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Showing papers on "Synchrotron radiation published in 2014"


Journal ArticleDOI
TL;DR: In this paper, the acceleration in the magnetic reconnection of electron-positron plasmas is studied by using a particle-in-cell simulation, and it is found that a significantly large number of nonthermal particles are generated by the inductive electric fields around an X-type neutral line when the reconnection outflow velocity, which is known to be an Alfv\'{e}n velocity, is on the order of the speed of light.
Abstract: Particle acceleration in the magnetic reconnection of electron-positron plasmas is studied by using a particle-in-cell simulation. It is found that a significantly large number of nonthermal particles are generated by the inductive electric fields around an X-type neutral line when the reconnection outflow velocity, which is known to be an Alfv\'{e}n velocity, is on the order of the speed of light. In such a relativistic reconnection regime, we also find that electrons and positrons form a power-law-like energy distribution through their drift along the reconnection electric field under the relativistic Speiser motion. A brief discussion of the relevance of these results to the current sheet structure, which has an antiparallel magnetic field in astrophysical sources of synchrotron radiation, is presented.

211 citations


Journal ArticleDOI
01 Jul 2014-IUCrJ
TL;DR: The room-temperature structure of lysozyme is determined using 40000 individual diffraction patterns from micro-crystals flowing in liquid suspension across a synchrotron microfocus beamline.

200 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that in a certain parameter regime, the fast-cooling electrons can have a harder energy spectrum than the fast cooling electrons in a decaying magnetic field, and it was suggested that the GRB prompt emission spectra whose low-energy photon spectral index has a typical value 2,3,4,5−1 could be due to synchrotron radiation in this moderately fast cooling regime.
Abstract: Gamma-ray bursts are among the most luminous explosions in the cosmos, but the mechanism behind the energetic radiation remains unclear. ‘Fast cooling’ electrons in a decaying magnetic field may offer an explanation. Synchrotron radiation of relativistic electrons is an important radiation mechanism in many astrophysical sources. In the sources where the synchrotron cooling timescale is shorter than the dynamical timescale, electrons are cooled down below the minimum injection energy. It has been believed that such ‘fast cooling’ electrons have a power-law distribution in energy with an index −2, and their synchrotron radiation has a photon spectral index1−1.5. On the other hand, in a transient expanding astrophysical source, such as a γ-ray burst (GRB), the magnetic field strength in the emission region continuously decreases with radius. Here we study such a system, and find that in a certain parameter regime, the fast-cooling electrons can have a harder energy spectrum. We apply this new physical regime to GRBs, and suggest that the GRB prompt emission spectra whose low-energy photon spectral index has a typical value2,3,4,5−1 could be due to synchrotron radiation in this moderately fast-cooling regime.

200 citations


Journal ArticleDOI
01 Mar 2014-IUCrJ
TL;DR: The structure solution of T. brucei cathepsin B from 80 in vivo grown crystals with an average volume of 9 µm3 obtained by serial synchrotron crystallography at a microfocus beamline is reported.

192 citations


Journal ArticleDOI
Zhihong Li1, Zhonghua Wu1, Guang Mo1, Xueqing Xing1, Peng Liu1 
TL;DR: In this paper, the authors present the development and current state of a small-angle X-ray scattering station at beamline 1W2A of the Beijing Synchrotron Radiation Facility, China.
Abstract: This article presents the development and current state of a small-angle X-ray scattering station at beamline 1W2A of the Beijing Synchrotron Radiation Facility, China. The source of the beamline is introduced from a 14-pole wiggler. A triangular bending Si(111) crystal is used to horizontally focus the beam and provide a monochromatic X-ray beam (8.052 keV). A bending cylindrical mirror coated with rhodium downstream from the monochromator is used to vertically focus the beam. The X-ray beam is focused on the detector which is fixed at 30 m from the source. The focused beam size (full width at half maximum) is 1.4 × 0.2 mm2 (horizontal × vertical) with a flux of 5.5 × 1011 phs/s at 2.5 GeV and 250 mA. Besides the routine mode of small-angle X-ray scattering, the combination of small- and wide-angle X-ray scattering, grazing incidence small-angle X-ray scattering, and time-resolved small-angle X-ray scattering in sub-second level are also available for the users. Dependent on the measurement requirements,...

152 citations


Journal ArticleDOI
31 Mar 2014
TL;DR: The EXAFS technique, which deals with fine structure oscillations observed in the X-ray absorption spectrum of an element from 50 eV to ~700 eV above its absorption edge, gives precise information regarding the short range order and local structure around the particular atomic species in the material as discussed by the authors.
Abstract: The EXAFS technique, which deals with fine structure oscillations observed in the X-ray absorption spectrum of an element from 50 eV to ~700 eV above its absorption edge, gives precise information regarding the short range order and local structure around the particular atomic species in the material. With the advent of modern bright synchrotron radiation sources, EXAFS has emerged to be the most powerful local structure determination technique, which can be applied to any type of material viz. amorphous, polycrystalline, polymers, surfaces and solutions etc. Over the last few years a comprehensive facility for carrying out EXAFS measurements with synchrotron radiation over variety of samples has been developed at the 2.5 GeV, Synchrotron Radiation Source (INDUS-2) at RRCAT, Indore, India. The facility consists of two operational beamlines viz., the energy dispersive EXAFS beamline (BL-08) and the Energy Scanning EXAFS beamline (BL-09).

144 citations


Journal ArticleDOI
TL;DR: In this article, the relativistic drift kink instability deforms and then disrupts the layer, resulting in significant plasma heating but few non-thermal particles, and a moderate guide field stabilizes the layer and enables particle acceleration.
Abstract: The discovery of rapid synchrotron gamma-ray flares above 100 MeV from the Crab Nebula has attracted new interest in alternative particle acceleration mechanisms in pulsar wind nebulae. Diffuse shock-acceleration fails to explain the flares because particle acceleration and emission occur during a single or even sub-Larmor timescale. In this regime, the synchrotron energy losses induce a drag force on the particle motion that balances the electric acceleration and prevents the emission of synchrotron radiation above 160 MeV. Previous analytical studies and two-dimensional (2D) particle-in-cell (PIC) simulations indicate that relativistic reconnection is a viable mechanism to circumvent the above difficulties. The reconnection electric field localized at X-points linearly accelerates particles with little radiative energy losses. In this paper, we check whether this mechanism survives in three dimension (3D), using a set of large PIC simulations with radiation reaction force and with a guide field. In agreement with earlier works, we find that the relativistic drift kink instability deforms and then disrupts the layer, resulting in significant plasma heating but few non-thermal particles. A moderate guide field stabilizes the layer and enables particle acceleration. We report that 3D magnetic reconnection can accelerate particles above the standard radiation reaction limit, although the effectmore » is less pronounced than in 2D with no guide field. We confirm that the highest-energy particles form compact bunches within magnetic flux ropes, and a beam tightly confined within the reconnection layer, which could result in the observed Crab flares when, by chance, the beam crosses our line of sight.« less

141 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the Fermi Gamma-Ray Space Telescope (GRSST) for time-resolved spectroscopy on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses.
Abstract: Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the Fermi Gamma-Ray Space Telescope. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. The GRB spectrum is therefore modeled with two emission components consisting of optically thin non-thermal synchrotron radiation from relativistic electrons and, when significant, thermal emission from a jet photosphere, which is represented by a blackbody spectrum. To produce an acceptable fit, the addition of a blackbody component is required in five out of the eight cases. We also find that the low-energy spectral index α is consistent with a synchrotron component with α = –0.81 ± 0.1. This value lies between the limiting values of α = –2/3 and α = –3/2 for electrons in the slow- and fast-cooling regimes, respectively, suggesting ongoing acceleration at the emission site. The blackbody component can be more significant when using a physical synchrotron model instead of the Band function, illustrating that the Band function does not serve as a good proxy for a non-thermal synchrotron emission component. The temperature and characteristic emission-region size of the blackbody component are found to, respectively, decrease and increase as power laws with time during the prompt phase. In addition, we find that the blackbody and non-thermal components have separate temporal behaviors as far as their respective flux and spectral evolutions.

123 citations


Journal ArticleDOI
TL;DR: In this article, a detailed analysis of time and energy-dependent synchrotron polarization signatures in a shock-in-jet model for γ-ray blazars is presented.
Abstract: We present a detailed analysis of time- and energy-dependent synchrotron polarization signatures in a shock-in-jet model for γ-ray blazars. Our calculations employ a full three-dimensional radiation transfer code, assuming a helical magnetic field throughout the jet. The code considers synchrotron emission from an ordered magnetic field, and takes into account all light‐travel‐time and other relevant geometric effects, while the relevant synchrotron self-Compton and external Compton effects are handled with the two-dimensional Monte-Carlo/Fokker‐Planck (MCFP) code. We consider several possible mechanisms through which a relativistic shock propagating through the jet may affect the jet plasma to produce a synchrotron and high-energy flare. Most plausibly, the shock is expected to lead to a compression of the magnetic field, increasing the toroidal field component and thereby changing the direction of the magnetic field in the region affected by the shock. We find that such a scenario leads to correlated synchrotron + synchrotron-self-Compton flaring, associated with substantial variability in the synchrotron polarization percentage and position angle. Most importantly, this scenario naturally explains large polarization angle rotations by 180 ◦ , as observed in connection with γ-ray flares in several blazars, without the need for bent or helical jet trajectories or other nonaxisymmetric jet features.

105 citations


Journal ArticleDOI
TL;DR: The potential of modern methods for X-ray diffraction Line Profile Analysis can be fully exploited with data collected at synchro- tron radiation beamlines, provided that optics and experimental set-up are suitably designed and characterized.
Abstract: The potential of modern methods for X-ray diffraction Line Profile Analysis can be fully exploited with data collected at synchro- tron radiation beamlines, provided that optics and experimental set-up are suitably designed and characterized. The Material Characterization by X-ray Diffraction beamline, MCX, at Elettra-Sincrotrone Trieste,

95 citations


Journal ArticleDOI
TL;DR: In this article, the potential of synchrotron radiation techniques to understand the structural and electronic properties of coordination compounds is discussed, including the contribution arising from more specialized techniques that have become more widely used in the last years, such as the total scattering approach in the XRPD data analysis and X-ray emission spectroscopy.

Journal ArticleDOI
TL;DR: Experimental demonstration of a novel short-period microwave undulator, essentially a Thomson scattering device, that has yielded tunable spontaneous emission and seeded coherent radiation and promises a shorter undulator period, a large aperture, and fast dynamic control.
Abstract: Static magnetic undulators used by x-ray light sources are fundamentally too limited to achieve shorter undulator periods and dynamic control. To overcome these limitations, we report experimental demonstration of a novel short-period microwave undulator, essentially a Thomson scattering device, that has yielded tunable spontaneous emission and seeded coherent radiation. Its equivalent undulator period (λu) is 13.9 mm while it has achieved an equivalent magnetic field of 0.65 T. For future-generation light sources, this device promises a shorter undulator period, a large aperture, and fast dynamic control.

Journal ArticleDOI
TL;DR: In this paper, a comprehensive spectral and morphological analysis of the remnant of supernova 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA) is presented.
Abstract: We present a comprehensive spectral and morphological analysis of the remnant of supernova (SN) 1987A with the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The non-thermal and thermal components of the radio emission are investigated in images from 94 to 672 GHz (λ 3.2 mm to 450 μm), with the assistance of a high-resolution 44 GHz synchrotron template from the ATCA, and a dust template from ALMA observations at 672 GHz. An analysis of the emission distribution over the equatorial ring in images from 44 to 345 GHz highlights a gradual decrease of the east-to-west asymmetry ratio with frequency. We attribute this to the shorter synchrotron lifetime at high frequencies. Across the transition from radio to far infrared, both the synchrotron/dust-subtracted images and the spectral energy distribution (SED) suggest additional emission beside the main synchrotron component (Sν∝ν−0.73) and the thermal component originating from dust grains at T ~ 22 K. This excess could be due to free–free flux or emission from grains of colder dust. However, a second flat-spectrum synchrotron component appears to better fit the SED, implying that the emission could be attributed to a pulsar wind nebula (PWN). The residual emission is mainly localized west of the SN site, as the spectral analysis yields −0.4 lesssim α lesssim −0.1 across the western regions, with α ~ 0 around the central region. If there is a PWN in the remnant interior, these data suggest that the pulsar may be offset westward from the SN position.

Proceedings ArticleDOI
TL;DR: In this article, a soft x-ray beamline on a bending magnet source of Indus-2 storage ring (2.5 GeV) was developed and the beamline layout is based on a spherical grating monochromator.
Abstract: This article describes the development of a soft x-ray beamline on a bending magnet source of Indus-2 storage ring (2.5 GeV) and some preliminary results of x-ray absorption spectroscopy (XAS) measurements using the same. The beamline layout is based on a spherical grating monochromator. The beamline is able to accept synchrotron radiation from the bending magnet port BL-1 of the Indus-2 ring with a wide solid angle. The large horizontal and vertical angular acceptance contributes to high photon flux and selective polarization respectively. The complete beamline is tested for ultrahigh vacuum (UHV) ∼ 10−10 mbar. First absorption spectrum was obtained on HOPG graphite foil. Our performance test indicates that modest resolving power has been achieved with adequate photon flux to carry out various absorption experiments.

Journal ArticleDOI
TL;DR: In this paper, the authors consider the GeV light curves of ten Gamma-Ray Bursts (GRBs) with measured redshift detected by the Fermi-LAT, and they consider the scenario in which the temporally extended LAT emission is dominated by synchrotron radiation from electrons accelerated at forward external shock.
Abstract: The physical origin of the > 0.1GeV emission detected from Gamma-Ray Bursts (GRBs) by the Fermi satellite has not yet been completely understood. In this work we consider the GeV light curves of ten GRBs with measured redshift detected by the Fermi-LAT. These light curves are characterised by a long-lived (& 10 2 seconds) emission, whose luminosity decays in time as a power-law. While the decay rate is similar for all GRBs (i.e. LLAT / t 1.2 ), the normalisation spans about two orders of magnitude in luminosity. However, after re-normalising the luminosities to the prompt energetics Eprompt the light curves overlap. We consider the scenario in which the temporally extended LAT emission is dominated by synchrotron radiation from electrons accelerated at the forward external shock. According to this model, at high-energies (i.e. above the typical synchrotron frequencies) a small dispersion of the Epromptnormalised light curves is expected. The fact that the LAT temporally extended emission follows this behaviour reinforces its interpretation in terms of afterglow radiation from external shocks. Assuming this scenario, we argue that the parameters ǫe and η (i.e., the fraction of shock-dissipated energy gained by the electrons, and the efficiency of the mechanism producing the prompt radiation, respectively) must be narrowly distributed.

Journal ArticleDOI
TL;DR: The application of scattering-type near-field optical microscopy to characterize various semiconducting materials using the electron storage ring Metrology Light Source (MLS) as a broadband synchrotron radiation source shows high sensitivity for spectroscopic material discrimination.
Abstract: We describe the application of scattering-type near-field optical microscopy to characterize various semiconducting materials using the electron storage ring Metrology Light Source (MLS) as a broadband synchrotron radiation source. For verifying high-resolution imaging and nano-FTIR spectroscopy we performed scans across nanoscale Si-based surface structures. The obtained results demonstrate that a spatial resolution below 40 nm can be achieved, despite the use of a radiation source with an extremely broad emission spectrum. This approach allows not only for the collection of optical information but also enables the acquisition of near-field spectral data in the mid-infrared range. The high sensitivity for spectroscopic material discrimination using synchrotron radiation is presented by recording near-field spectra from thin films composed of different materials used in semiconductor technology, such as SiO2, SiC, SixNy, and TiO2.

Journal ArticleDOI
TL;DR: In this article, a global null cone description of the electromagnetic field is applied to establish the nonexistence of B-mode radiation memory and the non-existence of E mode radiation memory due to a bound charge distribution.
Abstract: Gravitational radiation has a memory effect represented by a net change in the relative positions of test particles. Both the linear and nonlinear sources proposed for this radiation memory are of the 'electric' type, or E mode, as characterized by the even parity of the polarization pattern. Although 'magnetic' type, or B mode, radiation memory is mathematically possible, no physically realistic source has been identified. There is an electromagnetic counterpart to radiation memory in which the velocity of charged test particles obtain a net 'kick'. Again, the physically realistic sources of electromagnetic radiation memory that have been identified are of the electric type. In this paper, a global null cone description of the electromagnetic field is applied to establish the non-existence of B-mode radiation memory and the non-existence of E-mode radiation memory due to a bound charge distribution.

Journal ArticleDOI
TL;DR: Pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source that creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra.
Abstract: Synchrotron radiation facilities routinely operate in a multi-bunch regime, but applications relying on time-of-flight schemes require single bunch operation. Here we show that pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source. It has variable polarization, a photon flux of up to 107–109 ph s−1/0.1%BW at purity values of 104–102 and a repetition rate of 1.25 MHz. The quasi-resonant excitation of incoherent betatron oscillations of electrons allows horizontal pulse separation at variable (also circular) polarization accessible for both, regular 30 ps pulses and ultrashort pulses of 2–3 ps duration. Combined with a new generation of angularly resolving electron spectrometers this creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra. Our pulse picking scheme is particularly suited for surface physics at diffraction-limited light sources promising ultimate spectral resolution. Although synchrotron facilities routinely operate in a multi-bunch regime for maximum average brilliance, studies relying on time-of-flight schemes require single-bunch operation. Here, Holldack et al.isolate and apply single bunch X-ray pulses from multibunch radiation using pulse picking by resonant excitation.

Journal ArticleDOI
TL;DR: The performance of the instrument has been demonstrated by characterizing the evolution of 3D damage mechanisms in ceramic composite materials under tensile loading at 1750 °C.
Abstract: A compact ultrahigh temperature tensile testing instrument has been designed and fabricated for in situ x-ray micro-tomography using synchrotron radiation at the Advanced Light Source, Lawrence Berkeley National Laboratory. It allows for real time x-ray micro-tomographic imaging of test materials under mechanical load at temperatures up to 2300 °C in controlled environments (vacuum or controlled gas flow). Sample heating is by six infrared halogen lamps with ellipsoidal reflectors arranged in a confocal configuration, which generates an approximately spherical zone of high heat flux approximately 5 mm in diameter. Samples are held between grips connected to a motorized stage that loads the samples in tension or compression with forces up to 2.2 kN. The heating chamber and loading system are water-cooled for thermal stability. The entire instrument is mounted on a rotation stage that allows stepwise recording of radiographs over an angular range of 180°. A thin circumferential (360°) aluminum window in the wall of the heating chamber allows the x-rays to pass through the chamber and the sample over the full angular range. The performance of the instrument has been demonstrated by characterizing the evolution of 3D damage mechanisms in ceramic composite materials under tensile loading at 1750 °C.

Journal ArticleDOI
Haijun Huang1, Da Shu1, Yanan Fu, Jun Wang1, Baode Sun1 
TL;DR: Cavitation bubbles in Al-10 wt.%Cu melt has been investigated by adopting synchrotron radiation X-ray imaging technology and it is revealed that most of bubbles concentrate within an intense cavitation zone nearby the radiation face.

Journal ArticleDOI
TL;DR: Polarization is a fundamental property of light and is fundamentally linked to the internal geometry of a source of radiation as discussed by the authors, and it has made possible multiple astrophysical discoveries, including the discovery of the cosmic microwave background radiation.
Abstract: Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, GoldreichKylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

Journal ArticleDOI
TL;DR: In this paper, the diffuse gamma-ray flux with a semi-analytic approach was calculated and it was shown that the very high energy gamma-rays will be absorbed in the galaxies and converted into electron-position pairs, which then lose almost all their energy through synchrotron radiation in the strong magnetic fields in the starburst region.
Abstract: One attractive scenario for the excess of sub-PeV/PeV neutrinos recently reported by IceCube is that they are produced by cosmic rays in starburst galaxies colliding with the dense interstellar medium. These proton-proton ($pp$) collisions also produce high-energy gamma-rays, which finally contribute to the diffuse high-energy gamma-ray background. We calculate the diffuse gamma-ray flux with a semi-analytic approach and consider that the very high energy gamma-rays will be absorbed in the galaxies and converted into electron-position pairs, which then lose almost all their energy through synchrotron radiation in the strong magnetic fields in the starburst region. Since the synchrotron emission goes into energies below GeV, this synchrotron loss reduces the diffuse high-energy gamma-ray flux by a factor of about two, thus leaving more room for other sources to contribute to the gamma-ray background. For a $E_ u^{-2}$ neutrino spectrum, we find that the diffuse gamma-ray flux contributes about 20% of the observed diffuse gamma-ray background in the 100 GeV range. However, for a steeper neutrino spectrum, this synchrotron loss effect is less important, since the energy fraction in absorbed gamma-rays becomes lower.

Journal ArticleDOI
TL;DR: In this article, the effects of target density, laser intensity, target preplasma properties, and other parameters on the conversion efficiency, spectrum, and angular distribution of gamma-rays by synchrotron emission were analyzed.
Abstract: At laser intensities above 1023 W/cm2, the interaction of a laser with a plasma is qualitatively different to the interactions at lower intensities. In this intensity regime, solid targets start to become relativistically underdense, gamma-ray production by synchrotron emission starts to become an important feature of the dynamics and, at even higher intensities, electron-positron pair production by the non-linear Breit-Wheeler process starts to occur. In this paper, an analysis is presented of the effects of target density, laser intensity, target preplasma properties, and other parameters on the conversion efficiency, spectrum, and angular distribution of gamma-rays by synchrotron emission. An analysis of the importance of Breit-Wheeler pair production is also presented. Target electron densities between 1022 cm−3 and 5 × 1024 cm−3 and laser intensities covering the range between 1021 W/cm2 (available with current generation laser facilities) and 1024 W/cm2 (upper intensity range expected from the ELI facility are considered. Results are explained in terms of the behaviour of the head of the laser pulse as it interacts with the target.

Journal ArticleDOI
TL;DR: In this paper, the authors presented multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical.
Abstract: We present multi-wavelength observations of a typical long duration GRB 120326A at z = 1.798, including rapid observations using a Submillimeter Array (SMA) and a comprehensive monitoring in the X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku, yielded a spectral peak energy of E{sub peak}{sup src}=107.8{sub −15.3}{sup +15.3} keV and an equivalent isotropic energy of E{sub iso} as 3.18{sub −0.32}{sup +0.40}×10{sup 52} erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation (6.°69 ± 0.°16). The forward shock modeling, using a two-dimensional relativistic hydrodynamic jet simulation, was also determined by the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical (αo – α{sub X} = –1.45 ± 0.10) indicated different radiation processes in each of them. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and slow decay of the afterglow in submillimeter supports that this is a plausible idea. The more » observed temporal evolution and spectral properties, as well as forward shock modeling parameters, enabled us to determine reasonable functions to describe the afterglow properties. Because half of the events share similar properties in the X-ray and optical as the current event, GRB 120326A will be a benchmark with further rapid follow-ups, using submillimeter instruments such as an SMA and the Atacama Large Millimeter/submillimeter Array. « less

Journal ArticleDOI
TL;DR: A new modular X-ray-transparent experimental cell enables tomographic investigations of fluid rock interaction under natural reservoir conditions and is successfully used in three experiments at the bending-magnet beamline 2BM at the Advanced Photon Source.
Abstract: A new modular X-ray-transparent experimental cell enables tomographic investigations of fluid rock interaction under natural reservoir conditions (confining pressure up to 20 MPa, pore fluid pressure up to 15 MPa, temperature ranging from 296 to 473 K). The portable cell can be used at synchrotron radiation sources that deliver a minimum X-ray flux density of 109 photons mm−2 s−1 in the energy range 30–100 keV to acquire tomographic datasets in less than 60 s. It has been successfully used in three experiments at the bending-magnet beamline 2BM at the Advanced Photon Source. The cell can be easily machined and assembled from off-the-shelf components at relatively low costs, and its modular design allows it to be adapted to a wide range of experiments and lower-energy X-ray sources.

Journal ArticleDOI
TL;DR: In this paper, the authors presented multi-wavelength observations of a typical long duration GRB 120326A at 1.798 GHz, including rapid observations using a submillimeter array (SMA), and a comprehensive monitoring in X-ray and optical.
Abstract: We present multi-wavelength observations of a typical long duration GRB 120326A at $z=1.798$, including rapid observations using a submillimeter array (SMA), and a comprehensive monitoring in X-ray and optical. The SMA observation provided the fastest detection to date among seven submillimeter afterglows at 230 GHz. The prompt spectral analysis, using Swift and Suzaku yielded a spectral peak energy of $E^{\rm src}_{\rm peak}=107.8^{+15.3}_{-15.3}$ keV and equivalent isotropic energy of $E_{\rm iso}$ as $3.18^{+0.40}_{-0.32}\times 10^{52}$ erg. The temporal evolution and spectral properties in the optical were consistent with the standard forward shock synchrotron with jet collimation ($6^{\circ}.69\pm0^{\circ}.16$). The forward shock modeling using a 2D relativistic hydrodynamic jet simulation also determined the reasonable burst explosion and the synchrotron radiation parameters for the optical afterglow. The X-ray light curve showed no apparent jet break and the temporal decay index relation between the X-ray and optical ($\alpha{\rm o}-\alpha_{X}=-1.45\pm0.10$) indicated different radiation processes in the X-ray and optical. Introducing synchrotron self-inverse Compton radiation from reverse shock is a possible solution, and the detection and the slow decay of the afterglow in submillimeter supports that this is a plausible idea. The observed temporal evolution and spectral properties as well as forward shock modeling parameters, enabled to determine reasonable functions to describe the afterglow properties. Because half of events share similar properties in the X-ray and optical to the current event, GRB120326A will be a benchmarks with further rapid follow-ups, using submillimeter instruments such as SMA and ALMA.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the normal incidence of a laser pulse on a foil by means of three-dimensional numerical simulations in the range of intensities 2'×'1021'W cm−2 and electron densities 2 '×' 1022' W cm−3 and showed that in the case of oblique incidence of 3 PW, 10 fs laser pulses on a thin foil about 108 photons/0.1% bandwidth are produced at the energy level of 1'MeV that significantly exceeds performance of the modern Compton gamma-ray sources.
Abstract: Incoherent photon emission by ultrarelativistic electrons in the normal incidence of a laser pulse on a foil is investigated by means of three-dimensional numerical simulations in the range of intensities 2 × 1021–2 × 1025 W cm−2 and electron densities 2 × 1022–1 × 1024 cm−3. We focus on properties of the resulting synchrotron radiation, such as its overall energy, directivity of the radiation pattern, and slope of the energy spectrum. Regimes of laser-foil interactions are studied in the framework of a simple analytical model. The laser-plasma parameters for efficient gamma-ray generation are found and revealed to be close to the parameters for relativistic foil motion. It is shown that in the case of oblique incidence of a 3 PW, 10 fs laser pulse on a thin foil about 108 photons/0.1% bandwidth are produced at the energy level of 1 MeV that significantly exceeds performance of the modern Compton gamma-ray sources. Various applications of the gamma-ray bunches are discussed.

Journal ArticleDOI
TL;DR: XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation, and is demonstrated to be feasible for dynamic strain field mapping.
Abstract: We present a dynamic strain field mapping method based on synchrotron X-ray digital image correlation (XDIC). Synchrotron X-ray sources are advantageous for imaging with exceptional spatial and temporal resolutions, and X-ray speckles can be produced either from surface roughness or internal inhomogeneities. Combining speckled X-ray imaging with DIC allows one to map strain fields with high resolutions. Based on experiments on void growth in Al and deformation of a granular material during Kolsky bar/gas gun loading at the Advanced Photon Source beamline 32ID, we demonstrate the feasibility of dynamic XDIC. XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation.

Journal ArticleDOI
TL;DR: In this article, the authors presented the first implementation, in a high resolution soft-RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization.
Abstract: Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution soft-RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B4C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF (European Synchrotron Radiation Facility); it has been fully characterized and it has been used for a demonstration experiment at the Cu L3 edge on a high-Tc superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.

Journal ArticleDOI
TL;DR: In this paper, the authors used synchrotron X-ray reflectivity to study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers.
Abstract: Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.