Torino L.,ALBA Synchrotron Light Facility |
Iriso U.,ALBA Synchrotron Light Facility
Physical Review Special Topics - Accelerators and Beams | Year: 2016
Transverse beam size measurements in new generation of synchrotron light sources is a challenging task due to their characteristic small beam emittances and low couplings. Since the late 1990s, synchrotron radiation interferometry (SRI) has been used in many accelerators to measure the beam size through the analysis of the spatial coherence of the synchrotron light. However, the standard SRI using a double-aperture system provides the beam size projection in a given direction. For this reason, the beam shape is not fully characterized because information about possible transverse beam tilts is not determined. In this report, we describe a technique to fully reconstruct the transverse beam profile based on a rotating double-pinhole mask, together with experimental results obtained at ALBA under different beam couplings. We also discuss how this method allows us to infer ultrasmall beam sizes in case of limitations of the standard SRI. © 2016, American Physical Society. All rights reserved.
Bazaga-Garcia M.,University of Malaga |
Colodrero R.M.P.,University of Malaga |
Papadaki M.,University of Crete |
Garczarek P.,Wroclaw University of Technology |
And 9 more authors.
Journal of the American Chemical Society | Year: 2014
We report the synthesis, structural characterization, and functionality (framework interconversions together with proton conductivity) of an open-framework hybrid that combines Ca2+ ions and the rigid polyfunctional ligand 5-(dihydroxyphosphoryl)isophthalic acid (PiPhtA). Ca 2[(HO3PC6H3COOH)2] 2[(HO3PC6H3(COO)2H) (H2O)2]·5H2O (Ca-PiPhtA-I) is obtained by slow crystallization at ambient conditions from acidic (pH ≈ 3) aqueous solutions. It possesses a high water content (both Ca coordinated and in the lattice), and importantly, it exhibits water-filled 1D channels. At 75 °C, Ca-PiPhtA-I is partially dehydrated and exhibits a crystalline diffraction pattern that can be indexed in a monoclinic cell with parameters close to the pristine phase. Rietveld refinement was carried out for the sample heated at 75 °C, Ca-PiPhtA-II, using synchrotron powder X-ray diffraction data, which revealed the molecular formula Ca2[(HO3PC 6H3COOH)2]2[(HO3PC 6H3(COO)2H)(H2O)2]. All connectivity modes of the "parent" Ca-PiPhtA-I framework are retained in Ca-PiPhtA-II. Upon Ca-PiPhtA-I exposure to ammonia vapors (28% aqueous NH3) a new derivative is obtained (Ca-PiPhtA-NH3) containing 7 NH3 and 16 H2O molecules according to elemental and thermal analyses. Ca-PiPhtA-NH3 exhibits a complex X-ray diffraction pattern with peaks at 15.3 and 13.0 Å that suggest partial breaking and transformation of the parent pillared structure. Although detailed structural identification of Ca-PiPhtA-NH3 was not possible, due in part to nonequilibrium adsorption conditions and the lack of crystallinity, FT-IR spectra and DTA-TG analysis indicate profound structural changes compared to the pristine Ca-PiPhtA-I. At 98% RH and T = 24 °C, proton conductivity, σ, for Ca-PiPhtA-I is 5.7 × 10-4 S·cm-1. It increases to 1.3 × 10-3 S·cm-1 upon activation by preheating the sample at 40 °C for 2 h followed by water equilibration at room temperature under controlled conditions. Ca-PiPhtA-NH3 exhibits the highest proton conductivity, 6.6 × 10-3 S·cm-1, measured at 98% RH and T = 24 °C. Activation energies (Ea) for proton transfer in the above-mentioned frameworks range between 0.23 and 0.4 eV, typical of a Grothuss mechanism of proton conduction. These results underline the importance of internal H-bonding networks that, in turn, determine conductivity properties of hybrid materials. It is highlighted that new proton transfer pathways may be created by means of cavity "derivatization" with selected guest molecules resulting in improved proton conductivity. © 2014 American Chemical Society.
Vallcorba O.,CSIC - Institute of Materials Science |
Rius J.,CSIC - Institute of Materials Science |
Frontera C.,CSIC - Institute of Materials Science |
Peral I.,ALBA Synchrotron Light Facility |
Miravitlles C.,CSIC - Institute of Materials Science
Journal of Applied Crystallography | Year: 2012
DAJUST is the generic name of a software package for powder diffraction formed by the core programs AJUST and SGAID (both written in Fortran) controlled by an easy-to-use Java user interface (DAJUST-UI). While AJUST performs whole-pattern matching (cell-parameter refinement, profile fitting and intensity extraction), SGAID provides a list of the most probable space groups. For the extraction of the integrated intensities, AJUST uses the Le Bail procedure but with a different formula for refining the integrated intensities. Laboratory, synchrotron X-ray and neutron sources, and both reflection and transmission experimental geometries, are supported. Other program options include automated background estimation, asymmetry correction, and corrections for absorption, variable divergence and/or illumination. The extracted intensity data are written in text format and can be directly processed by the direct methods program XLENS [Rius (2011). Acta Cryst. A67, 63-67] and the multisolution direct-space structure determination program TALP [Vallcorba, Rius, Frontera & Miravitlles (2011). Acta Cryst. A67, C272]. © 2012 International Union of Crystallography. Printed in Singapore-all rights reserved.
Hassanzadegan H.,ALBA Synchrotron Light Facility |
Grino R.,Polytechnic University of Catalonia
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010
There are two important considerations in the development of an electrical model for RF cavities to be used for system analysis or LLRF loop design, being: transient response and cavity impedance mismatch. In the literature, however, either one or both of these issues are often neglected depending whether the RF cavity is being looked at from high-power or low-level RF perspectives. In this work, a transient model for storage ring RF cavities under beam loading is developed so that it represents the important RF aspects of the cavity such as impedance mismatch and reflected voltage as well as its transient response, for example at start-up or upon beam arrival. As a special case, the model is applied to the RF cavity of the ALBA storage ring to study the effects arising from beam loading, system start-up and delays on the performance of the LLRF regulation loops. For the simulation of the regulation loops in time domain a mathematical technique is introduced to map the RF frequency to baseband, leading to the baseband-equivalent model of the cavity with almost the same results as the conventional cavity model but with significantly higher simulation speed. © 2010 Elsevier B.V. All rights reserved.
Benedetti G.,ALBA Synchrotron Light Facility
IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference | Year: 2013
The potential hazards introduced by injecting into the ALBA storage ring with front end shutters open are determined through particle tracking simulations. The method is based on the possible overlap between phase space of forwards and backwards tracking between the straight section downstream the front end and the beamline. Realistic magnetic field, trajectory, aperture and energy errors are taken into account. Scenarios that could bring an injected beam of electrons passing through an open beamline front end are identified. The interlocks required to prevent such situations from arising are discussed. Copyright © 2013 by JACoW- cc Creative Commons Attribution 3.0 (CC-BY-3.0).
Aballe L.,ALBA Synchrotron Light Facility |
Foerster M.,ALBA Synchrotron Light Facility |
Pellegrin E.,ALBA Synchrotron Light Facility |
Nicolas J.,ALBA Synchrotron Light Facility |
Ferrer S.,ALBA Synchrotron Light Facility
Journal of Synchrotron Radiation | Year: 2015
The spectroscopic LEEM-PEEM experimental station at the CIRCE helical undulator beamline, which started user operation at the ALBA Synchrotron Light Facility in 2012, is presented. This station, based on an Elmitec LEEM III microscope with electron imaging energy analyzer, permits surfaces to be imaged with chemical, structural and magnetic sensitivity down to a lateral spatial resolution better than 20nm with X-ray excited photoelectrons and 10nm in LEEM and UV-PEEM modes. Rotation around the surface normal and application of electric and (weak) magnetic fields are possible in the microscope chamber. In situ surface preparation capabilities include ion sputtering, high-temperature flashing, exposure to gases, and metal evaporation with quick evaporator exchange. Results from experiments in a variety of fields and imaging modes will be presented in order to illustrate the ALBA XPEEM capabilities.
Perez F.,ALBA Synchrotron Light Facility
IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference | Year: 2013
ALBA is a 3 GeV, 3rd generation, synchrotron light source located in Cerdanyola del Vallès, near Barcelona (Spain), which started users operation in May 2012. In this paper we will report about the transition from commissioning to operation, the main problems faced during this first year, the actual status of the accelerators and we will provide an outlook to the next steps. Copyright © 2013 by JACoW.
Larocca T.J.,State University of New York at Stony Brook |
Crowley J.T.,State University of New York at Stony Brook |
Cusack B.J.,State University of New York at Stony Brook |
Pathak P.,State University of New York at Stony Brook |
And 4 more authors.
Cell Host and Microbe | Year: 2010
Borrelia burgdorferi, the agent of Lyme disease, is unusual as it contains free cholesterol and cholesterol glycolipids. It is also susceptible to complement-independent bactericidal antibodies, such as CB2, a monoclonal IgG1 against outer surface protein B (OspB). We find that the bactericidal action of CB2 requires the presence of cholesterol glycolipids and cholesterol. Ultrastructural, biochemical, and biophysical analysis revealed that the bacterial cholesterol glycolipids exist as lipid raft-like microdomains in the outer membrane of cultured and mouse-derived B. burgdorferi and in model membranes from B. burgdorferi lipids. The order and size of the microdomains are temperature sensitive and correlate with the bactericidal activity of CB2. This study demonstrates the existence of cholesterol-containing lipid raft-like microdomains in a prokaryote, and we suggest that the temperature dependence of B. burgdorferi lipid raft organization may have significant implications in the transmission cycle of the spirochetes which are exposed to a range of temperatures. © 2010 Elsevier Inc.
Pont M.,ALBA Synchrotron Light Facility
IPAC 2012 - International Particle Accelerator Conference 2012 | Year: 2012
ALBA is a 3.0 GeV third generation synchrotron light source which has beencommissioned during 2011. In October 2011, the seven beamlines of phase I startedcommissioning, 6 from insertion devices and 1 from a bending magnet. Since May 2012 thefacility is open to external users. Beam current has been continuously increased and wereached 200 mA in a multi-bunch filling pattern. Orbit stability is kept at ±1 umwith a slow orbit feedback running at 0.3 Hz. The paper will review the operation andperformance status of the different subsystems and review also the main objectives for2012: delivery of 3000 hours of beam to beamlines, installation of a fast orbit feedbacksystem and preparation for top-up operation. Copyright © 2012 by IEEE.
Hinterstein M.,TU Dresden |
Rouquette J.,Charles Gerhardt Institute |
Haines J.,Charles Gerhardt Institute |
Papet Ph.,Charles Gerhardt Institute |
And 4 more authors.
Physical Review Letters | Year: 2011
An in situ structural description of the origin of the ferroelectric properties as a function of the applied electric field E was obtained by synchrotron x-ray diffraction. A setup was used to average the effects of the preferred orientation induced by the strong piezoelectric strain and solve in situ the crystal structure as a function of the applied electric field. Hence, we were able to describe the microscopic origin of the macroscopic ferro- and piezoelectric properties of the most widely used ferroelectric material, lead zirconate titanate. © 2011 American Physical Society.