John Adams Institute

Below is a list of DPhil projects for 2025 for R&D projects and the John Adams Institute; potential graduate students are encouraged to contact supervisors if they have any questions with regard to these projects.

Professor Philip Burrows

The John Adams Institute for Accelerator Science (JAI) is a centre of excellence for advanced accelerator science and technology. We perform R&D, deliver training, provide expertise, and generate societal benefits through advances in technologies for healthcare and industry. The JAI comprises faculty, staff, and PhD students from the Physics Departments of Oxford University, Royal Holloway University of London (RHUL), and Imperial College London (ICL). Additional staff from the UK’s national laboratories, CERN, & other institutes contribute to our research and teaching programmes. Our research 
focus is on:

• Low-emittance, high-brightness electron beams, including next-generation electron-positron colliders (FCCee, ILC, CLIC, HALHF), the Diamond Light Source (DLS) and its upgrade Diamond-2, and a future UK FEL;
• High-energy/high-intensity hadron beams, including current and future energy-frontier proton colliders (LHC, HL-LHC, FCChh), and ISIS and its proposed upgrade ISIS-II;
• Advanced acceleration techniques, including laser- and beam-driven plasma-wakefield acceleration;
• Particle-beam therapy applications based on electron and hadron beams;
• Industrial applications, including frequency-scanning interferometry-based distance measurement. 

Through this programme we are supporting the UK’s strategic accelerator interests by taking lead roles in enhancing both our national and overseas facilities including: LHC, HL-LHC, FCC, CLIC and AWAKE at CERN; Diamond and Diamond-2, ISIS and ISIS-II, and CLF and the Extreme Photonics Applications Centre (EPAC) at STFC/RAL; CLARA at STFC/DL; FLASHforward at DESY; and ATF/ATF2 at KEK.

Opportunities to pursue a PhD thesis are indicated below.

Development of linacs for challenging environments
Professor Manjit Dosanjh (manjit.dosanjh@cern.ch)

STELLA (Smart Technologies to Extend Lives with Linear Accelerators), is a multidisciplinary effort to produce a comprehensive, linac-based, Radio Therapy system. The international STELLA collaboration, of which the JAI is a founder member, aims to transform the treatment of patients with cancer particularly in LMICs. It is apparent that linear accelerators in LMIC are down more often than those in wealthier countries. This is partly due to environmental factors, but also to lack of trained technical personnel, which increases not only the frequency of failures but the time to resolve them. To improve the recognition of problems and their nature, we aim to develop a system that uses machine learning and artificial intelligence to monitor the log files of a medical linac regularly to diagnose and predict issues, so that a warning system can be implemented. We have an extensive collaborative network in LMIC’s that would allow us eventually to implement such a system, enabling timely interventions.

Development and exploitation of novel beams for the study of radiobiology
Professor Manjit Dosanjh (manjit.dosanjh@cern.ch)

Very High-Energy Electron (VHEE) beams with energies in the range 100–200 MeV offer several advantages over conventional beams. In contrast to photon beams, VHEE beams of small diameter can be scanned and focused to conform to the tumour, thereby producing finer resolution for intensity-modulated treatments. The VHEE beams can be operated at very high dose rates, allowing the generation of the “FLASH effect”. Moreover, compared to proton-beam therapy, VHEE could constitute a superior alternative in terms of compactness, simplicity and ultimately cost-effectiveness. Before VHEE and VHEE-FLASH can be adopted for cancer treatment, it will be necessary to: characterise experimentally the properties of VHEE beams; establish the degree to which the VHEE technique improves penetration, focusing, and scanning; and determine the radiobiological effectiveness of VHEE in vitro and in vivo over a range of beam configurations including the FLASH regime. We propose to study physical beam characteristics and beam dosimetry for feasibility in both VHEE and FLASH irradiation with electrons in collaboration with the CLEAR team at CERN.

Modelling biological and flash effects in various modalities
Professor Manjit Dosanjh (manjit.dosanjh@cern.ch)

The University of Oxford Radiation Oncology institute has developed a mathematical model to predict the biological effects of different modalities, including oxygen and FLASH effects, which depend on pulse height, length and overall dose delivered. This model will be tested by varying and refining the parameters to obtain a clinically usable model to predict effects in treatment. The model works for all charged particles (and by extension also for photons). Preliminary data have been obtained for lower-energy electrons (6MeV), at dose rates commensurate with the FLASH effect. Ideally the model will be tested at CERN. The CERN Linear Electron Accelerator for Research (CLEAR) test facility provides the 50-200MeV and high-charge beam necessary to deliver VHEE and FLASH therapy.

Professor Philip Burrows

The AWAKE experiment is a unique proton-driven plasma wakefield experiment, aiming to demonstrate acceleration of electrons to high energies (tens of GeV) via accelerating gradients in excess of 1GV/m. JAI/Oxford is leading the design of the electron injection beamline for AWAKE Run 2, as well as developing novel instrumentation systems for measuring co-propagating proton and electron beams. The latter are based on coherent Cherenkov diffraction radiation techniques. There is the opportunity to design and develop prototypes that can be tested with beams at AWAKE, as well as the CLEAR facility at CERN, and to contribute to advancement of AWAKE during Run 2.

Dr Rob Williamson (rob.williamson@stfc.ac.uk) 

Collaborative projects between the John Adams Institute and ISIS Neutron and Muon Source may be available to interested applicants. ISIS Accelerator Physics Group' and Leptons to Hardrons 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.

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.

Professor Armin Reichold

We work on selected world leading scientific projects from the accelerator, astro and particle physics fields and approach their extremely challenging metrology problems by developing commercially viable instruments that can help to solve them. We do this in close collaboration with both the relevant scientist to find an optimal solution for the science problem and with our industrial partners, Etalon (part of the Hexagon group) and VadaTech to ensure that the instruments we develop and they build achieve the biggest possible impact also in industrial applications.

Among the most challenging metrological problems in science is the alignment and stabilisation of next generation accelerator elements. These often guide or focus or otherwise manipulate nanometre sized beams over many kilometres. The future linear e+-e- colliders ILC, CLIC or FCCee even have to collide such beams after having travelled tens of kilometres requiring extremely precise alignment and nanometre level stabilisation of their elements. Many other accelerator physics project such as the HL-LHC, CEPC or certain medical accelerators face similarly formidable metrology challenges. Oxford Physics will play a leading role in developing metrology instruments that can solve these problems.

The next generation of particle physics detectors for these “Higss factories” will contain extremely low mass tracking detectors, spanning tens of cubic meters, which have to measure charged particle trajectories to micron accuracy. The development and assembly of these structures requires position survey and vibration sensing technology of very high performance which we develop at Oxford Physics.

In astrophysics, many of the next generation of large telescopes such as the GMTO (Giant Magellan Telescope), EELT (European Extremely Large Telescope, KECK, CCAT now called FYST (Fred Young Sub-millimeter Telescope), SRT (Sardina Radio Telescope), LMT (Large Millimetre Telescope) already decided to use the industrial version of Oxfords metrology instruments (Absolute Multiline™) to solve the survey and stabilisation problems of their very large mirrors.

Similarly, many large accelerator centres such as CERN, SLAC, GSI, PSI as well as national institutes of standards, among them (NPL, PTB, le cnam, INRiM), are already using our technology produced under license by Etalon.

A new DPhil student would work with us to understand the impact of metrology and stabilisation problems on the performance of scientific instruments (e.g. how does a future collider luminosity depend on the alignment and stabilisation of its elements), propose solutions to these problems and build and characterise prototype instruments that can deliver the proposed solution. This will involve computer simulations, optical design, DAQ software and finally prototype experiments and their data analysis. During all of this the student is in close collaboration with our industry partners, learning how to make these instruments and their related software and firmware producible, maintainable and commercially viable. The student will also learn about the specific additional requirement for our instruments when they are used in industrial applications where ease of operation, reliability, repairability, traceability, cost and many other factors play larger roles than they do in science applications.

Choosing which scientific problem to focus on is a complex task which will evolve during the first year of the DPhil. This happens by learning about the already existing capabilities of our instruments and the achievable improvements or additions in functionality while comparing these to the general range of problems present in specific science projects.

In any case, the science project ultimately chosen will be one in which Oxford's Department of Physics plays a leading role and is well equipped to make important contributions. The largest range of project clearly lies in accelerator physics (JAI) or the particle physics sub-department but collaborations with the astrophysics sub-department are also possible.

Professor Philip Burrows

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 perform R&D at the Accelerator Test Facility in Tsukuba, Japan, and at the CERN Linear Electron Accelerator for R&D (CLEAR).  We are lead players in the design of the International Linear Collider, the Compact Linear Collider, and the Future Circular Collider, as well as an initiative for a possible future muon collider.

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).

Professor Richard D'Arcy 

Plasma acceleration is an exciting, emerging technology offering the potential to drastically reduce the size, cost, and carbon footprint of future high-energy particle accelerators. However, to be fully exploited by particle physics this technology must match the luminosity potential of more traditional technologies by operating many thousands (or even millions) of times per second—orders of magnitude beyond the state of the art in the field. We are offering a DPhil project to start in October 2025 to help answer the  ‘luminosity question’ of plasma accelerators.

The work of this project will build upon the foundational results recently published [cf. Nature 603, 58-62 (2022)], which demonstrated for the first time that plasma accelerators are in principle capable of accelerating tens of millions of bunches per second. With such an increase in repetition rate comes a concomitant increase in power within the system, which will manifest itself in an increased plasma temperature due to small but inherent inefficiencies in the plasma-acceleration process. How this temperature increases, on what timescale, and its effect on the properties of the plasma wake will be investigated. To map this temperature evolution, numerical codes will be utilised to describe the temperature effects, novel techniques will be developed in a dedicated laboratory in Oxford Physics to diagnose them, and both tools will be ultimately deployed at cutting-edge plasma-accelerator facilities in the UK, Germany, and the US.

Professor Simon Hooker

In a laser wakefield accelerator 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. Laser-driven plasma accelerators could therefore drive novel, very compact sources of particles and ultrafast radiation.

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 & Laser Physics. For this reason applications to work in this area should be made to the sub-departments of Atomic & Laser physics AND to Particle Physics.

Our work in this area is undertaken in the Oxford Plasma Accelerator Laboratory (OPAL), and at national laser facilities in the UK and elsewhere. Further information on our research can be found on the laser-plasma accelerator group website

We are offering three DPhil projects to start in October 2025, as outlined below.

1. Controlled electron injection in plasma-modulated plasma accelerators (P-MoPA)

Most work to date on laser-driven plasma accelerators has been done with single driving pulses, which must have an energy of order 1 J and a duration shorter than the plasma period (around 100 fs). These demanding parameters can be generated by Ti:sapphire laser systems, but these lasers have very low efficiencies (< 0.1%) and (for joule-scale pulse energies) are limited to pulse repetition rates below 10 Hz. These repetition rates and efficiencies are too low for the most demanding applications, such as driving compact light sources.

We recently proposed that GeV-scale plasma accelerators could be driven by commercially available thin-disk lasers (TDLs). These systems can provide the required pulse energy at pulse repetition rates in the kilohertz range – but the pulses that they generate are too long (a few picoseconds) to drive a plasma wave directly. We have developed a new concept to circumvent this: the Plasma-Modulated Plasma Accelerator (P-MoPA). 

In a P-MoPA, a long (~ 1 ps), high-energy (~ 1 J) TDL pulse is modulated spectrally by co-propagating it in a HOFI channel with a low-amplitude plasma wave driven by a short (< 100 fs), low-energy (< 100 mJ) “seed” laser pulse. This causes the drive pulse to develop spectral sidebands spaced by the plasma frequency. Removing the spectral phase of the sidebands in an optical “compressor” converts the spectral modulation to a temporal one, thereby forming a train of short pulses spaced by the plasma period. This pulse train can then resonantly excite a high-amplitude plasma wave in an accelerator stage with a plasma density equal to that of the modulator plasma.

In order to accelerate electrons in the accelerator stage of the P-MoPA, it will be necessary to develop novel methods for injecting a high-quality electron bunch into the resonantly excited, quasi-linear wakefield driven in the accelerator stage. The novel architecture of the P-MoPA scheme means that current schemes for controlling electron injection into wakefields driven by single laser pulses may not work well. In this project the student will explore possible injection schemes using particle-in-cell codes and other numerical tools. This will be accompanied by experimental work in Oxford and at international high-power laser facilities. It may be necessary for the student to work for one or more extended periods with our colleagues at Ludwig-Maximilians Universität, Munich.

2. Radiation generation in high-repetition rate plasma accelerators

Laser-driven plasma accelerators are ideally suited to driving very compact X-ray sources, with many potential applications in science and medicine, such as high-resolution medical imaging of deep-seated tumours.

Radiation can be generated from a laser-accelerated electron bunch in several ways. The transverse electric fields within the plasma wave itself can cause the electron bunch to oscillate as it is accelerated. This leads to the generation of broad-band “betatron” radiation, with photon energies typically in the 10 – 30 keV range. Alternatively, colliding a laser-accelerated bunch with an intense, counter-propagating laser pulse can generate Thomson and Compton radiation with photon energies in the 100 keV – 1 MeV range.

In this project the student will explore methods for generating X-rays from laser-accelerated electrons. Of particular interest will be radiation generation from electron bunches accelerated in HOFI channels by single- or multiple laser pulses (e.g. in a P-MoPA). It is anticipated that the project will involve a mix of numerical simulations and experiments in Oxford at OPAL and at national and international high-power laser facilities such as the Extreme Photonics Application Centre (EPAC) at Harwell..

3. Energy recovery in plasma accelerators

Laser- and particle-driven plasma accelerators have the potential to drive future generations of particle colliders. However, in order to detect and study rare events the collider must have a high luminosity, which requires accelerating bunches of high charge, to high energies, at high mean repetition rates. The time-averaged power of the laser- or particle-driver in future colliders is expected to be of order 100s kW per acceleration stage. As a consequence the accelerator stage must operate with high efficiency since otherwise: (i) unused wakefield energy damage the structure containing the plasma; and (ii) the running costs would be prohibitive.

A potential solution to this problem is to use a trailing laser pulses to damp the plasma wakefield remaining after the acceleration event. If the trailing pulse is out of resonance with the wakefield, then the frequency of the laser pulse will be up-shifted, allowing the unused wakefield energy to be removed in the form of blue-shifted photons. In principle the up-shifted laser pulse can be used elsewhere in the accelerator, or its energy can be re-converted to electrical power.

This project will involve particle-in-cell simulations in order to devise promising strategies for this energy recovery concept. Experiments will then be undertaken in Oxford at OPAL — and potentially at national or international laboratories, such as the Extreme Photonics Application Centre (EPAC) at Harwell.

Shinji Machida and Chris Warsop

A transverse tune, namely the betatron oscillation frequency in the periodic alternating gradient focusing system, is a fundamental parameter in optimising accelerator operation. Recent operation of J-PARC and SNS has empirically found that the tunes with almost equal value in the horizontal and vertical directions gives the minimum overall beam loss. This was a surprise because the coupling resonance of 2Qx-2Qy=0 (the Montague resonance) had been avoided historically and can be excited by the beam’s space charge octupole potential. At the design stage of the J-PARC Main Ring, for example, a separation of the two transverse tunes of a whole integer was chosen due to that reason. Although there are some explanations such as a circular cross-section of the beam is most stable, the exact mechanism remains a matter of conjecture. Clearer understanding of the mechanism as to why an almost equal tune is preferable has a significant impact on the operation of existing accelerators as well as the design of future high-intensity accelerators. The goal of this project is to provide a better understanding of the tune choice in high-intensity accelerators. 

The project will use two approaches. One is based on numerical simulation and the other is a Paul Trap (IBEX) experiment. To some extent, real accelerators like ISIS may also be used to check part of the findings. Numerical simulation of high-intensity beams in a ring accelerator has been developed and benchmarked significantly thanks to the recent completion of new facilities J-PARC and SNS. IBEX has progressed further since it started several years ago. With nonlinear elements recently implemented, the second DPhil project is about to finish this August. The study structure will cover the following main components. 

 Simulation 

1. Make a model with FODO focusing structure. 
2. Check if high-intensity beam physics is properly included: namely observation of space charge tune shift, incoherent and coherent resonances excited at particular intensities. 
3. Without injection process, scan the tune space and see 100% or 99% emittance growth. 
4. Try and see how the results change with different initial conditions: e.g. emittance ratio between horizontal and vertical.  
5. With injection painting, scan the tune space. Correlated painting might show similar results as ones without injection process. Anti-correlated painting adds complications because the tune shift in horizontal and vertical directions becomes asymmetric during injection. 
6. Analyse the simulation results: emittance exchange, tail development, excitation of coherent modes, … 

IBEX 

1. Identify tune range IBEX can explore, especially how asymmetrical tune can be tested. 
2. Modify the RF amplifier (we could ask an engineer at Oxford University) if the tune range covered is not enough. 
3. Further develop the MCP detector (and other diagnostics if necessary) to observe physical beam cross section. 
4. Simulate IBEX numerically with simple configurations to see if we model the beam behaviour in IBEX completely. 
5. Demonstrate experimentally the results from simulation: emittance exchange, tail development, excitation of coherent modes, … 

The project aims at achieving a clear understanding of the physics mechanism beyond empirical observation to give more confidence in future machine designs and can even reduce the cost of hardware because the range of specifications can be narrowed. Understanding the reason behind the empirical rule gives more foundation to the operation of existing accelerators like J-PARC and SNS as well. 

Professor Peter Norreys

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.

Professor Philip Burrows or Dr Ian Martin (ian.martin@diamond.ac.uk)

The Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.  JAI works closely with Diamond on R&D for key elements of the upgrade, Diamond II.  There are opportunities for possible DPhil projects in beam dynamics and beam instrumentation aiming towards improved accelerator performance.