bluuebunny/crossref_metadata_2025 huggingface dataset:
Shortwave infrared and visible light image fusion method based on dual discriminator GAN
Authors: Huang Pengxing , Liu Xiaojie , Zhao Shiqi , Ma Ruyue , Dong Hao , Wang Chenguang , Cao Huiliang , Shen Chong
Published: January 2024

In a tactical warfare setting, the efficacy of target detection becomes profoundly compromised due to prevalent environmental factors such as smoke, dust, and atmospheric interference. Such impediments invariably undermine the precision and reliability of identifying pivotal targets, thereby precipitating potentially dire ramifications. Remarkably, short-wave infrared technology has exhibited unparalleled proficiency in elucidating target attributes even amidst challenging conditions characterized by smoke, fog, or haze. Against this backdrop, the present study delineates a pioneering algorithmic framework that seamlessly amalgamates the imperatives of image registration and fusion. This is achieved through the deployment of an advanced dual-discriminator Generative Adversarial Network (GAN), specifically tailored for amalgamating short-wave infrared and visible light imagery within smoke-obscured contexts. Our methodology commences with the introduction of an augmented Speeded-Up Robust Features (SURF) algorithm, meticulously designed to rectify inherent misalignments within the input imagery. Subsequent enhancements encompass the refinement of the generator’s loss function and the integration of a multi-scale convolutional kernel, thereby facilitating the extraction and amalgamation of a more expansive array of salient features. This concerted effort culminates in the elevation of image fusion quality. To corroborate the efficacy and robustness of our proposed framework, rigorous validation procedures were conducted utilizing a meticulously curated dataset comprising short-wave infrared and visible light images. Empirical evaluations, encompassing both subjective and objective comparative analyses, unequivocally affirm the superior performance metrics of our fusion network. Specifically, our methodology surpasses alternative fusion techniques across multiple dimensions, including visual fidelity, perceptual quality, and structural congruence of synthesized images.
Dynamical system method of viscous fluid in f(T) gravity theory
Authors: Samaddar Amit , Sanasam Surendra
Published: January 2024

In this paper, using the recently introduced f(T) gravity framework, we have analyzed the viscous fluid cosmological model in FLRW cosmological model by assuming a specific form of the bulk viscosity coefficient as,

ζ
=

ζ

0

+

ζ

1

H
+

ζ

2

H

̇

H

+
H

and a non-linear f(T) model particularly,

f
(
T
)
=
T
−
α

−
T

where α is the model parameter. The bulk viscosity coefficients are estimated by using Hubble 31 data set. Using the phase space technique, we examine the asymptotic behaviour of our cosmological bulk viscous model. We found one stable critical point. Phase space analysis and the geometrical interpretations are given. We discover that according to our model, the Universe evolved from a matter-dominated decelerated phase (a past attractor) to a stable de-Sitter accelerated epoch (a future attractor). The evolution of EoS parameter shows the acceleration phase of the cosmic expansion whereas the negative behavior of viscosity-induced pressure indicates the accelerated expansion of the Universe. Additionally, the cosmic matter-energy density exhibits positive behavior. We look into how statefinder parameters behave for our model . We discover that the trajectory of our model starts at the quintessence and ends at the ΛCDM region. We use the Om diagnostic test, which reveals that our model displays quintessence behaviour. The energy condition criteria are analyzed, and we discover that SEC has been violated, whereas WEC, NEC and DEC satisfy the positivity criteria. Our f(T) cosmological model, with the influence of bulk viscosity successfully describes the expansion history of the Universe and provides a good fit to recent observational data.
Study on the removal of methylene blue by submerged Arc generated by titanium and iron electrodes
Authors: Mo Yongpeng , Yu Xi , Chen Honghao , Zhang Jiajian , Jia Rongzhao , Jia Shenli , Shi Zongqian
Published: January 2024

Methylene blue (MB) solution was treated by the submerged arcs generated by the titanium (Ti) and iron (Fe) electrodes, with a subsequent aging process. The removal ratio of each condition was recorded by the absorbance of the treated solution. The experimental results indicated that the submerged arc with Fe electrodes is more efficient with an efficiency nearly 90% after 3.5 min of treatment. Reversible decolorization was observed in the MB solution treated by the Fe submerged arc. However, the removal ratio in the MB solution treated by the Ti submerged arc continuously increased during both the treating and aging process. Furthermore, the particles eroded from the Ti electrodes were characterized by SEM and XRD, and the titanic oxides including TiO, TiO2 and Ti3O5 were found with different diameters ranging from 1 μm to 20 μm. Moreover, complete decomposition occurred during the treatment by the submerged arc generated by the Ti electrodes. The eroded particles from the Fe electrodes were examined by XRD, and the majority of the composition was iron. Unlike the Ti electrodes, the decolorization process by the submerged arc of Fe electrodes was more likely related to the formation of colorless leuco-MB and the physical adsorption by iron hydroxides. Additionally, the pH and chemical oxygen demand (COD) of the treated solutions were also discussed.
Identifying temporal correlations between natural single-shot videos and EEG signals
Authors: Yao Yuanyuan , Stebner Axel , Tuytelaars Tinne , Geirnaert Simon , Bertrand Alexander
Published: January 2024

Objective. Electroencephalography (EEG) is a widely used technology for recording brain activity in brain-computer interface (BCI) research, where understanding the encoding-decoding relationship between stimuli and neural responses is a fundamental challenge. Recently, there is a growing interest in encoding-decoding natural stimuli in a single-trial setting, as opposed to traditional BCI literature where multi-trial presentations of synthetic stimuli are commonplace. While EEG responses to natural speech have been extensively studied, such stimulus-following EEG responses to natural video footage remain underexplored. Approach. We collect a new EEG dataset with subjects passively viewing a film clip and extract a few video features that have been found to be temporally correlated with EEG signals. However, our analysis reveals that these correlations are mainly driven by shot cuts in the video. To avoid the confounds related to shot cuts, we construct another EEG dataset with natural single-shot videos as stimuli and propose a new set of object-based features. Main results. We demonstrate that previous video features lack robustness in capturing the coupling with EEG signals in the absence of shot cuts, and that the proposed object-based features exhibit significantly higher correlations. Furthermore, we show that the correlations obtained with these proposed features are not dominantly driven by eye movements. Additionally, we quantitatively verify the superiority of the proposed features in a match-mismatch task. Finally, we evaluate to what extent these proposed features explain the variance in coherent stimulus responses across subjects. Significance. This work provides valuable insights into feature design for video-EEG analysis and paves the way for applications such as visual attention decoding.
Nonlinear spatio-temporal filter to reduce crosstalk in bipolar electromyogram
Authors: Mesin Luca
Published: January 2024

Objective. The wide detection volume of surface electromyogram (EMG) makes it prone to crosstalk, i.e. the signal from other muscles than the target one. Removing this perturbation from bipolar recordings is an important open problem for many applications. Approach. An innovative nonlinear spatio-temporal filter is developed to estimate the EMG generated by the target muscle by processing noisy signals from two bipolar channels, placed over the target and the crosstalk muscle, respectively. The filter is trained on some calibration data and then can be applied on new signals. Tests are provided in simulations (considering different thicknesses of the subcutaneous tissue, inter-electrode distances, locations of the EMG channels, force levels) and experiments (from pronator teres and flexor carpi radialis of 8 healthy subjects). Main results. The proposed filter allows to reduce the effect of crosstalk in all investigated conditions, with a statistically significant reduction of its root mean squared of about 20%, both in simulated and experimental data. Its performances are also superior to those of a blind source separation method applied to the same data. Significance. The proposed filter is simple to be applied and feasible in applications in which single bipolar channels are placed over the muscles of interest. It can be useful in many fields, such as in gait analysis, tests of myoelectric fatigue, rehabilitation with EMG biofeedback, clinical studies, prosthesis control.
Design and analysis of a PAM launcher at 4.6 GHz for a new LHCD system on EAST
Authors: Li M.H. , Liu L. , Yang Y. , Zhao L.M. , Ma W.D. , Zhou T.A. , Wang M. , Ma W.Q. , Wu C.B. , Ding B.J. , Jia H. , Wu Z.G. , Zhou W.Y. , Li X.L. , Yin L. , Hillairet J. , Savoye-Peysson Y. , Goniche M. , Ekedahl A. , Gong X.Z.
Published: January 2024

To improve the Current Drive (CD) capability in long-pulse (up to ∼1000 s) H-mode operation, it has been decided to develop a new Lower Hybrid Current Drive system at 4.6 GHz with an active cooling Passive Active Multijunction (PAM) launcher on EAST. In this paper, both the radio frequency (RF) and the physical properties of this PAM are studied numerically. The same nominal parallel refractive index (N
|| = k
||c/ω, where k
|| is the parallel wavenumber, c the velocity of light, and ω the wave angular frequency) of 2.04 as the existing 4.6 GHz Full Active Multijunction (FAM) is chosen. Ray-tracing calculations indicate that good accessibility could be achieved when the LH waves radiate with this nominal N
|| in typical long-pulse H-mode plasmas. The coupling performance in terms of power reflection coefficient (R
C), power spectrum, maximum electric field, power directivity (D
P) and global CD capability is evaluated with the ALOHA code based on the linear coupling theory. Good coupling performance with averaged R
C ⩽ 1% and D
P ∼ 70% could be expected with the density (n
e) in front of the PAM close to the cut-off value (n
e_co). The simulated R
C remains below 6.5% over a wide density range 0.5 ⩽ n
e/n
e_co ⩽ 10, which is similar to the plasma edge conditions produced by Edge Localized Mode activity. A detailed comparison with the existing 4.6 GHz FAM launcher is also performed.
Preface of the IPAC23 Proceedings
Authors: Assmann Ralph W.
Published: January 2024

The 14th International Particle Accelerator Conference, IPAC’23, took place at the Venice Convention Centre, Venice, Italy, from Sunday to Friday, 7 to 12 May, 2023. The conference was hosted by the Elettra Sincrotrone Trieste (Elettra) and Istituto Nazionale di Fisica Nucleare (INFN) and organised under the auspices of the European Physical Society Accelerator Group (EPS-AG) and the International Union of Pure and Applied Physics (IUPAP). With its record participation, the highest number of submitted papers in an accelerator conference to date and the largest ever industrial exhibition, the conference covered a wide range of excellent results and projects in accelerator science, technology and industry. This proceedings volume includes the peer reviewed part of the papers that were presented at IPAC’23.
Optimizing Pb beam losses at the LHCb for maximum luminosity
Authors: Frasca A , Bruce R , Cerutti F , Ciccotelli A , Patecki M
Published: January 2024

In addition to the physics program with proton beams, the Large Hadron Collider (LHC) at CERN also provides collisions of fully-stripped Pb beams for about one month per year. When colliding Pb nuclei, electromagnetic interactions are the dominating processes because of the intense Coulomb field produced by the ions. These ’ultra-peripheral’ interactions give rise to ions with a changed magnetic rigidity. This causes losses in the machine that can impose limits on the luminosity. Among them, the bound-free pair production (BFPP) causes a localised power deposition downstream of each collision point, which could induce superconducting magnet quenches if not well controlled. These losses were studied and successfully mitigated for most LHC experiments, however the recent request by LHCb to increase the Pb-Pb luminosity requires a revision of BFPP collisional loss limitations. In this paper, the simulation of BFPP losses from Pb-Pb collisions around LHCb is presented. The loss patterns are discussed for different beam parameters. Finally, a mitigation strategy by means of an orbit bump is studied.
Simulations and measurements of collisional losses with Pb beams at the LHC
Authors: Frasca A , Abramov A , Bruce R , Cai R , Cerutti F , Esposito L , Lindström B , Van der Veken F , Ziliotto F , Patecki M
Published: January 2024

For about one month per operational year, the Large Hadron Collider (LHC) at CERN works as a heavy-ion collider. Four one-month Pb-Pb runs have been executed so far as well as two p-Pb runs. The LHC heavy-ion programme is scheduled to continue in the future, featuring increased luminosity and beam energy. Beam losses caused by ions fragmenting in the collision process risk introducing performance limitations. Losses occur immediately downstream of the collision points as well as at other locations in the ring, through multi-turn beam dynamics processes and interactions with ring collimators. This paper presents first simulations of collisional loss patterns for nuclear beams using a new simulation approach that relies on the SixTrack-FLUKA coupling simulation tool, including nuclear fragmentation and electron capture in the collisions. Simulations of the 2018 Pb-Pb and 2016 p-Pb runs are compared against experimental data and the prediction of collisional losses for future Pb-Pb and p-Pb runs is shown.
Bunch lifetime analysis based on the injection interval at SuperKEKB
Authors: Kaji Hiroshi , Funakoshi Yoshihiro , Uehara Sadaharu
Published: January 2024

We study the bunch lifetime dependence on the bunch position at the SuperKEKB main ring. The bunch lifetime ratio is evaluated from the injection interval. The lifetime imbalance is observed between the forward and backward of the bunch train at the positron ring. It becomes larger when the beam current becomes larger. The luminosity dependence on the RF-bucket spacing can be explained with the lifetime dependency which we determined in this analysis. The result indicates the existence of the unknown phenomenon which varies the Touschek lifetime with the RF-bucket spacing in the electron ring.
Benchmarking the FCC-ee positron source simulation tools using the SuperKEKB results
Authors: Alharthi F. , Chaikovska I. , Chehab R. , Zhao Y. , Latina A. , Enomoto Y. , Miyahara F. , Mytrochenko V.
Published: January 2024

For the Future Circular Collider (FCC-ee), particular attention is drawn to the crucial role of the positron source. Two positron production schemes are considered for the FCC-ee: the conventional scheme and the crystal-based (hybrid) scheme that involves channelling radiation in the oriented crystals. A start-to-end simulation toolkit should be developed to design and optimize positron production and capture by considering the positron injector parameters, including the electron drive beam and final system acceptance. This paper presents the first results of benchmarking the FCC-ee positron source simulation tools using the SuperKEKB positron source currently in operation. The model starts with the production of positrons and target studies in Geant4. Then, the RF-Track code is used to capture and track the generated positrons through the capture section composed of a matching device and several accelerating structures embedded in the solenoid field to accelerate the positrons up to 120 MeV. After that, the positrons are further accelerated up to the energy of the Damping Ring (1.1 GeV). Finally, the SuperKEKB capture system is applied to the FCC-ee positron injector within the framework of the design studies.
Beam Loading Compensation of Traveling Wave Linac to a Multi-bunch Pulse with Gaps
Authors: Kuriki M , Kuroguchi S , Tajino H , Takahashi T , Liptak Z , Omori T , Urakawa J , Yokoya K.
Published: January 2024

In the electron driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 4 mini-trains with several gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. The beam loading is compensated by amplitude modulation on the input RF in the positron booster composed from L-band and S-band traveling wave RF cavity. In this article, we derive the exact solution for the compensation with the gaps. In addition, we evaluate the effect of the time constant (delay) of the input RF modulation due to klystron Q-value.
Design, testing, and validating the CLIC module pre-alignment and alignment systems
Authors: Capstick M , Doebert S , Rossi C , Brown J
Published: January 2024

The Compact Linear Collider requires micron-level alignment of the key accelerator components within the two 21 km main LINACs to achieve the desired luminosity. Several Super Accelerating Structures (SAS) will be pre-aligned on a single common support structure to within 14μm. This common support structure will then be actively aligned relative to a Machine Reference Network, and in operation beam-based alignment will be used to achieve the final 1 μm alignment required. A design for the SAS pre-alignment system has been created, prototyped, and tested, and shown to match the design performance within 2.3 μm/turn, and to meet the specification requirements. A design for the active girder alignment system has also been created, prototyped, and initial testing has begun. This testing indicates that the system works as designed. Finally, the testing required to confirm this, and to fully validate the CLIC alignment procedure, is discussed.
An iterative algorithm to estimate the energy spectrum of an electron beam from PDD curves
Authors: Nichelatti Enrico , Astorino Maria Denise , Borgognoni Fabio , Ronsivalle Concetta
Published: January 2024

Electron beam central-axis percentage depth dose (PDD) curves in water phantom are routinely employed to evaluate the electron beam energy at the phantom surface, in particular the mean and most probable energies from the values of R
50 (half-value range) and Rp
(practical range). However, these two quantities are not enough to evaluate important details of the energy distribution, such as the FWHM (Full Width Half Maximum) and the possible presence of a low-energy tail. This paper presents a numerical method that allows estimating the shape of the energy spectrum from a PDD curve. The algorithm uses a database consisting of a set of depth dose curves for monochromatic beams computed by FLUKA in the range 0.1-7.0 MeV by steps of 0.1 MeV and, using an adaptive iterative Monte Carlo process, reconstructs the incident energy spectrum by minimizing the distance between the measured PDD and the computed one. Applications of a MATLAB code based on this algorithm to simulated and real measurements of electron beams done at APAM lab (ENEA Frascati) are presented. This approach represents a strong simplification with respect to energy analysis based on the use of a magnetic spectrometer.
Design Modelling of RF Injector for ICS Gamma-Ray Source System
Authors: Tracz P , Iuciuc E
Published: January 2024

High brightness beams are desired for application to Inverse Compton Scattering (ICS) systems for generation of high-quality x- and γ-rays. In the ICS mechanism high energy electron is interacting with photon. It results in scattered photon with high energy. Computer simulations of electron beam in the rf injector for ICS γ-rays source were carried out and results are presented. Different configurations of injector model were analysed.
Radio Frequency System, Power Converters and Cryomodule installation and tests as a Polish in-kind contribution to the European Spallation Source (ESS)
Authors: Bocian D , Gaj W , Halczynski P , Krawczyk A , Lipka A , Ryncarz T , Skalka F , Sienkwicz M , Skiba M , Swierblewski J , Wartak M , Zwozniak A
Published: January 2024

The European Spallation Source (ESS) project currently enters the final stage of installation. Since 2017, a group of engineers and technicians from The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Science (IFJ PAN) are involved in the project. The contribution to the project can be divided into three main tasks: Radio Frequency Distribution System (RFDS), RF (Radio Frequency) Power Stations and Cryomodules.

The RFDS in ESS project is one of the largest installations of this type consisting of 155 RF high power systems. Engineers and technicians from IFJ PAN were responsible for preparation, installation and RF measurements of the above-mentioned system. The team is also involved in preparation and conducting low and high power tests of the RF stations.

The IFJ PAN team is also responsible for the preparation as well as vacuum and cryogenic tests for 9 Medium and 21 High Beta Cryomodules, before they are installed in the tunnel.

The advanced quality control and quality assurance were mandatory for this work because the costs of failures, as well as potential delays, would have a huge impact in the project realisation. Therefore dedicated methods and approaches have been adapted to this work using experience gained by the IFJ PAN team on previous projects like LHC, XFEL and W7X.
Slow Extraction Techniques from Fixed Field Accelerators
Authors: Taylor R , Steinberg A. F. , Pasternak J , Appleby R. B. , Sheehy S. L. , Benedetto E
Published: January 2024

Fixed Field Accelerators are a candidate for future hadron cancer therapy facilities as their high repetition rate and large energy acceptance enables novel treatment modalities such as high dose rate FLASH. However, conventional dose delivery mechanisms are still necessary, requiring continuous beam delivery over 1–30s. This work is the first study of slow extraction from a scaling Fixed Field Accelerator, using the LhARA facility for baseline parameters. At a horizontal tune of 10/3, the intrinsic sextupole strength of the nonlinear FFA magnetic field is sufficient to excite the resonance, although extraction is better controlled using an additional excitation sextupole at a tune close to 8/3, with radiofrequency knock-out extraction. Including considerations of issues due to nonlinear fields and limitations required to keep the tune energy-independent, slow extraction from Fixed Field Accelerators is successfully demonstrated.
Numerical analysis on the air conditioning system of the experimental hall at TPS
Authors: Chang J C , Chan W S
Published: January 2024

Taiwan Photon Source (TPS) had delivered the first synchrotron light on the last day of 2014. Installation of 16 beamlines of the first and second phases of TPS beamline project was completed. The third phase project also was launched in 2021. To confront the situation that the experimental hall is more compact, we performed Computational Fluid Dynamic (CFD) simulation to analyse the effects of the air conditioning system and various heat sources to the temperature and flow fields in the experimental hall.
A pulser R&D for the HEPS booster bumper magnet
Authors: Wang Guanwen , Chen JinHui , Huo Lihua , Liu Peng , Wang Lei , Shi Xiaolei , Duan Zhe , Shi Hua , Wu Guanjian , Zhai Xinzhe
Published: January 2024

The High Energy Photon Source (HEPS) is a fourth generation photon source, including a storage ring, a booster ring and a Linac. Due to the small dynamic aperture of the storage ring, a novel on-axis swap-out injection scheme was chosen. Here, the 6GeV booster acts as an accumulating ring during that injection process. To extract 6 GeV beam from the booster before injection into the storage ring, four slow bumper magnets are applied to assist the extraction kicker to accomplish. The bumper pulse magnetic field waveform is a half-sine wave with 1ms pulse bottom width. Depending on the simulation and test, a classic LC resonance circuit topology with IGBT switching in series with fast recovery diodes is adopted. In addition, an energy recycle circuit and capacitor charging circuit are designed, to decrease power loss and reduce the influence on the output pulse current waveform during the capacitor re-charge process. A pulsed power supply prototype has been completed, and the testing results show that the bumper pulser can fully meet the all requirements of HEPS booster high energy extraction system.
ByPass optics design in NICA storage ring for experiment with polarized beams for EDM search
Authors: Kolokolchikov S , Aksentyev A , Melnikov A , Senichev Y , Syresin E , Ladygin V
Published: January 2024

Experiments with polarized beams for EDM search in the NICA accelerator complex implies the design of an additional ByPass channels. Such alternative channels will make possible to use NICA as a storage ring and get enough statistical data.
Spin coherence and betatron chromaticity of deuteron beam in NICA storage ring
Authors: Kolokolchikov S , Aksentyev A , Melnikov A , Senichev Y
Published: January 2024

A distinctive feature of the ”Quasi-Frozen Spin” mode in the synchrotron is the installation of special elements with both electrical and magnetic fields on straight sections that compensate spin rotation from MDM on arcs. Moreover, due to the presence of the longitudinal emittance and the momentum spread inside the beam, spin rotation may occur incoherently. In order to suppress this effect, sextupoles are installed, which also affect the suppression of chromaticity.
A Novel Dual-Channel Kicker for the Hefei Advanced Light Facility
Authors: Shang F. L. , Song W. , Shang L.
Published: January 2024

Hefei Advanced Light Facility (HALF) is designed as a fourth-generation light source based on the diffraction-limited storage ring (DLSR). The pre-research for this design is complete. Due to the smaller beam dynamic aperture, about 6 mm, a novel dual-channel kicker has been purposed and designed, with other two traditional kicker, combined the new injection system bump system. This paper presented the principle and layout and the detail of the novel dual-channel kicker.
Precise control of a strong X-Y coupling beam transportation for J-PARC muon g-2/EDM experiment
Authors: Iinuma Hiromi , Abe Mitsushi , Sasaki Ken’ichi , Nakayama Hisayoshi , Mibe Tsutomu , Ogawa Shinji , Yamanaka Takashi , Sato Yutaro
Published: January 2024

A strategy for designing a dedicated beam injection and storage scheme for the J-PARC Muon g-2/EDM experiment is described. To accomplish a three-dimensional beam injection into the MRI-type compact storage system, transverse beam phase spaces (X-Y coupling) and a pulsed kicker system are key to controlling the vertical motion inside the storage volume. Moreover, dedicated beam phase control through the beam channel of the storage magnet’s yoke is crucial. We introduce a five-dimensional phase-space correlation in addition to strong X-Y coupling to control the stored vertical beam size to a level as small as one-third that achievable by X-Y coupling alone.
Demonstration of Three-dimensional Spiral Injection for the J-PARC Muon g – 2/EDM Experiment
Authors: Matsushita R. , Iinuma H. , Oda K. , Ohsawa S. , Nakayama H. , Rehman M. A. , Furukawa K. , Saito N. , Mibe T. , Ogawa S.
Published: January 2024

In the J-PARC Muon g-2/EDM experiment, to measure muon anomalous magnetic moment (g-2) and electrical dipole moment (EDM), it is necessary to accumulate 300MeV/c muon beams with a 66 cm diameter region with a 3 T solenoid-type magnetic field. A new three-dimensional spiral injection scheme has been invented to achieve this target. Since this is the first instance to employ this injection scheme, a scale-down experiment with an electron beam of 297 keV/c and storage beam diameter of 24 cm is established at KEK. A simplified storage beam monitor using scintillating fiber has been designed and fabricated to measure the stored beam. The 100 ns width pulsed beam is injected and the signal maintains a few microseconds by the stored beam observed. According to this result, the beam storage is confirmed. The recent result implies that the stored beam deviated from the design orbit and caused betatron oscillations. To measure the beam deviation quantitatively and tune the beam, the storage monitor has been updated. The data from this stored beam monitor are the primary data for considering the conceptual design of the beam monitor for the muon g-2/EDM experiment. This poster will discuss the measurement of beam storage by three-dimensional spiral injection and beam tuning using a scintillating fiber monitor.
Field Quality Improvement of Septum Magnets for SuperKEKB Injection System
Authors: Mori T , Kikuchi M , Kodama K , Mimashi T , Naito T , Sakamoto Y , Takasaki S , Tawada M , Ueda T
Published: January 2024

The SuperKEKB accelerator is a electron-positron collider consisting of the 7 GeV electron ring (high energy ring or HER) and the 4 GeV positron ring (low energy ring or LER). The commissioning of the SuperKEKB accelerator is underway, aiming to supply a great number of interaction events of electrons and positrons to the Belle II detector which is used for discovering the new physics beyond the standard model. The important milestone is to obtain integrated luminosity of 15 ab–1 in the next decade, so that the luminosity should exceed 2 × 1035 cm–2s–1 in several years. To achieve the goal, both rings have to be filled with high current beam of a few amperes, where the high injection efficiency is vitally important because lifetime is expected to be very short. One of the key components of the injection system is the septum magnet. It has been found that a transverse fringe field near the septum plate has sizable multipole components. A tracking simulation shows such fringe fields generate a vertical non-Gaussian tail, which could cause a beam background as well as a bad injection efficiency. Though quadrupole component in the multipoles could be, in principle, cancelled by adjusting the quadrupole magnets in the upstream of the beam line, it turned out to be difficult in actual operation. Even the quadrupole component was perfectly cancelled, components higher than quadrupole would be still harmful, since it generates a beam halo in the ring after injection, which increases the beam backgrounds to the Belle II detector. This paper describes about improvement of the field quality of the septum magnet.
Commissioning simulations tools based on python Accelerator Toolbox
Authors: Liuzzo S. M. , Carmignani N. , Carver L.R. , Hoummi L. , Perron T. , White S. , Agapov I. , Boese M. , Hellert T. , Keil J. , Malina L. , Musa E. , Veglia B.
Published: January 2024

Storage ring commissioning-like simulations are necessary to assess the feasibility of proposed future lattice designs. This paper proposes a python package for commissioning-like simulations based on python accelerator toolbox (pyAT). The software includes: 1) errors definition, 2) correction routines from open trajectory to optics and coupling correction and 3) the evaluation of the relevant parameters, such as dynamic aperture (DA), injection efficiency (IE) and Touschek lifetime (TL). The software is fully exploiting parallel resources (local or on a computing cluster) and is thought to be easily configured for any machine (examples are given for EBS DBA and HMBA, for PETRA IV and for FCC-ee). Whenever possible analytic formulas are made available to the user. Several examples are detailed in this paper and included in the code as demonstrations of use.
Development of fast BBA for Diamond Light Source
Authors: Appleby J M , Abbott M G , Fielder R T , Gaughran M J
Published: January 2024

Beam-based alignment (BBA) is a standard tool at accelerators for aligning particle beams to the centre of quadrupole magnets. Traditional BBA measurements have been slow, potentially taking many hours for a whole machine. We have developed a tool, based on results previously reported at the ALBA synchrotron, that uses fast excitation of magnets to speed up measurements. We show the results of different measurement and analysis techniques in comparison to the currently used slow method.
Light Source Developments at UVSOR BL1U
Authors: Katoh M. , Ota H. , Yamazaki J. , Hayashi K. , Okano Y. , Salehi E. , Taira Y. , Mano A. , Fujimoto M. , Takashima Y. , Hosaka M. , Sakamoto F. , Kaneyasu T. , Zen H.
Published: January 2024

UVSOR, a low energy synchrotron light source, has been operational for about 40 years. It has been providing high brightness VUV radiation to users but also providing a research environment for light source developments. BL1U is a dedicated beamline for developments and applications of novel light source technologies. The beamline is equipped with two variable-polarization undulators with a phase-shifter magnet and with a femto-second laser system which is synchronized with the RF acceleration. We have been studying oscillator-type free electron laser, coherent harmonic generation, coherent synchrotron radiation, inverse Compton scattering and spatiotemporal-structured light. We have also been exploring their applications, in collaboration with researchers from universities and research institutes.
Photocathodes for the electron sources at FLASH and European XFEL
Authors: Juarez-Lopez D.P. , Lederer S. , Schreiber S. , Brinker F. , Monaco L. , Sertore D.
Published: January 2024

FLASH at DESY (Hamburg, Germany) and the European XFEL photoinjectors are operated by laser driven RF-guns. For both user-facilities cesium telluride (Cs2Te) photocathodes are successfully used since several years. We present recent data on the lifetime and quantum efficiency (QE) of the current photocathode at FLASH #105.2, operated before and after a long shutdown. In addition, data for the cathodes that recently have been exchanged at the European XFEL will be presented.
Recent progress of THz source at the SXFEL
Authors: Kang Y , Sun H , Zhang K Q , Feng C
Published: January 2024

Coherent, wide-tunable frequency and high intensity terahertz (THz) source is under preparation at the Shanghai Soft X-ray free-electron laser facility (SXFEL). The electron bunches modulated by frequency beating light can generate coherent, wide-tunable, high intensity THz radiation from 0.1 to 30 THz through wigglers. The electromagnetic wiggler with peak magnetic field up to 1.75 T is adopted and the parameters of the wiggler are optimized to ensure the generation of strong field THz radiation. Due to the limitation of layout space of the SXFEL, the length of wiggler is limited within 5 meters. By properly increasing the charge of the electron beam, the THz pulse energy can be kept at sub mJ level under the proposed different parameters of the wiggler. In this article, we will present the possible layout of THz source on the SXFEL and the S2E simulation of THz radiation of sub mJ magnitude within the 5-meter wiggler.
High-gain free-electron laser with orbital angular momentum seeded by an x-ray regenerative amplifier
Authors: Sun Hao , Feng Chao , Liu Bo
Published: January 2024

High-gain high-mode generation (HGHMG) free-electron laser has been experimentally confirmed to produce vortex light from a relativistic electron beam and is proposed to generate fully-coherent, high-brightness hard x-ray carrying orbital angular momentum at modern free electron laser facilities. However, this requires a coherent x-ray seed laser with sufficient power to perform the helical modulation on the electron beam. In this contribution, we propose a promising scheme to generate a fully coherent x-ray seed laser for the HGHMG system. In this scheme, an x-ray regenerative amplifier is used to offer a fully coherent x-ray seed laser to modulate the electron beam in a helical undulator. With the proposed technique, high-power and high-repetition-rate x-ray with orbital angular momentum can be produced, which will open routes to scientific research in x-ray science.
Carrier-envelope phase stabilization in FEL oscillators
Authors: Hajima R , Kawase K , Zen H , Ohgaki H
Published: January 2024

FEL oscillators can produce few-cycle optical pulses with a high-extraction efficiency when the oscillators are operated in the superradiant regime. Such FEL oscillators are unique light sources to explore intense light field science, especially in mid-infrared and longwave infrared where ultrashort pulses for the high-intensity applications are difficult to produce from conventional lasers. Since the laser-matter interaction in the intense field regime is described in terms of the oscillating electric field rather than the instantaneous intensity, the carrier-envelope phase (CEP) must be stabilized in many applications of few-cycle optical pulses to the intense light field science. Stabilization of CEP in FEL oscillators has been proposed with an external seed laser and coherent spontaneous emission from the electron bunches. In this paper, we study CEP stabilization in FEL oscillators assisted by coherent spontaneous emission from electron bunches with numerical simulations.
THz SASE FEL at PITZ: lasing at a wavelength of 100 μm
Authors: Krasilnikov M , Aboulbanine Z , Adhikari G , Aftab N , Asoyan A , Boonpornprasert P , Davtyan H , Georgiev G , Good J , Grebinyk A , Gross M , Hillert W , Hoffmann A , Kongmon E , Li X-K , Lueangaramwong A , Melkumyan D , Mohanty S , Niemczyk R , Oppelt A , Qian H , Richard C , Rossbach J , Schneidmiller E , Stephan F , Vashchenko G , Weilbach T , Yurkov M
Published: January 2024

Development of an accelerator-based tunable THz source prototype for pump-probe experiments at the European XFEL is ongoing at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The proof-of-principle experiments on the THz SASE FEL are performed utilizing the LCLS-I undulator (on loan from SLAC) installed in the PITZ beamline. The first lasing at a center wavelength of 100 μm was observed in the summer of 2022. The lasing of the narrowband THz source was achieved using an electron beam with an energy of ∼17 MeV and a bunch charge up to several nC. Optimization of beam transport and matching resulted in the measurement of THz radiation with a pulse energy of tens of μJ, measured with pyroelectric detectors. The THz FEL gain curves were measured by means of specially designed short coils along the undulator. The results of the first characterization of the THz source at PITZ will be presented.
A force-neutral adjustable phase undulator for a compact x-ray FEL
Authors: Xu Joseph Z. , Qian Maofei , Zholents Alexander
Published: January 2024

The magnetic and mechanical designs of a force-neutral adjustable phase undulator (FNAPU) are presented. The FNAPU combines two magnetic assemblies with equal periods, one with an undulator magnetic structure and one with a force compensation magnet structure. The latter is used to neutralize the magnetic force affecting the undulator magnetic structure and vice versa in all undulator phases. Assembling in proximity a group of different FNAPUs is discussed.
Numerical Simulation of an Electron Beam for Magnetic Bunch Compressor Commissioning at PITZ
Authors: Kongmon E , Krasilnikov M , Li X-K , Boonpornprasert P , Vashchenko G , Aftab N , Richard C , Gross M , Oppelt A , Stephan F , Rimjaem S , Lueangaramwong A
Published: January 2024

A THz free electron laser (FEL) prototype has been developed at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) for obtaining high intensity radiation for THz-pump and X-ray-probe experiments at the European XFEL. In this development, a magnetic chicane was recently installed to optimize the THz FEL performance. The aim of this study is to investigate the beam dynamics in the chicane for a trajectory commissioning by tracking the electron beam via ASTRA using a 3-dimensional (3-D) magnetic field of the chicane simulated with CST-EM Studio. The simulated results indicate the possibility to obtain a minimum-momentum dispersion of an electron beam after chicane with the high bunches charge of electron beam transportation.
Design, fabrication and cold-test of an X-band accelerating structure for linearizer
Authors: Huang X X , Tan J H , Wang C , Fang W C
Published: January 2024

X-band high gradient accelerating technology is a challenging and important technology in advanced electron linear accelerator facilities. The X-band accelerating structure can provide harmonic compensation to eliminate non-linear energy spread and realize linear compression of bunch in linac. In this paper, a special X-band traveling-wave accelerating structure is designed for linearizer, with accelerating gradient of 20 MV/m under the input power below 5 MW according to the requirement of Dalian Coherent Light Source. The fabrication and cold-test of the structure are successfully completed and the transmission efficiency of power is about 0.38.
A start-to-end optimisation of CLEAR for an inverse Compton scattering experiment, using RF-Track
Authors: Muşat V , Latina A , Malyzhenkov A , Aksoy A
Published: January 2024

The CERN Linear Electron Accelerator for Research (CLEAR) has been operating as a user facility since 2017, providing beams for various experiments. This paper describes a start-to-end optimisation of the CLEAR beamline as a driver for X-ray generation through inverse Compton scattering. The novel particle tracking code RF-Track was used to simulate the electron beam from the bunch generation at the cathode up to the interaction with a laser beam. Figures of merit of the scattered photon beam were computed in RF-Track, and optimised by tuning the beam parameters at injection and quadrupole strengths across the beamline. The aim of the optimisation was to maximise the scattered photon flux, and minimise the effects from static and dynamic imperfections. The start-to-end model of the CLEAR beamline was used to derive the impact of jitter on flux.
Radiation transport line for Terahertz Coherent Diffraction Radiation at ERL Test Accelerator in KEK
Authors: Honda Y. , Kato R. , Shimada M. , Takai R.
Published: January 2024

Coherent radiation from a short bunch of electron beams is expected to be utilized as a terahertz (THz) radiation source. We have conducted an investigation on a terahertz source based on coherent diffraction-radiation (CDR) that possesses a unique characteristic of radial polarization and is potentially useful for certain applications. Particularly, with the high repetition beam of an energy-recovery linac, it is possible to achieve a watt-class high power source. We have designed a CDR setup and THz transport line, and subsequently measured the THz beam profile at the end of the line. The results confirmed the preservation of the distinctive characteristics of CDR within the experimental area.
Commissioning of the ThomX Storage Ring
Authors: Kubytskyi V. , Chaikovska I. , Delerue N. , Mytrochenko V. , Loulergue A.
Published: January 2024

We will report on the ongoing ThomX ring commissioning, its status, its main challenges, our results and our planning. ThomX is a compact Compton-based X-ray source under commissioning at IJCLab in Orsay (France). This facility is composed of a 50-70 MeV linac, a transfer line and a storage ring whose circumference is 18 m. Compton scattering between the 50 MeV electron bunch of 1 nC and the 30 mJ laser pulses stacked in a Fabry-Perot cavity will result in the production of X-rays with energy ranging between 45 keV and 90 keV. We aim at a total flux of about 1013 X-rays per second. The injector commissioning started in the spring of 2021. The ongoing storage ring commissioning faces many challenges due to the rings low energy, its compactness, its non-linear beam dynamics, the time-limited beam storage and the need to achieve a very accurate and stable geometry of the collision region between the laser pulses and the electron bunch. The commissioning and operational experience is of great importance for the future Compton sources.
Copper Surface Treatment with deep UV Ultrafast Laser for Improved Photocathode Photoemissive Properties
Authors: Groussin B , Martinez Calderon M , Marsh B , Rossel R , Granados E
Published: January 2024

Cesium Telluride (Cs2Te) constitutes today the photoemissive semiconductor material of choice for electron accelerators due to its high quantum efficiency (QE) in the deep ultraviolet (DUV) spectral range, and capability to produce high charge over a long operation lifetime. Unfortunately, its chemical instability requires ultra-high vacuum (in the 10-10 mbar range). This inevitably complicates Cs2Te photocathode handling, and increases the overall cost compared to metallic counterparts. Copper photocathodes are alternative candidates, and although they are much more tolerant in terms of vacuum requirements, their use in high average current photo-injectors is limited due to their orders of magnitude lower QE (around 10-5 per unit). With the development of nanophotonics, plasmonic phenomena can now be exploited to tailor a new range of effects in the photoemission process. In this work, we focus on direct laser fabrication of nanostructures for plasmonic electric-field enhancement on copper, and study their potential for enhancing the quantum yield. We develop a methodology to fabricate the nanostructures by irradiating the Cu surface with 257 nm femtosecond pulses, well above copper’s work function. We directly obtained nanostructures 100-200 nm, matching the plasmonic resonance for photoinjector wavelengths. The study is accompanied by a parametric scan allowing to obtain the optimal laser machining parameters, and the analysis of the nanostructure morphologies obtained.
Simulation of Plasmonic Effects in Nanostructured Copper Surfaces for Field-assisted Photoemission
Authors: Groussin B , Martinez Calderon M , Marsh B , Granados E
Published: January 2024

Plasmonics in photoemission have recently gained interest due to their effect on important electron beam parameters such as emittance or quantum efficiency (QE), among others. For example, the presence of nanostructures at the surface of the photoemissive medium can increase the probability of electron emission if their morphological features match that of the plasmonic resonance when laser-irradiated in an electron gun. To determine the optimal size and geometry of these nanostructures and predict the resulting field enhancement, we conducted parametric electromagnetic simulations of nanostructured surfaces using COMSOL®. We investigated several types of geometries commonly found in laser processed copper substrates, optimized their performance under different irradiation wavelengths, and determined the expected maximal enhancement factor attainable.
Development of an X-band RF gun with four-feed coupler
Authors: Hu F , Zha H , Shi J , Gao J , Li Q , Gu W , Chen H
Published: January 2024

With the high accelerating gradient, radiofrequency (rf) gun has a significant feature of suppressing the growth of transverse emittance caused by space charge. Field emission cathodes were first used in vac-uum electronic devices, which do not require the high electron beam intensity, but the compact geometry size of the cathode. A new X-band (11.424 GHz) rf electron gun has been proposed with the highlight of four-feed coupler, which can eliminate the quadrupole field component observed and analysed from the imagine experiment carried on, which have affected the resolu-tion of the imaging system to some content.