ORCID Profile
0000-0002-7653-7205
Current Organisations
University of Oxford
,
University of Melbourne
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Synchrotrons; Accelerators; Instruments and Techniques | Medical Physics | Other Physical Sciences | Biological Physics |
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences | Expanding Knowledge in Technology
Publisher: IOP Publishing
Date: 07-2017
Publisher: American Physical Society (APS)
Date: 11-03-2013
Publisher: AIP Publishing
Date: 2021
DOI: 10.1063/5.0047815
Publisher: Oxford University Press (OUP)
Date: 07-2016
DOI: 10.1093/PTEP/PTW086
Publisher: IOP Publishing
Date: 11-2019
DOI: 10.1088/1742-6596/1350/1/012133
Abstract: We use the IBEX linear Paul trap to study the resonance at a cell tune of 1 4 with both equal and unequal transverse tunes, at a range on intensities. We compare this experimental result to simulation using the PIC code Warp. We find that the experimental result differs from the simulation, which may be explained by the ion loss in the IBEX experiment, which more closely replicates a real accelerator. Knowledge of the tune corresponding to greatest beam loss is important for the design of future high intensity machines.
Publisher: IOP Publishing
Date: 11-2019
DOI: 10.1088/1742-6596/1350/1/012132
Abstract: Here we describe the design of an experimental setup using the IBEX Paul trap to test nonlinear quasi-integrable optics, an accelerator lattice design to create stable high intensity beams. In 2010 Danilov and Nagaitsev found a realisable nonlinear potential which can create integrable optics in an accelerator when embedded in a linear lattice that provides round beams. This concept will be tested in the IOTA ring at Fermilab. It is important to further test this concept over a wide parameter range, preferably in a simplified experimental setup such as IBEX. The IBEX Paul trap is capable of replicating the transverse dynamics of a high intensity accelerator without dispersion or chromaticity.
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 06-2019
Publisher: Springer Science and Business Media LLC
Date: 10-01-2012
DOI: 10.1038/NPHYS2179
Publisher: IOP Publishing
Date: 05-2019
Abstract: In this paper we present the first quantitative measurement of the change in frequency (tune) with intensity of four transverse resonances in a high intensity Gaussian beam. Due to the nonlinear space charge forces present in high intensity beams, particle motion cannot be analytically described. Instead we use the simulator of particle orbit dynamics and the intense beam experiment, two linear Paul traps (LPTs), to replicate the system experimentally. In high intensity beams a coherent resonant response to both space charge and external field driven perturbations is possible, these coherent resonances are excited at a tune that differs by a factor C m from that of the incoherent resonance. By increasing the number of ions stored in the LPT and studying the location of four different resonances we extract provisional values describing the change in tune of the resonance with intensity. These values are then compared to the C m factors for coherent resonances. We find that the C m factors do not accurately predict the location of resonances in high intensity Gaussian beams. Further insight into the experiment was gained through simulation using Warp, a particle-in-cell code.
Publisher: American Physical Society (APS)
Date: 17-03-2015
Publisher: Wiley
Date: 24-08-2022
DOI: 10.1002/ACM2.13756
Abstract: The lack of equitable access to radiotherapy (RA) linear accelerators (LINACs) is a substantial barrier to cancer care in low- and middle-income countries (LMICs). These nations are expected to bear up to 75% of cancer-related deaths globally by 2030. State-of-the-art LINACs in LMICs experience major issues in terms of robustness, with mechanical and electrical breakdowns resulting in downtimes ranging from days to months. While existing research has identified the higher failure frequency and downtimes between LMICs (Nigeria, Botswana) compared to high-income countries (HICs, the UK), there has been a need for additional data and study particularly relating to multileaf collimators (MLCs). This study presents for the first time the analysis of data gathered through a dedicated survey and workshop including participants from 14 Indonesian hospitals, representing a total of 19 LINACs. We show the pathways to failure of radiotherapy LINACs and frequency of breakdowns with a focus on the MLC subsystem. This dataset shows that LINACs throughout Indonesia are out of operation for seven times longer than HICs, and the mean time between failures of a LINAC in Indonesia is 341.58 h or about 14 days. Furthermore, of the LINACs with an MLC fitted, These results highlight the pressing need to improve robustness of RT technology for use in LMICs, highlighting the MLC as a particularly problematic component. This work motivates a reassessment of the current generation of RT LINACs and demonstrates the need for dedicated efforts toward a future where cancer treatment technology is robust for use in all environments where it is needed.
Publisher: World Scientific Pub Co Pte Lt
Date: 30-04-2011
DOI: 10.1142/S0217751X11053237
Abstract: Non-scaling FFAGs have gained interest in the past decade for their potential application to charged particle therapy using proton and ion beams. However, linear ns-FFAGs naturally cross betatron resonances throughout acceleration. With an acceleration cycle of thousands rather than tens of turns, we find that resonance crossing produces severe orbit distortion in a linear proton/ion ns-FFAG in the presence of alignment errors. To overcome this, the PAMELA (Particle Accelerator for MEdicaL Applications) lattice design avoids resonance crossing with a non-linear ns-FFAG design. This design is outlined and a comparative analysis of alignment tolerances presented.
Publisher: JACoW Publishing, Geneva, Switzerland
Date: 2019
Publisher: American Physical Society (APS)
Date: 22-04-2010
Publisher: Elsevier BV
Date: 08-2012
Publisher: American Physical Society (APS)
Date: 10-06-2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2012
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.CLON.2019.10.010
Abstract: The lack of radiotherapy linear accelerators (linacs) in low- and middle-income countries (LMICs) has been recognised as a major barrier to providing quality cancer care in these regions, together with a shortfall in the number of highly qualified personnel. It is expected that additional challenges will be faced in operating precise, high-technology radiotherapy equipment in these environments, and anecdotal evidence suggests that linacs have greater downtime and higher failure rates of components than their counterparts in high-income countries. To guide future developments, such as the design of a linac tailored for use in LMIC environments, it is important to take a data-driven approach to any re-engineering of the technology. However, no detailed statistical data on linac downtime and failure modes have been previously collected or presented in the literature. This work presents the first known comparative analysis of failure modes and downtime of current generation linacs in radiotherapy centres, with the aim of determining any correlations between linac environment and performance. Logbooks kept by radiotherapy personnel on the operation of their linac were obtained and analysed from centres in Oxford (UK), Abuja, Benin, Enugu, Lagos, Sokoto (Nigeria) and Gaborone (Botswana). By deconstructing the linac into 12 different subsystems, it was found that the vacuum subsystem only failed in the LMIC centres and the failure rate in an LMIC environment was more than twice as large in six of the 12 subsystems compared with the high-income country. Additionally, it was shown that despite accounting for only 3.4% of the total number of faults, linac faults that took more than 1 h to repair accounted for 74.6% of the total downtime. The results of this study inform future attempts to mitigate the problems affecting linacs in LMIC environments.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: No location found
Start Date: 2017
End Date: 2022
Funder: Royal Society
View Funded ActivityStart Date: 2019
End Date: 2020
Funder: University of Melbourne
View Funded ActivityStart Date: 2018
End Date: 2018
Funder: Science and Technology Facilities Council
View Funded ActivityStart Date: 2018
End Date: 2018
Funder: Science and Technology Facilities Council
View Funded ActivityStart Date: 2016
End Date: 2020
Funder: Science and Technology Facilities Council
View Funded ActivityStart Date: 10-2022
End Date: 12-2023
Amount: $391,000.00
Funder: Australian Research Council
View Funded Activity