Thesis Topics

Below is a list of potential thesis topics for students starting in October 2020. We have a number of STFC studentships to use on topics of our choice. These studentships provide full support to UK students.

Students with other funding are welcome to apply for any of the listed topics.

Running Experiments:

ATLAS

The New Energy Frontier

During 2015-2018 the LHC delivered proton-proton collisions at record-breaking energies and luminosity. We now are producing Higgs bosons in large numbers, allowing us to enter the "precision era" of Higgs physics. Precision measurements of Higgs properties will be performed to seek evidence for physics beyond the Standard Model. Our sensitivity to the production Dark Matter and other exotic particles is also better than it has ever been before. For us this is a very exciting time, with great opportunities to discover new particles, to test theories and to explore nature at smallest scales with the most powerful accelerator in the world. The period 2019-2020 will be an exciting one, as we explore the energy frontier, and prepare hardware, software and analysis improvements for the major detector upgrades planned for the years ahead.

The Oxford ATLAS group has a world-leading physics program with major responsibilities in the areas of:

Our Research Activities

The ATLAS detector ran successfully during LHC operations and recorded roughly 140/fb of proton-proton collision data which has not all been analysed yet. Major responsibilities of the Oxford ATLAS group include:


Thesis Topics

New PhD students are expected to work in a combination of the above areas. Each of our students spends one year or more at CERN.
ATLAS D.Phil supervisors are Alan Barr, Claire Gwenlan, Chris Hays, Todd Huffman, Richard Nickerson, Georg Viehhauser, Daniela Bortoletto, Ian Shipsey and Tony Weidberg.

Potential graduate students are encouraged to contact supervisors if they have any questions with regard to the thesis topics.

LHCb

B physics and CP violation at the LHC at CERN

LHCb makes precision studies of CP violation in the decays of beauty and charm hadrons ('heavy flavour physics') at the CERN LHC. LHCb searches for physics beyond the Standard Model by investigating departures from the unitarity of the CKM matrix and checking whether or not this provides a consistent picture of observed CP-violation. The experiment also has high sensitivity to new physics effects by looking for enhanced rates of heavy flavour decays that are otherwise very rare in the Standard Model, or in unexpected angular distributions of such decays.

The LHCb detector has already collected a wealth of data, the analysis of which will likely form a significant fraction of the doctorate work. The detector is currently being upgraded, coming online in 2021, and which will greatly increase the data collection rate. Major responsibilities of the Oxford group are on the Ring Imaging Cherenkov (RICH) counters and Vertex locator (VELO); the RICH detectors provide particle identification of pions, kaons and protons over the momentum range from 1 to 100 GeV/c, and the VELO reconstructs B-decay vertices to a precision of around 150μm. The group also leads efforts on the particle identification calibrations that are core to the real-time analysis strategy that LHCb shall adopt for the 2020s.

A new graduate student would be expected to work on a combination of the following areas:

• Undertake a significant data analysis; the Oxford LHCb group has broad physics interests which include CP violation, b-hadron decays involving tau leptons, rare B hadronic decays, charm mixing, electroweak physics including a measurement of the W mass, and central exclusive production. A major topic of the group is the measurement of the CKM angle gamma, with special interest in the family of channels B→ D(*)0 K(*) with the D0 decaying into 2-, 3- and 4-body final states. We are also active in searching for very rare beauty and charm channels, including the B→ Dµµ family of decays. In addition we are pursuing studies in diffractive physics and QCD via central exclusive production, for which the unique forward acceptance of the experiment brings many advantages. A new student could expect to work in any one of the above areas, or develop an alternative analysis effort which is commensurate with the general interests of the group.

• Participate in the commissioning and operation of the RICH or VELO sub-systems, monitoring the performance of the detectors and their readout systems. Of particular interest is maintaining the calibration of the RICH system’s performance using real data, by selecting background-free samples of K’s and π’s from D*±→ D0 (→K π) π±, and Λ0 → pπ decays.

• Develop hardware or simulation for future LHCb upgrades, and which also have applications for other heavy flavour experiments. This could include studies of the physics performance, characterisation and design of future hybrid pixel detectors for precise measurement of heavy-flavour-decay vertices. Alternatively a student could work on the novel prototype TORCH detector to provide enhanced low-momentum particle identification, measuring time-of-flights to a precision of 15 ps.

A subset of the LHCb group are also involved with the BESIII experiment. BESIII, located in Beijing, uses electron positron collisions to create a charm hadron factory. Despite the radically different environments of LHCb and BESIII, there is a high level of synergy between them, and the combination of results is expected to lead to significant improvements in precision and sensitivity to new physics. There are opportunities for students to be involved in this exciting new venture as a part of their DPhil activities.

Students would usually be expected to spend a year or more at CERN as well as publishing much of their thesis work in peer-reviewed journals. Depending on the proposed thesis topic, the supervisors may be
Neville Harnew (neville.harnew@physics.ox.ac.uk),
Malcolm John (malcolm.john@physics.ox.ac.uk),
Sneha Malde (sneha.malde@physics.ox.ac.uk) or
Guy Wilkinson (guy.wilkinson@cern.ch).

Further information can be obtained from any of the above people, or from the LHCb-Oxford website https://www2.physics.ox.ac.uk/research/lhcb

T2K

Tokai to Kamioka Neutrino Oscillation Experiment

The Oxford T2K group is eager for new D.Phil students to join. We received our first data in November 2009 and have been taking data in both neutrino and anti-neutrino mode. The intensity of the neutrino beam is still increasing allowing for precision measurements. T2K has found the first hint that CP might not be a conserved symmetry in Neutrino Physics. For information about the group's activities and potential thesis analysis work, please see our home page at http://www2.physics.ox.ac.uk/research/t2k/thesis-topics

For more information, contact Professor Giles Barr (giles.barr@physics.ox.ac.uk), Professor Alfons Weber (alfons.weber@physics.ox.ac.uk) or Professor Dave Wark (dave.wark@physics.ox.ac.uk) or Dr Xianguo Lu (xianguo.lu@physics.ox.ac.uk)

Experiments in preparation:

ATLAS Upgrade

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.

Precision Higgs Physics at HL-LHC

Simulation of events in the ITk with a pileup of 140

LZ

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 will be 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/.

New students will join at an exciting time in the project, with commissioning to start late 2019 and physics data-taking in 2020. There will be opportunities to participate in on-site activities as well as offline analysis. LZ is a multi-physics machine, with sensitivity also to non-WIMP dark matter paradigms and 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 simulations and modelling. Lastly, with direct dark matter detection being a growing and increasingly competitive field, there could be possibilities to undertake R&D work to inform the design of the next generation detector.

Supervisor: Professor Hans Kraus hans.kraus@physics.ox.ac.uk

DUNE

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. In addition, the student would be expected to analyse data from protoDUNE.

For more information, contact Professor Giles Barr (giles.barr@physics.ox.ac.uk) or Professor Alfons Weber (alfons.weber@physics.ox.ac.uk) or Dr Xianguo Lu (xianguo.lu@physics.ox.ac.uk)

SNO+

Neutrino Physics at the SNOLAB facility in Canada

SNO+: Neutrino Physics at the SNOLAB facility in Canada

Some of the most exciting physics to emerge over the last decade has been in the field of neutrino physics. One of the forefront experiments here has been the Sudbury Neutrino Observatory (SNO), based in Canada, which was a recipient of the 2015 Nobel Prize in physics. The SNO group at Oxford have played a leading role in solving the "Solar Neutrino Problem" and clearly demonstrating, for the first time, that neutrinos exists as mixed states which allow them to apparently "oscillate" from one type to another. On the heels of this tremendously successful project, a follow-on experiment, SNO+, is being pursued with a remarkably diverse and interesting range of physics objectives. The main objective of this project is to sensitively search for a very rare process called "neutrinoless double beta decay." An observation of this would both permit a determination of the absolute neutrino masses and would establish that neutrinos act as their own antiparticles, which could have significant consequences for our understanding of the matter/antimatter asymmetry in the universe. This area of study is considered to be of extremely high importance in particle physics and the Oxford group has played a fundamental role in establishing the technique that will be used for this search. In addition, other physics goals include studies of low energy solar neutrinos, oscillations of reactor antineutrinos, searches for non-standard modes of nucleon decay, study of geo-neutrinos generated from within the earth, and to act as an important detector for neutrinos from galactic supernovae. The detector is currently being filled with liquid scintillator and isotope for neutrinoless double beta decay will be introduced in 2019. The incoming PhD student would participate in development, simulation, calibration, operation, analysis and the production of first results.

For further information, contact Professor Steve Biller (steven.biller@physics.ox.ac.uk) or visit the website http://snoplus.phy.queensu.ca/

LSST

The coalescence of a binary neutron star system, known as a kilonova, produces both electromagnetic and gravitational waves (GW). In August 2017, groundbreaking joint observations of optical radiation and gravitational waves from the kilonova, GW170817, heralded the era of gravitational-wave astronomy. Kilonova GW detections can provide the next generation of absolute distance measurements in the universe, and when combined with redshift measurements from an optical detection, these multi-messenger measurements enable independent estimates of the Hubble constant to those made using Supernovae Standard Candles. 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 be in position to take leadership on this emerging field and efficiently detect kilonova counterparts. 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 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 events as triggers with the LSST. Potential supervisors: Dr. Farrukh Azfar, Professor Ian Shipsey in collaboration with partners in the USA.

For further information contact Dr Farrukh Azfar (farrukh.azfar@physics.ox.ac.uk)

R&D projects and the John Adams Institute

John Adams Institute for Accelerator Science

The John Adams Institute was founded in April 2004 as one of two Institutes of Accelerator Science in the UK. The institute is a joint venture between Oxford University, Royal Holloway, University of London and Imperial College London. The current R&D projects are focused on the area of synergy between laser and plasma physics and accelerators; on research towards novel compact light sources and FELs; on design studies for future colliders and neutrino factories; on development of advanced beam instrumentation and diagnostics; on development of new accelerator techniques for applications in medicine, energy, and other fields of science; and research towards upgrades for existing facilities such as ISIS, Diamond, LHC, and new facilities such as ESS and Future Circular Collider. The institute is developing connections with industry, aiming to render the benefits of accelerator science and technology accessible to society. The Institute also has a vigorous outreach programme. Opportunities in a wide variety of research areas exist, as indicated below.

The sections shown below describe the thesis topics available at JAI in Oxford. For more details about the past projects and about projects available at JAI in RHUL and Imperial, visit this page For further information see this page http://www.adams-institute.ac.uk/training/admissions/ and contact Professor Phil Burrows (philip.burrows@physics.ox.ac.uk).

The Rutherford-Appleton Laboratory may also offer joint RAL-Oxford Studentships in accelerator topics. For further information see this page http://www.stfc.ac.uk/ASTeC/Groups/Intense+Beams+Group/17527.aspx and contact Dr John Thomason (john.thomason@stfc.ac.uk).

Optimization of support structures for future trackers

Future collider experiments will require support structures and services which will use significantly less material than current systems. This can only be achieved with modern engineering techniques using advanced composite materials (e.g. ultra-high modulus carbon fibre, high-thermal conductivity materials), state-of-the art fabrication techniques (e.g. 3d printing) and a high level of integration (e.g. co-curing).

After design the performance of the solutions developed to meet this challenge needs to be verified. This comprises measurements of mechanical stability under various thermal and mechanical loads at the sub-μm level and verification of the thermal performance. Because of the unique requirements for HEP experiments a mix of existing state-of-the-art and to-be-developed measurement techniques are required for this task.

While these R&D activities have a strong connection to mechanical engineering they require a good understanding of topics across many fields of physics (mechanics, thermodynamics, and optics) and are a great opportunity to unleash all the things you suffered through in your undergraduate years to enable future breakthroughs in particle physics.

For more information on these topics contact Georg Viehhauser (georg.viehhauser@physics.ox.ac.uk).

Next-generation high-energy colliders, beam feedback, instrumentation and control

FONT - The FONT group http://www-pnp.physics.ox.ac.uk/~font/ is the international leader in ultra-fast nanosecond timescale beam feedback systems for future high-energy electron-positron colliders. These feedbacks are mandatory for steering and maintaining colliding beams in all currently conceivable linear collider designs. They are also needed in single-pass electron linacs where a high degree of transverse beam stability is required, such as X-ray FELs. The key elements of the feedback are fast, precision Beam Position Monitor signal processing electronics, fast feedback processors, and ultra-fast high-power drive amplifiers. These components are designed, fabricated and bench-tested in Oxford, and subsequently deployed in beamlines for testing with real electron beams of the appropriate charge and time structure.

We work currently mainly at the Accelerator Test Facility in Tsukuba, Japan, and at the CLIC Test Facility (CTF3) at CERN. The group typically visits Japan 4 times per year, for the purpose of testing our novel feedback systems. We are developing a new phase feed-forward correction system at CTF3 and this is an exciting new project for us. Graduate students play a key role in these beam tests, and there are also opportunities to spend time in Japan, at CERN (Geneva) and SLAC (California), as well as to give posters and papers at international conferences.

We are a young and dynamic research team. 20 D. Phil. theses have been completed or are in progress and our graduates have moved on to jobs at CERN, SLAC (USA), Brookhaven (USA), DESY (Germany) and ESS (Sweden).

Thesis supervisor: Professor Philip Burrows (p.burrows@physics.ox.ac.uk)

Laser-Plasma Accelerators

In a laser wakefield acclerator an intense laser pulse propagating through a plasma excites a trailing plasma wave via the action of the ponderomotive force, which acts to expel electrons from the region of the laser pulse. The longitudinal electric field in this plasma wakefield can be as high as 100 GV / m, more than three orders of magnitude larger than that found in conventional RF accelerators such as those used at CERN. Particles injected into the correct phase of the plasma wave can therefore be accelerated to energies of order 1 GeV in only a few tens of millimetres.

Theoretical and experimental work on plasma accelerators in Oxford is undertaken by a collaboration of research groups in the sub-departments of Particle Physics and Atomic and Laser Physics.

Please note that applications to work in this area should be made to the sub-department of Particle Physics as explained https://lpax.web.ox.ac.uk/opportunities-graduate-research this page also gives further information on DPhil projects which are available in this area.

Next generation light sources and compact laser-plasma acceleration driven FEL

Particle accelerators are the technology driving cutting edge research at the forefront of modern physics. Current accelerators use rf technology to produce high energy particles for collisions but these machines are large and extremely expensive. Recent progress in laser plasma based accelerators has opened the possibility of using such systems as drivers for free electron lasers (FELs) and the JAI is looking at the development of an XUV radiation source capable of generating ultrashort fs XUV pulses using this technology. The aim is to develop a source small enough to be hosted in a university sized laboratory and brings together experitse in laser-driven plasma accelerators available in Professor Simon Hooker's group in the sub-department of Atomic and Laser Physics (http://www.physics.ox.ac.uk/users/hooker/), with the JAI Accelerator Physics expertise, to provide a strong interdisciplinary environment. A PhD project is currently available on the development of such radiation sources. An additional PhD topic will encompass work on plasma acceleration with particular emphasis on advanced beam diagnostics such as Smith-Purcell radiation and other methods.

The JAI also supports active research activity on 3rd and 4th generation light sources. We have established strong links with the Diamond Light Source (http://www.diamond.ac.uk) located at the Harwell Science and Innovation Campus near Didcot and are actively involved in the programmes for the improvement of the performance of the light source, with new innovation optics design and future machine upgrades. A THz source development programme has been set up in collaboration with RHUL. We are also involved in the design and optimisation of a 4th generation light source within the NLS project. Innovation, cost effective solutions are under investigation in collaboration with Diamond and other national laboratories with the aim of proposing a new national facility in the next years.

For more information about this group please contact Professor Riccardo Bartolini (r.bartolini@physics.ox.ac.uk)

Intense Hadron Beams R&D

Collaborative projects between the John Adams Institute and ISIS Neutron and Muon Source may be available to interested applicants. The Intense Beams Group use a number of advanced accelerator physics methods in order to explore the ways to design high current and versatile proton accelerators for scientific, energy, medical or other applications. Existing PhD student projects include applications of the FFA (Fixed-Field Alternating Gradient) type of accelerator and the use of Paul traps to study dynamics in proton accelerators.

For more information please contact Dr Suzie Sheehy (suzie.sheehy@physics.ox.ac.uk) or Dr. Shinji Machida at STFC (shinji.machida@stfc.ac.uk)

Nonlinear beam physics in circular accelerators

The dynamics of charged particle beam in accelerators is a highly interdisciplinary research area crossing electromagnetism, analytical mechanics, and accelerators technology. The application of advanced techniques in nonlinear dynamics opens a number of new applications that extend performance and capabilities of existing machines. The PhD programme focuses on the investigation of beam dynamics in proximity of nonlinear resonances to manipulate the beam phase space distribution and tailor it for new injection and extraction schemes, or novel concepts in advanced radiation sources.

The programme will develop solid theoretical framework as well as advanced computer simulations in nonlinear beam dynamics for leptons. The PhD programme based at CERN however it will have access to experimental shifts at the Diamond Light Source as well as at the European Synchrotron Radiation Facility.

For further information please contact Professor Riccardo Bartolini (riccardo.bartolini@physics.ox.ac.uk)

Super-Bright X-rays using Plasma Wigglers

Particle accelerators have made an enormous impact in all fields of natural sciences, from elementary particle physics, to the imaging of proteins and the development of new pharmaceuticals. Modern light sources have advanced many fields by providing extraordinarily bright, short X-ray pulses. Here we want the student to undertake a novel numerical study to characterise and optimise a plasma-based wiggler device.

Previous studies demonstrated that existing third generation light sources can significantly enhance the brightness and photon energy of their X-ray pulses by undulating their beams within plasma wakefields. This study showed that a three order of magnitude increase in X-ray brightness and over an order of magnitude increase in X-ray photon energy was achieved by passing a 3 GeV electron beam through a two-stage plasma insertion device. The production mechanism micro-bunches the electron beam and ensures the pulses are radially polarised on creation. We also demonstrated that the micro-bunched electron beam is itself an effective wakefield driver that can potentially accelerate a witness electron beam up to 6 GeV.

In this project, the student will simulate and help implement experimentally a novel extension to this concept, one where a single electron bunch experience the ponderomotive force of the X-rays and produces SASE radiation, ultimately leading to additional increases in brightness, into the XFEL regime.

For more information please contact Professor Peter Norreys (peter.norreys@physics.ox.ac.uk or Dr James Holloway (james.holloway@physics.ox.ac.uk)

PaMIr+ CASE Studentship Project

PaMIr is short for Phase Modulation Interferometry. The PaMIr group is developing a novel method to interferometrically measure rapid displacements with high accuracy and time resolution as well as low latency. PaMIr+ will extend this scope towards absolute distance measurements, which have abundant applications in large-scale science experiments. Among the highlight scientific applications so far are the alignment of the crab cavities in the upgrade HL-LHC, control of undulators at LCLS-II, relative positioning of the primary and secondary mirrors of several next generation telescopes (GMT, EELT, KECK), as well as future measurements of deployable space antennae on satellites.

PaMIr is a plug-compatible extension of an absolute distance interferometry technology (FSI, Frequency Scanning Interferometry) previously developed by Oxford Physics. This FSI technology is now used in its commercial form (Absolute Multiline™) in many scientific projects in accelerator science, particle physics, astrophysics but also in many industrial settings. The high speed, continuous differential measurements from PaMIr can be used in dynamic control loops to measure rapidly time variable positions continuously over long periods. These are needed in many of the above science problems and in the control of robots and CNC production machines in industry.

The PaMIr project is funded through an innovation partnership grant, which has inputs from STFC and from our two industrial partners, VadaTech Plc and Etalon GmBH. The student will be a member of the PaMIr group, which currently has five permanent members at Oxford. Prof Armin Reichold is the group leader, Dr Peter Qui is a PDRA, Dr Jubin Mitra is the groups FPGA engineer, Mr Mark Jones and Mr Johan Fopma are two further electronics engineers working part time on PaMIr. We have enjoyed input from four summer students and an MPhys student. Seven further part time team members are working on the project in our partner organisations.

The PaMIr+ CASE studentship is aimed at finding novel ways to use the phase modulation and DAQ technology developed in PaMIr directly to develop enhanced FSI techniques. This could allow FSI absolute measurements to become continuous over long times (rather than pulsed at the few Hz). It could further reduce the measurement latency for real time applications or make the technique capable of measuring extremely large (km range) or short (mm scale) distances. The student may also enable measurements of distances directly to non-co-operative, common surfaces such as machined metal or building materials. All of these enhancements could massively increase the applicability of FSI to problems in science and the wider society.

The student will initially develop simulation models for the new FSI techniques, then add the FSI capabilities into an existing PaMIr interferometry setup to measure, and improve the performance of the new technique. Integral part of these experiments will be the development of data acquisition and analysis protocols. DAQ aspects will contain software as well as FPGA firmware elements. Ultimately, some analysis algorithms may make their way into real time firmware.

In the first year, the students will enjoy the JAI’s world-renowned graduate training program, which will be flexibly augmented with elements from laser physics and optics. It is our firm belief that we can maximise the impact of our research on science and society by making it available as widely as possible in the form of a commercial instrument. The student will therefore spend approximately 9 months with our commercial partners to learn about and shape the development steps that lie between a laboratory prototype and a successful commercial product.