Below is a list of DPhil projects for 2024 on experiments in preparation; potential graduate students are encouraged to contact supervisors if they have any questions with regard to these projects.
High-Luminosity Large Hadron Collider (HL-LHC)
The High-Luminosity Large Hadron Collider (HL-LHC) project will increase the luminosity of proton-proton collisions by a factor of 10 beyond the LHC’s design value. A more powerful LHC enables the observation of rare processes that occur below the current sensitivity level, extends searches for new physics, and allows precision measurements of the Higgs boson and other particles. The HL-LHC is currently expected to begin operations in the second half of 2026, with a nominal levelled instantaneous luminosity of L=7.5×1034cm2s1 corresponding to an average of roughly 140 inelastic pp collisions each beam-crossing. The machine will deliver an integrated luminosity of 3000/fb to the ATLAS experiment over ten years starting in 2025. This is a factor ten greater than the target of 300/fb to be delivered by 2023.
The ATLAS collaboration must replace many subdetectors to take full advantage of this accelerator upgrade. Oxford and the UK are leading the Inner Tracker Upgrade (ITk) in the production of the barrel strip silicon tracker and the forward pixel tracker for the upgraded ATLAS detector.
Liquid argon detectors will play a major role in the future of neutrino physics. These high quality image detectors will allow studying neutrino interactions in great details. They have been chosen for the biggest neutrino project ever constructed – the Deep Underground Neutrino Experiment (DUNE) – and will provide the sensitivity required to study some of the big questions of neutrino physics such as the neutrino mass hierarchy and CP violation. To inform the final DUNE design, the collaboration is building a prototype that will be located at CERN. ProtoDUNE will acquire test-beam data from 2018 providing crucial data sets to understand the response of LAr detectors to different types of particles.
The DUNE group is currently looking to recruit PhD students. Several thesis topics are available within our group to work on DUNE and protoDUNE. The student would be expected to participate in studies to help understanding the physics reach of the future DUNE experiment as well as simulations to help make design decisions. The study topics within DUNE are vast and would allow the student to gain strong experience in programming, data simulation and analysis.
The ePIC detector is a planned experiment for the Electron-Ion Collider, to be built at Brookhaven Laboratory in New York. This will collide polarized electron and proton beams to probe beams to probe the complex structure of the proton and the nature of the strong interaction. The goal is to use processes like deep inelastic scattering to take precision measurement of quarks and gluons, mapping their distribution within protons and nuclei, and measuring how they contribute to the mass and spin.
Oxford will work with the UK groups to supply the outer layers of the silicon vertex tracker, using our experience from ATLAS, and state-of-the-art technology to build a system to track particle trajectories with maximum precision and minimise the material in the inner detector. Joining the project now will allow a student to help shape the design of new detector technology, as well as conducting physics simulation studies to establish the potential of this new machine to probe existing theories and search for new phenomena.
The coalescence of a binary neutron star system produces both electromagnetic and gravitational waves (GW). In August 2017, the event designated GW170817 heralded joint observations of both types of radiation from such a coalescence, opening a new window into the physics of neutron stars, neutron-rich nucleosynthesis, and post-merger dynamics. Such multi-messenger detections can also provide the next generation of absolute distance measurements in the universe, leading to independent estimates of the Hubble constant. Over the next 10 years, we expect the LIGO-VIRGO detectors to accumulate several times the current number of GW detections, and therefore efficiently detecting the optical counterpart is essential to maximise science gains. The Large Synoptic Survey Telescope (LSST) will begin observing in 2020, and with its fast, deep and wide survey capabilities will play a critical role in this emerging field quickly to detect optical counterparts to GW events. A student on this experiment would begin by helping to develop an observing strategy for the LSST to accomplish this and other goals concurrently - this project would involve proposing modifications to the existing observing schedule, using sensor characterisation and commissioning data to lay the groundwork for and make the first measurement of the Hubble constant using gravitational wave triggers with the LSST. Potential supervisors: Dr Farrukh Azfar, Professor Ian Shipsey in collaboration with partners in the USA.
In addition, core-collapse supernovae are expected to produce neutrinos and gravitational waves in advance of electromagnetic radiation. As in the case of neutron star mergers, the LSST is positioned to be among the first optical telescopes to take measurements of such rare phenomena early in their lifecycle, and improve their localization for more detailed, spectroscopic, and longer-term follow-up by other telescopes. A student pursuing this project will work with the alert mechanisms of the LSST, gravitational wave detectors (e.g, GraceDB), and neutrino detectors (SNEWS), along with models of supernovae and detector responses in order to improve our ability to peer into the dynamics of these violent and yet highly creative forces in the universe.
The nature of dark matter remains one of the biggest unsolved mysteries in modern science. A leading contender in the hunt for dark matter is the LUX-ZEPLIN experiment, which is the primary focus of the Oxford dark matter group. A 10 tonne liquid xenon time projection chamber is housed at the Sanford Underground Research Facility in South Dakota, with the aim of directly detecting the interactions of dark matter particles with the xenon target. Due to its size, LZ will reach a sensitivity that will either lead to dark matter discovery or, in the absence of a signal, will eventually be limited by the irreducible neutrino background. For further detail, see http://lz.lbl.gov/ or http://www.sanfordlab.org/. In 2022, the LZ Collaboration published their findings from a short run of the detector to demonstrate it has world-leading sensitivity for dark matter detection. See https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.041002 or https://arxiv.org/abs/2207.03764 .
New students joining in October 2024 will have exciting opportunities to participate in on-site activities as well as offline analysis. LZ is a multi-physics machine, with sensitivity to multiple dark matter paradigms over several orders of mass, and both standard-model and novel neutrino processes. Possible thesis topics could revolve around contributions to these high-level analyses, but could also be on the important detailed efforts to understand the detector performance through data quality cuts, simulations, and modeling. Lastly, with direct dark matter detection being a growing and increasingly competitive field, there are possibilities to undertake R&D work to inform the design of the next-generation detector.
The Mu3e experiment seeks to probe physics beyond the standard model by searching for the lepton flavour violating muon to three electron decay at the Paul Scherrer Institut (PSI), the national physics laboratory of Switzerland. We are attempting to be sensitive to a single event in 10^16 muon decays, that requires a detector of unique design and performance.
The Mu3e experiment is currently under construction at the high intensity Muon Beamline at PSI. The UK has responsibility for the outer pixel system and the Oxford group is currently fabricating the ultra-low mass outer pixel ladders that are based on an innovative new monolithic silicon detector design and highly integrated electro-mechanical structural components. When complete this will be amongst the lightest particle tracking systems ever constructed with an order of magnitude lower mass per tracking layer than the current LHC experiments.
DPhil students would be joining Mu3e at a very exciting time of final construction, commissioning and first data taking. This allows them to take part in silicon R&D aspects, robotic detector construction, physics data analysis, simulation and software development. There is also the possibility of working on the design of the phase2 upgrade of the system that will reach the ultimate sensitivity possible with this concept. Mu3e is a relatively small experiment meaning individuals can have a large impact and can take on significant responsibly.
For more information about the Oxford DPhil program and to apply please visit: https://www.physics.ox.ac.uk/study/postgraduates/dphil-particle-physics