Hywel Owen

• PhD
• Group Leader Accelerator Physics at Science and Technology Facilities Council

The materials engineering database relevant to fusion irradiation is poorly populated and it has long been recognized that a fusion spectrum neutron source will be required, the facility IFMIF being the present proposal. Re-evaluation of the regulatory approach for the EU proposed DEMO device shows that the purpose of the source can be changed from...

Electron storage rings used for the production of synchrotron radiation (SR) have an output photon brightness that is limited by the equilibrium beam emittance. By using interleaved injection and ejection of bunches from a source with repetition rate greater than 1 kHz, we show that it is practicable to overcome this limit in rings of energy ~1 GeV...

In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics coll...

The CLARA accelerator facility at Daresbury Laboratory, UK, was originally designed to operate as a free-electron laser test facility. To improve the user exploitation of the facility a dedicated full energy beam exploitation (FEBE) area has been designed and is currently being installed in a separate experimental bunker on the CLARA accelerator. T...

The Extreme Photonics application Centre (EPAC) is a new national facility to support UK science, technology, innovation and industry currently under construction at the Rutherford Appleton Laboratory, UK. EPAC is designed to facilitate a wide variety of user experiments with 1PW 10Hz laser systems. It is anticipated that early experiments will inc...

Laser wakefield accelerators (LWFAs) can produce high-energy electron bunches in short distances. Successfully coupling these sources with undulators has the potential to form an LWFA-driven free-electron laser (FEL), providing high-intensity short-wavelength radiation. Electron bunches produced from LWFAs have a correlated distribution in longitud...

The determination of relative stopping power (RSP) via proton computed tomography (pCT) of a patient is dependent in part on the knowledge of the incoming proton kinetic energies; the uncertainty in these energies is in turn determined by the proton source—typically a cyclotron. Here, we show that reducing the incident proton beam energy spread may...

Here we present results of start-to-end particle-in-cell and GPT simulations of coherent synchrotron radiation in the visible and ultraviolet. The radiation is produced by laser-driven attosecond electron bunches travelling through an undulator.

The determination of relative stopping power (RSP) via proton computed tomography (pCT) of a patient is dependent in part on the knowledge of the incoming proton kinetic energies; the uncertainty in these energies is in turn determined by the proton source -- typically a cyclotron. Here we show that reducing the incident proton beam energy spread m...

There is an increasing interest in employing technologies to decarbonise the shipping sector; one option is the use of nuclear energy to power civilian ships. Previous work has investigated the use of UO2 fuel and its behaviour in a novel, soluble-boron-free, low power density PWR that offered a 15 year core life to power a container ship with a de...

Attosecond duration relativistic electron bunches travelling through an undulator can generate brilliant coherent radiation in the visible to vacuum ultraviolet spectral range. We present comprehensive numerical simulations to study the properties of coherent emission for a wide range of electron energies and bunch durations, including space-charge...

Quasimonochromatic x rays are difficult to produce above 100 keV, but have a number of uses in x-ray and nuclear science, particularly in the analysis of transuranic species. Inverse Compton scattering (ICS) is capable of fulfilling this need, producing photon beams with properties and energies well beyond the limits of typical synchrotron radiatio...

Boron carbide is a material proposed as an alternative to graphite for use as an energy degrader in proton therapy facilities, and is favoured due to its mechanical robustness and promise to give lower lateral scattering for a given energy loss. However, the mean excitation energy of boron carbide has not yet been directly measured. Here we present...

There is limited validation of MONK using ²³²Th/²³³U benchmarks, and existing validation of Monte Carlo codes has generally used older nuclear data libraries. Here we use MONK-9A to systematically study a series of thermal ²³²Th/²³³U-based benchmark experiments, taken from the International Criticality Safety Benchmark Evaluation Project handbook a...

In proton therapy both the energy, which determines the range, and the distal slope, which reflects the rate at which the protons decelerate, are of import if we are to ensure accurate dose deposition and maximum tissue sparing. This publication describes a Geant4 model and presents a two-dimensional polynomial relationship between energy, the ener...

In the UK, one in two people will develop cancer during their lifetimes and radiotherapy (RT) plays a key role in effective treatment. High energy proton beam therapy commenced in the UK National Health Service in 2018. Heavier charged particles have potential advantages over protons by delivering more dose in the Bragg peak, with a sharper penumbr...

There is growing interest in the radiotherapy community in the application of FLASH radiotherapy, wherein the dose is delivered to the entire treatment volume in less than a second. Early pre-clinical evidence suggests that these extremely high dose rates provide significant sparing of healthy tissue compared to conventional radiotherapy without re...

Introduction: Cyclotron-based proton therapy facilities use an energy degrader of variable thickness to deliver beams of the different energies required by a patient treatment plan; scattering and straggling in the degrader give rise to an inherent emittance increase and subsequent particle loss in the downstream energy-selection system (ESS). Here...

The use of superconductivity is well-known as a method to increase the average field of a cyclotron and thereby to allow a substantial reduction of its size and mass. We present a compact high-field design for the first superconducting cyclotron with rare-earth (holmium) poles. Our design supports stable acceleration of protons to Ek = 70 MeV with...

If international agreements regarding the need to significantly reduce greenhouse gas emissions are to be met then there is a high probability that the shipping industry will have to dramatically reduce its greenhouse gas emissions. For emission reductions from ships greater than around 40% then alternatives to fossil fuels - such as nuclear energy...

If international agreements regarding the need to significantly reduce greenhouse gas emissions are to be met then there is a high probability that the shipping industry will have to dramatically reduce its greenhouse gas emissions. For emission reductions from ships greater than around 40\% then alternatives to fossil fuels - such as nuclear energ...

Purpose The development of 4DCT imaging allows clinicians to account for movement of both the target tumour and organs at risk, although the choice of method of image reconstruction can impact how accurately observers can contour nearby organs. Motion-compensated (MC) image reconstruction is a technique that reduces blurring compared to standard av...

The neutrino beam produced from muons decaying in a storage ring would be an ideal tool for precise neutrino cross section measurements and search for sterile neutrinos due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility pions would be directly injected into a racetrack storage ring, where circulating muon beam...

NORMA is a design for a normal-conducting racetrack fixed-field alternating-gradient accelerator for protons from 50 to 350 MeV. In this article we show the development from an idealized lattice to a design implemented with field maps from rigorous two-dimensional (2D) and three-dimensional (3D) FEM magnet modeling. We show that whilst the fields f...

The development and validation of a beam line MC model is an essential part of many projects, particularly those involving particle therapy. This is often a very time consuming and sometimes costly computational process. However, many experiments use the same beam lines and the medical physics community would benefit greatly from a structured code...

NORMA is a design for a normal-conducting race track fixed-field alternating-gradient accelerator (FFAG) for protons from 30 to 350 MeV. In this article we show the development from the nominal lattice design to a model implemented with field maps from 2D and 3D FEM magnet designs. We show that while the fields from the 2D model are sufficient, adj...

In this paper we present a proof to show that there exists no system of linear or nonlinear optics which can simultaneously close multiple local orbit bumps and dispersion through a single beam transport region. The second combiner ring in the CLIC drive beam recombination system, CR2, is used as an example of where such conditions are necessary. W...

Conventional proton cyclotrons are practically limited by relativistic effects to energies around 250 MeV, sufficient to conduct proton therapy of adults but not for full-body proton tomography. We present an adaptation of the cyclinac scheme for proton imaging, in which a c.250 MeV cyclotron used for treatment feeds a linac that delivers a lower i...

This conceptual design report describes the technical facility for the IsoDAR electron-antineutrino source at KamLAND. The IsoDAR source will allow an impressive program of neutrino oscillation and electroweak physics to be performed at KamLAND. This report provides information on the physics case, the conceptual design for the subsystems, alternat...

In this paper we present a new lattice design for a 30–350 MeV scaling fixed-field alternating gradient accelerator for proton therapy and tomography—NORMA (NOrmal-conducting Racetrack Medical Accelerator). The energy range allows the realization of proton computed tomography and utilizes normal conducting magnets in both a conventional circular ri...

The past few years have seen significant developments both of the technologies available for proton and other charged particle therapies, and of the number and spread of therapy centres. In this review we give an overview of these technology developments, and outline the principal challenges and opportunities we see as important in the next decade....

In this paper we present a proof to show that there exists no system of linear or nonlinear optics which can simultaneously close multiple local orbit bumps and dispersion through a single beam transport region. The second combiner ring in the CLIC drive beam recombination system, CR2, is used as an example of where such conditions are necessary. W...

When delivering proton therapy, dose accuracy can be aided by the use of Monte Carlo (MC) simulation, but very large numbers of incident particles must be followed to obtain good statistical uncertainty. To validate dose estimates from pencil beam approximations within the treatment field typically requires at least 10 million primaries. The recent...

In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics coll...

We present PyZgoubi, a framework that has been developed based on the tracking engine Zgoubi to model, optimise and visualise the dynamics in particle accelerators, especially fixed-field alternating-gradient (FFAG) accelerators. We show that PyZgoubi abstracts Zgoubi by wrapping it in an easy-to-use Python framework in order to allow simple constr...

The UK has no research nuclear reactors and relies on the importation of 99Mo and other medical radioisotopes (e.g. Iodine-131) from overseas (excluding PET radioisotopes). The UK is therefore vulnerable not only to global shortages, but to problems with shipping and importation of the products. In this context Professor Erika Denton UK national Cl...

The primary advantage of proton beam therapy as a cancer treatment is its ability to maximize the radiation dose delivered to the target volume and minimize the dose to surrounding healthy tissue, due to the inherently narrow Bragg peak at the end of the proton range. This can be further enhanced by imaging the target volume and surrounding t...

We discuss the use of two novel techniques to deliver low emittance from a compact electron ring at energies around 1 GeV, suitable for EUV and soft X-ray synchrotron radiation production. The first method is the circulation of nonequilibrium electron bunches, which is made feasible using high repetition rate linacs and very fast bunch-by-bunch inj...

We present a design for a 30-350 MeV scaling racetrack FFAG accelerator for medical application - NORMA (NOrmal-conducting Racetrack Medical Accelerator)-which utilises normal-conducting magnets. NORMA consists of 12 FDF triplet cells with a maximum drift length of ∼2 m; an additional drift space inserted into two places forms a racetrack lattice w...

In the nominal EMMA design, particles are accelerated rapidly in the serpentine channel between RF buckets. Many integer tunes are crossed in less than a turn in this regime without significant amplitude growth. Slower acceleration inside an RF bucket in EMMA allowed the exploration of slower integer tune crossing speeds. The effect on the coherent...

Recent and ongoing shortages in reactor-based supplies of molybdenum-99 for hospital production of the important medical radioisotope Technetium-99m have prompted the re-examination of the alternative production methods using conventional and laser-based particle accelerators. At present the UK has no domestic source of molybdenum-99 and relies exc...

Full-text preprints here: http://www.tandfonline.com/eprint/5VjmpQcNhE2uNTjecmBA/full Over the last twenty years the treatment of cancer with protons and light nuclei such as carbon ions has moved from being the preserve of research laboratories into widespread clinical use. A number of choices now exist for the creation and delivery of these part...

The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model up to scales of several hundred GeV, has triggered interest in ideas for future Higgs factories. A n...

This report describes the conceptual design of a proposed free electron laser test facility called CLARA that will be a major upgrade to the existing VELA accelerator test facility at Daresbury Laboratory in the UK. CLARA will be able to test a number of new free electron laser schemes that have been proposed but require a proof of principle experi...

The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e+e− co...

The next generation of lepton flavor violation experiments need high intensity and high quality muon beams. Production of such beams requires sending a short, high intensity proton pulse to the pion production target, capturing pions and collecting the resulting muons in the large acceptance transport system. The substantial increase of beam qualit...

Recent developments for the delivery of proton and ion beam therapy have been significant, and a number of technological solutions now exist for the creation and utilisation of these particles for the treatment of cancer. In this paper we review the historical development of particle accelerators used for external beam radiotherapy and discuss the...

The materials engineering data base relevant to fusion irradiation is poorly populated and it has long been recognized that a fusion spectrum neutron source will be required, the facility IFMIF being the present proposal. Reevaluation of the regulatory approach for the EU proposed DEMO device shows that the purpose of the source can be changed from...

DOI:https://doi.org/10.1103/PhysRevLett.110.179903

The conceptual design for a nonscaling fixed field alternating gradient accelerator suitable for charged particle therapy (the use of protons and other light ions to treat some forms of cancer) is described.

EMMA is the worlds first non-scaling FFAG, based at Daresbury Laboratory. EMMA has a very large acceptance and has demonstrated acceleration in the serpentine channel. PRISM (Phase Rotated Intense Slow Muon source) is a next generation muon to electron conversion experiment aiming to obtain intense quasi-monochromatic low energy muon beams by perfo...

PIP, the Proton Isotope Production accelerator, is a low energy (6-10 MeV) proton nsFFAG design that uses a simple 4-cell lattice. Low energy reactions involving the creation of specific nuclear states can be used for neutron production and for the manufacture of various medical isotopes. Unfortunately a beam rapidly loses energy in a target and fa...

CLARA will be a novel FEL test facility focussed on the generation of ultra-short photon pulses with extreme levels of stability and synchronisation. The principal aim is to experimentally demonstrate that sub-cooperation length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate dir...

EMMA (Electron Model for Many Applications) is the only non-scaling electron FFAG, located at Daresbury Laboratory. Since the recent demonstration of acceleration in the so-called serpentine channel, the EMMA beam dynamics have been further studied. This entails the exploration of the large transverse and longitudinal acceptance and the effects of...

DAEδALUS (Decay At rest Experiment for δcp At a Laboratory for Underground Science) has been proposed to measure the value of the CP violating phase δ through the oscillation of low energy muon antineutrinos to electron antineutrinos. With a single large detector, three accelerators at different distances enable the oscillation to be measured with...

This whitepaper reviews design options for the IsoDAR electron antineutrino source. IsoDAR is designed to produce $2.6 \times 10^{22}$ electron antineutrinos per year with an average energy of 6.4 MeV, using isotope decay-at-rest. Aspects which must be balanced for cost-effectiveness include: overall cost; rate and energy distribution of the electr...

An advantage of the cyclotron in proton therapy is the continuous (CW) beam outputwhich reduces complexity and response time in the dosimetry requirements and beam controls.A CW accelerator requires isochronous particle orbits at all energies through theacceleration cycle and present compact isochronous cyclotrons for proton therapy reach only250 M...

Results are presented from a slow integer tune crossing experiment performed in the EMMA ns-FFAG accelerator. Under nominal conditions EMMA accelerates an electron beam from 10 to 20 MeV rapidly in 5 to 10 turns in a novel serpentine channel causing several transverse integer tunes to be crossed. During this rapid acceleration it has been shown tha...

The potential for thorium as an alternative or supplement to uranium in fission power generation has long been recognised, and several reactors, of various types, have already operated using thorium-based fuels. Accelerator Driven Subcritical (ADS) systems have benefits and drawbacks when compared to conventional critical thorium reactors, for both...

EMMA (Electron Machine for Many Applications) is the world's first prototypenon-scaling electron FFAG hosted at Daresbury Laboratory. Several upgrade possibilities forEMMA are explored, from creating a dispersionfree region in the ring to facilitateinjection and extraction to making an insertion in EMMA by turning it into aracetrack-style machine....

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAGoperating at Daresbury Laboratory. After demonstrating serpentine channel acceleration andfast resonance crossing in 2011, studies continue of the beam dynamics to explore the largetransverse and longitudinal acceptance, the detailed effects of integer tune crossing...

We present a novel modular magnetic system that can introduce a large and continuously-variable path length difference without simultaneous variation of the longitudinal dispersion. This is achieved by using a combination of an electrically-adjustable magnetic chicane and a mechanically-adjustable focus- ing chicane. We describe how such a system m...

CONSORT is the UK's last remaining civilian research reactor, and its present core is soon to be removed. This study examines the feasibility of re-using the reactor facility for accelerator-driven systems research by replacing the fuel and installing a spallation neutron target driven by an external proton accelerator. MCNP5/MCNPX were used to mod...

EMMA (Electron Model for Many Applications) is a proof-of-principle demonstration of a non-scaling, fixed-field, alternating gradient accelerator (nsFFAG). Although nsFFAGs are related to cyclotrons and scaling FFAGs, the normal requirement is broken that the orbit radius scales with beam energy at all azimuths, meaning that a large energy variatio...

Due to the combination of fixed magnetic field operation with strong focusing, non-scaling FFAGs have a significant potential for future particle accelerator applications. However, this technology has a number of unique features, which must be fully studied before this potential can be realised. To do this, a proof-of-principle non-scaling FFAG, ca...

The status of the PAMELA (Particle Accelerator for MEdicaL Applications) project to design an accelerator for proton and light ion therapy using non-scaling Fixed Field Alternating Gradient (ns-FFAG) accelerators is reviewed and discussed.

EMMA (Electron Model with Many Applications) is the first proof-of-principle non-scaling FFAG accelerator and is presently under construction at Daresbury Laboratory in the UK. To probe different parts of the bunch phase space during the acceleration from 10 to 20 MeV (which requires rapid resonance crossing), electron bunches are needed with suffi...

The New Light Source (NLS) project was launched in April 2008 by the UK Science and Technology Facilities Council (STFC) to consider the scientific case and develop a conceptual design for a possible next generation light source based on a combination of advanced conventional laser and free-electron laser sources. Following a series of workshops an...

The PAMELA (Particle Accelerator for MEdicaL Applications) project is to design an accelerator for proton and light ion therapy using non-scaling Fixed Field Alternating Gradient (FFAG) accelerators, as part of the CONFORM project, which is also constructing the EMMA electron model of a non-scaling FFAG at Daresbury. This paper presents an overview...

EMMA – the Electron Model of Many Applications – is to be built at the STFC Daresbury Laboratory in the UK and will be the first non-scaling FFAG ever constructed. EMMA will be used to demonstrate the principle of this type of accelerator and study its features in detail. The design of the machine and its hardware components are now far advanced an...

During the last few years Europe has made enormous progress towards free electron laser (FEL)-based research infrastructures. The FLASH facility [11. Ayvazyan , V. 2006 . Eur. Phys. J. D , 37 : 297 [CrossRef], [Web of Science ®]View all references] at DESY in Hamburg, Germany, has been in user operation since the summer of 2005; FERMI@Elettra [2Vie...

The CONFORM project, recently funded as part of the UK 'Basic Technology' initiative, will build a 20 MeV Non-Scaling FFAG (EMMA) at Daresbury. The experience gained will be used for the design of a proton machine (PAMELA) for medical research, and other applications for Non-Scaling FFAGs in different regimes will be explored. The successful develo...

Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA high-current ERL branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of recent developments...

A detailed design of a free electron laser (FEL) amplifier operating in the extreme ultra violet (XUV) and seeded directly by a high harmonic source is presented. The design is part of the 4th generation light source (4GLS) facility proposed for the Daresbury Laboratory in the UK which will offer users a suite of high brightness synchronised source...

The CONFORM project, recently funded as part of the UK ‘Basic Technology’ initiative, will build a 20 MeV Non-Scaling FFAG (EMMA) at Daresbury. The experience gained will be used for the design of a proton machine (PAMELA) for medical research, and other applications for Non-Scaling FFAGs in different regimes will be explored. The successful develo...

The designs for 4GLS and Arc-en-Ciel contain an Energy Recovery Linac (ERL) and a beam current of 100mA accelerated to 550 MeV and 2 GeV respectively. This will be challenging with regards to beam stability, since the interaction with the beam and any Higher Order Modes (HOMs) contained within the cavity could lead to the beam being lost, due to th...