educational and political system, we have a responsibility to engage with the local and national community to communicate the benefits of our research.

A main resource for our public engagement activities will be the continuation and extension of our Particle Physics for Scottish Schools roadshow programme. We will continue to exhibit the PP4SS at the Edinburgh International science festival as well as using it in our calendar of visits to schools, both local and further afield. With the phasing-in of the new Scottish Curriculum for Excellence, particle physics is being included in Scottish secondary school education for the first time. We plan to host a residential weekend workshop for around 50 physics school teachers from across Scotland. Given the wide geographical spread of Scotland, using the teachers as multipliers is a very effective way of targeting engagement at school pupils. We also will continue to foster our existing links to the Scottish authorities to promote our field as one which combines the generation of fundamental knowledge with the driving of leading-edge technological developments, the inspiration of the coming generations of students of scientific faculties and the education of students to highest standards before they branch into industry.

In addition to our public engagement activities we see new scope to facilitate knowledge exchange with the commercial private sector. We can share our experiences in the use and application of test, measurement and analysis procedures and by providing access and training to state-of-the-art technologies. Small and medium size commercial players may not have the resources to set up and develop the research and development capabilities we have. Instead it may be efficient and cost-effective for them to set up project based collaborations with us, to advance their innovation cycle. We will offer the spectrum of capabilities of our Advanced Detectors Development Centre (ADDC), comprising measurements in the dark, under controlled illumination, in magnetic fields, under controlled irradiation and climatic conditions, determining Quantum Efficiencies of photon detectors, failure analysis on wafer and die samples under controlled temperature cycles and ageing profiles. The promotion of these opportunities for commercial partners will be facilitated through the structures of the research services and commercialisation company, ERI, of the University of Edinburgh in collaboration with the School of Physics and Astronomy's Business Development Executive and the Knowledge Transfer officer of the Scottish Universities Physics Alliance (SUPA). We also engage in STFC's Higgs Centre for Innovation where a Business Incubator Centre (BIC) will facilitate technology transfer to and exchange with commercial companies. At the BIC PhD students will have the opportunity to interact directly with companies, thereby improving their training and facilitating transitions into the commercial sector.