Showing papers on "Synchrotron radiation published in 2009"

Beam Echo Effect for Generation of Short-Wavelength Radiation

Abstract: The Echo-Enabled Harmonic Generation (EEHG) FEL uses two modulators in combination with two dispersion sections to generate a high-harmonic density modulation starting with a relatively small initial energy modulation of the beam. After presenting the concept of the EEHG, we address several practically important issues, such as the effect of coherent and incoherent synchrotron radiation in the dispersion sections. Using a representative realistic set of beam parameters, we show how the EEHG scheme enhances the FEL performance and allows one to generate a fully (both longitudinally and transversely) coherent radiation. We then discuss application of the echo modulation for generation of attosecond pulses of radiation, and also using echo for generation of terahertz radiation. We present main parameters of a proof-of-principle experiment currently being planned at SLAC for demonstration of the echo modulation mechanism.

Gamma-Ray Studies of Blazars: Synchro-Compton Analysis of Flat Spectrum Radio Quasars

Abstract: We extend a method for modeling synchrotron and synchrotron self-Compton radiations in blazar jets to include external Compton (EC) processes. The basic model assumption is that the blazar radio through soft X-ray flux is nonthermal synchrotron radiation emitted by isotropically distributed electrons in the randomly directed magnetic field of outflowing relativistic blazar jet plasma. Thus, the electron distribution is given by the synchrotron spectrum, depending only on the Doppler factor ?D and the mean magnetic field B, given that the comoving emission region size scale R' b c?D tv /(1 + z), where tv is the variability time and z is the source redshift. Generalizing the approach of Georganopoulos, Kirk, & Mastichiadis to arbitrary anisotropic target radiation fields, we use the electron spectrum implied by the synchrotron component to derive accurate Compton-scattered ?-ray spectra throughout the Thomson and Klein-Nishina regimes for EC scattering processes. We derive and calculate accurate ?-ray spectra produced by relativistic electrons that Compton-scatter (1) a point source of radiation located radially behind the jet, (2) photons from a thermal Shakura-Sunyaev accretion disk, and (3) target photons from the central source scattered by a spherically symmetric shell of broad-line region gas. The calculations of broadband spectral energy distributions from the radio through ?-ray regimes are presented, which include self-consistent ?? absorption on the same radiation fields that provide target photons for Compton scattering. The application of this baseline flat spectrum radio/?-ray quasar model is considered in view of data from ?-ray telescopes and contemporaneous multiwavelength campaigns.

Measuring the cosmic-ray acceleration efficiency of a supernova remnant.

Abstract: Cosmic rays are the most energetic particles arriving at Earth. Although most of them are thought to be accelerated by supernova remnants, the details of the acceleration process and its efficiency are not well determined. Here we show that the pressure induced by cosmic rays exceeds the thermal pressure behind the northeast shock of the supernova remnant RCW 86, where the x-ray emission is dominated by synchrotron radiation from ultrarelativistic electrons. We determined the cosmic-ray content from the thermal Doppler broadening measured with optical spectroscopy, combined with a proper-motion study in x-rays. The measured postshock proton temperature, in combination with the shock velocity, does not agree with standard shock heating, implying that >50% of the postshock pressure is produced by cosmic rays.

Bio-metals imaging and speciation in cells using proton and synchrotron radiation X-ray microspectroscopy

Abstract: The direct detection of biologically relevant metals in single cells and of their speciation is a challenging task that requires sophisticated analytical developments. The aim of this article is to present the recent achievements in the field of cellular chemical element imaging, and direct speciation analysis, using proton and synchrotron radiation X-ray micro- and nano-analysis. The recent improvements in focusing optics for MeV-accelerated particles and keV X-rays allow application to chemical element analysis in subcellular compartments. The imaging and quantification of trace elements in single cells can be obtained using particle-induced X-ray emission (PIXE). The combination of PIXE with backscattering spectrometry and scanning transmission ion microscopy provides a high accuracy in elemental quantification of cellular organelles. On the other hand, synchrotron radiation X-ray fluorescence provides chemical element imaging with less than 100 nm spatial resolution. Moreover, synchrotron radiation offers the unique capability of spatially resolved chemical speciation using micro-X-ray absorption spectroscopy. The potential of these methods in biomedical investigations will be illustrated with examples of application in the fields of cellular toxicology, and pharmacology, bio-metals and metal-based nano-particles.

High-speed X-ray phase imaging and X-ray phase tomography with Talbot interferometer and white synchrotron radiation

Abstract: X-ray Talbot interferometry, which uses two transmission gratings, has the advantage that broad energy bandwidth x-rays can be used. We demonstrate the use of white synchrotron radiation for high-speed X-ray phase imaging and tomography in combination with an X-ray Talbot interferometer. The moire fringe visibility over 20% was attained, enabling quantitative phase measurement. X-ray phase images with a frame rate of 500 f/s and an X-ray phase tomogram with a scan time of 0.5 s were obtained successfully. This result suggests a breakthrough for time-resolved three-dimensional observation of objects that weakly absorb X-rays, such as soft material and biological objects.

Variable polarization measured in the prompt emission of GRB 041219A using IBIS on board INTEGRAL

Abstract: Polarization measurements provide direct insight into the nature of astrophysical processes. Unfortunately, only a few instruments are available for this kind of measurements at gamma-ray energies, and the sources need to be very bright. Gamma-Ray Bursts (GRBs) are ideal candidates due to their large flux over limited time intervals, maximizing the available signal-to-noise ratio. To date a few polarization measurements have been reported, claiming of a high degree of polarization in the prompt emission of GRBs but with low statistical evidence. We used the IBIS telescope on board the INTEGRAL satellite to measure the polarization of the prompt gamma-ray emission of the long and bright GRB 041219A in the 200-800 keV energy band. We find a variable degree of polarization ranging from less than 4% over the first peak to 43+/-25% for the whole second peak. Time resolved analysis of both peaks indicates a high degree of polarization, and the null average polarization in the first peak can be explained by the rapid variations observed in the polarization angle and degree. Our results are consistent with different models for the prompt emission of GRBs at these energies, but they favor synchrotron radiation from a relativistic outflow with a magnetic field which is coherent on an angular size comparable with the angular size of the emitting region (~1/Gamma) . Indeed this model has the best capabilities to maintain a high polarization level, and to produce the observed variability.

Synthetic spectra from particle-in-cell simulations of relativistic collisionless shocks

Abstract: We extract synthetic photon spectra from first-principles particle-in-cell simulations of relativistic shocks propagating in unmagnetized pair plasmas. The two basic ingredients for the radiation, namely accelerated particles and magnetic fields, are produced self-consistently as part of the shock evolution. We use the method of Hededal and Nordlund and compute the photon spectrum via Fourier transform of the electric far field from a large number of particles, sampled directly from the simulation. We find that the spectrum from relativistic collisionless shocks is entirely consistent with synchrotron radiation in the magnetic fields generated by Weibel instability. We can recover the so-called 'jitter' regime only if we artificially reduce the strength of the electromagnetic fields, such that the wiggler parameter K ident to qBlambda/mc {sup 2} becomes much smaller than unity (B and lambda are the strength and scale of the magnetic turbulence, respectively). These findings may place constraints on the origin of non-thermal emission in astrophysics, especially for the interpretation of the hard (harder than synchrotron) low-frequency spectrum of gamma-ray bursts.

Variable polarization measured in the prompt emission of GRB 041219A using IBIS on board INTEGRAL

Abstract: Polarization measurements provide direct insight into the nature of astrophysical processes. Unfortunately, only a few instruments are available for this kind of measurements at gamma-ray energies, and the sources need to be very bright. Gamma-Ray Bursts (GRBs) are ideal candidates due to their large flux over limited time intervals, maximizing the available signal-to-noise ratio. To date a few polarization measurements have been reported, claiming of a high degree of polarization in the prompt emission of GRBs but with low statistical evidence. We used the IBIS telescope on board the INTEGRAL satellite to measure the polarization of the prompt gamma-ray emission of the long and bright GRB 041219A in the 200-800 keV energy band. We find a variable degree of polarization ranging from less than 4% over the first peak to 43+/-25% for the whole second peak. Time resolved analysis of both peaks indicates a high degree of polarization, and the null average polarization in the first peak can be explained by the rapid variations observed in the polarization angle and degree. Our results are consistent with different models for the prompt emission of GRBs at these energies, but they favor synchrotron radiation from a relativistic outflow with a magnetic field which is coherent on an angular size comparable with the angular size of the emitting region (~1/Gamma) . Indeed this model has the best capabilities to maintain a high polarization level, and to produce the observed variability.

Modelling the response function of energy dispersive X-ray spectrometers with silicon detectors

Abstract: A new, analytical description of the physical processes determining the spectral response of an energy dispersive X-ray spectrometer with a silicon detector (Si(Li) or silicon drift detector (SDD)) is presented. The model considers the detector statistical noise, the electronic noise, the incomplete charge collection (ICC) that gives rise to the peak tailing, the escape effect, the fluorescence of the front contact or the dead layer and hot photoelectrons that cause the shelf. Only five free parameters are necessary to model the response function: the electronic noise, three parameters describing the shape of the charge collection efficiency beneath the front contact and the thickness of the detector front layer. Once the five parameters are adjusted to have agreement between a measured and a calculated response function, the response function can be calculated for any other photon energy in the range from 0.1 keV to 30 keV. The algorithm is implemented in IDL and MATLAB and is available also as MATLAB stand-alone program. It enables the determination of the optimum parameter set by fitting a calculated response function to a measured one for monochromatic radiation. A (m,n)-type matrix can be calculated whereby m represents the number of channels for the response function and n the number of photon energies in the selected range. The matrix can be used to convolute a calculated spectrum for comparison with a measured one. The calculated response functions are in agreement with the pulse height distributions measured with monochromatic synchrotron radiation in the energy range from 0.1 keV to 10 keV for three spectrometers with detector crystals different in construction. It is shown that the improved description of the detector response enables the detection of minor components of characteristic lines in fluorescence spectra, which have been attributed earlier to the detector.

Synthetic Spectra from PIC Simulations of Relativistic Collisionless Shocks

Abstract: We extract synthetic photon spectra from first-principles particle-in-cell simulations of relativistic shocks propagating in unmagnetized pair plasmas. The two basic ingredients for the radiation, namely accelerated particles and magnetic fields, are produced self-consistently as part of the shock evolution. We use the method of Hededal & Nordlund (2005) and compute the photon spectrum via Fourier transform of the electric far-field from a large number of particles, sampled directly from the simulation. We find that the spectrum from relativistic collisionless shocks is entirely consistent with synchrotron radiation in the magnetic fields generated by Weibel instability. We can recover the so-called "jitter'' regime only if we artificially reduce the strength of the electromagnetic fields, such that the wiggler parameter K = qB lambda/mc^2 becomes much smaller than unity ("B" and "lambda" are the strength and scale of the magnetic turbulence, respectively). These findings may place constraints on the origin of non-thermal emission in astrophysics, especially for the interpretation of the hard (harder than synchrotron) low-frequency spectrum of Gamma-Ray Bursts.

A versatile electron-ion coincidence spectrometer for photoelectron momentum imaging and threshold spectroscopy on mass selected ions using synchrotron radiation

Abstract: We present a photoelectron-photoion coincidence (PEPICO) spectrometer named DELICIOUS II which combines a velocity map imaging apparatus with a Wiley–McLaren time of flight analyzer for the study of gas phase samples in interaction with the synchrotron radiation (SR) This versatile system is capable of providing photoelectron images on mass-selected compounds with kinetic energy resolutions of ΔE/E=5% and a 17 eV bandwidth, as well as threshold photoelectron spectra with a measured resolution of 08 meV, as demonstrated on the 3p−1 ionization of argon This instrument is also employed for threshold PEPICO experiments, allowing the selection of the parent ion’s internal state with sub-meV resolution for light masses (<40 amu) and with typically 2 meV resolution for a mass of 100 amu and with a mass resolving power above 200 The continuous operation of the extraction fields and the independence from the electron’s time of flight are well adapted to the quasicontinuous multibunch mode of the SR This, toge

Advanced photoelectric effect experiment beamline at Elettra: A surface science laboratory coupled with Synchrotron Radiation.

Abstract: We report the main characteristics of the advanced photoelectric effect experiments beamline, operational at Elettra storage ring, featuring a fully independent double branch scheme obtained by the use of chicane undulators and able to keep polarization control in both linear and circular mode. The paper describes the novel technical solutions adopted, namely, (a) the design of a quasiperiodic undulator resulting in optimized suppression of higher harmonics over a large photon energy range (10-100 eV), (b) the thermal stability of optics under high heat load via cryocoolers, and (c) the end station interconnected setup allowing full access to off-beam and on-beam facilities and, at the same time, the integration of users' specialized sample growth chambers or modules.

GRB 080319B: evidence for relativistic turbulence, not internal shocks

Abstract: We show that the excellent optical and gamma-ray data available for GRB 080319B rule out the internal shock model for the prompt emission. The data instead point to a model in which the observed radiation was produced close to the deceleration radius (∼10 17 cm) by a turbulent source with random Lorentz factors of ∼10 in the comoving frame. The optical radiation was produced by synchrotron emission from relativistic electrons, and the gamma-rays by inverse-Compton scattering of the synchrotron photons. The gamma-ray emission originated both in eddies and in an inter-eddy medium, whereas the optical radiation was mostly from the latter. Therefore, the gamma-ray emission was highly variable whereas the optical was much less variable. The model explains all the observed features in the prompt optical and gamma-ray data of GRB 080319B. We are unable to determine with confidence whether the energy of the explosion was carried outwards primarily by particles (kinetic energy) or magnetic fields. Consequently, we cannot tell whether the turbulent medium was located in the reverse shock (we can rule out the forward shock) or in a Poynting-dominated jet.

Multiple-element spectrometer for non-resonant inelastic X-ray spectroscopy of electronic excitations

Abstract: A multiple-analyser-crystal spectrometer for non-resonant inelastic X-ray scattering spectroscopy installed at beamline ID16 of the European Synchrotron Radiation Facility is presented. Nine analyser crystals with bending radii R = 1 m measure spectra for five different momentum transfer values simultaneously. Using a two-dimensional detector, the spectra given by all analysers can be treated individually. The spectrometer is based on a Rowland circle design with fixed Bragg angles of about 88°. The energy resolution can be chosen between 30–2000 meV with typical incident-photon energies of 6–13 keV. The spectrometer is optimized for studies of valence and core electron excitations resolving both energy and momentum transfer.

Study of the spectral and temporal characteristics of x-ray emission of the gamma-ray binary ls 5039 with suzaku

Abstract: We report on the results from Suzaku broadband X-ray observations of the galactic binary source LS 5039. The Suzaku data, which have continuous coverage of more than one orbital period, show strong modulation of the X-ray emission at the orbital period of this TeV gamma-ray emitting system. The X-ray emission shows a minimum at orbital phase ~0.1, close to the so-called superior conjunction of the compact object, and a maximum at phase ~0.7, very close to the inferior conjunction of the compact object. The X-ray spectral data up to 70 keV are described by a hard power law with a phase-dependent photon index which varies within Γ 1.45- 1.61. The amplitude of the flux variation is a factor of 2.5, but is significantly less than that of the factor ~8 variation in the TeV flux. Otherwise the two light curves are similar, but not identical. Although periodic X-ray emission has been found from many galactic binary systems, the Suzaku result implies a phenomenon different from the standard origin of X-rays related to the emission of the hot accretion plasma formed around the compact companion object. The X-ray radiation of LS 5039 is likely to be linked to very high energy electrons which are also responsible for the TeV gamma-ray emission. While the gamma rays are the result of inverse Compton (IC) scattering by electrons on optical stellar photons, X-rays are produced via synchrotron radiation. Yet, while the modulation of the TeV gamma-ray signal can be naturally explained by the photon-photon pair production and anisotropic IC scattering, the observed modulation of synchrotron X-rays requires an additional process, the most natural one being adiabatic expansion in the radiation production region.

Simultaneous soft X-ray transmission and emission microscopy

Abstract: Novel low-energy X-ray fluorescence (LEXRF) system based on a multiple Si drift detector (SDD) configuration has been developed and implemented in the European TwinMic X-ray microspectroscopy station operating at the Italian synchrotron radiation facility ELETTRA. The setup, hosting up to eight large-area SDDs with specially adapted readout electronics, has demonstrated excellent performance for elemental analysis in the 280–2200 eV photon energy range, which covers the K and L edges of light elements, starting from C. The great advantage is the simultaneous acquisition of LEXRF, absorption and phase contrast maps, providing complementary information on elemental composition and morphology of specimen at submicrometer length scales.

On the origin of spectral states in accreting black holes

Abstract: The origin of dramatically different electron distributions responsible for Comptonization in black hole X-ray binaries (BHBs) in their various states is discussed. We solve the coupled kinetic equations for photons and electrons without approximations on the relevant cross-sections accounting for Compton scattering, synchrotron radiation, and Coulomb collisions. In the absence of external soft photons, the electrons are efficiently thermalized by synchrotron self-absorption and Coulomb scattering even for pure nonthermal electron injection. The resulting quasi-thermal synchrotron self-Compton spectra have very stable slopes and electron temperatures similar to the hard states of BHBs. The observed hard X-ray spectral slopes, the cutoff at 100 keV, and the MeV tail together require low magnetic fields, ruling out the magnetic dissipation mechanism. The motion of the accretion disk toward the black hole results in larger Compton cooling and lower equilibrium electron temperature. Our self-consistent simulations show that in this case both electron and photon distributions attain a power-law-dominated shape similar to what is observed in the soft state. The electron distribution in the Cyg X-1 soft state might require a strong magnetic field, being consistent with the magnetically dominated corona.

Synchrotron radiation : production and properties

Abstract: Preface 1. Synchrotron radiation and electromagnetic waves 2. Electromagnetic radiation is produced by electrons 3. Electromagnetic radiation-observed and imagined 4. Radiation from moving electrons 5. Synchrotron radiation from dipole magnets 6. The spectral distribution of synchrotron radiation 7. Photon spectral distribution integrated over vertical angles 8. Introduction to electron storage rings 9. Synchrotron radiation from electron storage rings 10. Behaviour of the electron beam in a synchrotron radiation storage ring. The concept of phase space 11. Behaviour of the electron beam in a synchrotron radiation storage ring. Betatron oscillations 12. Behaviour of the electron beam in a synchrotron radiation storage ring. Energy oscillations. 13. Insertion devices-wigglers. 14. Insertion devices- undulators 15. Recent developments and future prospects Appendix 1: Vector Algebra Index

A threshold photoelectron-photoion coincidence spectrometer with double velocity imaging using synchrotron radiation

Abstract: A novel threshold photoelectron-photoion coincidence (TPEPICO) imaging spectrometer at the U14-A beamline of the Hefei National Synchrotron Radiation Laboratory is presented. A set of open electron and ion lenses are utilized to map velocity imaging of photoelectrons and photoions simultaneously, in which a repelling electric field using an extra lens is applied to magnify images of photoelectrons instead of traditional accelerating electric field in order to suppress the contribution of energetic electrons in the threshold photoelectron spectroscopy (TPES) and the mass-selected TPEPICO spectroscopy. The typical energy resolution of TPES is measured to be 9 meV (full width at half maximum), as shown on the P21/2 ionization of argon. The measured mass resolving power for the present TPEPICO imaging spectrometer is above 900 of M/ΔM. Subsequently as a benchmark, oxygen molecule is photoionized by monochromatic synchrotron radiation at 20.298 eV and dissociates to an oxygen atomic ion and a neutral oxygen at...

Performance of a picosecond x-ray delay line unit at 8.39 keV.

Abstract: A prototype device capable of splitting an x-ray pulse into two adjustable fractions, delaying one of them with the aim to perform x-ray photon correlation spectroscopy and pump-probe type studies, was designed, manufactured, and tested. The device utilizes eight perfect silicon crystals in vertical 90° scattering geometry. Its performance has been verified with 8.39 keV synchrotron radiation. The measured throughput of the device with a Si(333) premonochromator at 8.39 keV under ambient conditions is 0.6%. Time delays up to 2.62 ns have been achieved, detected with a time resolution of 16.7 ps.

X-ray diffractometry for the structure determination of a submicrometre single powder grain.

Abstract: A high-precision diffractometer has been developed for the structure analysis of a submicrometre-scale single grain of a powder sample at the SPring-8 BL40XU undulator beamline. The key design concept is the combination of a stable focused synchrotron radiation beam and the precise axis control of the diffractometer, which allows accurate diffraction intensity data of a submicrometre-scale single powder grain to be measured. The phase zone plate was designed to create a high-flux focused synchrotron radiation beam. A low-eccentric goniometer and high-precision sample positioning stages were adopted to ensure the alignment of a micrometre-scale focused synchrotron radiation beam onto the submicrometre-scale single powder grain. In order to verify the diffractometer performance, the diffraction pattern data of several powder grains of BaTiO3, of dimensions ∼600 × 600 × 300 nm, were measured. By identifying the diffraction data set of one single powder grain, the crystal structure was successfully determined with a reliable factor of 5.24%.

Developing VUV spectroscopy for protein folding and material luminescence on beamline 4B8 at the Beijing Synchrotron Radiation Facility.

Abstract: The new 4B8 beamline provides UV-VUV light in the wavelength range from 360 to 120 nm. It uniquely enables two kinds of spectroscopy measurements: synchrotron radiation circular dichroism spectroscopy and VUV excited fluorescence spectroscopy. The former is mainly used in protein secondary structure studies, and the latter in VUV excited luminescent materials research. Remote access to fluorescence measurement has been realised and users can collect data online. Besides steady-state measurements, fluorescence lifetime measurements have been established using the time domain method, while a laser-induced temperature jump is under development for protein folding dynamics using circular dichroism as a probe.

High-Pressure, High-Temperature Single-Crystal Growth, Ab initio Electronic Structure Calculations, and Equation of State of ε-Fe3N1+x

Abstract: The high-pressure behavior of the hard material e-Fe3N1+x was studied up to 33 GPa with in situ X-ray diffraction experiments using diamond anvil cells in combination with synchrotron radiation as ...

Synchrotron-radiation-based Mössbauer spectroscopy.

Abstract: We have developed a new method that yields Mossbauer absorption spectra using synchrotron radiation (SR); this method is applicable for almost all Mossbauer nuclides including those that cannot be measured by previous methods using radioisotope (RI) sources. The Mossbauer spectrum of the 68.752 keV excited state of 73Ge, which cannot be measured using a RI source, was measured using SR. Our results show that this method can be used to perform advanced Mossbauer spectroscopy measurements owing to the excellent features of SR.

X-ray polarization in relativistic jets

Abstract: We investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P ≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P ≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasiuniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization.

Reversed Cherenkov-transition radiation by a charge crossing a left-handed medium boundary.

Abstract: We analyze the radiation from a charged particle crossing the boundary between an ordinary medium and a ``left-handed'' metamaterial. We obtain exact and approximate expressions for the field components and develop algorithms for their computation. The spatial radiation in this system can be separated into three distinct components, corresponding to ordinary transition radiation having a relatively large magnitude, Cherenkov radiation, and reversed Cherenkov-transition radiation (RCTR). The last one is explained by reflection and refraction of reversed Cherenkov radiation at the interface. Conditions for generating of RCTR are obtained. We note properties of this radiation that have potential applications in the detection of charged particles and accelerator beams and for the characterization of metamaterial macroscopic parameters ($\ensuremath{\epsilon}$, $\ensuremath{\mu}$).

High-resolution spectroscopy on an X-ray absorption beamline.

Abstract: A bent-crystal spectrometer based on the Rowland circle geometry has been installed and tested on the BM30b/FAME beamline at the European Synchrotron Radiation Facility to improve its performances. The energy resolution of the spectrometer allows different kinds of measurements to be performed, including X-ray absorption spectroscopy, resonant inelastic X-ray scattering and X-ray Raman scattering experiments. The simplicity of the experimental device makes it easily implemented on a classical X-ray absorption beamline. This improvement in the fluorescence detection is of particular importance when the probed element is embedded in a complex and/or heavy matrix, for example in environmental sciences.

Development of an energy-domain 57Fe-Mössbauer spectrometer using synchrotron radiation and its application to ultrahigh-pressure studies with a diamond anvil cell.

Abstract: An energy-domain 57Fe-Mossbauer spectrometer using synchrotron radiation (SR) with a diamond anvil cell (DAC) has been developed for ultrahigh-pressure measurements. The main optical system consists of a single-line pure nuclear Bragg reflection from an oscillating 57FeBO3 single crystal near the Neel temperature and an X-ray focusing device. The developed spectrometer can filter the Doppler-shifted single-line 57Fe-Mossbauer radiation with a narrow bandwidth of neV order from a broadband SR source. The focused incident X-rays make it easy to measure a small specimen in the DAC. The present paper introduces the design and performance of the SR 57Fe-Mossbauer spectrometer and its demonstrative applications including the newly discovered result of a pressure-induced magnetic phase transition of polycrystalline 57Fe3BO6 and an unknown high-pressure phase of Gd57Fe2 alloy placed in a DAC under high pressures up to 302 GPa. The achievement of Mossbauer spectroscopy in the multimegabar range is of particular interest to researchers studying the nature of the Earth's core.