bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-loss millimeter-wave resonators with an improved coupling structure
Authors: Anferov A , Harvey S P , Wan F , Lee K H , Simon J , Schuster D I 
Published: January 2024

Abstract
Millimeter-wave superconducting resonators are a useful tool for studying quantum device coherence in a new frequency domain. However, improving resonators is difficult without a robust and reliable method for coupling millimeter-wave signals to 2D structures. We develop and characterize a tapered transition structure coupling a rectangular waveguide to a planar slotline waveguide with better than 0.5 dB efficiency over 14 GHz, and use it to measure ground-shielded resonators in the W band (75–110 GHz). Having decoupled the resonators from radiative losses, we consistently achieve single-photon quality factors above 105, with a two-level-system loss limit above 106, and verify the effectiveness of oxide removal treatments to reduce loss. These values are 4–5 times higher than those previously reported in the W band, and much closer to typical planar microwave resonators. The improved losses demonstrated by these on-chip millimeter-wave devices shed new light on quantum decoherence in a different frequency regime, offer increased selectivity for high-frequency detectors, and enables new possibilities for hybrid quantum experiments integrating millimeter-wave frequencies.
Exponential relaxation of the energy and desorption dynamics of atoms colliding with a surface
Authors: Zeng Dandan , Jiang Jianzheng , Liu Chong , Fan Jing 
Published: January 2024

Abstract
Atom–surface collisions are one of the most important topics in surface science. To further disclose the physical mechanism underlying atom–surface interaction at the microscopic level, we study the dynamics of an incident atom with a molecular dynamics simulation. Emphasis is put on the temporal evolutions of energy and residence times of the colliding atoms. The incident atoms experience two stages after colliding with the surface. First, the atoms relax to the equilibrium state in an exponential fashion. Then, the atoms become equilibrated with the surface and depart from the surface with a converged desorption rate. Two parameters are proposed to characterize the process: the characteristic energy relaxation time and the equilibrium residence time. At the relaxation stage, the desorption rate varies with the energy, and the probability distribution function (PDF) of the residence time obeys a power law. At the equilibrium state, the desorption rate is invariable, and the PDF of the residence time decays exponentially. We further find that the desorption rate for both stages can be calculated by a consistent Arrhenius equation, with the desorption activation energy and kinetic energy evolving with time in the relaxation stage. It appears that the gas–surface interaction dynamics can be explained by trapping-desorption theory in both the relaxation state and the equilibration state.
Accretion flow in deformed Kerr spacetime: spectral energy distributions from free-free emission
Authors: Patra Subhankar , Majhi Bibhas Ranjan , Das Santabrata 
Published: January 2024

Abstract
In this paper, we study the properties of accretion flow including its spectral features in Johannsen and Psaltis (JP) non-Kerr spacetime. In doing so, we numerically solve the governing equations that describe the flow motion around the compact objects in a general relativistic framework, where spin (ak
) and deformation parameters (ε) demonstrate the nature of the central source, namely black hole (BH) or naked singularity (NS). With this, we obtain all possible classes of global accretion solutions (i.e., O, A, W and I-type) by varying the energy (E) and angular momentum (λ) of the relativistic accretion flow, and examine the role of thermal bremsstrahlung emission in studying the spectral energy distributions (SEDs) of the accretion disc. We divide the parameter space in λ-E plane in terms of the different classes of accretion solutions for BH and NS models. We further calculate the disc luminosity (L) corresponding to these accretion solutions, and observe that I-type solutions yield higher L and SEDs than the remaining types of solutions for both BH and NS models. For BH model, SEDs for W and I-type solutions differ significantly from the results for O and A-type solutions for low E values. On the contrary, for NS model, SEDs for different accretion solutions are identical in the whole parameter space of λ and E. We also examine the effect of ε on the SEDs and observe that a non-Kerr BH yields higher SEDs than the usual Kerr BH. Finally, for accretion solutions of identical E and λ, we compare the SEDs obtained from BH and NS models, and find that naked singularity objects produce more luminous power spectra than the black holes.
Electron beam analysis and sensitivity studies for the EuPRAXIA@SPARC_LAB RF injector
Authors: Giribono A , Alesini D , Bacci A , Bellaveglia M , Cardelli F , Chiadroni E , Del Dotto A , Faillace L , Ferrario M , Gallo A , Ghigo A , Giannetti G , Mostacci A , Opromolla M , Petrillo V , Piersanti L , Pompili R , Romeo S , Rossetti Conti M , Rossi A R , Shpakov V , Silvi G J , Vaccarezza C 
Published: January 2024

Abstract
The interest in plasma-based accelerators as drivers of user facilities is growing worldwide thanks to their compactness and reduced costs. The EuPRAXIA@SPARC_LAB collaboration is preparing a technical design report for a multi-GeV plasma-based accelerator with outstanding electron beam quality to pilot an X-ray FEL, the most demanding in terms of beam brightness. The beam dynamics has been studied aiming to a reliable operation of the RF injector to generate a so-called comb-beam with 500 MeV energy suitable as driver of the Beam-driven Plasma Wakefield Accelerator. A case of interest is the generation of a trailing bunch with 1 GeV energy, less than 1 mm-mrad transverse emittance and up to 2 kA peak current at the undulator entrance. The comb-beam is generated through the velocity bunching technique, an RF compression tool that enables high brightness beams within relatively compact machine. Since it is based on a rotation of the beam phase space inside the external RF fields, it could be particularly sensitive to amplitude and phase jitters in the RF injector. The electron beam dynamics and the machine sensitivity to the possible jitters are presented in terms of effect on the beam quality so to provide the basis for the jitter tolerances.
Hydrodynamic Model for Particle Beam-Driven Wakefield in Carbon Nanotubes
Authors: Martín-Luna P , Apsimon O , Barberá-Ramos M , Bonatto A , Bontoiu C , Xia G , Resta-López J 
Published: January 2024

Abstract
The charged particles moving through a carbon nanotube (CNT) may be used to excite electromagnetic modes in the electron gas produced in the cylindrical graphene shell that makes up a nanotube wall. This effect has recently been proposed as a potential novel method of short-wavelength-high-gradient particle acceleration. In this contribution, the existing theory based on a linearized hydrodynamic model for a localized point-charge propagating in a single wall nanotube (SWNT) is reviewed. In this model, the electron gas is treated as a plasma with additional contributions to the fluid momentum equation from specific solid-state properties of the gas. The governing set of differential equations is formed by the continuity and momentum equations for the involved species. These equations are then coupled by Maxwell’s equations. The differential equation system is solved applying a modified Fourier-Bessel transform. An analysis has been realized to determine the plasma modes able to excite a longitudinal electrical wakefield component in the SWNT to accelerate test charges. Numerical results are obtained showing the influence of the damping factor, the velocity of the driver, the nanotube radius, and the particle position on the excited wakefields. A discussion is presented on the suitability and possible limitations of using this method for modelling CNT-based particle acceleration.
High Intensity Beam Operation of J-PARC RCS With Minimum Beam Loss
Authors: Saha P.K. , Harada H. , Shobuda Y. , Tamura F. , Okita H. , Okabe K. , Nakanoya T. , Hatakeyama S. , Moriya K. , Takayanagi T. , Hotchi H. 
Published: January 2024

Abstract
The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) at present operates at a high intensity beam near to 1 MW beam power. The beam loss and the corresponding residual radiation are key issues for beam intensity ramp up. Based on detail numerical simulations and systematic beam studies the beam loss has been well mitigated to a minimum level. The residual beam loss at 1 MW beam power is mostly due to unavoidable foil scattering of the circulating beam during injection. We have identified almost all major beam loss sources and optimized to minimize the beam loss for achieving a stable operation at 800 kW beam power since April 2022.
Determination of the Invariant Spin Axis in a COSY model using Bmad
Authors: Vitz M , Lehrach A , Pretz J 
Published: January 2024

Abstract
The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary particles. A permanent EDM of a subatomic particle violates time reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, an indication for further CP violation than established in the SM (Standard Model of Particle Physics). The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich has performed a direct EDM measurement for deuterons with the so-called precursor experiments at the storage ring COSY (COoler SYnchrotron) by measuring the orientation of the ISA (Invariant Spin Axis). In order to interpret the measured data and to disentangle a potential EDM signal from systematic effects, spin tracking simulations in an accurate simulation model of COSY are needed. Therefore a model of COSY was implemented using the software library Bmad. Systematic effects were considered by including element misalignments, effective dipole shortening, longitudinal fields and steerer kicks. These effects rotate the ISA in addition to the EDM and have to be analyzed and understood. The most recent spin tracking results as well as the methods to find the ISA are presented in this paper.
Metallic Neutral Vapours Diffusion in Electron Cyclotron Resonance Ion Sources: Fluid Dynamics and Particle Tracing Simulations
Authors: Pidatella A , Galatà A , Maimone F , Mishra B , Naselli E , Celona L , Lang R , Mauro G S , Santonocito D , Torrisi G , Mascali D 
Published: January 2024

Abstract
Resistive oven technique is used to inject vapours of metallic species in electron cyclotron resonance (ECR) plasma traps, where plasma provides step-wise ionization of neutral metals, producing charged ion beams for accelerators. We present a numerical survey of metallic species suitable for oven injection in ECR ion sources, studying neutrals diffusion and deposition under molecular flow regime. These aspects depend on geometry of the evaporation inlet, thermodynamics, and plasma parameters, which strongly impact on ionization and charge-exchange rate, thus on the fraction of reacting neutrals. We considered diffusion of metals with and without plasma. The plasma and its parameters have been modelled considering an established self-consistent particle-in-cell model. Numerical predictions might be relevant to reduce the metal consumption, to increase the overall efficiency, and to improve the plasma ion source performances. As test case, we studied the 134Cs isotope, as one of the alkali metals of interest for the modern nuclear physics.
Suppression of Microbunching Instability based on optimized velocity bunching in linac-driven FELs
Authors: Cheng Wencai , Zhu Zihan , Zhao Minghua , Zhang Meng , Gu Duan 
Published: January 2024

Abstract
The microbunching instability (MBI) driven by beam collective effects can cause significant electron beam quality degradation in advanced x-ray free electron lasers. Typically, multiple stage magnetic bunch compressors used to generate high peak current electron beam will dramatically amplify the microbunching instability. In this paper, by redesigning the solenoid elaborately and adopting a dual-mode buncher cavity with the third harmonic mode used to correct the RF curvature, it is potential for the electron beam to be further compressed in velocity bunching (VB) process. Therefore, a VB plus one bunch compressor could be a promising alternative scheme to achieve moderate peak current beam for high-repetition-rate X-ray FELs to suppress the additional MBI gain due to multi-stage magnetic bunch compressors.
Study of beam-beam interaction in FCC-ee including updated transverse and longitudinal Impedances
Authors: Zhang Y. , Migliorati M. , Zobov M. 
Published: January 2024

Abstract
Beam-beam interaction in FCC-ee can be seriously affected by the vacuum chamber coupling impedance resulting in a safe tune areas reduction, tune shifts and spread, bunch length and energy spread variation. The interplay of the two effects has a drastic impact on the stability of colliding bunches and respectively on the achievable luminosity. In this paper, beam-beam collisions in FCC-ee with 4 interaction points are studied including the updated transverse and longitudinal impedances.
PLACET3: 6D tracking through PETS and accelerating structures wakefields
Authors: Costa Raul , Latina Andrea , Olvegård Maja 
Published: January 2024

Abstract
We present the latest updates to the PLACET3 tracking package, which focus on the impact of both transverse and longitudinal wakefields on a beam travelling through accelerating and decelerating structures. The main focus of this update was the first implementation of 6D tracking through Power Extraction and Transfer Structures (PETS) for the Compact Linear Collider (CLIC), which is described through short and long-range longitudinal wakefields. Additionally, we present the impact of different numerical schemes on the computation of wakefields in accelerating structures.
Macroparticle Collisionality in PIC solver
Authors: Engeda A , Franchetti G 
Published: January 2024

Abstract
This paper presents a new numerical technique for the calculation of the Coulomb interaction between nearby charged particles. The efficiency of this method is demonstrated by distributing charged particles in a three dimensional sphere for an amount of particles, Npar
, ranging from 1 × 105 to 1.6 × 106. Using the presented method, the computation of the mean field and Coulomb near field interaction can be performed separately.
Machine learning-based optimization of storage ring injection efficiency
Authors: Schirmer D , Althaus A , Hüser S , Khan S , Schüngel T 
Published: January 2024

Abstract
Since the DELTA accelerator facility does not use a White circuit-driven fast topping-up mode, each software-driven injection ramp cycle takes about 7 seconds. Depending on the injection efficiency, 150 to 200 ramp cycles are required to reach the maximum beam current of 130 mA in the storage ring. Thus, for fast post-injection, a high electron transfer rate is crucial. During the injection process, a large number of parameters (e. g., magnet settings, timings of pulsed elements) have to be adjusted manually. The injection efficiency depends mainly on the settings of the booster extraction elements, the T2 transfer line magnets, and the storage ring injection components. In order to automate the injection procedure and to improve the electron transfer efficiency, the application of innovative machine learning concepts was studied.
Commissioning of X-LAB: a very high-capacity X-band RF test stand facility at the University of Melbourne
Authors: Volpi Matteo , Giansiracusa P. J. , Sheehy S. L. , Williams S. D. , Rassool R. P. , Taylor G. , Pushkarna P. , Dowd R. T. , Zingre K. , Boronat M. , Catalan-Lasheras N. , McMonagle G. 
Published: January 2024

Abstract
The Compact Linear Collider (CLIC) beam-based acceleration baseline uses high-gradient travelling wave accelerating structures at a frequency of 12 GHz. In order to prove the performance of these structures at high peak power and short pulse width RF, two klystron-based test facilities will be put in operation this year. The first Southern Hemisphere X-band Laboratory for Accelerators and Beams (X-LAB) is currently being commissioned at the University of Melbourne, it will house half of the CERN X-band test stand XBOX3, which has been renamed Mel-BOX. Like XBOX3, Mel-BOX employs a novel means of combining high average power but relatively low peak power (6 MW) klystron units to direct power to two testing slots with a repetition rate of up to 400 Hz. As well as the repetition rate, peak power, pulse length and pulse shape can be customised to fit the testing requirements. This novel means of producing high power and high repetition RF pulses can eventually be used for many other applications where multiple test slots are required. This proceedings focuses on the integration and 1st commissioning of Mel-BOX with short pulses. There are also plans for it to form the basis for developing a compact accelerator for medical or university applications, such as radiotherapy and compact light sources [1].
Study on Beam Orbit Shift due to Synchrotron Radiation
Authors: Wang C H , Lan J K , Zhouf T Y , Sun B G 
Published: January 2024

Abstract
The beam orbit stability is the crucial indicator to evaluate the performance of the synchrotron radiation source. In order to obtain higher beam quality, higher stability requirements are placed on the beam orbit. The stability can be improved through accurate measurement of beam orbit by beam position monitors (BPMs) and appropriate feedback system. However, due to radiation of the synchrotron beams on the vacuum chamber, the thermal effect of synchrotron radiation causes the thermal deformation of the vacuum chamber. The thermal deformation drives the BPM fixed on the vacuum chamber to move, which will induce error to the beam orbit. We analyze the effect of beam current on the vacuum chamber movement and the effect of vacuum chamber movement on the beam orbit. We also built an online vacuum chamber displacement measurement system on Hefei Light Source II (HLS II), which is used to validate and correct our analysis. After analysis and verification, the vacuum chamber moves with the change of current. The larger the change of current, the larger the vacuum chamber displacement. The vacuum chamber displacement has a hysteresis compared to the current change.
A compact dielectric grating-based charged particle bunch length diagnostic device at ARES
Authors: Stacey B , Assmann R , Hillert W , Kuropka W , Vinatier T 
Published: January 2024

Abstract
Dielectric gratings are already used in Dielectric Laser Acceleration due to their high damage thresholds at high acceleration gradients. When an electron bunch passes close to one of these gratings, it emits radiation, and the features of this radiation will be dependent upon the beam position relative to the grating, the bunch charge, and the bunch length. A compact high-resolution diagnostics device will be developed that consists of multiple gratings with different periods; these types of devices are required for the accurate operation of future compact accelerators which are currently undergoing development and testing. ARES linac at DESY is able to provide sub-fs electron bunches and has a range of high-resolution diagnostic devices installed, such as the PolariX Transverse Deflecting Structure, which will allow for performance verification of a new diagnostic. The electron bunches can be altered, allowing for the measurement and analysis of the emitted radiation for different bunch lengths and charges. This work will present the current progress in this area, including the presentation and discussion of simulations, and a discussion of the planned experiments at ARES.
Study on beam position measurement based on diode detection in HLS-II
Authors: Lan J K , Wang C H , Zhouf T Y , Sun B G 
Published: January 2024

Abstract
In order to improve the sensitivity and long-term stability of beam position measurement for Hefei Light Source – II (HLS-II), it is necessary to improve the measurement method. The beam position monitor (BPM) electronics is used to measure the beam position and is an important part of the beam position measurement system. In this paper, a beam position measurement system based on the compensated diode detection (CDD) technology for electron storage ring was proposed. Since HALF under construction, the parameters of HLS-II were used to design the system and simulate the system circuits to verify its feasibility.
Design Aspects of the Emittance Diagnostic for the Scorpius Accelerator
Authors: Raphaelian M.L. , Dzenitis D.M. , Littleton S.T. , Mazotti A.A. , Weber F.A. , Pogue N.J. , Duffy P. , Falabella S. , Stem W.D. 
Published: January 2024

Abstract
A multi-pulse linear induction accelerator, Scorpius, will be constructed at the NNSS U1A facility for use in radiographic experiments. One of the many diagnostics, the injector emittance diagnostic, will provide information on the quality of the beam emanating from the injector and therefore the quality of the beam in the accelerator. A slit-harp design was chosen for the emittance diagnostic. We have modeled the performance of the diagnostic for various simulated Scorpius beams, using several computational tools depending on the physics of the effects under investigation. Additional modeling of electron stopping power, energy deposition, heat dissipation, and x-ray attenuation drove material choices for the collimator jaws and harp wires. The signal chain is designed around constraints of signal extraction, biasing to suppress crosstalk between harp wires via secondary electron emission, and multi-pulse record capability. The ensemble of materials, electrical, and mechanical aspects of the design to reconstruct the emittance from the injector of the accelerator are described.
TPS Fast Orbit Feedback Upgrade
Authors: Chiu P. C. , Huang C. H. , Wu C. Y. , Hsu K.T. , Liao C.Y. , Cheng Y.S. , Hu K.H. 
Published: January 2024

Abstract
The orbit feedback system for the Taiwan Photon Source (TPS) was delivered in 2014. With the installation of an increasing number of insertion devices, a variety of wide-band disturbances are produced. In 2019, a proposal was put forth to enhance the stability of the orbit through the implementation of the fast orbit feedback (FOFB) system upgrade. The upgrade plan encompasses the revision of the power supply controller and an increase in the feedback computation rate from 10 kHz to 30 kHz. Following the upgrade, the bandwidth of the TPS fast orbit feedback system has been expanded from 250 Hz to 400 Hz in the vertical plane and from 200 Hz to 250 Hz in the horizontal plane. The integrated power spectrum density of the orbit could be reduced by approximately 20% with effective measures.
Status and upgrade of the visible light diagnostics port for energy spread measurements at KARA
Authors: Patil M. M. , Bründermann E. , Caselle M. , Funkner S. , Goffing C. , Niehues G. , Steinmann J. L. , Widmann C. , Müller A.-S. , Centis Vignali M. , Boscardin M. , Paternoster G. 
Published: January 2024

Abstract
At the visible light diagnostic (VLD) port at the Karlsruhe Research Accelerator (KARA), it is possible to study the energy spread of electron bunches by measuring the horizontal bunch profile of the incoherent synchrotron radiation. KALYPSO, an MHz-rate line-array detector, has been employed to measure the bunch profile. Recently, the KALYPSO system has been upgraded to a version of a microstrip sensor based on TI-LGAD. The measurements have shown that the system’s overall sensitivity was significant - at least by a factor of 20 improved, enabling the study of bunch profiles at low bunch charges. This contribution will present an overview of the upgraded setup and preliminary results.