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25e0ebd4-c241-4863-b175-1c318b65ee19 | REAL-TIME COMPREHENSIVE ELECTRON BEAM DIAGNOSTICS
THROUGH MACHINE LEARNING IN ULTRAFAST ELECTRON
DIFFRACTION SYSTEM
Jiapeng Li, Cheng-Ying Tsai∗, Kuanjun Fan, School of Electrical and Electronic Engineering,
Huazhong University of Science and Technology, Wuhan, China
Abstract
Mega-electron-volt (MeV) ultrafast electron... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
74327bb0-3a43-4b77-b63a-985b679764ed | tionofelectronbeamparametersdirectlyfromdiffraction
patterns. Deep neural networks trained on physics-based
simulationsdecodesignaturesthatbeamparametersimprint
on diffraction images. The method exploits distinct physical
mechanisms: geometric effects from beam size, angular dis-
tortionsfromdivergence,chromaticaberrat... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
96a96ca0-987e-4ed3-9536-505693136227 | trafast materials characterization.
INTRODUCTION
MeVultrafastelectrondiffraction(UED)[1 –3]employs
the pump-probe technique to observe atomic-scale dynamic
processes with femtosecond temporal resolution. Experi-
mental success will depend highly on electron beam qual-
ity, including beam size, divergence, energy spread... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
43a4e1ed-700b-4f23-abc0-cbc08ccfb91e | SETUP OF MACHINE PARAMETERS
Based on the MeV UED under construction at Huazhong
University of Science and Technology [8 –13], the system
employs a 1.4-cell photocathode RF gun, driven by 266-nm
∗Email:jcytsai@hust.edu.cnultraviolet laser to generate photoelectrons from a copper
cathode. The 2856-MHz RF cavity provides ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
d3830089-a6e9-47ef-ab19-ce908c9e552c | lation between bunch parameters and diffraction images,
we employed the ASTRA particle tracking simulations [14]
with the diffraction utilizing the familiar polycrystalline alu-
minum sample. The initial bunch charge was set to 1pC,
using5×104macroparticlestoadequatelyaccountforspace
charge effects. By adjusting key pa... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
95c2906d-73e2-4a6e-9b5d-6b7c4ad595df | tion.Transversebeamsizebroadensdiffractionringsthrough
geometricconvolutioneffects;beamdivergencecausesthe
final electron momentum to be the vector sum of transverse
momentum and diffraction momentum transfer, resulting in
image displacement and distortion; energy spread produces
radial blurring in higher-order rings t... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
b8e2a06e-2fb3-42f2-bea9-8baf355795cb | ducedoscillationamplitudesindiffractionintensitychanges.
Detailedanalysisoftemporalevolutioncurvecharacteristics
enables bunch length reconstruction and can in principle
achievethe non-invasivebunchlengthmeasurement based
on diffraction images.
Figure1illustratesournumericalmethodology:impact
ofelectronbeamonthesampleg... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 0 |
bf9b76af-bbeb-45dc-b439-5d54a35997d1 | Figure1:Schematicdiagramofbunchparameterreconstruc-
tion based on diffraction images. The electron beam probes
a polycrystalline aluminum sample to generate diffraction
rings.AResNet-35networkextractstransversebeamsize,di-
vergenceangle,andenergyspreadfromsingle-framediffrac-
tionimages.Thebunchlengthisdeterminedbyanal... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
f6546a97-2e8b-4552-a0ff-585531d2ca1d | lay times from −200to+2000fsto learn how bunch length
affects the dynamic curves of time-resolved diffraction.
Tointuitivelydemonstratetheeffectsofbunchparameters
on diffraction images, Fig. 2 presents simulation results un-
derdifferentconditions.ComparingFig.2(a)and(b),signif-
icantdifferencesindiffractionringwidthar... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
722e3acf-69eb-4964-913a-e7ac22c1b317 | poralconvolutioneffects.Thesesimulationresults validate
our physical model and provide rich feature information for
neural network training.
SIMULATION RESULTS
Thedeeplearningmodeldemonstratesexcellentperfor-
mance in bunch parameter prediction. Results from 7680
test samples show all parameters tightly distributed alo... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
90507be4-5e5b-4c36-98c3-2a8e642da73a | ofa55-fsbunchatdelaytime 500fs,withtheinsetshowing
distinct changes in diffraction rings; (d) diffraction image
of a 220-fs bunch at the same delay time 500fs, with the
inset showing significantly smoother temporal response and
changes in the center and width of diffraction rings. The
color scale represents normalized ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
2b9f4ed7-59da-4913-9aad-923d9d855ccc | pect of this work. Traditional methods such as using RF-
deflecting cavities are costly and invasive, while using co-
herent transition radiation (CTR) or Smith-Purcell radia-
tion (SPR) requires specialized radiation collection systems.
We achieve the non-invasive measurement based on time-
resolved diffraction, utili... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
a2c1bda5-d1c4-4017-813d-ad41f16d34b3 | achieving the first simultaneous extraction of six-
dimensional phase space information from electron
diffractionimages.Theadvantagesofthismethodinclude:
no additional hardware requirements, utilizing standard | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 1 |
ba4496ed-5991-418e-8e3c-20855260c556 | Figure 3: Prediction results of the beam transverse param-
eters and energy spared. (a) Beam size in 𝑥direction; (b)
divergence angle in 𝑥direction; (c) beam size in 𝑦direction;
(d)divergenceangle in 𝑦direction;(e)energyspread.Scat-
ter point colors represent probability density (purple-low,
yellow-high), with dash... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 2 |
fcd87f14-fb7c-43a8-8cf0-df75c1079f85 | than melting, avoiding sample damage.
To verify the sensitivity to time-of-flight jitter on the pro-
posed method, we artificially added Gaussian-distributed
temporal jitter with 𝜎 =100fs(simulating synchronization
jitter in actual systems) in ASTRA simulations. The predic-
tion accuracy showed no significant change, ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 2 |
2e7532ea-ae81-457c-b3a3-5aaefc79d17e | Figure4:Predictionresultsofthebunchlength.(Left)Com-
parisonbetweenpredictedandactualbunchlengthvalueson
thetestset.Scatterpointcolorsrepresentprobabilitydensity
distribution,withthedashedlineindicatingtheideal1:1cor-
respondence.NormalizedMAE=0.01480,correspondingto
anactualerrorofapproximately 8.7fs,with𝑅2= 0.99599 ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 2 |
04a61bc1-ad2e-407f-9965-2b8605da3cd1 | ofdifferentfacilities.Atthealgorithmiclevel,uncertainty
quantification methods will be introduced to provide con-
fidence intervals for each predicted parameter, enhancing
the interpretability of diagnostic results. Moreover through
integration with accelerator control systems, this intelligent
diagnostic tool may enab... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 2 |
4b8ca322-5884-4dae-8c90-8eede85624c7 | anisms.
ACKNOWLEDGMENT
This work is supported by the Fundamental Research
FundsfortheCentralUniversities(HUST)underProjectNo.
2021GCRC006andNationalNaturalScienceFoundationof
China under project No. 12275094.
REFERENCES
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87e0aafe-1405-4c7b-b78d-e260bb980c0b | 2022. doi:1/zero.alt4.11/zero.alt43/RevModPhys.94./zero.alt445/zero.alt4/zero.alt44
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[5]Z. Zhang et al., “Toward fully... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 3 |
9c369fc4-1118-47b7-b63d-90712a062e79 | Learning”, Adv. Mater. , vol. 35, p. 2206997, 2023.
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[8]C.-Y. Tsai et al., “Low-energy high-brightness electron beam
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Methods Phys. Res. A , vol. 937, pp. 1–20, 2019.
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22a36c57-0533-4620-bfae-0aef4267453b | Nucl. Eng. Technol. ,vol.56, no. 10, pp. 4237–4246, 2024.
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[12]H. Qiet ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 3 |
bc5392e1-df6e-4938-9408-1e93e104d87d | [14]ASTRA:aspacechargetrackingalgorithm, https://www.
desy.de/~mpyflo/
[15]K. Heet al., “Deep residual learning for image recognition”,
in2016ConferenceonComputerVisionandPatternRecogni-
tion (CVPR) , Las Vegas,NV,USA,Jun. 2016, pp. 770–778.
doi:1/zero.alt4.11/zero.alt49/CVPR.2/zero.alt416.9/zero.alt4 | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRMC - Parallel Talk Session 5_ FRMC\FRMC6.pdf | 3 |
35f79b03-d7ad-440e-bbd1-c21979350edf | THE START-TO-END BEAM DYNAMIC S SIMULATION STUDY AND ITS
APPLICATION IN THE HIGH-INTE NSITY CYCLOTRON OF CIAE*
Tianjian Bian†, Fengping Guan, Shizhong An, Sumin Wei, Luyu Ji, Jinrong Lu, Lin Dai, Ruijin Liu,
Yuzhuo Huang, Peng Huang, China Institute of Atomic Energy, Beijing, China
Abstract
The beam dynamics simul... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
c97732f0-1467-4fd2-adab-019220ddc96d | In this paper, start-to-end (S2E) beam-dynamics simula-
tions are performed for an 18 MeV/1 mA high-intensity cy-clotron. Every subsystem, the injection line, spiral inflector,
central region, acceleration re gion, extraction region and
uniform beam-transport line, is modelled quantitatively. Furthermore, the central... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
15ac9970-b473-4e6f-99d4-3b512dc57800 | sation of beam loss are essential. Traditionally, cyclotron beam-dynamics simulations ar e usually performed section-
by-section with assumed initial conditions. Although effi-
cient, this approach introduces cumulativ e errors that pre-
vent quantitative analysis in high-intensity, beam-loss-sen-
sitive machines.
S... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
67ee3ad9-d908-41ef-acbd-eca919d24d8f | ing improvement in beam performance is evaluated. Fur-
thermore, this paper proposes a uniform beamline based on combined-function quadrupole-octupole magnets, and ex-
perimental results show 83% uniformity. INJECTION LINE
The injection beamline focuses and bunches the 35 keV
beam from the H ⁻ ion source. The CYCIAE-... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
8163e302-8952-4abb-91de-6e06953c1475 | Figure 1: Phase space (left plot) and the emittance growth
as function of current (right plot).
Six-dimensional phase space coordinates at the injec-
tion-line exit provide the initial conditions for the spiral in-flector simulation.
SPIRAL INFLECTOR
The spiral inflector bends the axially injected beam into
the me... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
a1ccda77-2643-4531-886e-458ed047395c | density distribution (b).
___________________________________________
* Work supported by Sustained Support Research Project (Grant No.
BJ040261224908), the National Natur al Science Foundation of Chin a
(Grant No. 12375156), China National Nuclear Corporation Fundamental
Research Project (Grant No. CNNC -JCYJ-2024... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 0 |
9383ca66-0936-4b9b-bb38-2456fda67018 | Figure 3 illustrates the axial-defocusing effect of the spi-
ral inflector. At the inflector exit, the beam extends to ap-
proximately ±10 mm, causing approximately 10% losses
in the first acceleration gap. This axial mismatch subse-quently drives further beam loss in the central region.
Figure 3: (a) The axia... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 1 |
adacff34-8448-4a7f-81ec-5735c0af1a42 | degradation.
Starting from the original design, we optimized the
crossing phases of the four acceleration gaps (gap 1-4).
Figure 4 shows the radial-pha se space of the fourth turn,
where the RF phase and radial position are recorded as the
particles cross the gaps. A 40° phase-width beam is injected into the fir... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 1 |
191b1d38-be07-42d0-8308-143ed9060fea | Figure 5 visualises the beam in the spiral inflector and
central region, where the formation of the banana-shaped profile is clearly observed. Particle coordinates from both
the original and optimised central region designs are used
for comparison in subsequent simulations.
ACCELERATION REGION
The Walkinshaw reson... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 2 |
c3b3ae7a-9482-41eb-aa47-1beebd149052 | the resonance are more likely to be lost.
Figure 6 compares the axial beam envelopes obtained
with the original and the optimized central-region designs.
Owing to the removal of large-phase-width particles, the
optimized case shows weaker envelope oscillations and the axial envelope is approximately 25% smaller tha... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 2 |
5671ecae-8908-46b7-b075-37117f0a5c1b | stripping and improving extraction efficiency. Furthermore, relative to the original design, the optimized central region
produces a more compact distribution and a narrower en-
ergy spread in the extracted beam, as shown in Figure 8. This improves beam quality and reduces the risk of losses
at the foil frame and al ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 2 |
6f9337d5-3394-4913-b189-b9552a86a32b | Table 1: The Emittances at the Cyclotron and Beamline
Interface
Normalized
𝜺
𝒙
(π mm∙mrad) Normalized
𝜺𝒛
(π mm∙mrad)
Original 1.7999 0.88742
Optimized 1.0314 0.61256
UNIFORM BEAMLINE
A high-power proton beam from a cyclotron bombards a
fixed target to generate an intense neutron flux or to
produce r... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 2 |
138ff591-c12b-4e5c-8a58-7fc88c085bcb | function multipole magnets to reshape the Gaussian beam
into a rectangular profile with almost uniform distribution.
Uniform beamlines based on multipole magnets are
seldom used in compact accelerators (to the best of our
knowledge, no such uniform beamline exists), because the
beta function at the magnets and th... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 3 |
b5fc09cc-782f-4624-8ced-a619cebbd1fb | beamline.
Owing to limited space in the accelerator hall, the
18 MeV cyclotron is equipped with two beamlines, a
straight one and a bent one, that share a common segment
and deliver the beam to neutron targets 1 and 2,
respectively, as shown in Figure 11. The neutron target 1 is
used for BNCT experiment and the t... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 3 |
5bf16dbe-99fd-4883-9774-b526bf0e281b | without observable surface damage. Throughout the run
the vacuum remained below 5 × 10 ⁻⁷ mbar, confirming that
beam loss was low and insufficient to degrade the vacuum.
Figure 12: (a) Measured and (b) simulated particle-density
distributions on neutron target 1.
SUMMARY
During the development of the 18 MeV/1 ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 3 |
a997fcf4-8367-4dc5-b272-f13900615ef6 | further improvement and needs fine-tuning to achieve a
more homogeneous beam distribution.
REFERENCES
[1] A. Adelmann, A. Alba, and A. Fallahi, “OPAL for Self-Con-
sistent Start-to-End Simulatio n of Undulator-Based Facili-
ties”, presented at North American Particle Accelerator Con-
ference, Albuquerque, New Mexi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 3 |
cb83d01f-7f9a-4fb9-95f4-7ffe404555a9 | doi:10.1103/physrevstab.16.023501
[4] Y . Yuri, N. Miyawaki, T. Kamiya, W. Yokota, K. Arakawa,
and M. Fukuda, “Uniformization of the transverse beam pro-
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doi:10.1103/physrevstab.10.104001 | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\FRNC - Parallel Talk Session 5_ FRNC\FRNC2.pdf | 3 |
43abf1c3-4ef8-42bb-ab28-8d430ac335f4 | PRELIMINARY DESIGN OF THE BEAM TRANSPORT SYSTEM FOR THE
SUPER TAU-CHARM FACILITY*
Ruixuan Huang†,1, Jingyu Tang1, Ze Yu1, Youjin Yuan2
1University of Science and Tec hnology of China, Hefei, China
2Institute of Modern Physics, Chines e Academy of Sciences, Lanzhou, China
Abstract
The injector of the Super Tau-Ch... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
a427b3fa-3776-44e8-9054-fd3922e26ff6 | jection line from the positron linac to the damping ring
(PL2DR), the extraction and transport line from the damp-
ing ring to the main linac (DR2ML), and the final transport
lines from the main linac to the collider rings (ML2CR).
Each segment addresses unique challenges, including transverse emittance preservation... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
70e0bc5c-5e33-4b47-a50e-b0eec25dae75 | dented precision [1-3]. It is envisioned to achieve a peak
luminosity of 5 × 10
34 cm-2s-1 with a center of mass energy
of 2-7 GeV [4-6]. STCF will serve as a unique facility for
precision measurements in th e charm energy region. The
injector is a sophisticated accelerator system to provide high-quality, full-ener... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
d5aff7cf-18e2-4184-935b-de51f71a3280 | a tungsten target to produce positrons. The positron beam
with a bunch charge of 1.0 nC is accelerated to 1.0 GeV in
the positron linac (PL) and injected into a damping ring
(DR) for emittance reduction. Another electron beam with an intensity of 1.0 nC/bunch at 30 Hz is generated from a
photocathode RF gun and ac... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
eba29f2e-2439-416f-85f7-4afdb0871276 | convey the electron and positi on beams separately from the
injector to the collider rings, totally having a length of about 550 m. Optics design an d beam tracking are carried
out to confirm the optics matching and a sufficiently small
emittance of both e-/e+ beams. The main components of
the transport system are... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
09cf689c-df85-412e-9e96-2a803f40dd65 | PL2DR, an energy-spread co mpression system (ECS) is
carefully designed to match a very limited RF acceptance
of the DR. In the DR2ML, a bunch compression sys-
tem (BCS) is necessary to facilitate the transition to the ML. While in the ML2CR, tight restrictions on the geometrical
conditions lead to a large curvature... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
369a02c0-1ffb-4c55-9be9-01c485332b7a | (Fig. 2), the 𝛽 functions at the exit of injection septum in
the DR is adjusted to 𝛽
௫/௬=9.5/4.1 m, and the dispersion
is suppressed to zero, just as the DR required.
____________________________________________
* Work is supported by the National Key R&D Program of China unde r
Contract No. 2022YFA1602202, the N... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 0 |
f177bafa-d8bc-4e9e-8316-bd13ac2d6fe7 | Figure 1: A schematic layout of STCF injector with transport system highlight ed in green dashed lines.
Figure 2: The 𝛽 and dispersion functions for PL2DR.
Figure 3: The 𝛽 and dispersion functions for part of
DR2ML.
Optics of ML2CR
The transport lines of ML2CR has the task of separating
the e-/e+ beams and in... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 1 |
0c92928e-22a8-45d7-b83b-bc97a811fd44 | realized by six 10-degree dipoles. In the R&D stage, the
coupled optics of the alternating bending lattice are treated
by the superposition of separate optics analyses for the hor-
izontal and vertical planes, as shown in (Fig. 4). The
𝛽 functions at the exit of injection septum in the CR is ad-
justed to 𝛽
௫/௬= 1... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 1 |
0c3d5e69-5bb7-40b3-8d3e-187361b74740 | emittance and energy spread are both crucial parameters,
which should be carefully restrained. We used the tracking
code Elegant [8] for beam dynamics optimization. Space
charge effect and coherent synchrotron radiation in dipoles are considered in simulati on. The input beams are mod-
elled as a 3- σ truncated Gaus... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 1 |
c3382c06-bca9-4699-8fce-c13be7eccd34 | sections. Critical beam parameters at the injection point of
each transport line are summarized in Table 1. To ensure a
consistent comparison, all th e emittance discussed in this
paper are the normalized RMS values.
Transverse Emittance Control
For the positron beam, it is quite challenging to preserve
the emitt... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
292de4b3-fae6-4f7f-b937-2aaaa01bf992 | requirements for ML injection.
Figure 6: Evolution of transverse emittance in DR2ML.
Likewise, along the ML2CR lines, a measurable increase
in the beam emittance is also observed. By optimizing the
optics and suppressing the high-order dispersion terms, the emittance growth at the entrance of CR is limited to withi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
863889c2-0844-469f-b673-1e9be1a76871 | The RMS energy spread of the positron beam is substan-tially decreased from 0.6% to 0.2% and the RMS bunch
length is increased from 1.5 mm to 4.3 mm.
The beam extracted from the DR are characterized by a
long bunch length, which mandates the use of a BCS to facilitate downstream acceleration. The BCS comprises an
R... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
7d94eaf3-6ebe-42cc-b5ae-4e34d0e58f6b | three transport segments (PL2DR, DR2ML and ML2CR),
effectively accommodating the distinct challenges of each
section, from energy spread and bunch compression to
complex geometrical constraints. Through meticulous
beam dynamics optimization using the code Elegant, the transverse normalized emittance growth has been... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
95b589e0-5d63-4f32-8e6a-803238e94391 | Charm Facility: The Accelerator”, Nucl. Sci. Tech., vol. 36 ,
pp. 242 , Sep. 2025, arXiv: 2509.11522 [physics.acc-ph].
doi:10.48550/arXiv.2509.11522
[2] Y e Zou et al, “Optics design of the Super Tau-Charm Facility
collider rings”, Jul. 2025, arXiv: 2507.18924 [physics.acc-
ph]. doi:10.48550/arXiv.2507.18924
[3] Linha... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
fedef126-4ff3-47cf-bdf0-0689a27a9129 | doi:10.7693/wl20200803
[6] P . Raimondi et al, “Application of frequency map analysis to
beam-beam effects study in crab waist collision scheme”,
in Proc. EP AC’08, Genoa, Italy, 2008, pp. 2620 .
doi:10.1103/PhysRevSTAB.14.014001
[7]The CEPC Study Group, “CEPC Technical Design Report -
Accel erator”, Radiation Detecti... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THNC - Parallel Talk Session 3_ THNC\THNC3.pdf | 2 |
27e88f14-5ee7-4483-bc65-68e6eabb22ef | TRACKING SIMULATION OF LONGITUDINAL BEAM DYNAMICS IN A
TRIPLE RF SYSTEM FOR ELECTRON STORAGE RINGS
Jincheng Xiao, Tianlong He∗, Weimin Li†
National Synchrotron Radiation Laboratory, USTC, Hefei, China
Abstract
For diffraction-limited storage rings, the triple radio-
frequency(RF)systemhasbeenproposedtoachievefurther
bu... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
7deeec92-d4c5-4172-9a8f-a7a69cc8c61d | INTRODUCTION
TheuseofadoubleRFsystemtolengthenthebunchto
mitigateintrabeamscattering(IBS)andTouschekscattering
effects has been widely adopted in fourth-generation light
sources[1,2]. Morerecently,atripleRFsystemhasbeenpro-
posedtofurtherextendthebunchlengthandmeetspecific
requirementsforlongitudinalinjection. Theoreti... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
7b2f1721-089d-46ad-a189-a4da05db1891 | opedfordoubleRFsystems[4 –6],whicharegoodreferences
toimplementtrackingsimulationfortripleRFsystems. In
thiswork,weextendtheSTABLEcode—aGPU-accelerated
multi-particle,multi-bunchtrackingmethod—byincorporat-
ingadditionalfunctionalmodulestoenablethesimulationof
triple RF systems [6]. This extended code is then applied t... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
b337cb50-231a-42e8-9141-31b1b7443a45 | ∗htlong@ustc.edu.cn
†lwm@ustc.edu.cnlongitudinal beam dynamics in a triple RF system, relevant
functionalmodulesareintegratedintothecode. Theprocess
for running this code is shown in Fig. 1.
Figure 1: The flowchart of STABLE.
Related Function Modules
PI feedback module To achieve a realistic LLRF feed-
back for the RF ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
0c9483ea-b474-40b6-8fc3-1c56b7df0dd8 | tively. Last the generator current phasor is updated with
Δ˜𝐼𝑔+˜𝐼𝑔0, where ˜𝐼𝑔0is the initialized generator current pha-
sor, and it is subsequently applied to the cavity voltage after
a specified delay 𝑑. A detailed flowchart illustrating this
process is provided in Fig. 6 of Reference [7].
Initially, this modu... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
1a1076f7-1805-46c1-9974-4d2bf10c4437 | at the target voltage. In the passive RF cavity mode, the
cavity voltage is determined solely by the beam loading
voltage. IntheactiveRFcavitymode,aPIfeedbackmodule
isincorporated,ensuringthatthetotalcavityvoltageisthe
sumofthebeamloadingvoltageandthetransmittervoltage. | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 0 |
daee9356-c216-4cd3-b8ad-c65ca1e8939b | Parameter Initialization
Before running the STABLE code, it is essential to ini-
tialize the relevant parameters. A dedicated initialization
section has been implemented in the code, organizing the
parameters into a structured variable to prevent data con-
flicts during computation. The main parameter settings are
divi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
32412731-d27c-474b-b163-0f25b30c5f63 | tivemode,thetargettotalcavityvoltagemustbespecified.
Typically,therequiredcavityvoltagesforthetargetbunch
lengthening scheme are precomputed using analytical for-
mulas.
Inthisstudy,theparametersarebasedontheMCand3HC
settingsinHALF’sdoubleRFsystemscheme. Forthethree
activelycontrolledRFcavitiesinthetripleRFsystemunder
... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
7d9118f1-39de-4e43-85c0-53af68c05a37 | ing voltage in equilibrium should be as close as possible
to the target cavity voltage to minimize transmitter power.
Thedetuningfrequency Δ𝑓andunloadimpedance 𝑅𝑠are
calculated accordingly:
𝑅𝑠=𝑉𝑐
2𝐼0𝐹cos(𝜓), (3)
Δ𝑓=𝑛𝑓𝑟𝑓tan(𝜓)
2𝑄𝑠, (4)
where𝜓isthedetuningangleand 𝑄𝑠istheunloadquality
factor.
PI Feed... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
bec6ac61-30a5-4f92-b7e0-b26075f9bee1 | small𝐾𝐼resultsinslowconvergenceofthecavityvoltage
to the target value.
Inthisstudy, 𝐾𝑃issetto1,while 𝐾𝐼ischosenwithinthe
range of 0.01 to 0.1.
APPLICATION TO HALF
Benchmark Test
To verify the accuracy of the modified STABLE code,
we computed the steady-state bunch distribution in HALF’s
triple RF system under opt... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
07938e55-5655-4c55-aa14-838b9b94073b | analytical method results, and the scatter points in blue rep-
resent the tracing simulation results.
Figure2showsthatthetrackingsimulationresultsclosely
match those obtained from the semi-analytic calculation,
confirmingthecorrectnessoftheextendedSTABLEcode.
All simulations were conducted using a GeForce RTX 4070
GPU,... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
03206ac7-bc9f-4a26-93df-e270f2aca943 | of PTBL is positively correlated with both the beam current
andtheR/QvalueoftheHC.Therefore,todesigntheHC
parameters of the triple RF system effectively, it is essential
to study PTBL using tracking simulations.
It is commonly believed that adding a higher-order HC
with an opposite detuning direction can help dampen th... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 1 |
bbf36398-04cc-467e-935f-2d928699d779 | PTBLinducedbythelower-orderHC.However,ourtrack-
ingresultsshowthatthisassumptionisincorrect. Figure3
presents the tracking results of the beam’s longitudinal mo-
tionafter300,000turnsatstandardbeamcurrentusingSTA-
BLE.
Figure3: Thebunch-by-bunchcenters(bottom)andbunch
lengths(top)distributionfor800bunchesatbeamcurrent
... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 2 |
727bc576-3f37-4359-a751-b20b44c4737d | Another Bunch Equilibrium Density Distribution
Itisworthmentioningthatduringthestudyoftheanoma-
lous PTBL phenomenon, an unexpected bunch equilibrium
density distribution was observed. When 3HC was set as
an ideal cavity and 5HC as apassive cavity (thus no longer
providingoptimalbunchstretching),thebunchcenterwas
found... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 2 |
7c0388c0-b8d6-4efc-b641-354035173aa5 | thesynchronousphase. Moreover,thebunchlengthbecomes
7ps, much less than expected.
Notably, when the working mode of 5HC was changed
to an active cavity, this instability was suppressed under the
sametargetcavityvoltage. Thisdemonstratesthatcontrol-
lingthecavityvoltagethroughPIfeedbackcaneffectively
mitigatetheinstabil... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 2 |
a44a0ee5-969a-49f2-b664-06ecd7044ada | phenomenon may be driven by the beam loading of 5HC
anddampedby3HC,highlightingacomplexinteractionthat
warrants further investigation.
CONCLUSION
In this paper, we expanded the STABLE code and modu-
larized it to facilitate and enhance the study of longitudinal
beamdynamicsinatripleRFsystem. Benchmarktestresults
indica... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 2 |
b8864201-35c0-4b3f-ba8b-712468b6e462 | ally, the influence of higher-order modes on longitudinal
beam motion will be considered in subsequent research.
ACKNOWLEDGEMENTS
This work was supported by the National Natural Sci-
ence Foundation of China (No.12375324, No.12105284,
andNo.11475167)andtheFundamentalResearchFundsfor
the Central Universities (No.WK23100... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 2 |
1abd05c9-2fb8-4dde-8a2b-1da5b188eb62 | [3]G. Bassi, A. Khan, and V. Smaluk, “Bunch lengthening in-
duced by a combination of higher-harmonic cavities of differ-
entorderinlow-emittancerings”,in Proc. IPAC’24 ,Nashville,
TN, USA, May 2024, pp. 2952–2955.
doi:10.18429/JACoW-IPAC2024-THBD2
[4]G. Skripka, R. Nagaoka, M. Klein, F. Cullinan, and
P. F. Tavares , “... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 3 |
b7c0d7b7-445b-48e2-baa5-7e9bf1453085 | lationforlongitudinalbeamdynamicsofarbitrarybunchtrains
in electron storage rings”, Phys. Rev. Accel. Beams , vol. 24, p.
104401, 2021.
doi:10.1103/PhysRevAccelBeams.24.104401
[7]T.L.He,W.W.Li,Z.H.Bai,andW.M.Li,“Analyticformulas
fortheD-modeRobinsoninstability”, Phys. Rev. Accel. Beams ,
vol. 27, p. 064402, 2024.
doi:1... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP02.pdf | 3 |
0fcbcc35-8787-4fc2-b1f1-dd4112c75c68 | A UNIVERSAL NUMERICALOPTIMIZATIONFRAMEWORK FOR
STUDYING SEEDEDFREE-ELECTRONLASER SCHEMES
Zihan Wang, Zhenghe Bai∗, Guangyao Feng†
National Synchrotron Radiation Laboratory, USTC, Hefei,China
Abstract
Seeded free-electron lasers (FELs) have become indis-
pensable tools across numerous scientific fields, owing to
theirhi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
1ee72b44-465d-4f92-bca1-c3bf1ab8e865 | INTRODUCTION
Free-electron lasers (FELs) represent a transforma-
tive light source capable of generating high-brightness,
megawatt-level pulsed beams with femtosecond-scale du-
ration and exceptional spatial-temporal coherence [1]. A
leadingapproachtogeneratingshort-wavelengthradiation
in the ultraviolet and X-ray regi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
b4006add-3a3c-49b7-a74c-2db794faf7b5 | opticalcomponents. Thispre-bunchedbeamthentraverses
an undulator magnet. Within the high-gain FEL regime,
theinducedmicro-bunchingisamplifiedthroughcoherent
emission and energy extraction, generating intense, fully
coherentradiationattheseedwavelengthoritsharmonics.
Achievingmicro-bunchingisthemostimportantaspectof
see... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
12290df6-19ae-422e-b22b-4621fec943aa | muchhigherharmonicdensitymodulationinthebeamfrom
a relatively smallinitialenergymodulation.
DifferentseededFELsproducedistinctmicro-bunching
patternsduetotheiruniquephasespacemanipulationmech-
∗baizhe@ustc.edu.cn
†fenggy@ustc.edu.cnanisms. In this paper, we propose a general-purpose numer-
ical framework utilizing inte... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
62795c69-3503-4277-8ec7-b2956b564b11 | element definition layer specifies all seed lasers and optical
elementsavailablefortheoptimizationprocess,withtheir
parameters treated as variables within this framework. The
initial beam state defines critical parameters of the initial
beam configuration, including beam energy,relative energy
spread, and phase space d... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
1a62d68a-5306-4c95-9a7a-244e2543b0fd | First, all available seed lasers, optical elements, and criti-
cal parameters of the initial beam configuration are defined
in the element definition layer and the initial beam state.
Theseinitialconditionsarethenpassedtothe“blackbox”
layer for application of IOA. Within this layer, potential
schemesaresimulated. Forea... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
4f2f8605-0e02-4e88-a43e-7dc650b456e2 | inghigh-performanceseededFELsthatuseonlyseedlasers
for energymodulation and chicanes for density modulation.
Forsimplicity and generality,we neglectthe process in the
last radiator. Considering the synchronization challenges
inherentinmulti-lasersystemsandthecomplexityofcon-
figuration, we configure the element definit... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 0 |
b94b7e76-2c15-4835-a6d4-4e34a1dba416 | Element Definition Layer
Seed Laser Module Chicane
Quadrupole
…
Initial Beam State
(𝑋,𝑋′,𝑌,𝑌′,𝑍,𝛿) Beam Vector :
𝐸0 and 𝜎𝐸
Initial 𝑍−𝛿 Phase Space“Black Box” Layer
Intelligent
OptimizationFinal Beam State
Beam Vector : (𝑋,𝑋′,𝑌,𝑌′,𝑍,𝛿) CalculationAnalysis
Final 𝑍−𝛿 Phase SpaceObjective Layer
𝑏𝑛=1
�... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 1 |
5f412708-778e-4445-8245-17eb8464ac91 | ticbunchingfactordesignatedasoptimizationtargets. For
each scheme, the maximum harmonic number at which the
bunchingfactorexceeds0.02isdesignatedasitscharacteris-
tic harmonic number. The characteristic bunching factor is
defined as that corresponding to the characteristic harmonic
number. Table1liststherangesofkeypara... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 1 |
70537038-aa66-4595-bdaa-4be6518a6b72 | a modified characteristic bunching factor. The expressionforthis modifiedcharacteristicbunchingfactoratthe h-th
harmoniccan beexpandedas:
̃𝐵(ℎ) = 𝐵(ℎ)−𝑁e⋅𝑓(ℎ) (1)
where𝐵(ℎ)isthecharacteristicbunchingfactorforthe h-th
harmonic, 𝑁eisthenumberofphysicalelements,and 𝑓(ℎ)
isapre-definedevaluationfunctionthatisalwaysp... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 1 |
1ee01aad-bd89-442c-aae0-83ac6f84a3d8 | anismdiffersfrombothHGHGandEEHG.Forharmonic
numbers exceeding 50, the other three schemes utilizing
three lasers can also achieve significantly larger bunching
factorsthroughpreciseconfigurationsoflasersandchicanes.
This optimization frameworksuccessfullyreproduces es-
tablished results for HGHG and EEHG while revealin... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 1 |
664623cf-35bf-4361-bfee-3dc62cb18a9c | 20 40 60 80 100 120 140 160 180 200
Characteristic Harmonic Number0.10.150.20.250.30.35Characteristic Bunching FactorLC
LLC
LCLC
LCLLC
LLCLC
LCLCLCFigure2: Characteristic harmonic numbers and characteris-
tic bunching factors of different schemes from the optimiza-
tion framework, where the evaluation function is defin... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 2 |
f0f740f8-ab87-40dc-bfda-6b487604b608 | EEHG.However,theirconfigurationsareinherentlymore
complex. Furthermore, their physical mechanism closely
resembles that of EEHG, differing primarily in the addition
ofanextrapre-bunchingstage,thusenhancingthebunching
factors at specificharmonicnumbers.
CONCLUSION
In this work, we proposed a universal numerical opti-
mi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 2 |
3ea64e4e-6afa-40ba-813c-b95d499e71a2 | chicanesalone.
This optimization framework enables the discovery of
novel seeded FEL configurations. Future work will enhance
theframeworkbyincorporatingadditionalphysicalelements
andmodifyingtheinitialbeamstate,withthegoalofcon-
sidering other physical mechanisms. Our research revealed
thatrelyingsolelyonharmonicnumbe... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 2 |
b7647aae-86a7-4242-adad-08152e7a6789 | [2]E.L. Saldin, E.A. Schneidmiller, and M.V. Yurkov, “Influence
of nonlinear effects on statistical properties of the radiation
from SASE FEL”, Nucl. Instrum. Methods A, vol. 407, pp.
285–290, 1998. doi:1/zero.alt4.1/zero.alt416/S/zero.alt4168-9/zero.alt4/zero.alt42(98)/zero.alt4/zero.alt4/zero.alt436-9
[3]L.H.Yu,“Gene... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP03.pdf | 2 |
a838d7e4-2512-4c87-9fd1-855e1492d7c4 | MINIMIZING THE FLUCTUATION OF STORAGE RING RESONANCE
DRIVING TERMS USING THE STEP-BY-STEP CHROMATICITY
COMPENSATION METHOD
Wanbin Li∗, Yuejing Huang, Zihan Wang, Bingfeng Wei†, Penghui Yang, Zhenghe Bai‡
NSRL, University of Science and Technology of China, Hefei, China
Abstract
Our recent studies showed that reducing t... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 0 |
a01244c2-f694-45fc-84f0-76615b11e9c4 | INTRODUCTION
Achieving a large dynamic aperture (DA) is a critical ob-
jective in thelattice design of a low-emittance storagering.
The numerical approach based on particle tracking is highly
powerfulforDAoptimizationbutcomesattheexpenseof
highcomputational cost. Theanalytical approachbased on
the minimization of reson... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 0 |
0ff0eeae-59f8-4936-b47b-2299ccdbe9c9 | RDT fluctuations.
THE SCC METHOD REVISITED AND
MODIFICATION
Figure1: Schematicofthestep-by-stepchromaticitycom-
pensation method.
∗wanbin_li@mail.ustc.edu.cn
†weibf@ustc.edu.cn
‡baizhe@ustc.edu.cnIn the SCC method [3], shown in Fig. 1, the horizontal
and vertical chromaticities are corrected by taking 𝑁small
steps fro... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 0 |
26b28d2c-fa6a-4d4a-aada-d484b4abdb47 | becomes indistinguishable, making it hard to identify the
best pair for chromaticity correction at each step. Conse-
quently, this causes the effectiveness of the SCC method to
break down.
Ourrecentstudiesfoundaverystrongcorrelationbetween
reducing RDT fluctuations and enlarging DA. Based on this
correlation, the fluct... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 0 |
1e9a6523-33ac-4366-bb57-0ef50b9cecfc | TheHLS-IIIstorageringlattice[4]wasusedtoapplyand
validate the SCC method. The optical functions and magnet
layoutofthelatticearepresentedinFig.2. Thelatticehas
seven families of sextupoles used for chromaticity correc-
tion and nonlinear dynamics optimization. To facilitate a
comparisonbetweentheSCCmethodwithRDTfluctua... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 0 |
7b65d971-2d17-4113-95c6-13872a90b541 | beingminimizedandthescanningmethodbasedonparticle
tracking, the seven families of sextupoles were regrouped
into five, including two focusing ( 𝑆𝐹1,𝑆𝐹 2) and three defo-
cusing (𝑆𝐷1,𝑆𝐷 2,𝑆𝐷 3) families. This makes six sextupole
pairs for evaluation: ( 𝑆𝐹1,𝑆𝐷 1), (𝑆𝐹1,𝑆𝐷 2), (𝑆𝐹1,𝑆𝐷 3),
(𝑆𝐹2,𝑆𝐷... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 1 |
86c61ea5-9cdb-400c-8f91-8710a2d9464f | from an arbitrary chromaticity point ( 𝜉𝑥2,𝜉𝑦2) to (𝜉𝑥1,𝜉𝑦1),
as shown in Fig. 3. The changes of 𝑓3,rmsalong the three
paths are shown in Fig. 4. Figures 3 and 4 demonstrate that
the final value of 𝑓3,rmsis essentially identical for a fixed
endpoint (𝜉𝑥1,𝜉𝑦1), independent of the chromaticity com-
pensatio... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 1 |
e07ed2ec-4909-4124-957b-622eae5abfbe | in Fig. 6. Notably, unlike the original SCC method that
maximizes the DA area, our SCC method that minimizes
RDTfluctuationsavoidsconvergencedegradationevenas 𝑁
increases to a very large value. The fast convergence of the
SCCmethodisevidentfromacomparisonbetween 𝑁=10
and𝑁=1000, showing that the overall usage proport... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 1 |
9a3a3f64-77b1-4768-b692-d8aa3ed5ad6c | rithm. The DE algorithm was parameterized with the sex-
tupolestrengthsasvariables, 𝑓3,rmsastheobjectivefunction,
a population size of 100 and a maximum iteration of 60.
Figure 7 presents a comparison of the sextupole strengths
obtained using the SCC method ( 𝑁= 1000) and the DE
algorithm(after60generations),bothwith... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 2 |
582919f7-44b7-42e2-b808-c8542f93d940 | and 6000.
Figure 8 shows the 𝑓3,rmsvalues obtained using the SCC
method and the DE algorithm for computation counts of
300(correspondingto 𝑁=50and 3generations),1200( 𝑁
= 200 and 12 generations), and 6000 ( 𝑁= 1000 and 60
generations). A clear observation is that the SCC method
converges markedly faster than the DE... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 2 |
0f86725a-549d-4562-bf65-35470b1608cb | displayed in the figure. It is seen that the results from the
twomethodsareincloseagreement,indicatingthattheSCC
method with RDT fluctuations being minimized can rapidly
find solution regions with large DAs.
Minimizing Third- and Fourth-order RDT Fluctu-
ations
Figure 10: The 𝑓3,rms+𝑤·𝑓4,rms(𝑤= 0.01 m−1) values
obt... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP04.pdf | 2 |
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