Technical Report: The Fastest Relativistic Jets from Quasars and Active Galactic Nuclei

This workshop was held to gather scientists interested in exploiting beamlines I06 and I10 of the Surface and Interfaces Village at Diamond Light Source from June 10–11, 2009. Sarnjeet Dhesi introduced the meeting with a short explanation of the village structure at Diamond. This village includes the Nanoscience beamline (I06), catering for soft X-rays for Photo-Emission Electron Microscopy (PEEM) and X-ray Magnetic Circular and Linear Dichroism (XMCD and XMLD), and the Beam Line for Advanced Dichroism Experiments (BLADE, beamline I10), which is a polarized soft X-ray beam for XMCD, XMLD, and soft X-ray diffraction. I06 has been operational for over two years, while I10 is scheduled to come on-line in late 2010. In addition, there are two surface science beamlines (I07 and I09) in the village dedicated to surface diffraction and X-ray standing waves.     

Synchrotron radiation in archaeometry

January 2008 was the time of the official opening of SOLEIL's beamlines and guest house. This transition from construction to operational phase was made possible after commissioning of the 17°C water circuits of the beamlines. Users have access to eleven beamlines, from infrared to hard X-ray (AILES, SMIS, DESIRS, CASSIOPEE, TEMPO, DIFFABS, ODE, CRISTAL, SAMBA, PROXIMA1 and SWING). The LUCIA beamline, which has been operational on SLS since June 2004, will be installed at SOLEIL from mid-2008, and the XPEEM station of the future “soft X-ray microscopy” beamline is already producing fascinating XMCD and XMLD results at ELETTRA. Five beamlines are under construction.     

Combined X-ray-Atomic Force Microscopy Tools at the ESRF: The First 10 Years

In the last 10 years, the Surface Science Lab of the ESRF has developed four Atomic Force Microscopes (AFM) compatible with the sample environments of several X-ray beamlines [1 http://www.esrf.eu/UsersAndScience/Experiments/SciInfra/SurfaceSciLab [Google Scholar]], the motivation being to combine many synchrotron-radiation-based techniques with in situ, real-time AFM. To this end, novel experimental techniques and operational schemes particularly adapted to the investigation of nano-sized materials were designed and tested. Several ESRF beamlines have been involved, including ID01, ID03, ID13, ID17, and BM05. This development was initially financed by the European X-Tip project STPR 505634-1 (2004–2008), and then by the French ANR-09-NANO-042 PIANHO Project (2009–2012).     

Spin- and angle-resolved photoelectron spectroscopy from solid surfaces with circularly polarized light

Spin-polarized photoemission with circularly polarized light represents a relatively new technique in surface science. It became feasible with the increased availability of circularly polarized light in the vacuum ultraviolet and soft X-ray regime, generated in dedicated synchrotron radiation facilities. Another important ingredient was the development of efficient electron spin polarization detectors. Supported by group theoretical considerations, this technique was first employed to study the process of optical spin orientation in single crystalline non-magnetic materials. In these samples, spin-dependent effects arise solely from spin-orbit coupling. The experiments revealed the strong influence of spin-orbit coupling on the details of the electronic band structure, such as the symmetry character of the electronic wave functions, hybridization phenomena, and the behavior of degeneracies. The results opened the way to a detailed understanding of the electronic structure and permit a rigorous test of both state-of-the-art bulk band theories and fully relativistic photoemission calculations. Since 1990, spin-polarized photoemission with circularly polarized light is also used to investigate ferromagnetic systems. These experiments led to the discovery of the counterpart of optical spin orientation in ferromagnets, namely, the magnetic dichroisms. Magnetic dichroism means that the spin-dependent photoexcitation from a ferromagnetically ordered system manifests itself already in the photoelectron intensity distributions. Because of this particular property, techniques based on magnetic dichroisms are currently receiving wide interest in the spectroscopic investigation of magnetic systems and phenomena.

The following article reviews the current status of the field of spin- and angle-resolved photoemission from solids using circularly polarized radiation. We survey the development of this technique over the last 10 years, covering its applications to both non-magnetic and ferromagnetic systems.     

上海光源硬X射线相干衍射成像实验方法初探

相干X射线衍射成像方法是一种先进的成像技术,分辨率可达纳米量级.国际上大多数的同步辐射装置和自由电子激光装置都建立了该成像方法,并有将其作为主要成像技术的趋势.上海光源作为目前国内唯一的一台第三代同步辐射光源,尚未建立基于硬X射线的相干衍射成像实验平台.随着一批以波荡器为光源的光束线站投入使用,使得该方法的建立成为了可能.本文基于上海光源BL19U2生物小角散射线站,通过有效的光路设计,搭建了相干衍射实验平台,在12 keV和13.5 keV能量点均获得了硬X射线相干光束,并基于小孔衍射测量了入射光束的空间相干长度.该平台支持常规和扫描相干衍射实验模式,对小孔衍射图样及波带片扫描衍射图样实现了正确的相位重建,证明了该平台初步具备开展硬X射线相干衍射成像实验的能力.硬X射线相干衍射成像实验平台为国内首次建立,将为国内该实验方法的发展和应用提供有效的软硬件支持.     

Beamline 12.2.2: An Extreme Conditions Beamline at the Advanced Light Source

The Advanced Light Source (ALS) is a 1.9-GeV, third-generation synchrotron optimized for the production of VUV and soft X-rays from undulators. There is also a hard X-ray program at the ALS, which is based around three 6-T superconducting bending magnets [1 Robin, D. Proceedings of the 2002 European Particle Accelerator Conference. Paris, France. pp.215Geneva: EPAC..  [Google Scholar]] that shift the critical energy from 3 keV to 12 keV. The extreme conditions beamline at the ALS is situated on Beamline 12.2.2, which benefits from radiation produced by one of these superbend sources. The beamline is designed for X-ray diffraction, X-ray spectroscopy, and X-ray imaging of samples held in diamond-anvil high-pressure cells (DACs). In a DAC, samples are on the order of 10 to 50 μm in diameter and 10 to 30 μm thick and are contained in a metal gasket of typical inner diameters of 100 to 150 μm. For high-quality diffraction patterns with little or no contamination from diffraction from the gasket, the X-ray beam size needs to be on the order of 10 μm × 10 μm.     

Overview of the tunable beamlines for protein crystallography at the EMBL Hamburg Outstation; an analysis of current and future usage and developments

The EMBL Hamburg Outstation currently operates two tunable protein crystallography beamlines suitable for single and multiple anomalous diffraction (SAD/MAD) experiments. The first beamline, designated X31, is located on a bending magnet of the DORIS III storage ring whereas the second beamline, BW7A, is positioned at a multipole wiggler at the same storage ring. X31 is equipped with an energy stabilization device to ensure constant wavelength during longer data-collection periods. The in-house built crystallographic end-station is now equipped with a Mar345 imaging-plate scanner as a detector. The wiggler beamline BW7A features a novel sagitally focusing monochromator. The end-station used here has also been developed and built in-house. The beamline is currently operated with a Mar 165 CCD detector. In this paper the hardware and software developments of the last years will be summarized and the outlook for substantial upgrades will be given. The future plans include the design and construction of a third tunable beamline, designated X12, for protein crystallography. The development of automated beamlines for protein crystallography is of particular importance with respect to structural genomics initiatives. The analysis of the projects of the last years shows the wide range of anomalous scatterer used on the tunable beamlines thus demonstrating the need of a wide range of accessible energies and fast and reliable energy changes.     

DMLS 2011: Fourth International Workshop on Diamonds for Modern Light Sources

The fourth in a series of workshops devoted to the use of diamonds at synchrotrons and free electron lasers (FELs) was held on May 5-6, 2011, at the Advanced Photon Source. The previous DMSL workshop was held in Japan in 2008. The workshop was supported in part by Argonne National Laboratory; Applied Diamond, Inc.; SINMAT, Inc.; and elementsix, Ltd. The scope was to assess : 1) the status, size, quality, and availability of synthetic type IIa diamonds; 2) the status of CVD diamonds; 3) applications for beamline optics; 4) applications for beam position monitors (BPMs) and detectors; 5) applications at FELs; and 6) novel applications, such as for an X-ray free electron laser oscillator (XFELO). On May 5, Linda Young (APS/XSD) gave the workshop welcome. There were three sessions on each of the two days. A website was created and will be kept live where the detailed age-nda and list of speakers will remain available (http://www.aps.anl.gov/News/Conferences/2011/DMLS). As part of the session on BPMs and detectors, there were several speakers from outside the light source community, which demonstrated that there is a larger science audience for these applications than just light sources. Highlights of the workshop include: 1) reports of supplier facilities for thinning and polishing; 2) reports on tests of supplier-provided bonds to CVD cooling manifolds; 3) a report of more than 99% reflectivity from diamond for hard X-rays, significant for XFELO feasibility, measured at the APS; 4) a report on thermal expansion measurements at low temperatures made at the APS (no negative thermal expansion, thermal expansion below 1e-9); 5) a report from Brookhaven National Laboratory on substantial progress in diamond beam flux monitors (BPMs), and fast detectors; 6) a presentation on plans for a self-seeding at LCLS with diamond crystals. A synopsis of each technical session follows below.     

Residual stress/strain analysis in thin films by X-ray diffraction

Residual stresses are found in the majority of multilayer thin film structures used in modem technology. The measurement and modeling of such stress fields and the elucidation of their effects on structural reliability and device operation have been a “growth area” in the literature, with contributions from authors in various scientific and engineering disciplines.

In this article the measurement of the residual stresses in thin film structures with X-ray diffraction techniques is reviewed and the interpretation of such data and their relationship to mechanical reliability concerns are discussed.     

Effect of defects on the reflectivity of Cr/C multilayer soft X-ray mirror at 4.48 nm

Cr/C is a promising material combination for multilayer mirror in the “near water window region” (4.4-6.7 nm). In the present paper, the effect of defects on the reflectivity of Cr/C soft X-ray multilayer mirror deposited by magnetron sputtering was studied. Formation of thin interlayer due to the interdiffusion, rough interface due to the non-sharp layer and contamination of O happened during the deposition process were found by a method combined by XPS, soft X-ray reflectivity at 4.48 nm and grazing incidence hard X-ray reflectivity at 0.154 nm. The XPS results show that both interlayers (Cr-on-C and C-on-Cr) are mixture composed of C sp2, C sp3, CO, CO, CrCr and CrO bondings. No chromium carbide was found at the interlayer probably due to the blocking of oxides’ formation. Through the analysis of X-ray reflectivity, we obtained the multilayer structure parameters (thickness and roughness) and optical constants of each layer at 4.48 nm. Based on those results, a further calculation was carried out. The result shows that the formation of the thin interlayer contributes little to the decrease of the reflectivity, the rough interface decreases the reflectivity most and the contaminant (O) not only decreases the reflectivity but also shifts the position of the peak.     

Flipper: A new instrument for xmcd at the srs

We propose to build at SOLEIL a facility for the accurate measurement of the properties of optical elements and detectors from the extreme ultraviolet (EUV), soft X-ray spectral regions up to the hard X-rays. The beamline will serve as a standard for such measurements and hence we call it a calibration and standards beamline, or alternatively, a metrology beamline. This beamline will also be valuable as a general-purpose beamline to prepare, test and set up a wide range of experiments. A complementary important aspect of this installation is the realization of a primary standard (as in BESSY II) [1 Ulm, G. 2003. Radiometry with synchrotron radiation. Metrologia, 40: S101–S106. [Crossref], [Web of Science ®] , [Google Scholar]]: in this case, the metrology beamline of SOLEIL could become the national primary standard source in collaboration with the Laboratoire National d'Essais (LNE) partner of this project. In another field, this installation will be used in the design and characterization of several diagnostics for the Megajoule Laser in Bordeaux in collaboration with the CEA DIF, also a partner of this project.     

The electrodeposition of copper onto UHV-prepared GaAs(0 0 1) surfaces

Synchrotron surface X-ray diffraction has been used to investigate in situ the morphology and epitaxy of monolayer amounts of copper electrodeposited from aqueous electrolyte onto ultra-high vacuum prepared, smooth, Ga- or As-terminated GaAs(0 0 1) surfaces. The fcc lattice of the epitaxial Cu islands is rotated by 5° and tilted by about 9° with respect to the GaAs substrate lattice, leading to eight symmetry equivalent domains of Cu islands terminated by {1 1 1} facets.     

The Berkeley Center for Structural Biology at the Advanced Light Source

The Berkeley Center for Structural Biology (BCSB) operates and develops a suite of protein crystallography beamlines at the Advanced Light Source (ALS) located at Lawrence Berkeley National Laboratory (LBNL). Although the ALS was conceived as a low-energy (1.9-GeV), third-generation synchrotron source of vacuum ultraviolet (VUV) and soft X-ray radiation, it was realized during the development of the facility in the mid-1990s that a multipole wiggler coupled with brightness-preserving optics would result in a beamline whose performance in the energy range of 5 to 15 keV would be sufficient for most protein crystallographic experiments. Later, the hard X-ray capabilities of the ALS were expanded by the addition of three superconducting bending magnets, resulting in additional protein crystallography facilities at the ALS [1 A.A. MacDowell, J Synchrotron Radiation 11(6), 447–55 (2004).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]].     

A novel deposition method to grow ZnO nanorods: Spray pyrolysis

ZnO layers were deposited by chemical spray pyrolysis (CSP) using zinc chloride aqueous solutions onto indium tin oxide (ITO) glass substrates at growth temperatures in the region of 400–580 C. The layers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-temperature () photoluminescence (PL) measurements. The flat film of ZnO obtained at 400 C evolves to a structured layer by raising the temperature up to 500 C. Deposition around 550 C and above results in a layer comprising well-shaped hexagonal ZnO nanorods with diameter of 100–150 nm and length of up to 1 micron. XRD shows strong c-axis orientation of ZnO being in accordance with the SEM study. Deposition of nanorods was successful using ITO with grain size around 100 nm, whereas on fine-grained ITO (grain size < 50 nm) with smooth surface fat crystals with diameter up to 400 nm and length of about 300 nm were formed. Sharp near band edge (NBE) emission peaks centered at 3.360 and 3.356 eV dominated the PL spectra of ZnO at , originating from the exciton transition bound to neutral donors. PL and XRD results suggest that ZnO rods prepared by spray pyrolysis are of high optical and crystalline quality.     

Photoluminescence and structural properties of GaInNAs/GaAs quantum wells grown by molecular beam epitaxy under different arsenic pressures

GaInNAs/GaAs quantum wells grown by molecular beam epitaxy under different arsenic pressures have been studied using photoluminescence (PL), X-ray diffraction (XRD) and secondary-ion mass spectrometry (SIMS). The best optical properties are achieved with the V/III beam equivalent pressure ratio (V/III_BEP) of 10. The PL emission wavelength remains unchanged for 8V/III_BEP12, suggesting that within this range neither the alloy composition nor the nitrogen sticking coefficient is changed. For the lower and higher V/III_BEP ratios the PL wavelength is red-shifted or blue-shifted, respectively. The XRD results indicate that the nitrogen incorporation into the group-V sub-lattice is enhanced at low As pressures and reduced at high As pressures. The PL behaviour can thus be understood as a competition between As and N adatoms in occupying anion lattice sites.     

Epitaxial Heusler alloy films on GaAs(0 0 1) substrates

We present results on fabrication, and structural and electrical properties of single-crystal heterostructures grown by molecular beam epitaxy. The exact stoichiometry of the Heusler alloy films can be achieved for almost lattice matched films. As evidenced by high-resolution X-ray diffraction, transmission electron microscopy, and resistivity measurements, we find an optimum growth temperature of , to obtain ferromagnetic layers with high crystal and interface perfection as well as high degree of atomic ordering. .     

Asymmetric di-jet production in polarized hadronic collisions

Using the collinear QCD factorization approach, we study the single-transverse-spin dependent cross section Δσ(S) for the hadronic production of two jets of momenta P₁=P+q/2 and P₂=−P+q/2. We consider the kinematic region where the transverse components of the momentum vectors satisfy PqΛ_QCD. For the case of initial-state gluon radiation, we show that at the leading power in q/P and at the lowest non-trivial perturbative order, the dependence of Δσ(S) on q decouples from that on P, so that the cross section can be factorized into a hard part that is a function only of the single scale P, and into perturbatively generated transverse-momentum dependent (TMD) parton distributions with transverse momenta .     

The effect of the aminating temperature on the synthesis of gallium nitride nanowires doped with magnesium

GaN nanowires doped with Mg have been synthesized at different temperature through ammoniating the magnetron-sputtered Ga₂O₃/Au layered films deposited on Si substrates. X-ray diffraction (XRD), Scanning electron microscope (SEM), high-resolution TEM (HRTEM) equipped with an energy-dispersive X-ray (EDX) spectrometer and photoluminescence (PL) were used to analyze the structure, morphology, composition and optical properties of the as-synthesized sample. The results show that the ammoniating temperature has a great impact on the properties of GaN. The optimally ammoniating temperature of Ga₂O₃/Au layer is 900 C for the growth of GaN nanowires(NWs). The band gap emission (358 nm) relative to that (370 nm) of undoped GaN NWs has an apparent blueshift, which can be ascribed to the doping of Mg. Finally, the growth mechanism is also briefly discussed.     

Large-Field X-ray Imaging at SPring-8 BL20B2

The medium-length (215 m) bending-magnet beamline 20B2 is allocated to medical applications and various X-ray micro imaging techniques (e.g., angiography, computed tomography, phase contrast imaging and diffraction topography) [1 S. Goto, Nuclear Instruments and Methods in Physics Research A 467–468, 682–685 (2001).[Crossref], [Web of Science ®] , [Google Scholar]]. The unique properties of BL20B2 are high spatial coherence (large coherent length) and its wide beam cross-section, which come from its long beam transport path and bending magnet light source. The horizontal angular aperture of BL20B2 is 1.5 mrad, as in all bending magnet beamlines at SPring-8. The horizontal beam width at the end station is larger than 300 mm for a 215 m beamline length.