In this paper we discuss the finite-element analysis (FEA) of a one-dimensional beryllium compound refractive lens (Be-CRL) that was undertaken to study the feasibility of installing the CRL in the Inelastic X-ray Scattering (IXS) beamline of National Synchrotron Light Source-II (NSLS-II) (a new state-of-the-art medium-energy third-generation storage ring). The current insertion device for this beamline is an IVU22-6m in-vacuum planar undulator delivering a total power of ~9 kW with a peak power density of ~90 kW/mrad2. Through analysis, based on calculation of spectral angular distribution of undulator radiation from IVU22, we determined that it is essential to install a 30 µm graphite filter upstream of the CRL in order to restrict the temperature rise in the CRL to 65°C for acceptable thermal strain.
The electronic structure of Co (100 Å)/Cu (50 Å) bilayer film on Si(100) has been investigated using valence band photoemission at 50 eV. The aim is to understand the Co/Cu interface and the nature of intermixing in Co and Cu layers. The valence band of Co/Cu interface shows three features at −0.3, −1.17 and −1.9 eV binding energy. The experimental observations are explained with the help of calculations based on projected augmented wave pseudopotential method using density functional theory. The origin of −0.3 eV feature is mainly due to the Co 3d minority spin states while the features at −1.17 and −1.9 eV are due to the formation of Co and Co–Cu mixed nanoclusters at the interface.
Fourier transform infrared (FTIR) spectroscopy has gained significant attention among the forensic scientists because it shows high sensitivity and selectivity, and offers near-real-time detection. Application of the multivariate statistical techniques for the analysis of the spectra is necessary in order to enable feature extraction, proper evaluation and identification of obtained spectra. In this paper we show the development of a feasible procedure for the characterization of spectroscopic signatures of the explosive materials in the remnants after explosion. In our research especially designed and prepared sample catchers were used during the blasts of three various high explosives: C-4, TNT and PETN. Principal component analysis (PCA) was performed using broad spectral data range (600–4000 cm−1) for sample classification into separate classes. Most of the information contained in spectral data was compressed by PCA in few relevant principal components that explain most of the variance of spectral data. The results show that FTIR spectroscopy in combination with multivariate methods are well suited for identification and differentiation purposes even in very large data sets and could be employed by forensic laboratories for rapid screening analysis.
In the past few years, we have witnessed the appearance of exotic magnetism of atoms in nano-scaled systems associated with compounds that are non-magnetic in their bulk form. Different models ranging from orbital magnetism delocalized over the whole molecule to localized one associated to the modification of the elec-tronic structure have been proposed. Hence, one of the main challenges is to deter-mine the mechanism that induces both the magnetic moment and the exchange interactions, leading to the ferromagnetic-like behaviour in these nanostructures. Aimed at obtaining a deeper insight into the induction of magnetic moments on nominally non-magnetic atoms, we have performed an XMCD study on rare-earth – iron Laves phase compounds containing Ga or Ge. XMCD probes the magnetic polarization of both Ga and Ge in these compounds. Our results show that when the rare-earth (R) is non-magnetic this polarization is uniquely due to the hybridization with the Fe neighbours, while it is enhanced when R is magnetic due to the Fe – R hybridization. As a consequence, the magnetic polarization of both Ge and Ga atoms differs as this hybridization does.
Within the framework of a wide study of pieces of cultural heritage from the Andalusian baroque period, synchrotron radiation techniques were used to characterize the metallic parts of mirrors and musical organ pipes. By using X-ray fluorescence (XRF) and X-ray diffraction (XRD) with micrometre resolution information was obtained which was relevant either in the conservation or in the identification of these pieces. By monitoring with micro X-ray diffraction (μXRD) the degradation process of the amalgam of the mirrors, the evolution of the corrosion products could be followed. The identification and distribution of trace elements of tin and lead phases forming the organ metal pipes was carried out with the aid of micro X-ray fluorescence (μXRF). This technique allowed for the quantification of the elemental distributions in the major and minor components, knowledge useful to improve the manufacture of modern musical organs.
We report here an extensive study of the ZnO nanoparticles (NPs) capped with different organic molecules by X-ray absorption spectroscopy (XAS) methods to proceed in the understanding of their unusual magnetism. We have performed a detailed ab initio calculation of the Zn K-edge XAS aimed at determining the influence of the different coordination induced by the capping. The results suggest that the observed differences of the XAS spectra are due to the formation of a well-defined interface between the oxide NPs and the capping molecules. The appearance of magnetism should be related to the modifications induced in the NPs by the surface bonds between Zn and the capping molecule.
We have synthesized nickel by means of pulsed laser ablation. A nickel disc was used for ablation with the focused output of fundamental harmonic from Nd:YAG laser. X-ray diffraction result shows that the synthesized nanoparticles are of pure metallic nickel with a face-centred cubic structure and the average particle size is 35 nm. The extended X-ray absorption fine structure (EXAFS) studies of pure nickel foil and the synthesized nanoparticles show similar structures. The position of the main peak is same in these nanoparticles with reference to the nickel foil. The only difference was observed in the reduction of the amplitude. The nearest-neighbour distance is similar as for pure nickel foil. The Debye–Waller factor is also similar. There is no trace of oxide and hydroxide in the EXAFS data, suggesting that the synthesized nanoparticles contain only nickel metal.
National Synchrotron Light Source II (NSLS-II) will be a 3-GeV 792 m circumference third generation synchrotron radiation facility with ultra low emittance and extremely high brightness. There will be a total of 90 multipole storage ring girders supporting the vacuum chambers, multipole magnets and various pieces of ancillary equipment. A major effort is being made to meet the stringent assembly and alignment requirements for the girder assemblies using relatively few and removable positioning fixtures. Girder assembly and alignment will be accomplished in four phases. Each of these phases will be described along with the fixtures required.
National Synchrotron Light Source (NSLS-II) is a new 3 GeV, 500 mA, high-brightness synchrotron light source facility being built at the Brookhaven National Laboratory. Approved for construction in January 2009, the NSLS-II project is expected to be completed in June 2014. In this paper we discuss the present status of the mechanical design and construction of some major components of this facility, namely (i) conventional facilities, (ii) injector complex (iii) storage ring, (iv) RF system and (v) beamlines.
A new design for a polychromator Bragg bender at ID24 Dispersive EXAFS beamline (ESRF) shows improvements in stability, in the shape of the bent crystal and in the efficiency of adjustments to find the best focal spot.
In common high-end precision systems, thermal effects, in general, play a very important role with respect to the final performance of the system. Mainly driven by miniaturization, performance and reliability enhancement, the requirements of these systems have enormously increased over the last few decades. To stimulate exchange of knowledge and cooperation in the precision engineering community a special interest group was initiated by the Euspen. During a meeting in 2006 it turned out that thermal effects occur in many different applications and in all forms. The complexity of the thermal effects and the high impact on the performance of systems motivated the group to organize a conference in 2007. All kinds of applications were mentioned, starting from traditional machine tools up to next-generation lithography tools and analysis tools. The huge diversity of the thermal issues in all kinds of market segments was also very clearly discussed.
Finite-element analysis (FEA) is utilized to model the temperature distribution and heat-induced deformation of the first mirror of the coherent soft X-ray beamline at NSLS-II. The FEA results of the cooling design show a thermal bump on the area illuminated by the beam plus an overall mirror bending. The resulting slope errors are almost linear over the area where the power is absorbed and have a complex dependence on the mirror thickness. The linear change of the slope error means a constant convex radius of curvature whose defocusing effect can be corrected with a bendable mirror positioned downstream in the beamline. In this paper we discuss the design optimization of the mirror thickness using FEA as a tool.
In early 2007 an elliptically polarized Apple II undulator was installed on an LNLS storage ring. It will provide photons to the first PGM beamline at LNLS designed to deliver photons ranging from 100 to 1000 eV with a resolving power of over 10 000. The beamline is about to start the commissioning process and this paper describes mainly the monochromator design and construction.
Strain in silicon on insulator (SOI) and strained-silicon(s-Si)/silicon–germanium (SiGe)/Si-substrate crystals is analysed by means of synchrotron X-ray microbeam diffraction. It is found that strain features of the s-Si/SiGe/Si crystals are much different from those of SOI crystals from the lattice tilt and lattice parameter distribution points of view. The two-dimensional lattice tilt maps obtained by scanning the synchrotron X-ray microbeam of about 1 μm in size on the sample surface are useful to study local strain distribution in those materials.
The beam position monitors (BPMs) with submicron-level resolution act as the major eyes of storage ring in detecting the position of electron beams and are used for feedback system to guide the beam orbit to the desired track. Compared to major improvements on backend electronics, the physical devices generate and transmit signals had little improvement due to the lack of control on manufacturing processes including all mechanical tolerance requirements. The design started with ANSYS to simulate mechanical deformation. Due to the small size (submillimetre) and complicated assembly of feedthrough structure, it is difficult to achieve 1 % tolerance (submicron) in all aspects including machining and brazing. The smallest tolerance for machining is 5 µ and the overall tolerance will be 30 µm. The influence of the tolerance on mechanical will be shown on time-domain reflectometry measurement. The resulted heat-related issue will also be discussed and addressed since the problem happened at SLAC (private communication with Albert Sheng at Stanford Linear Accelerator Center) and DIAMOND (presented at the RF Button Heating Mini-Workshop at EPAC 2008). Manufacturing steps will be described. The consequence of mismatch on manufacturing will be discussed. All related measurement and simulation data are presented in this paper.
A cryogenic plant will be installed at the National Synchrotron Light Source II (NSLS-II) to supply the liquid helium for six superconducting cavities. This paper describes the configuration of the cryogenic plant and the main design considerations for selecting equipment and components.
Both in-vacuum undulators (IVUs) and cryogenic permanent magnet undulators (CPMUs), each important to third-generation light sources, are best characterized in their operating environment. To create a precision Hall probe map of an IVU/CPMU (IVU hereafter), an in-vacuum magnetic measurement (IVMM) system is proposed. Point-by-point measurement of field and trajectory error informs corrective tuning.A novel design concept for a universal IVMM System has been developed and explored. The IVMM seals to the rectangular Ultra High Vacuum (UHV) flange of the IVU and shares its common vacuum space. Moreover, a modular design permits a wide range of IVUs of varying magnetic length to be mapped with a single IVMM, and is thus cost effective when multiple IVUs of varying configurations are planned. Here we review aspects of the modular IVMM design concept.
This paper will describe the results of in situ high-energy X-ray measurements performed on stable and supercooled oxide liquids using containerless techniques. As will be discussed in the companion paper (Weber et al.), the use of an aerodynamic levitator furnace with laser heating allows the structures of refractory oxide liquids to be probed. Because of the contactless nature of this sample environment liquids can be deeply supercooled, and this provides opportunities to study the metastable structures of supercooled liquids. Of particular interest are the so-called fragile liquids that depart from Arrhenius-law viscosity behaviour and that, by definition, have temperature-dependent structures. The focus of this paper is the study of two oxide systems, MgO–SiO2 and Al2O3–SiO2. These two liquids have highly disordered stable liquid structures that differ substantially from the structures of the equivalent glasses. We present data showing how these structures change when supercooled and demonstrate dramatic changes in short-range (coordination number) and intermediate-range order during vitrification. These data have been collected by isothermal measurement and also fast quenching methods using the recently developed method of rapid acquisition using a Perkin Elmer amorphous silicon flat panel detector; this gives a large Q coverage for incident energies of >115 keV. The rapid data acquisition enables the vitrification process to be observed directly.
A new X-ray absorption cell dedicated to in situ and operando experiments in heterogeneous catalysis has been built and tested. It allows measurement of X-ray absorption spectroscopy (XAS) spectra in transmission mode under the flow of various gas mixtures at elevated temperatures (600°C) and pressures (50 bar). The working conditions are representative of phenomena that take place in fixed bed reactors.
Containerless techniques (levitation) completely eliminate contact with the sample. This unique sample environment allows deep supercooling of many liquids and avoids contamination of high-temperature melts. Recent experiments at the Advanced Photon Source (APS) high-energy beamline 11 ID-C used aerodynamic levitation with laser beam heating and acoustic levitation with cryogenic cooling. By using these two methods, liquids were studied over much of the temperature range from −40 to +2500°C. This paper briefly describes the instrumentation and its use and is illustrated with examples of measurements on molten oxides and low-temperature liquids.
