bluuebunny/crossref_metadata_2025_split huggingface dataset:
First-principles prediction of 1H-Na2Se monolayer: effects of external strain and point defects associated with constituent atoms
Authors: Vu Tuan V , Nguyen Duy Khanh , Guerrero-Sanchez J , Hoat D M 
Published: December 2022

Abstract
In this work, a new Na2Se monolayer in 1H-phase, with interesting properties similar to transition metal dichalcogenides (TMDs), has been predicted using first-principles calculations. Results reveal good stability and wide direct gap semiconductor nature, with an energy gap of 0.82(1.45) eV as determined by standard PBE(hybrid HSE06) functional. This two-dimensional (2D) material exhibits poor stability under compressive strain due to the sensitive ZA acoustic phonon mode. In contrast, it only becomes unstable with tensile strain from 9% due to the elongation of chemical bonds reflected in the optical E” phonon mode. Under effects of lattice tension, the direct gap character is preserved and the band gap increases nearly linearly according to increase the strain strength. In addition, the effects of point defects associated with Na and Se atoms, including vacancies, antisites, and atom adsorption are also examined. Results indicate significant magnetization induced by Na single vacancy, Se
Na
antisite (one Na atom substituted by one Se atom), and Na adsorption on-top of hollow (T
H
) site. In these cases, feature-rich magneto-electronic properties as half-metallic and magnetic semiconductor natures are obtained. In contrast, the formation of 2Na+1Se combined vacancies as well as other defects related to Se atoms leads to an effective band gap modification, even metallization in some cases. Results introduces new promising 2D material for optoelectronic applications and proposes point defect engineering to create artificially novel features for spintronic applications.
Large magnetocaloric effect near room-temperature by tuning the magneto-structural transition in (Mn, Fe)(Ni, Fe)Si alloy
Authors: Panda Shantanu Kumar , Mallick Jyotirekha , Datta Subhadeep , Biswal Sambit Kumar , Guha Shampa , Kar Manoranjan 
Published: December 2022

Abstract
The observation of near room-temperature coupling of both magnetic and structural transitions in Fe substituted Mn-Ni-Si alloy leads to an interesting magneto-structural transition (MST) phenomenon which intensifies the required magnetocaloric parameters for magnetic cooling applications. The crystal structure analysis reveals that temperature as well as Fe substitution work as the driving forces for deforming the orthorhombic unit cell and to stabilize the hexagonal phase. The correlation between the unit cell parameters of both phases confirms that a large change in unit cell volume (∼2.9%) is mainly responsible for the structural transition. The simultaneous substitution of Fe across Ni and Mn sites helps to tune the MST temperature. Both magnetization and calorimetric studies confirm the existence of first-order type structural transition across MST. The [Mn0.64 Ni0.64 Fe0.72 Si] alloy exhibits a large isothermal magnetic entropy change (ΔS

M
) of −19.2

±

0.4 J kg−1 K−1 accompanied by a large value of effective refrigerant capacity (RC

effe
) of 181.8

±

3.7 J kg−1 due to a magnetic field change of 0–30 kOe. The estimated total entropy change associated with the complete structural transition from the calorimetric studies sets an upper limit for the entropy change of the system. The low cost and non-toxic nature of constituent elements, composition-dependent tunability of the transition temperature, and near room-temperature large magnetocaloric parameters make this alloy potentially suitable to be used as a refrigerant in solid-state magnetic cooling technology.
Electron drift velocity in acetylene and carbon dioxide determined from rf breakdown curves
Authors: Lisovskiy V A , Dudin S V , Platonov P P , Yegorenkov V D 
Published: December 2022

Abstract
In this work, we measured the breakdown curves of radio-frequency (13.56 MHz) capacitive discharge in acetylene and in carbon dioxide. The electron drift velocity values were determined in the reduced electric field range 319 Td ≤ E/N ≤ 3409 Td (1 Townsend = 10−17 Vcm2) in acetylene and 272 Td ≤ E/N ≤ 6240 Td in carbon dioxide from turning points on the measured breakdown curves. Treating the electron motion equations and the gas breakdown criterion in the rf electric field we have demonstrated that the method of electron drift velocity determination we employed is universal for arbitrary gasses, and a possible dependence of the electron mobility and diffusion on the reduced electric field strength E/N does not affect the drift velocity values obtained with it. We have demonstrated that in the range of E/N values we have studied the ionization rate exceeds the attachment rate considerably therefore one may neglect the effect the attachment of free electrons to gas molecules plays on electron drift velocity. We have explained the reason why the values of the electron drift velocity we have obtained differ from those obtained by other authors.
Hybrid perovskites thin films morphology identification by adapting multiscale-SinGAN architecture, heat transfer search optimized feature selection and machine learning algorithms
Authors: Vakharia Vinay , Shah Milind , Suthar Venish , Patel Vivek K. , Solanki Ankur 
Published: December 2022

Abstract
The automation in image analysis while dealing with enormous images generated is imperative to deliver defect-free surfaces in the optoelectronic area. Five distinct morphological images of hybrid perovskites are investigated in this study to analyse and predict the surface properties using machine learning algorithms. Here, we propose a new framework called Multi-Scale-SinGAN to generate multiple morphological images from a single-image. Ten different quality parameters are identified and extracted from each image to select the best features. The heat transfer search is adopted to select the optimized features and compare them with the results obtained using the cuckoo search algorithm. A comparison study with four machine learning algorithms has been evaluated and the results confirms that the features selected through heat transfer search algorithm are effective in identifying thin film morphological images with machine learning models. In particular, ANN-HTS outperforms other combinations : Tree-HTS, KNN-HTS and SVM-HTS, in terms of accuracy,precision, recall and F1-score.
Combined electromagnetohydrodynamic flow in microchannels with consideration of the surface charge-dependent slip
Authors: Xing Jingnan , Liu Yongbo 
Published: December 2022

Abstract
In microscale systems, hydrodynamic slip is considered to significantly influence the fluid flow field. Existing theories of electromagnetohydrodynamic flow in hydrophobic microchannels have postulated a constant slip length and ignored the effect of the surface charge on slip. In this study, we extended prior models by considering a combined pressure-driven and electromagnetohydrodynamic flow in microchannels with consideration of surface charge-dependent slip. An analytical solution for this simple model was derived. After a detailed discussion of the obtained results, we demonstrate that the more realistic surface-charge-dependent case has smaller velocities and flow rates than the surface-charge-independent slip case. Considering the effect of the surface charge on slip, the flow rate can be reduced by up to 7% in the currently selected parameter range. Our results are useful for optimizing electromagnetohydrodynamic flow models in microchannels.
On the role of mode resonances in regulating zonal-flow-moderated plasma microturbulence
Authors: Li P.-Y. , Pueschel M.J. , Terry P.W. , Whelan G.G. 
Published: December 2022

Abstract
The onset of turbulent heat transport at a higher temperature gradient than the critical gradient of linear instability, known as the Dimits shift, is a recurring feature of nonlinear simulations for magnetically confined fusion plasmas. Resonance in the nonlinear coupling between the modes that dominate energy transfer can lead to suppression of turbulence and transport above the linear critical gradient. As an expression of this resonance, gyrokinetic simulations show a quasi-coherent interaction between streamers and sidebands coupled through the zonal flow within the Dimits regime. This mechanism is further confirmed by use of artificial complex frequencies which break the resonance. By incorporating corresponding saturation physics, the standard quasilinear model for rapid head flux prediction is improved, which can now predict reduced heat flux in the Dimits regime. In particular, the triplet correlation time, the lifetime of the nonlinear interaction, is shown to be well-approximated by combinations of linear eigenvalues, and yields good representations of the heat flux variation both in and above the Dimits regime. Thus, a reduced but predictive model for transport near the critical gradient of zonal-flow saturated turbulence now exists.
PETRA III Operation with High Availability
Authors: Bieler M. , Keil J. , Kumar Sahoo G. , Schaumann M. , Wanzenberg R. 
Published: December 2022

Abstract
The Synchrotron Light Source PETRA III at DESY is one of the most brilliant storage-ring based X-ray sources for high-energy photons worldwide, which offers scientists unique X-ray experiments in a wide range of fields since 2009. The light source is operated mainly in two operation modes with 480 and 40 bunches at a beam energy of 6 GeV with a maximum beam current of up to 120 mA. High reliability is one of the key requirements for a synchrotron radiation facility. The key performance indicators, availability and mean time between failures (MTBF), could be significantly improved during the operation periods of the last years. As the final milestones of the extension project that started in 2014, a new undulator was installed for the beamline P62 in the Paul P. Ewald hall in 2020, and a new dipole beamline (P66) have been installed in the North East section of PETRA III in 2021.
Commissioning and First Results of the SSRF Phase-II Beamline Project
Authors: Tai Renzhong , Zhao Zhentang 
Published: December 2022

Abstract
The SSRF Phase-II Beamline Project started November 20, 2016 with a 6-year construction period. This project is mainly to construct 18 new beamlines and more than 30 end-stations, as well as the corresponding storage ring upgrades, the user auxiliary laboratories, the beamline technology support laboratories, and the infrastructures. Till now, 11 beamlines have passed the technical acceptance test and been in running. The remaining seven beamlines will be finishing their technical acceptance test soon. The commissioning of the upgraded accelerator is successful including the lattice modification, the new 3rd harmonic superconducting cavity installation and the 650 W helium cryogenic system construction.
Analysis of the error budget for a superconducting undulator SASE line at European XFEL
Authors: Marchetti B. , Casalbuoni S. , Grattoni V. , Serkez S. 
Published: December 2022

AbstractEuropean XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines. SCUs made of NbTi, working at 2 K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV. The effect of mechanical errors in the distribution of the undulator parameter K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50 keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.6 T peak magnetic field.
Design, construction, and magnetic field characterization of a Segmented Adaptive-Gap In-Vacuum Undulator prototype for NSLS-II
Authors: Musardo M. , Chubar O. , Tanabe T. , Rank J. , Banerjee A. , Corwin T. , Harder D. , Eng C. , Kitegi C. 
Published: December 2022

AbstractSegmented Adaptive-Gap in-Vacuum Undulator (SAGU) prototype with different period lengths and gaps in segments for production of high flux and brightness hard X-rays is under development at NSLS-II. According to radiation flux and brightness calculation results, SAGU promises a significant spectral performance gain compared to a conventional in-vacuum undulator, especially in hard X-ray range. In order to reduce the cost of the project, three existing mechanical carriages of Mini-Gap Undulators from the former NSLS X-ray ring were partially de-assembled, redesigned and optimized in order to meet the required mechanical performance of the device. The magnetic module assembly of the first segment has been carried out using a sorting technique which progressively optimizes the magnetic field quality of the device. Additional magnetic tuning, using small dipole kick magnets and virtual shimming, is planned to further improve the electron trajectory straightness, in particular to compensate the angular kicks experienced by the electron beam at segment junctions as it travels through the device. This paper will describe the magnetic and mechanical design as well as the field measurement results, and the magnetic adjustment implemented to properly tune the field strength and minimize the total field integral produced by the segments.
Goubau-Line Set Up for Bench Testing Impedance of IVU32 Components
Authors: Volz Paul , Meseck Atoosa 
Published: December 2022

Abstract
The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz-Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. It will deliver radiation in the soft X-ray range to several beamlines. The proximity of the undulator structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of its impedance characteristics is required prior to installation and operation, as unforeseen heating of components could have catastrophic consequences. To understand and measure the IVU’s impedance characteristics a Goubau-line test stand is being designed. A Goubau-line is a single wire transmission line for high frequency surface waves with a transverse electric field resembling that of a charged particle beam out to a certain radial distance. A concept optimized for bench testing IVUE32-components will be discussed, microwave simulations will be presented, and progress towards a test bench prototype will be shown.
Possibilities at the Polar beamline with APS-U
Authors: Strempfer J , Kearney S , Khan A , Capatina D , Reininger R , Shu D , Wolford C , Golebiowski M , Rebuffi L , Shi X , Kołodziej T , Huang X , Shvyd’ko Y , Choi Y , Fabbris G , Kesgin I , Ivanyushenkov Y , Gluskin E , Haskel D 
Published: December 2022

Abstract
The Polar beamline will make use of the small emittance of the new APS-U storage ring and will offer extremely brilliant and coherent beam of variable polarization in the hard x-ray range. Tailored optics and experimental equipment will enable high spatial resolution dichroic spectroscopy, reflectivity and diffraction in combination with extreme pressures, low temperatures and high magnetic fields. Dichroic direct and ptychographic imaging of magnetic structures is being developed and will make use of the largely enhanced coherence of the low emittance source. We present an overview of the planned instrumentation and the upcoming new exciting possibilities.
Tools for rapid and reliable change of optical configuration at LIX
Authors: Chodankar S. , Yang Lin 
Published: December 2022

Abstract
The LIX beamline (16-ID) at NSLS-II is a scattering beamline dedicated to probing structures in biological samples. The beamline supports both solution scattering and microbeam scanning structural mapping experiments. In addition to providing a stable and reliable beam, the beamline optical system must be able to quickly change configuration to support multiple modes of operation that require different beam properties such as photon energy and spot size, and with minimal effort from the experimenter. In order to do so, we have fine-tuned optical components and implemented automation. The beam stability is maintained using multiple beam position monitors and corresponding feedback on optical components. Vibrational stability of instruments is monitored and correspondingly mitigated. We describe the software and devices developed to automate configuration changes and outline the process of using these tools during operations.
Design of Tender X-ray Absorption Spectroscopy Beamline in Taiwan Photon Source
Authors: Liu D G , Lee M H , Lu Y J , Liang C C , Chang C F , Tu J L , Lee J F , Chen C L 
Published: December 2022

Abstract
A new tender X-ray absorption spectroscopy beamline for operating over the photon energy range from 1.7 keV to 11 keV is under construction at port 32 of the Taiwan Photon Source (TPS). The TPS 32A beamline uses two back-to-back water-cooled double crystal monochromators (DCMs), InSb(111) and Si(111), for achieving the wide energy tunability. The beamline design takes advantage of the low emittance of the TPS accelerator and a bending magnet (BM) to obtain a high-brightness focussed beam. In order to overcome the issue of poor thermal conductivity of InSb(111) crystals while facing high thermal load, we have implemented the following features : (i) we have controlled the flux and heat load by optimizing the source collection angle of 2 × 0.15 mrad2 (h × v), and (ii) we have installed water cooled double-bounce high harmonic rejection mirrors (HHRMs) with a variable incidence angle upstream of the DCM to reduce the heat load on the first InSb crystal. The DCM is followed by a 2:1 toroidal focusing mirror (TFM) which focuses the beam parallel to the floor of the experimental endstation. The simulated focus beam size is 0.9 × 0.9 mm2 (h × v, FWHM) using the InSb(111) DCM at 1.7 keV, and 0.2 × 0.45 mm2 (h × v, FWHM) using the Si(111) DCM at 4 keV, respectively. The photon flux is 1010 -1012 photons s−1 in the energy range of 1.7 to 11 keV at the sample stage after passing through the Be windows. The design parameters of photon flux and beam spot size will facilitate a tender X-ray source for carrying out high-quality X-ray absorption spectroscopy experiments.
The SXP instrument at the European XFEL
Authors: Grychtol P. , Kohlstrunk N. , Buck J. , Thiess S. , Vardanyan V. , Doblas-Jimenez D. , Ohnesorge J. , Babenkov S. , Dommach M. , La Civita D. , Vannoni M. , Rossnagel K. , Schönhense G. , Molodtsov S. , Izquierdo M. 
Published: December 2022

Abstract
The successful implementation of the baseline instruments at the European XFEL has triggered a second phase of instrument developments aiming to extend the portfolio of available techniques. At the soft X-ray undulator (SASE 3), the Soft X-ray Port (SXP) instrument is currently under construction. Conceived as an open port, it focuses primarily on femtosecond time-resolved X-ray photoelectron spectroscopy (TR-XPES), which has proven to be a powerful tool to understand the properties of materials and the interaction between their internal degrees of freedom. The extension of this technique to the soft X-ray energy range is only possible at MHz free electron lasers (FELs) due to space-charge effects which limit the maximum photon flux per pulse on the sample. In this contribution, the SXP instrument at the European XFEL and the implementation of TR-XPES using a momentum microscope are presented. The photon energy range available at SASE 3, 0.25 keV to 3.5 keV, and the variable polarization will allow for the simultaneous characterization of the electronic, magnetic, chemical and structural properties of materials with femtosecond time resolution. To this end, a wide range of laser excitation wavelengths, ranging from the XUV to the THz region, will be available.
Bimorph mirrors at synchrotron beamlines: from walking to flying
Authors: Sutter John P. , Alcock Simon G. , Nistea Ioana-Theodora , Signorato Riccardo , Foster Andrew , Sawhney Kawal 
Published: December 2022

Abstract
With brighter synchrotron sources, automated sample changers, and faster detectors, there is a strong scientific need for rapid and precise variation of the X-ray beam profile, rather than the “set and forget” operation of years past. Piezoelectric bimorph deformable mirrors already allow quick beam profile changes without the heat generation and wear of mechanical devices. Now, their early technological limitations – excessively constraining holders, progressive “junction effect” distortion, and communication bottlenecks with power supplies – are being overcome by a collaboration of scientists and engineers both in industry and at Diamond Light Source. A new generation of bimorph mirrors maintains a stable figure over extended periods of operation. Improved holders and flexible electrical connectors are greatly reducing the mechanical strain imparted to bimorphs, thereby improving their speed, accuracy, and stability. A more sophisticated high voltage power supply has on-board signal processing capacity, allowing large focusing changes within seconds and providing programmable time-varying voltage profiles to counteract piezoelectric creep. The communication between beamline systems and power supplies is being freed of bottlenecks and now runs stably up to 1 Hz. Early tests have already shown that bimorph mirrors can repeatedly switch the size of an X-ray beam in well under 10 seconds. Bimorph mirrors at synchrotron beamlines are now growing beyond the largely static operation of the past and gaining a new dynamism through development projects that are now well advanced. We report on how these endeavours will make it easier for beamlines to utilise the full potential of bimorph mirrors.
Study of Ni/AlN/Ni waveguide system for 8.05 keV incident energy
Authors: Kiranjot  , Modi M H 
Published: December 2022

Abstract
Ni/AlN/Ni waveguide system provides intensity enhancement by a factor of ~30 at 8.05 keV photon energy. In the present study, the effect of deviation of structural parameters (thickness of each layer) along with the surface-interface properties on electric field intensity (EFI) inside an ion beam sputter deposited Ni/AlN/Ni waveguide is investigated. EFI calculations are performed using structural parameters obtained from X-ray reflectivity (XRR) measurements performed using Cu-Kα source. Deposited waveguide structure provides intensity enhancement (~26) slightly lower than optimized value (~30). Furthermore, temporal stability of the structure is investigated using combined XRR and grazing incidence X-ray fluorescence (GIXRF) techniques (at 15 keV photon energy) after about 15 months. Some structural changes are observed which, however, do not lead to further decrease in intensity enhancement inside the waveguide, making it suitable for applications at 8.05 keV photon energy.