bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of flow and heat transfer over two inline square cylinders
Authors: Sohankar A. , Khodadadi M. , Rangraz E. , Alam Md. Mahbub
Published: December 2019

Laminar flow around and heat transfer from two inline square cylinders under an active flow control (uniform blowing and suction) are numerically investigated at Reynolds numbers of 70–150, a Prandtl number of 0.71, and a cylinder-gap spacing (G) ratio of G/d = 1–5, where d is the cylinder side. A finite-volume code based on a collocated grid arrangement is employed in the two-dimensional numerical simulations. Uniform blowing and suction are applied to the upstream cylinder only (referred to as UFC) or applied to both cylinders (referred to as OFC). The purpose of using these two flow controls is to reduce time-mean and fluctuating forces and to suppress vortex shedding. The noncontrol case is referred to as the reference case where vortex shedding occurs from both cylinders for G/d ≥ 3 and from the downstream cylinder only for G/d < 3. For UFC, vortex shedding from the upstream cylinder is suppressed for G/d = 1–5 examined. A drag reduction of more than 50% occurs for the upstream cylinder with G/d = 1–5, while the downstream cylinder has such a high drag reduction for G/d ≥ 3 only. In the case of OFC, vortex shedding from either cylinder is suppressed while the time-mean and fluctuating forces reduce for the entire G/d range. The maximum reduction in the total drag force (sum of both cylinders) is about 70%. The blowing hinders heat transfer from the cylinders while the suction enhances it.
Improved calibration of the OMEGA gas Cherenkov detector
Authors: Zylstra A. B. , Herrmann H. W. , Kim Y. H. , McEvoy A. , Meaney K. , Glebov V. Yu. , Forrest C. , Rubery M.
Published: December 2019

Inertial fusion implosions are diagnosed using γ rays to characterize the implosion physics or measure basic nuclear properties, including cross sections. For the latter, previously reported measurements at laser facilities using gas Cherenkov detectors are limited by a large systematic uncertainty in the detector response. We present a novel in situ calibration technique using neutron inelastic scattering, which we apply to the new GCD-3 detector. The calibration accuracy is improved by ∼3× over the previous method.
Flexible ultrahigh energy storage density in lead-free heterostructure thin-film capacitors
Authors: Yang B. B. , Guo M. Y. , Li C. H. , Song D. P. , Tang X. W. , Wei R. H. , Hu L. , Lou X. J. , Zhu X. B. , Sun Y. P.
Published: December 2019

Flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin-film capacitors were deposited onto LaNiO3 buffered fluorophlogopite mica substrates using a cost-effective all-solution chemical solution deposition method. The Ba2Bi4Ti5O18 film showed a high recoverable energy storage density (Ure) of 41.2 J/cm3 and efficiency (η) of 79.1%. The BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 film showed improved energy storage properties with an ultrahigh Ure of 52.6 J/cm3 and η of 75.9% due to its enhanced breakdown field strength and polarization. Meanwhile, both films showed good mechanical flexibility, excellent fatigue endurance up to 5 × 108 cycles, and excellent thermal stability over a wide temperature range from room temperature to 160 °C. These results indicate that the lead-free, flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin film capacitors show promise in the field of flexible electronics.
Subacute co-exposure to low doses of ruthenium(III) changes the distribution, excretion and biological effects of silver ions in rats
Authors: Vedeanu Nicoleta , Voica Cezara , Magdas Dana Alina , Kiss Bela , Stefan Maria-Georgia , Simedrea Ramona , Georgiu Carmen , Berce Cristian , Vostinaru Oliviu , Boros Rodica , Fizesan Ionel , Rusu Marius Emil , Grozav Adriana , Loghin Felicia , Popa Daniela-Saveta
Published: December 2019

Environmental contextAlthough ruthenium is a technology-critical element used in several new industries, little is known about its environmental impact or possible human health risks. We report a toxicological evaluation of laboratory animals during co-exposure to ruthenium and silver. We identified interactions between the two elements that could lead to unwanted biological effects. AbstractRuthenium is one of the rarest metals on Earth that is classified as a technology-critical element (TCE). Silver, however, is well known for its antibacterial and immunostimulant properties. The increasing use of Ru and Ag in medicine and daily life makes simultaneous exposure possible, with unknown pharmacokinetic or toxicological consequences for the human organism. Thus, the present study investigated the influence of co-exposure to RuIII on the subacute toxicity of Ag ions in rats after repeated daily administration for 28 days of low doses by oral gavage. The subacute toxicity was investigated by the evaluation of several biochemical and hematological parameters, evaluation of specific oxidative stress biomarkers from liver and kidney, and histopathological investigation of liver and kidney tissue samples after 28 days of exposure in female rats. In addition, Ag and Ru concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) in urine, liver and kidney parenchyma in male rats. The obtained results showed that co-exposure to low doses of RuIII and Ag did not produce any significant biochemical, hematological or histopathological alterations in the treated female rat groups, except for an increased red cell distribution width (RDW) value. A decrease of urinary excretion of Ag and of the Ag concentration in kidneys was observed in the male rat group co-exposed to RuIII and Ag. This is the first invivo study investigating the toxic effect of co-exposure to low doses of Ag and Ru ions, and the obtained results may justify further research on this subject, mainly on the investigation of possible competitive mechanisms.
Climate variability reduces employment in New England fisheries
Authors: Oremus Kimberly L.
Published: December 2019

Climate change is already affecting fish productivity and distributions worldwide, yet its impact on fishing labor has not been examined. Here I directly link large-scale climate variability with fishery employment by studying the effects of sea-surface pressure changes in the North Atlantic region, whose waters are among the world’s fastest warming. I find that climate shocks reduce not only regional catch and revenue in the New England fishing sector, but also ultimately county-level wages and employment among commercial harvesters. Each SD increase from the climatic mean decreases county-level fishing employment by 13%, on average. The South Atlantic region serves as a control due to its different ecological response to climate. Overall, I estimate that climate variability from 1996 to 2017 is responsible for a 16% (95% CI: 10% to 22%) decline in county-level fishing employment in New England, beyond the changes in employment attributable to management or other factors. This quantitative evidence linking climate variability and fishing labor has important implications for management in New England, which employs 20% of US commercial harvesters. Because the results are mediated by the local biology and institutions, they cannot be directly extrapolated to other regions. But they show that climate can impact fishing outcomes in ways unaccounted by management and offer a template for study of this relationship in fisheries around the world.
Postreproductive killer whale grandmothers improve the survival of their grandoffspring
Authors: Nattrass Stuart , Croft Darren P. , Ellis Samuel , Cant Michael A. , Weiss Michael N. , Wright Brianna M. , Stredulinsky Eva , Doniol-Valcroze Thomas , Ford John K. B. , Balcomb Kenneth C. , Franks Daniel W.
Published: December 2019

Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after stopping reproduction. This unusual life history trait is thought to have evolved, in part, due to the inclusive fitness benefits that postreproductive females gain by helping kin. In humans, grandmothers gain inclusive fitness benefits by increasing their number of surviving grandoffspring, referred to as the grandmother effect. Among toothed whales, the grandmother effect has not been rigorously tested. Here, we test for the grandmother effect in killer whales, by quantifying grandoffspring survival with living or recently deceased reproductive and postreproductive grandmothers, and show that postreproductive grandmothers provide significant survival benefits to their grandoffspring above that provided by reproductive grandmothers. This provides evidence of the grandmother effect in a nonhuman menopausal species. By stopping reproduction, grandmothers avoid reproductive conflict with their daughters, and offer increased benefits to their grandoffspring. The benefits postreproductive grandmothers provide to their grandoffspring are shown to be most important in difficult times where the salmon abundance is low to moderate. The postreproductive grandmother effect we report, together with the known costs of late-life reproduction in killer whales, can help explain the long postreproductive life spans of resident killer whales.
Toward a metabolic theory of life history
Authors: Burger Joseph Robert , Hou Chen , Brown James H.
Published: December 2019

Significance

Data and theory reveal how organisms allocate metabolic energy to components of the life history that determine fitness. In each generation, animals take up biomass energy from the environment and expend it on survival, growth, and reproduction. Life histories of animals exhibit enormous diversity—from large fish and invertebrates that produce literally millions of tiny eggs and suffer enormous mortality, to mammals and birds that produce a few large offspring with much lower mortality. Yet, underlying this enormous diversity are general life history rules and trade-offs due to universal biophysical constraints on the channels of selection. These rules are characterized by general equations that underscore the unity of life.
Approaching infinite affinity through engineering of peptide–protein interaction
Authors: Keeble Anthony H. , Turkki Paula , Stokes Samuel , Khairil Anuar Irsyad N. A. , Rahikainen Rolle , Hytönen Vesa P. , Howarth Mark
Published: December 2019

Much of life’s complexity depends upon contacts between proteins with precise affinity and specificity. The successful application of engineered proteins often depends on high-stability binding to their target. In recent years, various approaches have enabled proteins to form irreversible covalent interactions with protein targets. However, the rate of such reactions is a major limitation to their use. Infinite affinity refers to the ideal where such covalent interaction occurs at the diffusion limit. Prototypes of infinite affinity pairs have been achieved using nonnatural reactive groups. After library-based evolution and rational design, here we establish a peptide–protein pair composed of the regular 20 amino acids that link together through an amide bond at a rate approaching the diffusion limit. Reaction occurs in a few minutes with both partners at low nanomolar concentration. Stopped flow fluorimetry illuminated the conformational dynamics involved in docking and reaction. Hydrogen–deuterium exchange mass spectrometry gave insight into the conformational flexibility of this split protein and the process of enhancing its reaction rate. We applied this reactive pair for specific labeling of a plasma membrane target in 1 min on live mammalian cells. Sensitive and specific detection was also confirmed by Western blot in a range of model organisms. The peptide–protein pair allowed reconstitution of a critical mechanotransmitter in the cytosol of mammalian cells, restoring cell adhesion and migration. This simple genetic encoding for rapid irreversible reaction should provide diverse opportunities to enhance protein function by rapid detection, stable anchoring, and multiplexing of protein functionality.
Valproic acid interactions with the NavMs voltage-gated sodium channel
Authors: Zanatta Geancarlo , Sula Altin , Miles Andrew J. , Ng Leo C. T. , Torella Rubben , Pryde David C. , DeCaen Paul G. , Wallace B. A.
Published: December 2019

Valproic acid (VPA) is an anticonvulsant drug that is also used to treat migraines and bipolar disorder. Its proposed biological targets include human voltage-gated sodium channels, among other membrane proteins. We used the prokaryotic NavMs sodium channel, which has been shown to be a good exemplar for drug binding to human sodium channels, to examine the structural and functional interactions of VPA. Thermal melt synchrotron radiation circular dichroism spectroscopic binding studies of the full-length NavMs channel (which includes both pore and voltage sensor domains), and a pore-only construct, undertaken in the presence and absence of VPA, indicated that the drug binds to and destabilizes the channel, but not the pore-only construct. This is in contrast to other antiepileptic compounds that have previously been shown to bind in the central hydrophobic core of the pore region of the channel, and that tend to increase the thermal stability of both pore-only constructs and full-length channels. Molecular docking studies also indicated that the VPA binding site is associated with the voltage sensor, rather than the hydrophobic cavity of the pore domain. Electrophysiological studies show that VPA influences the block and inactivation rates of the NavMs channel, although with lower efficacy than classical channel-blocking compounds. It thus appears that, while VPA is capable of binding to these voltage-gated sodium channels, it has a very different mode and site of action than other anticonvulsant compounds.
A systematic capsid evolution approach performed in vivo for the design of AAV vectors with tailored properties and tropism
Authors: Davidsson Marcus , Wang Gang , Aldrin-Kirk Patrick , Cardoso Tiago , Nolbrant Sara , Hartnor Morgan , Mudannayake Janitha , Parmar Malin , Björklund Tomas
Published: December 2019

Adeno-associated virus (AAV) capsid modification enables the generation of recombinant vectors with tailored properties and tropism. Most approaches to date depend on random screening, enrichment, and serendipity. The approach explored here, called BRAVE (barcoded rational AAV vector evolution), enables efficient selection of engineered capsid structures on a large scale using only a single screening round in vivo. The approach stands in contrast to previous methods that require multiple generations of enrichment. With the BRAVE approach, each virus particle displays a peptide, derived from a protein, of known function on the AAV capsid surface, and a unique molecular barcode in the packaged genome. The sequencing of RNA-expressed barcodes from a single-generation in vivo screen allows the mapping of putative binding sequences from hundreds of proteins simultaneously. Using the BRAVE approach and hidden Markov model-based clustering, we present 25 synthetic capsid variants with refined properties, such as retrograde axonal transport in specific subtypes of neurons, as shown for both rodent and human dopaminergic neurons.
Seneca’s De Beneficiis and non-verbal politeness in ancient Rome
Authors: Hall Jon
Published: December 2019

This paper examines the philosophical treatise De Beneficiis written by Seneca the Younger
(c. 4 bce to 65 ce) and discusses some of the insights that it offers regarding the
pragmatics of interpersonal encounters in ancient Rome. In particular, it identifies types of appropriate and inappropriate
non-verbal behaviour sometimes employed when making requests. Seneca’s close observation of these social nuances alerts us to the
importance of non-verbal elements for a complete understanding of (im)politeness in everyday life.
Conceptualizations of linguistic politeness in Latin
Authors: Unceta Gómez Luis
Published: December 2019

This paper presents an analysis of conceptions of linguistic politeness in ancient Rome. Using lexical analysis, it scrutinizes first-order data recoverable from the Latin sources at our disposal, in order to determine the notions and dimensions of politeness that Romans were sensitive to. This kind of approach is helpful, primarily, when developing a suitable theoretical framework for dealing with the particular expressions of linguistic politeness in Latin. Moreover, it provides us with additional explanations of the historical dimension of politeness and of the creation and development of notions of politeness in Europe.
The individual on the move
Authors: Zhu Yifan , Kim Kyung Hye
Published: December 2019

The concept of ‘individualism’ is central to modern understandings of human behavior and society, yet it is also
an example of a “new” concept introduced to Chinese society in the early 1900s. Due to the complex interplay between linguistic,
socio-cultural, and ideological factors involved, the meaning of ‘individualism’ has undergone continual change from the early
1900s to today. As translation not only plays a vital role in knowledge dissemination, but is also a site where dynamic knowledge
negotiation is carried out, this study uses a corpus-based methodology to examine the ways in which ‘individualism’ has been
redefined, re-established and reconstructed in China through translation during the period between 1910 and 2010. The study
ultimately argues that concepts and ideas are constantly renegotiated and redefined as they travel from one culture to another,
and as they travel through time.
Beam optics design of the superconducting region of the JAEA ADS
Authors: Yee-Rendon B , Kondo Y , Maekawa F , Meigo S , Tamura J
Published: December 2019

The Japan Atomic Energy Agency (JAEA) is proposing an Accelerator Driven Subcritical System (ADS) for the transmutation of the nuclear waste. ADS will consist of a superconducting CW proton linear accelerator of 30 MW and a subcritical nuclear reactor core. The main part of the acceleration will take part in the superconducting region using five types of radio frequency cavities. The ADS operation demands a high intensity and reliability of the beam. Therefore, the beam optics design plays a fundamental role to reduce the beam loss, control emittance growth and beam halo.
Experimental observation of low-order collective oscillation modes in a strong-focusing lattice
Authors: Ito K , Kurauchi T , Higaki H , Okamoto H
Published: December 2019

In a conventional linear Paul trap (LPT), four electrode rods are placed symmetrically around the trap axis to generate a radio-frequency (rf) quadrupole field for transverse ion confinement. The periodic nature of the external focusing potential can give rise to serious ion losses under a specific condition. The loss mechanism is essentially the same as the coherent betatron resonance well-known in intense beam dynamics [1, 2]. In fact, the collective motion of an ion plasma in the LPT is shown equivalent to that of a charged-particle beam traveling through an alternating-gradient (AG) focusing lattice. In the present study, we perform the direct measurement of low-order coherent oscillation modes in the LPT by detecting image currents induced on the electrodes' surfaces. The four-rod structure of the LPT allows us to pick up weak signals from the dipole and quadrupole oscillations of a plasma bunch. These signals are Fourier analyzed to evaluate the coherent oscillation tune at different initial ion densities. The measured tune of the quadrupole mode is used to deduce the tune depression as a function of ion number stored in the LPT.
Accumulating laser-coolable ions in a linear Paul trap for ultrahigh-density beam dynamics experiment
Authors: Ito K , Masuda T , Higaki H , Okamoto H
Published: December 2019

An ion plasma confined in a linear Paul trap (LPT) exhibits the dynamic behavior physically equivalent to that of a charged-particle beam in an alternating-gradient (AG) transport channel. The Simulator of Particle Orbit Dynamics (S-POD) is a compact apparatus designed on the basis of this fact for diverse beam-physics experiments. We have so far employed Ar+ ions that can readily be produced from neutral Ar gas atoms through the electron bombardment process. A space-charge-induced tune shift of up to about 20% of the bare tune can be achieved in Ar+ plasmas. We are now preparing for future S-POD experiment to explore even higher beam-density regions. For this purpose, a large number of Ca+ ions need to be stored in the LPT. Since S-POD is equipped with a powerful laser cooler for Ca+, the use of this ion species vastly expands the density range we can survey. The production of an intense bunch of Ca+ ions is, however, not so easy because of some technical reasons. By optimizing the operating condition of a multi-sectioned LPT, we succeeded in increasing the number of accumulated Ca+ ions to the level comparable to Ar+ ion plasmas. This paper reports on updated results of the experiment.
Coupling and Space Charge studies at the CERN PSB
Authors: Asvesta F , Antoniou F , Bartosik H , Di Giovanni G P , Papaphilippou Y
Published: December 2019

In the nominal optics of the CERN PS-Booster (PSB), the fourth order coupling resonance is excited by space charge (Montague resonance [1]) due to the same integer tune values. This resonance can be avoided by changing the tunes to different integers. A new PSB opticsis presented and emittance measurements crossing the coupling resonance for the nominal and the new optics are shown.
Can a Paul Ion Trap Be Used to Investigate Nonlinear Quasi-Integrable Optics?
Authors: Martin L. K. , Kelliher D. J. , Sheehy S. L.
Published: December 2019

Here we describe the design of an experimental setup using the IBEX Paul trap to test nonlinear quasi-integrable optics, an accelerator lattice design to create stable high intensity beams. In 2010 Danilov and Nagaitsev found a realisable nonlinear potential which can create integrable optics in an accelerator when embedded in a linear lattice that provides round beams. This concept will be tested in the IOTA ring at Fermilab. It is important to further test this concept over a wide parameter range, preferably in a simplified experimental setup such as IBEX. The IBEX Paul trap is capable of replicating the transverse dynamics of a high intensity accelerator without dispersion or chromaticity.
Novel FPGA-based Instrumentation for Personnel Safety Systems in Particle Accelerator Facility
Authors: Pioli S. , Frasciello O. , Beretta M. M. , Ciambrone P. , Di Giulio C. , Buonomo B. , Belli M. , Valente P. , Variola A.
Published: December 2019

Personnel Safety System for particle accelerator facility involves different devices to monitor gates, shielding doors, dosimetry stations, search and emergency buttons. In order to achieve the proper reliability, fail-safe and fail-proof capabilities, these systems are developed compliant with safety standards (like the IEC-61508 on “Functional Safety”, ANSI N43.1 “Radiation Safety for the design and operation of Particle Accelerator” and NCRP report 88) involving stable technologies like electro-mechanical relays and, recently, PLC.

As part of the Singularity project at Frascati National Laboratories of INFN, this work will report benchmark of a new FPGA-based system from the design to the validation phase of the prototype currently operating as personnel safety system at the Beam Test Facility (BTF) of Dafne facility.

This novel instrument is capable of: devices monitoring in real-time at 1 kHz, dual modular redundancy, fail-safe and fail-proof, multi-node distributed solution on optical link, radiation damage resistance and compliant with IEC-61508, ANSI N43.1 and NCRP report 88.

The aim of this FPGA-based system is to illustrate the feasibility of FPGA technology in the field of personnel safety for particle accelerator in order to take advantage of a fully digital system integrated with facility control system, evaluate the related reliability and availability and realize a standard, scalable and exible hardware solution also for other fields with similar requirements like machine protection systems.
Timing Synchronization System for Beam Injection from the SACLA Linac to the SPring-8 Storage Ring
Authors: Ohshima T , Maesaka H , Hosoda N , Matsubara S
Published: December 2019

We developed a timing synchronization system for injection from the linac of the XFEL machine, SACLA, to the storage ring (SR) of SPring-8. This injection scheme is demanded by the low-emittance upgraded ring in the future. Since the RF frequencies of the linac and the SR do not have an integer multiples relation, we have to introduce a new scheme to synchronize the beam ejection timing of the linac to the desired RF bucket timing of the SR. The timing is roughly adjusted by re-clocking the master trigger signal of the linac with the SR bucket timing. The residual timing difference is compensated by applying frequency modulation to the linac master oscillator. The amount of the timing difference is obtained by sampling the linac reference signal with an ADC where the SR reference signal is used as a sampling clock. We built this synchronizing system with MTCA.4 modules. The system was installed to the linac and the measured timing jitter was better than 4 ps in rms, which was enough to obtain high injection efficiency.
Alarm system of IRFEL at NSRL
Authors: Chen X , Song Y , Shao Z , Li C , Xuan K , Wang J , Liu G
Published: December 2019

An InfraRed Free Electron Laser Light (IRFEL) is under commissioning at National Synchrotron Radiation Laboratory (NSRL). The control system of IRFEL is a distributed system based on Experimental Physics and Industrial Control System (EPICS). The alarm system is an essential part of the control system. It is developed based on the software Phoebus. The module named “Alarms” in Phoebus can store states and configuration information of the Process Variable (PV) in the Kafka topics. To meet our requirements, 3 kinds of alarm message distribution applications are developed, i.e. Web-Based GUI, WeChat and SMS. This paper will introduce the alarm system architecture and the implementations of the applications for alarm message distribution.
Development of a silicon strip detector for novel accelerators at SINBAD
Authors: Jaster-Merz S , Assmann R W , Burkart F , Dorda U , Kraemer U , Panofski E , Stanitzki M
Published: December 2019

At the SINBAD facility (DESY Hamburg), novel particle acceleration techniques like dielectric laser acceleration (DLA) structures will be tested using the ARES linac. Due to the small size of these structures, the accelerated electron beams only have a very low (sub-pC) charge. To determine the energy distribution of these beams, a silicon strip detector for the ARES linac spectrometer is currently under development. This detector fulfils the requirements of high spatial resolution for low charge density beams. The detector consists of two 1 cm × 1 cm silicon strip sensors and readout components. The design of the detector, its components and an estimate of its behaviour for a specific electron beam distribution are presented and discussed.
A Channel Access Software Platform for Beam Dynamics Applications in Scripting Languages
Authors: Chrin J. , Aiba M. , Snuverink J.
Published: December 2019

To facilitate the seamless integration of EPICS (Experimental Physics and Industrial Control System) into high-level applications in particle accelerators, a dedicated modern C++ Channel Access interface library, CAFE, provides a comprehensive and user- friendly interface to the underlying control system. Functionality is provided for synchronous and asynchronous interaction of single and composite groups of channels, coupled with an abstract layer tailored towards beam dynamics applications and complex modelling of virtual accelerators. Equivalent consumable solutions in scripting and domain-specific languages can then be accelerated by providing bindings to the relevant methods of the interface platform. This is exemplified by CAFE's extensive MATLAB® interface, incarnated through a single MATLAB executable (MEX) file, and a high performance Python interface written in the Cython programming language. A number of gratifying particularities specific to these language extension modules are revealed.
Design a precise stability controller for high power pulse modulator based on FPGA
Authors: Liu Y , Tong J , Gu M , Lin L , Yuan Q
Published: December 2019

Shanghai Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) has been fulfilled the construction assignments and passed the acceptance check at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The stability of microwave system is one of the major factors to get better beam performance. It is mainly determined by klystron and modulators power supply. The beam voltage stability of pulse modulator, which is the cathode voltage source of the microwave amplifier, is directly affecting the microwave amplitude and phase. The requirement of the microwave stability is 0.04% (rms) for amplitude and 0.05% (rms) for phase tolerance. This paper shows the design considerations of stability improvement and suitable upgrade scheme of the controller for Shanghai SXFEL pulse modulator.
A novel microwave switch-based LLRF system for long-term system phase drift calibration
Authors: Lin Z.Y. , Du Y. C. , Huang W.H. , Tang J.H. , Tang C.X. , Huang G. , Xu Y.L , Zhang D. , Sun Z.C.
Published: December 2019

Long-term phase stability is a significant issue for Low-level RF systems. Crosstalk and temperature effect on the RF field detectors would significantly limit the performance of phase detecting and phase locking. A novel microwave switch-based LLRF system has been developed in Tsinghua Accelerator Lab. Microwave switches are applied in the chopper circuit to turn continuous waves into pulse waves in the time domain to avoid mutual interference of signals. In this paper, the LLRF sys-tem based on microwave switches is presented. The result of preliminary long-term experiments shows the phase stability can achieve about 50fs RMS slow drift. The peak-to-peak value of the slow drift was ~100fs (~2 °C p-p) in 4 days.
New Undulator and Front End for XAIRA beamline at ALBA
Authors: Campmany J. , Marcos J. , Massana V.
Published: December 2019

A new microfocus beamline for macromolecular crystallography, XAIRA, is being built at ALBA synchrotron light source. The light source for this new beamline is an in-vacuum undulator that can reach the spectral range from 4 keV up to 20 keV. The in-vacuum undulator was tendered in 2018 and awarded to Kyma-RI consortium, and will be delivered to ALBA in November 2019. The Front End has been designed accordingly. It was tendered in 2018 and awarded to FMB. It will be delivered in October 2019. In this paper we present the ID and FE designs.
Analysis on the thermal response to beam impedance heating of the post LS2 proton synchrotron beam dump
Authors: Teofili L , Marongiu M , Migliorati M , Giordano F , Lamas I , Nuiry F-X , Romagnoli G , Salvant B
Published: December 2019

The High Luminosity Large Hadron Collider (HL-LHC) and the LHC-Injection Upgrade (LIU) projects at CERN are upgrading the whole CERN accelerators chain to increase beam brightness and intensity. In this scenario, some critical machine components have to be redesigned and rebuilt. Due to the increase in beam intensity, minimizing the electromagnetic interaction between the beam and devices is a crucial design task. Indeed, these interactions could lead to beam instabilities and excessive thermo-mechanical loadings in the device. In this context, this paper presents an example of multi-physics study to investigate the impedance related thermal effects. The analysis is performed on the conceptual design of the new proton synchrotron (PS) internal dump.
New Design of Vacuum Chambers for Radiation Shield Installation at Beam Injection Area of J-PARC RCS
Authors: Kamiya J , Kotoku H. , Shobuda Y. , Takayanagi T. , Yamamoto K. , Yanagibashi T. , Horino K. , Miki N.
Published: December 2019

One of the issues in the J-PARC 3 GeV rapid cycling synchrotron is the high residual radiation dose around the beam injection point. A radiation shield is necessary to reduce radiation exposure of workers when maintenance is performed there. A space to install the radiation shield should be secured by newly designing a structure of the vacuum chamber at the injection point and the alumina ceramics beam pipes for the shift bump magnets. To make the space for the shield, the chamber is lengthened along the beam line and the cross-sectional shape is changed from circle to rectangle. The displacement and inner stress of the vacuum chamber due to atmospheric pressure were evaluated to be enough small by the calculation. For the ceramics beam pipe’s rf-shield, the damping resistor was effective to reduce the induced modulation voltages by the pulsed magnetic field.
Establishing A Laser Treatment To Suppress The Sec-Ondary Electron Emission
Authors: Wang Yigang , Wang Siwei , Zhu Bangle , Pei Xiangtao , Zhang Bo , Ge Xiaoqin , Wang Yong
Published: December 2019

Laser treatment has a significant influence on suppressing the secondary electron emission (SEE) in electron storage rings. A new synchrotron radiation light source, the Hefei Advanced Light Source(HALS), is under consideration and it has a strict requirement to suppress the SEE. In this paper, we used a laser with the wavelength of 355nm to process with copper sample. After the laser treatment, the secondary electron yield (SEY) reduces from 2.05 to 0.86. We also used the scanning electron microscope (SEM) to analysis the surface of the sample after the laser treatment. This paper reports the experiment set up and preliminary results.
Research On Secondary Electron Emission Characteristics of Diamond-Like Carbon Thin Films
Authors: Zhang Y X , Wang Y G , Ge X Q , Zhang B , Wei W , Wang S H , Zhu B L , Shao J Q , Li W M , Wang Y
Published: December 2019

In modern particle accelerators, the build-up of electron cloud is a main limiting factor for the achievement of high-quality beam. Among the techniques to mitigate it, coating the internal walls of the beam pipes with a thin film which has a low secondary electron yield (SEY) is considered to be one of the most effective means. From several earlier studies, it was found that diamond-like carbon (DLC) thin films are potential coatings. This paper is mainly about the research on secondary electron emission characteristics of DLC thin films. The secondary electron emission (SEE) tests were done at temperature of 298 K and vacuum pressure of 2 × 10–9 Torr. Here, we obtained the characteristics of the SEE from DLC film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. The maximum secondary electron yield (SEY), δmax, of the DLC thin films under different primary electron doses were also obtained, respectively.
Impact of Flux Jumps on High-Precision Powering of Nb3Sn Superconducting Magnets
Authors: Martino Michele , Arpaia Pasquale , Ierardi Stefano
Published: December 2019

Nb3Sn superconducting magnets represent a technology enabler for future high-energy particle accelerators. A possible impediment, though, comes from flux jumps that, so far, could not be avoided by design unlike for NbTi technology. However, the impact of flux jumps on the magnet powering has not been properly investigated to date. Flux jumps appear during current ramps at relatively low value of current and tend to disappear towards nominal current. They are usually detected as voltage jumps between different magnet coils but they might also produce overall voltage jumps across the magnet electrical terminals. Such jumps might perturb the power converter feedback control loop and therefore potentially jeopardize its precision performance during energy ramps. This work aims at: (i) presenting preliminary experimental test results on some HL-LHC Nb3Sn model and prototype magnets, and (ii) attempting to build a simplified electrical model of the flux jumps, with focus only at its interaction with the power converter feedback control loop. Such a work is a starting point for outlining possible power converters control strategies able to minimize flux jumps impact on high-precision powering of Nb3 Sn superconducting magnets.
Upgrade of the Cryogenic Control System for SRF Modules at the Taiwan Light Source
Authors: Chung F. T. , Chang M. H. , Yu T. C. , Wang C. , Yeh M. S. , Chang F. Y. , Chen L. J. , Liu Z. K. , Chang L. H. , Lo C. H. , Li Y. T. , Chang S. W. , Lin M. C.
Published: December 2019

An upgrade of the cryogenic control system for superconducting radio-frequency (SRF) modules of the Taiwan Light Source (TLS) has been completed. The biggest challenge was to recover all protection and operational functions, while minimizing the quantity of vented helium from SRF modules while replacing valve controllers. Gradually, this work was finished within several one- and ten-day scheduled machine shutdown periods for accelerator maintenance. No large helium vent nor pollution of the cryogenic system occurred during all component replacements and function verifications. Functions of the cryogenic electronics were improved, whereas the valve controllers are upgraded to new versions to increase reliability and availability. Communications with the data acquisition system was also secured by buffered signal processing module so that device shutdown of the data acquisition system will not interrupt the cryogenic valve operation.
Electromagnetic design and characterization of an S-band 3-cell rf acceleration cavity
Authors: Montoya-Soto G R , Yee-Rendon B. , Duarte-Galvan C. , Valerio-Lizarraga C. A.
Published: December 2019

An S-Band (2998 MHz) Radio Frequency (RF) cavity to accelerate electrons was developed taking into account the beam space charge, the relativistic change in velocity of the low energy beam particle distribution through the cavity, and the emittance growth. The electromagnetic design and geometry optimization were done using the codes Poisson Superfish (PSF) and CST Studio (CST). In addition, beam dynamics simulations were done using the program Travel to optimize the emittance and take into account the space charge effect.
Commissioning of RF system of the 200 MeV proton cyclotron
Authors: Chen Gen , Liu Guang , Zhao Yanping , Peng Zhen , Zhang Xin , Chao Chujie , Long Xuyun , Yu Chuansong , Karamyshev Oleg , Karamysheva Galina , Shirkov Grigori , Caruso Antonio , Calabretta Luciano
Published: December 2019

The SC200 superconducting accelerator which is designed for proton therapy is currently under construction. The RF (Radio Frequency) system has been designed and constructed as a subsystem of the SC200. To verify the stability of the RF system, a high-power feeding test was performed for the cavity. This paper mainly reports on the overview of RF systems and the preliminary high-power commissioning, as well as the problems found and improvements made during the commissioning process. The results show that the RF system has initially achieved the designed goal, and each loop (amplitude, tuning, phase) can work effectively. The cavity can operate in a ~50 kW continuous wave state. Next, the formal RF conditioning will be carried out after the complete assembly of cyclotron, so as to confirm the cavity can run smoothly under 80 kW, which is part of the whole commissioning process.
High power test of the first C-band spherical pulse compressor prototype
Authors: Li Z. B. , Fang W. C. , Gu Q. , Tan J. H. , Huang X. X. , Zhao Z. T.
Published: December 2019

Recently, a new C-band (5712 MHz) compact spherical radio frequency (RF) pulse compressor was designed and tested for Shanghai Soft X-ray Free Electron Laser Facility (SXFEL). This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two TE1,1,3 modes and a dual-mode polarized coupler. The peak power multiply factor is 6.1 and average power gain 3.8 in theory. During the high power test, a peak power multiply factor of 5.74 and average power gain of 3.77 was achieved. This paper presents the RF measurement of the C-band spherical pulse compressor and the high power test results.
Multipacting studies of the coaxial coupler for BNCT DTL
Authors: Fan M X , Liu H C , Li A H , Qu P H , Wang Y , Wu X L , Li B , Chen Q , Peng J , Wang A X , Fu S N
Published: December 2019

Multipacting is a phenomenon in which electrons grow sharply under certain conditions in a RF structure. It may lead to the breakdown or even damage to the equipment. Therefore, it is very important to calculate the Multipacting range in the RF equipment design. Since the phenomenon is too complicated to use the formula to fully predict it, numerical simulation is employed. There are many computer codes (such as Track3P, MultiPac, CST PS, etc.) used to simulate the phenomenon, but most of them are not commercial. In this paper, theories used in coaxial line for predicting multipacting are introduced; the CST PS is chosen to simulate the multipacting of coaxial coupler for BNCT DTL; finally, methods of suppressing multipacting are discussed.
Utilizing the high shunt impedance TM020-mode cavity in the double RF systems for the storage ring of the Thailand new light source
Authors: Juntong N , Phimsen T , Chulakham N , Malichan S
Published: December 2019

The utilization of the TM020-mode cavity for the storage ring based light source was pioneered by SPring-8 with its high quality factor and hence its high shunt impedance. KEK-LS has also studied the possibility of using this type of cavity for their storage ring. The TM020-mode cavity has larger transverse dimension compared to the traditional TM010-mode cavity, but with its higher shunt impedance it can be designed to fit in the new low emittance storage ring regardless. The new storage ring based light source project in Thailand aims to optimum the low emittance beam in nano-meters region with the energy of 3 GeV. The TM020-mode cavity was considered as the main cavity and the harmonic cavity for the storage ring. They have been designed to have their pipe aperture fits the storage ring beam ducts. The main cavity has a high shunt impedance of 8.3 MΩ with the 51,000 unloaded quality factor. The harmonic cavity has a high shunt impedance and an unloaded quality factor of 2.45 MΩ and 36,000, respectively. The damping mechanism of the parasitic modes and the tuning mechanism of the operating mode of these cavities were also studied. There will be four main cavities and six harmonic cavities in the new storage ring. Detailed design and study of these cavities will be presented.
Design of the elliptical superconducting cavities for the JAEA ADS
Authors: Yee-Rendon B , Kondo Y , Maekawa F , Meigo S , Tamura J
Published: December 2019

The superconducting CW proton linear accelerator for an Accelerator Driven Subcritical System (ADS) proposed by Japan Atomic Energy Agency (JAEA) employs elliptical cavities for the final acceleration of 180 MeV to 1.5 GeV. Since this energy region implies a changed of β from 0.55 to 1, two cavity models were developed using the geometrical betas of 0.68 and 0.89 to improve the acceleration efficiency. The study of the electromagnetic design was simulated using SUPERFISH (SF) code and python program to do variable scan, the results were benchmarked with CST Microwave Studio program (CST).
Is it possible to use additive manufacturing for accelerator UHV beam pipes?
Authors: Jenzer S. , Alves M. , Bilgen S. , Bonis J. , Brisset F. , Djelali S. , Gonnin A. , Guerrier M. , Grasset D. , Letellier-Cohen F. , Mercier B. , Mistretta E. , Sattonnay G.
Published: December 2019

Additive Manufacturing (AM) enables 3D metallic objects to be built by adding layer- upon-layer of material. This technology can be applied to produce Ultra High Vacuum components for particle accelerators. We investigated in this work the reproducibility of AM 316L stainless steel properties for different specimens supplied by several manufacturers with the same process. Microstructure and mechanical properties of AM samples depends on manufacturers: indeed, they are largely influenced by processing parameters, which produces heterogeneous and anisotropic microstructures that differ from traditional wrought counterparts. The outgassing rates of vacuum AM 316L tubes were determined and the secondary electron yield was also measured. Results are very promising to consider the use of AM to construct accelerator beam pipe components.
Optics Design and Beam Dynamics simulation for a VHEE Radiobiology beam line at PRAE accelerator
Authors: Han Y , Faus Golfe A , Vallerand C , Bai B , Duchesne P , Prezado Y , Delorme R , Poortmans P , Favaudon V , Fouillade C , Pouzoulet F , Dosanjh M
Published: December 2019

The Platform for Research and Applications with Electrons (PRAE) is a multidisciplinary R&D facility gathering subatomic physics, instrumentation, radiobiology and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV. In this paper we report the complete optics design and performance evaluation of a Very High Energy Electron (VHEE) innovative radiobiology study, in particular by using Grid mini-beam and FLASH methodologies, which could represent a major breakthrough in Radiation Therapy (RT) treatment modality.
Simulation of collisionless shocks in plasmas with high metallicity
Authors: Kropotina J A , Levenfish K P , Bykov A M
Published: December 2019

The results of hybrid simulation of low-beta supercritical quasi-parallel shocks in high metallicity plasma are presented. The structure of upstream and downstream turbulence is addressed and velocities of the corresponding scattering centers are derived. It is shown that independently of their chemical composition the shocks experience self-reformation process. However, the period of self-reformation as well as the wave spectrum is greatly affected by the presence of substantial admixture of weakly charged heavy ions. Also the downstream magnetic field amplification is stronger for the high metallicity case.
r-modes in stratified neutron stars with entrainment
Authors: Kantor E M , Dommes V A , Gusakov M E
Published: December 2019

We calculate the temperature-dependent r-mode spectrum of superfluid neutron stars with npeµ (neutron, proton, electron, muon) core composition. This study is an extension of the previous work by Kantor, Gusakov [MNRAS 469, 3928 (2017)], where such spectrum was calculated under simplifying assumption of vanishing entrainment between superfluid neutrons and superconducting protons. We show that accounting for the entrainment leads to non-analytic behavior of the spectrum at small rotation rates. Namely, we find that in the leading order in rotation accounting for any non-zero value of entrainment eliminates superfluid r-modes. We show that next-to-leading order in rotation restores the superfluid r-modes in the spectrum. We calculate this spectrum and show that for certain neutron star models normal r-mode experiences stabilizing resonances with superfluid r-modes. This confirms the scenario of Gusakov, Chugunov, and Kantor [PRL 112, 151101 (2014)] that explains neutron stars in low-mass X-ray binaries.
Wolf-Rayet stars in young massive star clusters as potential sources of Galactic cosmic rays
Authors: Kalyashova M E , Bykov A M , Osipov S M , Ellison D C , Badmaev D V
Published: December 2019

For most elements, the isotopic ratios seen in cosmic rays (CRs) are similar to those in the solar wind. The most important exception to this is 22Ne/20Ne where the CR value is ∼ 5 times that of the solar wind. According to most recent models of nucleosynthesis, a large amount of 22Ne is generated in Wolf-Rayet (WR) stars. In the winds of carbon sequence of WR stars, i.e., WC stars, the isotopic ratio 22Ne/20Ne can be much larger than in the solar wind. Here, we consider CRs produced by 22Ne-enriched WR winds in young massive star clusters assuming the acceleration occurs from an ensemble of shock waves from the massive stars’ winds. We estimate the fraction of all Galactic CRs such sources may produce for a given set of parameters.