Accelerator Physics
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Open Access
Abstract: The existing 100 MeV linac at the Diamond Light Source will be used as the pre-injector into the upgraded Diamond-II booster ring for injection into the new 3.5 GeV storage ring. In preparation for the upcoming upgrade, we have characterised the linac beam properties, to provide an input for beam tracking simulations and to optimise the linac beam dynamics. We present the latest linac performance results, the optimisation of the linac and linac-to-booster beam transport and the injection efficiency into the current Diamond booster ring.
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May 2026
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Accelerator Physics
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Open Access
Abstract: Top-up operation at the Diamond-II storage ring will involve injecting bunches of electrons into the ring whilst the photon beamlines are in use. It is important, for the safety of the users, that electrons from the newly injected bunches cannot travel down the photon beampipe to the front end. For each beamline, all possible trajectories through the ID straight were identified and tracked through the machine to determine if any combinations of magnet settings exist that would simultaneously allow for stored beam and for electrons to be extracted through the front end. The full range of strengths for all the magnets/kickers were considered to account for any magnet power supply failures or different operating modes. Here we present the method used to track the electrons, summarise the results for the beamlines simulated so far and describe the interlocks required to ensure safe operation.
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May 2026
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Accelerator Physics
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Abstract: Diamond-II will use fast stripline kickers for transparent single bunch injection during top-up operations. A prototype stripline and pulser have been developed,and have undergone evaluation in the existing Diamond accelerator. Two types of feedthrough connector have been tested, and suitable cables and attenuators have been identified. We present results from an array of checks for the stripline assembly both in isolation and installed in the accelerator with beam. This includes impedance analysis and other effects on electron beam dynamics, as well as analysis of kick strength and timing.
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May 2026
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Accelerator Physics
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C.
Pakuza
,
E.
Belli
,
S.
Burger
,
S.
Doebert
,
M.
Gasior
,
E.
Gschwendtner
,
M.
Krupa
,
T.
Lefevre
,
T.
Levens
,
B.
Moser
,
A.
Topaloudis
,
M.
Turner
,
P.
Muggli
,
L.
Stant
Abstract: The AWAKE experiment at CERN is a proof-of-principle facility that uses proton-driven plasma wakefields to accelerate externally injected electrons. Since initial operations in 2016, multiple experimental phases have been completed, with the most recent being Run 2b. Beam diagnostics played a crucial role during this phase, enabling reliable operation and characterisation of the particle beams. The next phase, Run 2c, planned to begin in 2029, will introduce a second electron beamline delivering 150 MeV, 200 fs (RMS)-long electron bunches together with a second plasma. The increased experimental scale and the new measurement requirements impose new demands on beam instrumentation, requiring upgrades to existing systems and the development of new, specialised diagnostics. This contribution presents a non-exhaustive overview of the diagnostic systems used during Run 2b, describes the planned upgrades and developments for Run 2c, and discusses the associated integration challenges.
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May 2026
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Accelerator Physics
Optics
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Open Access
Abstract: Customized beam shaping has a wide range of applications from visible light to hard X-rays. While laser beam shaping has matured over recent decades, enabling breakthroughs in optical communication, optical tweezers, and advanced microscopy, extending these techniques to high-brightness X-ray sources could significantly enhance synchrotron applications such as macromolecular crystallography, spectroscopy, and high-resolution imaging. However, X-ray beam shaping remains challenging due to limitations in the available optics and the finite phase-space of synchrotron sources. We introduce a novel method that exploits the monochromatic angular spectrum of undulator radiation combined with the compound refractive lenses (CRLs) to produce a variable circular focal spot with a top-hat intensity profile. By fine-tuning the undulator gap and monochromator settings, this approach enables dynamic control of the spatial beam profile while preserving continuous energy tunability within the limits imposed by the optical configuration and experimental conditions. This technique delivers flexible beam shaping without requiring complex new optical designs, construction, or operational overhead. This method has been successfully demonstrated on a macromolecular crystallography beamline at the Diamond Light Source (DLS), confirming its practicality, adaptability, and potential for widespread adoption in synchrotron-based research.
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May 2026
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Accelerator Physics
Controls
Magnets
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Abstract: Injection efficiency into the Diamond Light Source Storage Ring (SR) is currently optimised by operators performing a grid scan over the final pair of corrector magnets inside the Booster-to-Storage Ring (BTS) transfer line. The phase advance between the pair is sufficient to provide good control over the position and angle of the beam as it enters the SR. However, the method is slow and the strengths of the corrector pair can approach power supply limits over time as machine conditions drift. We propose a Bayesian optimisation algorithm to optimise leading right-singular vector coefficients obtained from a Singular Value Decomposition (SVD) of the BTS response matrix over all corrector magnets, improving sample efficiency. We further transform the proposed coefficients through a non-linear map to restrict the set of solutions to a desirable range as determined by the user. We compare our results to the grid scan technique and suggest further refinements to the algorithm.
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May 2026
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Accelerator Physics
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Open Access
Abstract: Impedance and collective effects are significant concerns for the design of modern accelerators. During development of the Diamond-II storage ring, effort was initially focussed on design for the arcs containing the majority of magnets, and geometric impedance was focussed on single bunch effects. We now present updates to the Diamond-II impedance database and the impact on collective effects including additional detail in straights, including injection, insertion devices and RF elements, as well as inclusion of long-range impedance for more elements for multibunch dynamics.
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May 2026
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Accelerator Physics
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Open Access
Abstract: X-ray beam position monitors (XBPMs) play a crucial role in accurately measuring the position of the white beam in synchrotron front ends. Traditional XBPM designs typically feature four tungsten blades arranged at the full width at half maximum (FWHM) of the white beam. However, the high absorption and lower thermal resistance of tungsten limit the proximity of the blades to the X-ray source, which may negatively impact measurement precision. This study investigates the performance of an innovative XBPM design that utilises silicon carbide (SiC) blades, which provide enhanced thermal conductivity and reduced absorption. This advancement may allow for closer placement of the blades to the beam, potentially improving measurement accuracy. This experimental setup aims to assess the impact of SiC blades on measurement accuracy, signal-to-noise ratio, and linearity compared to conventional tungsten XBPMs. The results will offer valuable insights into the benefits and limitations of SiC-based XBPMs compared to their tungsten counterparts.
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Nov 2025
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Accelerator Physics
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Open Access
Abstract: At Diamond, it was previously observed that the response of the beam changes with mode number when excited by the transverse multi-bunch feedback (TMBF). This study presents the results of various experimental campaigns carried out to investigate the behaviour of tune-sweep waveforms for a variety of stored beam conditions and TMBF settings. We demonstrate that it is unlikely that wakefields cause the mode dependence in the output TMBF waveforms. Investigations to explain what is causing the mode-dependent behaviour are ongoing.
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Nov 2025
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Accelerator Physics
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Y.
Ma
,
M. j. V.
Streeter
,
F.
Albert
,
N.
Bourgeois
,
S.
Cipiccia
,
J. M.
Cole
,
S. j. D.
Dann
,
K.
Falk
,
E.
Gerstmayr
,
I.
Gallardo González
,
A.
Higginbotham
,
A. E.
Hussein
,
D. A.
Jaroszynski
,
A. s.
Joglekar
,
B.
Kettle
,
K.
Krushelnick
,
N.
Lemos
,
N. C.
Lopes
,
C.
Lumsden
,
O.
Lundh
,
S. P. D.
Mangles
,
K. G.0000-0003-4826-9001
Miller
,
W.
Mori
,
Z.
Najmudin
,
Q.
Qian
,
P. P.
Rajeev
,
D.
Seipt
,
M.
Shahzad
,
M.
Šmíd
,
R.
Spesyvtsev
,
D. R.
Symes
,
G.
Vieux
,
L.
Willingale
,
J. C.
Wood
,
A. G. R.
Thomas
Open Access
Abstract: We report on a single-shot longitudinal phase-space reconstruction diagnostic for electron beams in a laser wakefield accelerator via the experimental observation of distinct periodic modulations in the angularly resolved spectra. Such modulated angular spectra arise as a result of the direct interaction between the ultrarelativistic electron beam and the laser driver in the presence of the wakefield. A constrained theoretical model for the coupled oscillator, assisted by a genetic algorithm, can recreate the experimental electron spectra and, thus, fully reconstructs the longitudinal phase-space distribution of the electron beam with a temporal resolution of approximately 1.3 fs. In particular, it reveals the slice energy spread of the electron beam, which is important to measure for applications such as x-ray free electron lasers. In our experiment, the root-mean-square slice energy spread retrieved is bounded at 9.9 MeV, corresponding to a 0.9%–3.0% relative spread, despite the overall GeV energy beam having approximately 100% relative energy spread.
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Sep 2025
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