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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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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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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Accelerator Physics
Electrical Engineering
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Open Access
Abstract: Diamond-II is a major upgrade to the current synchrotron
facility, Diamond Light Source. The low emittance electron
beam requires more stable, low drift beam position mon-
itor electronics which are also essential for the Fast Orbit
Feedback system. This paper presents simulated results of
the analog frontend for the electron beam position monitors.
This work aims to deliver an analog frontend with stable gain
and high linearity that meets the dynamic range and noise
figure requirements effectively to capture beam positions for
single and multi-bunch operation. Performance evaluations
have been conducted using the SystemVue simulation suite.
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Sep 2025
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Accelerator Physics
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Open Access
Abstract: Pulse Picking by Resonant Excitation (PPRE) enables synchrotron facilities to provide single-bunch light for timing users without interrupting multi-bunch operation*. We report the first vertical-plane PPRE tests at Diamond using the Multi-Bunch Feedback system, achieving vertical bunch-size growth and measurable X-ray enlargement. A simple novel optimisation improved PPRE purity by reducing the baseline emittance. Beyond readily-available diagnostics, we demonstrate how crystallographic diffraction can be used as a user-relevant method to characterise PPRE with statistically significant evidence of isolating a single excited bunch. Together, these methods provide a practical and user-orientated framework for synchrotron facilities considering similar timing-mode capabilities.
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Sep 2025
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Accelerator Physics
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Open Access
Abstract: The slow losses measured by Beam Loss Monitors (BLMs) at synchrotron light source facilities offer useful but indirect insight into the state of the beam. Patterns arise across the set of BLMs depending on the movement of insertion devices, beam current, temperature, humidity, and other contributors. A variety of neural network models were designed and evaluated to model this behaviour under user beam operation to enable anomaly detection and aid fault investigations.
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Sep 2025
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Accelerator Physics
Controls
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Abstract: Diamond-II will require two types of stripline kickers during normal operation: the kicker actuators for the transverse multibunch feedback system; and the injection stripline kickers which enable transparent injection. Both are very similar in design as they need to kick individual bunches without disturbing the following bunches. The main difference is the voltage requirements. The feedback kicker is expected to be driven with a maximum peak voltage of ~100 V using a broadband power amplifier, whereas the injection stripline kicker is driven with a trapezoid voltage signal with a maximum peak voltage of 20 kV using a dedicated power supply. This paper will describe the design and prototyping for both stripline kickers along with discussion of the required steps to get to final designs for each type.
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Sep 2025
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Accelerator Physics
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Younes
Chahid
,
Carolyn
Atkins
,
Stephen
Hodbod
,
John
Robinson
,
Xia
Liu
,
Stephen
Watson
,
Maia
Jones
,
Mark
Cliffe
,
Dayo
Ogunkanmi
,
Richard
Kotlewski
,
Lee
Chapman
,
Scott
Beamish
,
Jorge
Linde Cerezo
,
Thomas
Wearing
,
Ahmad
Baroutaji
,
Arun
Arjunan
,
Chantal
Fowler
,
Paul
Vivian
Open Access
Abstract: Many of the 70 synchrotron facilities worldwide are undergoing upgrades to their infrastructure to meet a growing demand for increased beam brightness with nanometre-level stability. These upgrades increase the mechanical and thermal challenges faced by beamline components, creating opportunities to apply novel methodologies and manufacturing processes to optimize hardware performance and beam accuracy. Absorbers are important beamline components that rely on water-cooled channels to absorb thermal energy from excess light caused by synchrotron radiation or photon beams created by insertion devices, all within a limited volume, to protect downstream equipment and ensure safe, reliable operation. Additive manufacturing (AM) has been shown to meet criteria relevant to synchrotron environments like leak tightness and vacuum compatibility. However, there is a research gap on the heat transfer and pressure drop impact of different AM conformal cooling channel geometries, as well as the print quality of AM copper parts using low-power infrared lasers and their compliance with absorber requirements. In this study, an intermediate model of a Diamond Light Source photon absorber was optimized to incorporate AM conformal cooling channels, leading to two concept designs named `Horizontal' and `Coil'. When compared with the baseline design, the lightweight Horizontal concept performed the best in this study, with simulations showing a maximum temperature drop of 11%, a calculated pressure drop reduction of 82%, a mass reduction of 86%, and the consolidation of 21 individually brazed pipes into a single manifold. The AM print quality and compliance with the synchrotron environment was examined by producing custom benchmark artefacts and measuring their surface roughness, dimensional accuracy and porosity levels, which are characteristics that can affect heat absorption, structural integrity, thermal conductivity and vacuum performance. The study demonstrates the benefits and addresses outstanding challenges in reducing thermal fatigue, as well as the size, vibrations and energy consumption of AM absorbers.
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Jul 2025
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Accelerator Physics
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Abstract: With the aim of maintaining transparent and efficient injection during top-up, a kick-and-cancel injection scheme has been developed for Diamond-II. In this, stripline kickers are used with 3 ns pulses to deflect individual bunches, with the stored bunch receiving two kicks separated by 180 degrees phase advance to leave it on-axis and the injected bunch timed to arrive at the second kick. In this paper we present progress with the hardware design and recent prototyping results, alongside updates to the simulations.
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Jun 2025
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Accelerator Physics
Magnets
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Abstract: Superconducting undulators (SCUs) may be capable of
generating stronger magnetic fields at shorter periods than
can be achieved using permanent magnet or planar undulators.
Therefore, the range of x-ray wavelengths that an XFEL
facility can generate for users could be expanded by exploiting
SCU technology. Prototyping work is ongoing at STFC
to build a helical superconducting undulator (HSCU) of 1 m
length with 13 mm period and 5 mm magnetic gap designed
for future XFEL facilities. As part of this work, a test cryostat
has been built to cool 325 mm long prototype magnets
to 4 K and to measure the field profile of the HSCU using a
calibrated cryogenic Hall sensor. The magnetic field measurements
are necessary to confirm the peak-to-peak field
quality and trajectory wander of an electron beam through
the device in order to understand the impact of the HSCU
on the FEL radiation output. We present here a description
of the test cryostat and the results of the magnetic field
measurement regime performed on the prototype HSCU
coil.
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Jun 2025
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