Accelerator Physics

Along with our colleagues in the Lancaster University's Engineering Department, the members of the Lancaster accelerator physics group are part of the Cockcroft Institute of Accelerator Science and Technology based at the Daresbury Science and Innovation Campus near Warrington, Cheshire.

Particle accelerators are powerful tools that lie at the heart of research into particle physics but also play major roles in fields such as medicine. Wherever a beam of high-energy particles or light can be of use, particle accelerators offer a solution.

There are always demands for particle beams with higher energies and higher intensities, but there are limitations to what can be achieved using the accelerators of today. Some of these limitations are practical ones determined by cost and size whereas others are fundamental and relate to unanswered questions about the ways in which charged particles interact with electromagnetic fields. We use our expertise in particle physics and mathematical physics to address these limitations. You can find out more about our plasma interactions research on our dedicated plasma physics research pages.

On the experimental side of our work, we investigate a range of topics such as how we can use beams of polarised particles to help probe mysteries in particle physics.  On the theoretical side, we develop new effective classical and quantum theories for analysing matter in extreme conditions, with implications for cosmic particle acceleration as well as for experiments in the laboratory.

Key Research

  • The development and design of high-flux sources of positrons and gamma-rays for future high-energy colliders and other applications. For example, developing the positron source for the International Linear Collider
  • Simulating the dynamics and interactions of polarised particle beams in experiments such as Fermilab muon g-2
  • Leading the CASCADE collaboration in its search for weakly-interacting sub-eV particles such as axions using radio-frequency cavities
  • Investigating wave propagation in spatially dispersive media and photonic structures
  • Exploring radiation reaction in ultra-intense laser-plasmas as members of the ALPHA-X collaboration

People

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Accelerator Physics, Cockcroft Institute

+44 (0)1524 593742 B053, B - Floor, Physics Building

Accelerator Physics, Mathematical Physics

Accelerator Physics, Cockcroft Institute, Mathematical Physics, Quantum Technology Centre

+44 (0)1524 592843 C048, C - Floor, Physics Building

Accelerator Physics, Cockcroft Institute, Mathematical Physics, Quantum Technology Centre

+44 (0)1524 594980 C050, C - Floor, Physics Building

Accelerator Physics, Mathematical Physics

Accelerator Physics, Cockcroft Institute, Experimental Particle Physics

+44 (0)1925 603242 Physics Building

Accelerator Physics, Cockcroft Institute, Mathematical Physics, Quantum Technology Centre

+44 (0)1524 593610

Publications

PhD Opportunities

  • Super-macro-particles to improve in Particle-in-cell codes.

    Supervisor

    Dr Jonathan Gratus (Lancaster University)
    Dr Hywel Owen (Manchester University)

    Description

    A studentship is available from Oct 2019 on the development of the theory, computer coding and testing of an exciting new idea for improving the numerical simulation of charged particles.

    Particle-in-cell (PIC) codes are essential for the numerical simulation of charged particles in both conventional accelerators and plasmas. They are used extensively for an understanding of the physics and design of future machines. A typical code may have to track 1010 particles and may need to run on high-performance computer clusters.

    We are investigating a revolutionary new method which promises to dramatically reduce the computation needed for simulations. This method increases the dynamical information of each particle while reducing the total number of particles.

    To aid in this task we need an enthusiastic PhD student to incorporate the new dynamical equations into existing PIC codes and compare the results with standard simulations.

    The applicant will be expected to have a first or upper second class degree in mathematics, physics, computer science, engineering or other appropriate qualification. A full graduate programme of training and development is provided by the Cockcroft Institute.

    Potential applicants are encouraged to contact Dr Jonathan Gratus (j.gratus@lancaster.ac.uk) for more information.

    Closing Date

    The position will remain open until filled.

    Funding Note

    The PhD anticipated starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union (subject to residency status)

  • Muon g-2 experiment

    Supervisor

    Dr Ian Bailey

    Description

    The Fermilab muon g-2 experiment is attempting to measure the anomalous magnetic moment of the muon: a quantity which is sensitive to the existence of ‘new physics’. The magnetic moment will be determined by measuring the energies and directions of electrons coming from the decay of a beam of muons orbiting inside a storage ring. In this project, you will learn skills in accelerator beam dynamics as part of the Cockcroft Institute of Accelerator Science and Technology. You will apply these skills to enhance simulations of the g-2 muon spin dynamics and help analyse the experimental data as part of the g-2 collaboration.

  • Search for the axion

    Supervisors

    Dr Ian Bailey
    Professor Yuri Pashkin
    Dr Edward Laird

    Description

    In recent years, there has been a growing interest in the 'hidden sector' and non-traditional dark matter candidates such as axions and dark photons. If either of these hypothetical particles exists, they can be detected through their interaction with strong magnetic fields. This interaction should lead to the generation of photons whose frequency is related to the mass of the hypothetical particles. This calls for the development of sensing techniques that are capable to detect extremely weak electromagnetic signals in a wide frequency range.

    There are growing efforts around the UK to undertake a nationwide project aimed at the detection of axions and dark photons using various methods. Superconducting quantum circuits offer the possibility to build amplifiers with extremely low noise temperature covering a wide frequency range.

    In this project, you would have opportunities to develop superconducting detector technologies and/or develop computer simulations to optimise the sensitivity of future resonant detectors of axions and dark photons. This project will be undertaken in collaboration with the University of Sheffield and the Cockroft Institute. You may also have the opportunity to work on either the ADMX experiment in the US or planned experiments in the UK. In the latter case, you will use nanofabrication and cryogenic facilities of the Lancaster Quantum Technology Centre.

  • Laser Driven Relativistic Particle Acceleration

    Supervisor

    Prof Steven Jamison

    Description

    We seek a PhD candidate to undertake experimental research on laser driven relativistic particle beam acceleration. The research will be carried out at STFC Daresbury National Laboratory, in an exciting and collaborative project involving students and staff from Lancaster University, University of Manchester and STFC Daresbury National Laboratory.

    Relativistic particle acceleration driven by ultrafast optical lasers holds potential to revolutionise high energy particle accelerators. In the application of ultrafast electron diffraction, laser driven acceleration offers control of particle beams on the femtosecond (10-15s) time scale. In addition, the high-field strengths available in ultrafast lasers may enable orders of magnitude reduction in size and cost of kilometre-scale accelerators of x-ray-free-electron lasers and high-energy particle physics.

    The successful candidate will join a research team developing novel acceleration concepts using ultrafast lasers, and working towards a number of proof-of-concept demonstrations of laser acceleration of relativistic beams. They will carry out work in the optimisation of multi-MV/m optical and infrared sources, in high-field non-linear optics, in mm-scale accelerating structures, and in developing systems for the experimental demonstration of acceleration of relativistic beams. Through their research with high-power laser and electron-beam facilities, they will develop skills in ultrafast laser science, in relativistic particle beams physics, and in the theory and modelling of ultrafast optics and particle dynamics.

    The applicant will be expected to have a first or upper second class degree in physics, medical physics, electrical engineering or other appropriate qualification. A full graduate programme of training and development is provided by the Cockcroft Institute. The student will register at the Lancaster University, supervised by the THz acceleration project lead, Professor Steven Jamison.

    The student will join a vibrant group of students and post-doctoral researchers already making significant progress in this area. The studentship will also work closely with scientists and Engineers at STFC Daresbury Laboratory National Laboratory. There will also be opportunities for travel and collaboration with scientific institutes and universities outside the U.K.

    The Physics Department is holder of an Athena SWAN Silver award and JUNO Championship status and is strongly committed to fostering diversity within its community as a source of excellence, cultural enrichment, and social strength. We welcome those who would contribute to the further diversification of our department.

     Interested candidates should contact Prof Steven Jamison s.jamison@lancaster.ac.uk for further information.  For general information about PhD studies in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk.  You can apply directly at http://www.lancaster.ac.uk/physics/study/phd/ stating the title of the project and the name of the supervisor in your application.

     Closing Date

    Applications will be accepted until the post is filled.

  • Magnetic field generation and evolution in unmagnetised plasmas: from astrophysics to the laboratory

    Supervisor

    Dr Elisabetta Boella

    Description

    Context

    One of the most puzzling questions in plasma astrophysics regards the origin and evolution of magnetic fields starting from unmagnetized plasmas. A full explanation for the Universe magnetogenesis [1,2] or the spontaneous magnetic field creation in gamma-ray bursts, supernovae explosions, active galactic nuclei, etc [3] is still missing. The Biermann battery (BB) [4] and the Weibel (WI) [5] or current filamentation instability (CFI) [6] have often been invoked as possible mechanisms for magnetic field generation in unmagnetized plasmas. Previous works speculated that they could concur to create seed magnetic field [7,8,9], however how these fields evolve on long temporal and big spatial scales to magnitudes necessary for turbulent dynamo amplification [1,2] or equipartition values essential for shock dissipation [3] is still unknown.

    The relevant physics is extremely rich, non-linear, multidimensional and multiscale, requiring modelling both the plasma microphysics and the relaxation processes. A kinetic approach must be adopted and Particle-In-Cell (PIC) codes [10], which can take full advantage of parallel High-Performance Computing resources, constitute the most effective tools. For astrophysical scenarios, where observations provide fewer details, the computational component has enhanced relevance, as a probe of the dynamics of these plasmas and as a tool to identify laboratory scenarios, which could enable direct and controlled probing of appropriately scaled astrophysical events. In fact, recently it has been realized that High Energy Density experiments leveraging high power laser facilities, such as OMEGA or NIF [11], could represent a new opportunity to study regimes very close to astrophysical conditions. First proof-of-principle (POF) experiments have been conducted [12], however, multidimensional features remain totally unexplored and until recently could not be appropriately investigated with numerical simulations due to the lack of appropriate tools and the extreme computing power required to resolve the plasma dynamics.

    Leveraging the full power of PIC massively parallel simulations, the goal of this project is to gain knowledge on the formation and evolution of the magnetic field in unmagnetized plasmas. Astrophysical and laboratory scenarios will be investigated with the aim of identifying settings where the physics of relevance in astrophysical contexts can be reproduced by intense laser or beam-plasma interaction.

    Objectives

    In this project, a suite of PIC codes will be employed to shed light onto the processes of magnetic field generation and long-term evolution in unmagnetized plasmas. The project is organized along 3 challenges (C).

    C1: development of a global multidimensional picture of the coupling between the micro and the macroscales of WI and CFI in electron-ion (e-p+) plasmas. A multidimensional picture of the magnetic field dynamics for longer times and realistic conditions is still missing. Exploring the instability for a wide range of parameters in multidimensional configurations will allow inferring the evolution of the fields, the saturation mechanism and the possible role of other physical processes, such as the turbulent dynamo, in amplifying the fields.

    C2: identification of the laboratory conditions that will allow exploring experimentally the WI and the CFI. The possibility to investigate WI and CFI in the laboratory with intense lasers or particle beams will be explored resorting to a detailed comparison between the available parameters in the laboratory and the parameters explored in C1. This challenge will lead to the identification of the experimental conditions under which the scenarios studied in C1 can be reproduced in the laboratory, resorting to full-scale simulations. The latter will be based on already or near future available user facilities. It is thus expected that these results will lead to the proposal of experimental campaigns.

    C3: analysis of the interplay between BB and WI in large systems. The role of the electron WI has been identified in kinetic simulations of the BB effect [9]. Furthermore, it has been found that a temperature gradient causes a temperature anisotropy, which scales as the inverse of the gradient and triggers the WI [9]. However, it has not been verified yet if this theoretical prediction could hold at longer spatial and temporal scales.

    Methodology

    At the core of the project is the ability to perform ab initio fully kinetic plasma simulations based on the PIC technique. PIC codes model plasmas as particles that interact self-consistently via the electromagnetic fields, which they produce. These models work at the most microscopic level and are therefore the ideal toolbox to address the questions raised in this proposal. The parallel PIC codes that will be made available for this project are: OSIRIS is a fully explicit PIC code [13]. It is a suitable tool to investigate electron physics. The code has demonstrated a high parallel efficiency up to 95%. ECsim is a new semi-implicit PIC code [14]. Since Maxwell and Newton equations are discretized using an implicit scheme in time, the code does not present any stability or accuracy issues, allowing for the use of coarser spatial and temporal discretization respect to OSIRIS, thus reducing the computational time. These properties are fundamental for the successful completion of the project. The code has demonstrated good scaling qualities, with excellent performances up to 1000 processors.

     

  • Terahertz magnonics

    Supervisor

    Dr Rostislav Mikhaylovskiy

    Description

    Finding a fundamentally new way for data processing in the fastest and most energy efficient manner is a frontier problem for applied physics and technology. The amount of data generated every second is so enormous that the heat produced by modern data centres has already become a serious limitation to further increase their performance. This heating is a result of the Ohmic dissipation of energy unavoidable in conventional electronics. At present, the data industry lacks a solution for this problem, which in future may contribute greatly to the global warming and energy crisis.

    An emerging alternative approach is to employ spin waves (magnons) to realize waveform-based computation, which is free from electronic Joule heating. However, the present realization of this approach, called magnonics, uses electric currents to generate and modulate magnons. In the course of this PhD project, we will work towards the replacement of the current by light using antiferromagnetic materials, in which spins precess on a picosecond (one trillionth of a second) timescale and strongly coupled to electromagnetic waves [1]. Yet, the antiferromagnetic THz magnons remain practically unexplored.

    To excite THz magnons we will use ultrashort strong electromagnetic fields produced either by table-top ultrafast lasers or by electron bunches at electron-beam facilities of Cockcroft Institute. We will push the driven spin dynamics into a strongly nonlinear regime required for practical applications such as quantum computation or magnetization switching [2]. We will investigate nonlinear interaction of intense and highly coherent magnons with an eye on reaching regimes of auto-oscillations, nonlinear frequency conversion and complete magnetization reversal.

    This interdisciplinary project at the interface between magnetism and photonics offers training in ultrafast optics, THz and magneto-optical spectroscopies as well as in physics of magnetically ordered materials. Also, there will be opportunities for travel and experiments using THz free-electron laser facilities such as FELIX (Nijmegen, Netherlands) and TELBE (Dresden, Germany). 

    Funding

    The PhD starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union.

    Interested candidates should contact Dr Rostislav Mikhaylovskiy for further information.

     

  • Super-macro-particles to improve in PIC codes

    Supervisor

    Dr Jonathan Gratus

    Description

    PIC codes are used extensively in both conventional beam dynamics and laser-plasma interactions. Macro-particles are essential given the large number of particles one wishes to simulate. In order to calculate the input for Maxwell's equations, the charge and current of each macro-particle is \smeared" or \diluted" over the nearest cell points.

    We propose an improved method of modelling the macro-particles. Current PIC codes only record the position and velocity of each macro-particle. By contrast, our new method will in addition record the higher moments. These new super-macro-particles (SMPs) will then have to be smeared over a large number of cells, the higher moments being used to reconstruct the phase space distribution of charge. This method will increase
    the sophistication of the algorithm, albeit at a small cost compared to the usual method of simply increasing the number of macro-particles. The potential advantages, however, may be huge, equivalent to replacing tens or hundreds of macro-particles with a handful of these new SMPs. Indeed, if enough moments are chosen, an entire bunch of particles could be represented by a single SMP.

    There are two key steps for the successful implementation of this algorithm. The rst is to calculate the correct dynamical equations for the moments. The second is the reconstruction of the phase space distribution for each SMP. Using powerful techniques of di erential geometry, JG has already shown that the equations of motion for the quadrupole moment have unexpected features. [1]

    By October 2019 a general analytic formula for both the dynamics of the SMPs and the reconstruction of the distribution will have been calculated and we are looking for a PhD student to help implement this algorithm. As a prelude to full-scale 3-dimensional implementation, lower dimensional codes could be run and benchmarked against existing codes.

    The SMP approach will be excellent at calculating CSR wakes where the distance between the centres is large. There is also the possibility of incorporating space-charge into SMPs. Radiation reaction is dicult to model for standard macro-particles as the only information is position an velocity. However, since SMP have information about higher moments one can model space-charge by altering the equation for the second and
    higher moments.

    Currently, we wish to develop the algorithm and demonstrate proof of principle. However, it is hoped the code could be applied to several existing projects, in particular, FELs where the CSR is so important.

    As far as is known to the proposers (after signi cant searching) no similar approach has been considered. Although several people, starting with Esirkepov [2] and including Vay et al [3] do consider smearing the macro-particles over several cells with a chosen shape.

    Program of PhD: We will search for a student with an interest in programming. In the rst year, as well as the CI lectures, the student will learn the necessary di erential geometry and theory of distributions in order to understand the nature of the algorithm. The will also improve their coding skills maybe leading to writing a simple 1d PIC code. She or he will then implement a 1d SMP can compare the result.  In years two and three the student will familiarise themselves with an existing 3d PIC code and implement the SMP.

    References

    [1] Gratus, J., Banaszek, T. \The correct and unusual coordinate transformation rules for electromagnetic quadrupoles" Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. Volume 474, 2213 (2018)

    [2] \T.Zh. Esirkepov, Exact charge conservation scheme for Particle-in-Cell simulation with an arbitrary form-factor", Computer Physics Communications, Volume 135, Issue 2, 144 (2001)

    [3] J.-L. Vay, C.G.R. Geddes, E. Cormier-Michel, D.P. Grote, \Numerical methods for instability mitigation in the modelling of laser wake eld accelerators in a Lorentz- boosted frame," Journal of Computational Physics, Volume 230, Issue 15, 5908 (2011)

  • Bunch pro le shaping using time-dependent wire media

    Supervisor

    Dr Jonathan Gratus

    Description

    Background: The successful collaboration of Jonathan Gratus, Rosa Letizia, Paul Kinsler, Taylor Boyd and Rebecca Seviour [1, 2, 3], has shown that the electric eld pro le in a waveguide or cavity can be shaped using a wire medium with varying wire radius. Using space-time symmetry it is reasonably straightforward to convert the concept of spatial dispersive inhomogeneous media into time and frequency dependent media. Thus one can relatively quickly arrive at the time-dependent permittivity one will need in order to shape an electron bunch. The challenge for the numerical simulation of this model is the challenge of implementing directly time-dependent media.

    This project will support a $1.4million EPSRC proposal (Gratus, Letizia, Kinsler, Seviour (Hudders eld), McCall (Imperial)) which among other things will experimentally verify the existence of wave pro le shaping in wire media.

    Taylor Boyd, who as a result of this project has 4 peer-reviewed journal articles will be submitting soon. The work is ideally suited for a PhD student.

    Program of PhD

    During the fi rst year, as well as undergoing the Cockcroft postgraduate training, the student will learn about spatially and temporally dispersive, time-dependent and inhomogeneous media. In addition, they would learn to run CST and run the pro les already develop successfully by our collaboration. He or she will then be able to develop the time-dependent pro les necessary for bunch shaping. These theoretical results could be veri ed using a simple 1D EM solver. In year 2 the student will explore VSim together with the extension of open source code such as MEEP and MPB to go to 3D.

    References

    [1] Taylor Boyd, Jonathan Gratus, Paul Kinsler, Rosa Letizia and Rebecca Seviour \Mode pro le shaping in wire media: towards an experimental veri cation." Applied Sciences, Vol. 8, No. 8, 1276, 01.08.2018.

    [2] Taylor Boyd, Jonathan Gratus, Paul Kinsler and Rosa Letizia \Customizing longitudinal electric eld pro les using spatial dispersion in dielectric wire arrays." Optics Express, Vol. 26, No. 3, 05.02.2018, p. 2478-2494.

    [3] Taylor Boyd, Jonathan Gratus, Paul Kinsler and Rosa Letizia \Subwavelength mode pro le customisation using functional materials." Journal of Physics Communications, Vol. 1, No. 2, 025003, 06.09.2017.

Postgraduate Training

All postgraduate students in the accelerator physics group are members of the Cockcroft Institute of Accelerator Science and Technology. The Cockcroft Institute runs a two-year postgraduate education programme in accelerator science and technology which is compulsory for its own PhD students and also available to students in other groups and at other universities. The lectures are recorded to be webcast and archived.

The lecture programme has an initial 3 months introductory period starting in October and runs once a week until December of each year. Lectures cover the basics of accelerator science and technology, including beam dynamics and magnet design.

The advanced portion of the lecture programme runs from January to September and on a two-year cycle covers topics such as:

  • Hamiltonian beam dynamics
  • Free electron lasers
  • Radio frequency engineering
  • Laser plasma acceleration

All of our PhD students complete a number of assessments covering the Cockcroft Institute introductory course syllabus and are given the opportunity to carry out computational laboratory exercises including computational tools such as CST Microwave Studio, OPERA and MADX, to design RF cavities, magnets and particle beam lines respectively.

Depending on the nature of the PhD topic being covered, our students may also attend some of the graduate training offered by our colleagues in the Mathematical Physics group or Experimental Particle Physics groups.

Additional training opportunities

Further specialised training in accelerator physics may be offered through attendance at one or more of the CERN accelerator schools.

In addition to attending international conferences relevant to their degree, our students attend the annual accelerator PhD student conference at the Cockcroft Institute where they present their work and receive feedback on their presentation skills.

In common with all Lancaster postgraduate students, our students have access to a wide range of other general and transferable-skills training courses through the university.