Multipurpose Beamline Research Articles

Spatial-frequency features of radiation produced by a step-wise tapered undulator.

A scheme to generate wide-bandwidth radiation using a step-wise tapered undulator with a segmented structure is proposed. This magnetic field configuration allows to broaden the undulator harmonic spectrum by two orders of magnitude, providing 1 keV bandwidth with spectral flux density exceeding 1016 photons s-1 mm-2 (0.1% bandwidth)-1 at 5 keV on the sample. Such a magnetic setup is applicable to superconducting devices where magnetic tapering cannot be arranged mechanically. The resulting radiation with broadband spectrum and flat-top shape may be exploited at a multipurpose beamline for scanning over the spectrum at time scales of 10-100 ms. The radiation from a segmented undulator is described analytically and derivations with numerical simulations are verified. In addition, a start-to-end simulation ofan optical beamline is performed and issues related to the longitudinally distributed radiation source and its image upon focusing on the sample are addressed.

XDS: a flexible beamline for X-ray diffraction and spectroscopy at the Brazilian synchrotron.

The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage-ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X-ray spectrum (above ∼10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi-purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X-ray absorption spectroscopy at energies above 18 keV and high-resolution diffraction experiments. More recently, new setups and photon-hungry experiments such as total X-ray scattering, X-ray diffraction under high pressures, resonant X-ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.

Diffraction and XAFS - the multi-purpose beamline KMC-2

Diffraction and XAFS - the multi-purpose beamline KMC-2

Pair distribution function analysis at the Brazilian synchrotron light source

The XDS beamline of the Synchrotron Light National Laboratory (LNLS), was designed to take advantage of the 4T superconducting multipole wiggler inserted in the storage ring. This multipurpose beam line is employed for X-ray diffraction and X-ray absorption spectroscopy in the energy range between 5 and 30 keV. The X-ray diffraction patterns can be acquired in two different arrangements: a) Bragg-Brentano configuration, using a scintillation detector with an analyzer and b) Debye-Scherrer configuration, where the sample is mounted into capillaries and the diffraction pattern is acquired with an arrangement of 6 Mythen detectors or a scintillator. The sample can be measured at different atmospheres and temperatures. The viability of the beamline for pair distribution function analysis (PDF) was tested measuring two different standards: 1) Al2O3 and 2) BaTiO3. The patterns were acquired at room temperature using the two detection setups at an energy of 20 keV. The samples were mounted inside 0.3 mm boron-rich glass capillaries. In addition to the sample pattern, we also measured the empty capillary (background) to subtract it to the sample data. The acquired and normalized patterns were converted into total scattering PDF (G(r)) with the PDFgetX3.[1] The experimental G(r) was fitted with the PDFgui.[2] Both data sets were fitted in the corresponding structural phase with cell parameters close to the ones reported in the literature. In the special case of the BaTiO3 sample, it was very carefully modeled. We particularly focused in evaluating if we can discriminate the correct structural phase, as this sample presents different phases (orthorhombic, tetragonal and cubic). We could identify that the sample, at room temperature, was at the expected tetragonal phase. Finally, we will present a preliminary analysis of the following systems: Pb1-xRxZr1-yTiyO3 (R=La&Ba) and Ba1-xRxZr1-yTiyO3 (R=La&Ca) at the ferro- and paraelectric states by PDF.

Study of time and pressure dependent phenomena at the hard x-ray beamline BL9 of DELTA

The beamline BL9 of DELTA (Dortmund ELecTron Accelerator) is a multi-purpose beamline operating in an energy range between 4 and 27 keV. A short overview of the beamline and the experimental endstation is given. Exemplarily three typical applications, namely x-ray diffraction from interfaces, small angle x-ray scattering under high hydrostatic pressure and fast x-ray reflectivity measurements, are discussed in some detail in order to demonstrate the capabilities of the beamline.

Radiation shielding study against gas bremsstrahlung for the BMIT POE3 at the Canadian light source

A dose rate study is undertaken when gas bremsstrahlung strikes a monochromator, a copper absorber and a tungsten beam stop in the third primary optical enclosure (POE3) of the BioMedical Imaging and Therapy (BMIT) insertion device (ID) beamline 05ID-2. In the POE3, computed tomography, diffraction enhanced imaging and K-Edge subtraction monochromators are housed to conduct various diagnostic and therapeutic studies in the experimental hutch. The safety features of this beamline must be examined with great care, as this multipurpose beamline is intended for use in vivo on animals and humans. A tungsten beam stop, two safety shutters, and a lead movable wall are placed in the POE3 for the safe operation of the BMIT beamline. However, for one particular mode of operation, gas bremsstrahlung and monochromatic X-ray beams propagate closely together until the former is stopped by the tungsten beam stop while the safety shutters remain open to allow the passage of the latter to the experimental area SOE1. It is thus imperative to know the anticipated dose rate around the POE3, especially behind the back wall and on the roof. The dose rate estimates are presented based on a realistic model of the POE3 with its safety features.

A new small-angle X-ray scattering set-up on the crystallography beamline I711 at MAX-lab

A small-angle X-ray scattering (SAXS) set-up has recently been developed at beamline I711 at the MAX II storage ring in Lund (Sweden). An overview of the required modifications is presented here together with a number of application examples. The accessible q range in a SAXS experiment is 0.009-0.3 A(-1) for the standard set-up but depends on the sample-to-detector distance, detector offset, beamstop size and wavelength. The SAXS camera has been designed to have a low background and has three collinear slit sets for collimating the incident beam. The standard beam size is about 0.37 mm x 0.37 mm (full width at half-maximum) at the sample position, with a flux of 4 x 10(10) photons s(-1) and lambda = 1.1 A. The vacuum is of the order of 0.05 mbar in the unbroken beam path from the first slits until the exit window in front of the detector. A large sample chamber with a number of lead-throughs allows different sample environments to be mounted. This station is used for measurements on weakly scattering proteins in solutions and also for colloids, polymers and other nanoscale structures. A special application supported by the beamline is the effort to establish a micro-fluidic sample environment for structural analysis of samples that are only available in limited quantities. Overall, this work demonstrates how a cost-effective SAXS station can be constructed on a multipurpose beamline.

KMC-1: A high resolution and high flux soft x-ray beamline at BESSY

The crystal monochromator beamline KMC-1 at a BESSY II bending magnet covers the energy range from soft (1.7 keV) to hard x-rays (12 keV) employing the (n,-n) double crystal arrangement with constant beam offset. The monochromator is equipped with three sets of crystals, InSb, Si (111), and Si (422) which are exchangeable in situ within a few minutes. Beamline and monochromator have been optimized for high flux and high resolution. This could be achieved by (1) a windowless setup under ultrahigh-vacuum conditions up to the experiment, (2) by the use of only three optical elements to minimize reflection losses, (3) by collecting an unusually large horizontal radiation fan (6 mrad) with the toroidal premirror, and (4) the optimization of the crystal optics to the soft x-ray range necessitating quasibackscattering crystal geometry (theta(Bragg,max)=82 degrees) delivering crystal limited resolution. The multipurpose beamline is in use for a variety of user facilities such as extended x-ray absorption fine structure, ((Bio-)EXAFS) near-edge x-ray absorption fine structure (NEXAFS), absorption and fluorescence spectroscopy. Due to the windowless UHV setup the k edges of the technologically and biologically important elements such as Si, P, and S are accessible. In addition to these experiments this beamline is now extensively used for photoelectron spectroscopy at high kinetic energies. Photon flux in the 10(11)-10(12) photons/s range and beamline resolving powers of more than E/DeltaE approximately 100.000 have been measured at selected energies employing Si (nnn) high order radiation in quasibackscattering geometry, thus photoelectron spectroscopy with a total instrumental resolution of about 150 meV is possible. This article describes the design features of the beamline and reports some experimental results in the above mentioned fields.

The INE-Beamline for actinide research at ANKA

The Institut für Nukleare Entsorgung (INE) at the Forschungszentrum Karlsruhe (FZK), Germany, has constructed and is operating a beamline at the synchrotron source ANKA dedicated to actinide speciation investigations related to nuclear waste disposal as well as applied and basic actinide research. Experiments on nuclides not suited as nuclear fuel with activities up to 106 times the limit of exemption inside a safe and flexible containment concept are now possible. The design is for a multi-purpose beamline, i.e., a number of methods (XAFS, surface sensitive and spatially resolved techniques) are envisaged on one and the same sample, with X-ray energies from 2472 eV (SK edge) to 23220 eV (RhK edge). The commissioning of the INE-Beamline was officially completed in September 2005 and meanwhile regular user operation has been started. Here we present a description of this new facility and examples for X-ray absorption studies on actinides and homologues performed during the beamline commissioning phase.

The INE-beamline for actinide research at ANKA

The Institut für Nukleare Entsorgung (INE) at the Forschungszentrum Karlsruhe is presently constructing and will commission and operate an x-ray spectroscopy beamline dedicated to actinide research at the new synchrotron source ANKA. One great advantage of the INE-Beamline is that on-site, in situ actinide research is possible for studying, e.g., solid-water interface chemical reactions, which are not possible at other facilities. The design is for a multi-purpose beamline, i.e., a number of methods (XAFS, surface sensitive and spatial resolved techniques) are possible on one and the same sample. Planned is a safe and flexible containment concept for activities up to 106 times the limit of exemption. The design will allow spectroscopic investigations using photon energies from the K edge of S (2477 eV) to the Rh K-edge (23 220 eV). The optics include collimating and focusing mirrors for a sub-mm beam dimension at the sample position. A later upgrade is planned to install auxiliary μ-focusing optics (e.g., a single bounce elliptical monocapillary or planar compound refractive lenses). The monochromator at the INE-Beamline is a Lemonnier type double-crystal x-ray monochromator (DCM), built at the Universität Bonn, Physikalisches Institut. The pressure inside the small diameter (380 mm) vacuum housing is ∼106 mbar, allowing fast changes of crystals, avoiding long pumping times. Multi-layer mirrors can be used in the DCM for wide band-pass experiments, e.g., for x-ray fluorescence analysis measurements. Installation of beamline components has been completed in October 2003. Operation begin is targeted for 2004.

The design of the material science beamline, I811, at MAX-II

The material science beamline is a multi-purpose beamline intended for experiments in the photon energy range 2.4–20 keV. The beamline will be located at port I811 of the MAX-II ring. According to our planning the first experiments will be conducted in the spring 2001. In order to overcome the relatively low energy of the electron-beam in the MAX II ring (1.5 GeV) we will use a super-conducting multi-pole wiggler insertion device. The disadvantage with this solution is the high K value ( K=20) of the device, which leads to a divergent X-ray beam. The optical solutions for the beamline therefore emphasizes on solving the divergence problem of the photon beam and the high heat load on the optical elements.

Performance of the grating-crystal monochromator of the ALOISA beamline at the Elettra Synchrotron

The new beamline ALOISA, now operational at the Elettra Synchrotron, is designed for surface studies by means of several experimental techniques: surface x-ray diffraction and reflectivity, photoemission spectroscopy, photoelectron diffraction, e−-Auger coincidence spectroscopy. A new monochromator has been specifically designed and realized for this multipurpose beamline: it makes use of a channel-cut Si crystal dispersive element for the 3–8 keV range and of a plane mirror-plane grating element for the 200–2000 eV range. Both dispersive elements share the same optical system. In the low energy range (200–900 eV) the spectral resolving power exceeds 5000 while maintaining a throughput higher than 1010 photons/s/200 mA/0.02% BW. In the case of the N2 1s→π* and Ne 1s→3p transitions, the extremely high signal-to-noise ratio of the absorption spectra allowed a very accurate determination of the corresponding natural linewidth (116±2 and 250±10 eV, respectively). Moreover, the vibrational structure of the CO–oxygen 1s→π* transition has been fully resolved. In the high energy range, the measured flux exceeds 1010 photons/s/200 mA up to 6.5 keV with a resolving power of ∼7500.