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The structure of porous silicon layers was accurately investigated by diverse x-ray methods. A series of samples with etching times varying from 1 to 10 min was produced by chemical etch using a HF/HNO3-based solution assisted with NaNO2. The porosity determined from low-angle x-ray reflectivity spectra was found to fluctuate from 35% to 55% as the etch proceeds. Reciprocal space mapping around the (004) Si lattice point revealed that the Si crystallites are deformed due to a distribution of in-plane compressive strain caused by the neighboring pores, which leads to an expansion of the perpendicular lattice parameter. No signature of mosaicity was found. The perpendicular strain could be precisely determined by fitting the x-ray-diffraction spectra, measured in the triple-axis configuration, to a set of Voigt and Gaussian distributions. These strain distributions are certainly associated with the different population of crystallite sizes formed during the stain etching process. We were able here to determine the temporal evolution of the strain inside the nanostructured porous silicon. [ABSTRACT FROM AUTHOR]

We report on a feasibility study of scintillation detectors with fast decay times which might be used to enable spectroscopy in a high-count-rate, high-energy x-ray environment, such as is used for cargo inspection. Such detectors need to have a small size and high density in order to reliably detect x rays between 1 and 9 MeV with good spatial resolution and need to be suitable for read-out with semiconductor photo-detectors. Three inorganic scintillator detectors with decay constants less than 10 ns were selected: ZnO (in the form of wafers of 4.5 \times 0.5 \times 20~mm and single crystals of 5 \times 5 \times 30~mm), BaF2~ (5 \times 5 \times 30~mm) and PbWO4~(6 \times 6\times 20~mm). ZnO has a known problem of self-absorption of the emitted scintillation light. Using the wafers to create stacks of different thicknesses, the effective attenuation length was determined to be 2.25 \pm 0.25~mm for one batch of ZnO and 1.5\pm 0.3~mm for another batch, making ZnO unlikely for the proposed use. Although the larger ZnO crystal also scintillates, light transmission was so poor that no signal was measured in tests with gamma ray sources. ZnO was thus discarded as a viable candidate for the purposes of this study. The full width at half maximum (FWHM) of the pulses produced by BaF2 was measured to be \sim 2~ns, consistent with being dominated by the response of the photomultiplier tube used in the measurement. BaF2 by itself, however, emits in the UV, which is unsuitable for use with semiconductor readout. In another series of measurements, BaF2 was coupled to fast wavelength-shifting PVT sheets with Eljen DSB1 dye, and the FWHM of the signal measured this way was \sim 4.8~ns, with a fast decay constant of \sim 11.2~ns. The long decay component appears to be suppressed somewhat by the use of the wavelength shifter. The measured FWHM of the pulses produced by PbWO4 was \sim 3~ns, with a decay constant of \sim 8.3~ns and no long component. These results suggest that dense sub-10-ns scintillators exist that can be used for high-count-rate x-ray cargo inspection with good spatial resolution. PbWO4 is very dense, has no long decay component or self-attenuation and scintillates in the visible spectrum, but due to its low light output, it needs to be read out by a silicon photomultiplier or similar device. BaF2 is a possible alternative, when used in combination with a fast wavelength shifter. [ABSTRACT FROM PUBLISHER]

The bremsstrahlung X-ray spectrum produced by X-ray sources used in cargo inspection systems is attenuated and modified by materials in the cargo in a Z-dependent way and then detected in a radiographic detector array. We have previously shown that it is possible to obtain spectral information indirectly by analyzing statistical fluctuations (the “noise”) in radiographic data, in a technique we call Noise Spectroscopy (NS) or Z-SCAN (Z-determination by Statistical Count-rate ANalysis). The technique is especially effective when the detector array consists of fast scintillation detectors and waveform digitization electronics, measuring both the waveform mean and variance during each X-ray pulse. This previous work, however, used photo-multiplier tubes, which are not especially suitable for a practical implementation. Here we describe the results of R&D performed to produce an effective version of the technique that lends itself to implementation in a single detector array that can be used both for radiography and for NS, with the same imaging spatial resolution as in conventional systems. We characterize the performance of biased photodiodes in combination with trans-impedance preamplifiers, read out with commercially available waveform digitizers. We report on experiments performed with a 16-channel detector array in a test beam, with test samples of different atomic number Z. We also report the implementation of an NS algorithm in an FPGA. In combination, we show that a practical implementation of Noise Spectroscopy in cargo inspection systems is feasible. [ABSTRACT FROM PUBLISHER]

Abstract: We introduce Noise Spectroscopy (NS) and show the results of an analysis of three data-sets demonstrating the feasibility of this technique. The NS effect is first shown to be present in a set of X-ray radiography images of low- and high-Z materials taken using the 6MV Rapiscan Eagle P60HP portal cargo inspection system. Image-Based NS is, however, relatively insensitive. Using a data-set obtained using a fast plastic scintillator and photo-multiplier tube (PMT), we demonstrate that NS works very well when using fast detectors, fast electronics and waveform digitization. Another data-set was taken using Lutetium–Yttrium Ortho-Silicate (LYSO), which is suitable for use in X-ray cargo radiography. Although LYSO is slower than plastic scintillator, it was shown that NS also works very well using this material, paving the way for NS to be implemented using the primary imaging array of X-ray cargo inspection systems. [Copyright &y& Elsevier]

In this article, we use simulated and experimental data to explore how three operator-controllable parameters-(1) signal level, (2) detector resolution, and (3) number of factors chosen for analysis-affect quantitative analyses of scanning transmission electron microscopy-energy dispersive X-ray spectroscopy spectrum images processed by principal component analysis (PCA).We find that improvements in both signal level and detector resolution improve the precision of quantitative analyses, but that signal level is the most important. We also find that if the rank of the PCA solution is not chosen properly, it may be possible to improperly fit the underlying data and degrade the accuracy of results. Additionally, precision is degraded in the case when too many factors are included in the model. [ABSTRACT FROM AUTHOR]

Recent progress on the x-ray spectroscopy of kaonic helium atoms as well as on the precision laser spectroscopy of antiprotonic helium atoms are presented. Some historical background connecting these two exotic helium atoms is also discussed. [ABSTRACT FROM AUTHOR]

The performance of a gas proportional scintillation counter filled with either pure Xe or Ar-Xe mixtures is described for the 0.1-10 keV X-ray energy range. It is shown that the spectra tail distortion exhibited by Xe filled gaseous detectors for soft X-rays below 2 keV is reduced if Ar-Xe mixtures are used. The peak-to-valley ratio increases by a factor of about 2 or 3 as the Xe concentration is reduced from 100% to 5%. Moreover, the energy resolutions for such mixtures are similar to the ones for pure Xe. [ABSTRACT FROM AUTHOR]

Abstract: Doubly-curved crystals (DCCs) can be very useful devices to focus and monochromatize radiation from an X-ray tube or a synchrotron, especially for X-ray fluorescence analysis. However, production of a DCC is somewhat difficult. In this paper we will present some basic theory about DCC geometries, different ways of DCC production and methods to test the quality of the DCCs. [Copyright &y& Elsevier]

X-ray-induced redox changes can lead to incorrect assignments of the functional states of metals in metalloprotein crystals. The need for on-line monitoring of the status of metal ions (and other chromophores) during protein crystallography experiments is of growing importance with the use of intense synchrotron X-ray beams. Significant efforts are therefore being made worldwide to combine different spectroscopies in parallel with X-ray crystallographic data collection. Here the implementation and utilization of optical and X-ray absorption spectroscopies on the modern macromolecular crystallography (MX) beamline 10, at the SRS, Daresbury Laboratory, is described. This beamline is equipped with a dedicated monolithic energy-dispersive X-ray fluorescence detector, allowing X-ray absorption spectroscopy (XAS) measurements to be made in situ on the same crystal used to record the diffraction data. In addition, an optical microspectrophotometer has been incorporated on the beamline, thus facilitating combined MX, XAS and optical spectroscopic measurements. By uniting these techniques it is also possible to monitor the status of optically active and optically silent metal centres present in a crystal at the same time. This unique capability has been applied to observe the results of crystallographic data collection on crystals of nitrite reductase from Alcaligenes xylosoxidans, which contains both type-1 and type-2 Cu centres. It is found that the type-1 Cu centre photoreduces quickly, resulting in the loss of the 595 nm peak in the optical spectrum, while the type-2 Cu centre remains in the oxidized state over a much longer time period, for which independent confirmation is provided by XAS data as this centre has an optical spectrum which is barely detectable using microspectrophotometry. This example clearly demonstrates the importance of using two on-line methods, spectroscopy and XAS, for identifying well defined redox states of metalloproteins during crystallographic data collection. [ABSTRACT FROM AUTHOR]

Epitaxial (epi) stacking faults on silicon wafers were investigated by combining different surface analytical methods. Automatic scanning electron microscope energy-dispersive X-ray spectroscopy analysis provided an overview of the defect situation on the wafer surface (coordinates and composition) before information on the topography by atomic force microscope and data on the stress fields of epi defects by micro-Raman spectroscopy were collected. Sputtering of the defects was carried out by argon or oxygen ions to find the cause of the defect. Delaminated particles were analyzed by Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry. The results demonstrate that the geometrical type of an epi defect depends on the chemical composition and the physical phase of the contamination. [ABSTRACT FROM AUTHOR]

We present some methods of X-ray data analysis employed in our laboratory for deducing the physical parameters of flaring plasma. For example, we have used a flare well observed with Polish instrument RESIK aboard Russian CORONAS-F satellite. Based on a careful instrument calibration, the absolute fluxes in a number of individual spectral lines have been obtained. The analysis of these lines allows us to follow the evolution of important thermodynamic parameters characterizing the emitting plasma throughout this flare evolution. [ABSTRACT FROM AUTHOR]

Abstract: The Controlled-Drift Detector is a fully depleted silicon detector that allows 2D position sensing and energy spectroscopy of X-rays in the range 0.5–30keV with imaging capability up to 100kframe/s, event timing of few ns and limited readout channels. In this paper we review the Controlled-Drift Detector operating principle and we present its applications in X-ray absorption imaging and in Compton electrons tracking. [Copyright &y& Elsevier]

The conversion coefficients from air kerma to ICRU operational dose equivalent quantities for STUK's realisation of the X-radiation qualities N-15 to N-60 of the ISO narrow (N) spectrum series were determined by utilising X-ray spectrum measurements. The pulse-height spectra were measured using a planar high-purity germanium spectrometer and unfolded to fluence spectra using Monte Carlo generated data of the spectrometer response. To verify the measuring and unfolding method, the first and second half-value layers and the air kerma rate were calculated from the fluence spectra and compared with the values measured using an ionisation chamber. For each radiation quality, the spectrum was characterised by the parameters given in ISO 4037-1. The conversion coefficients from the air kerma to the ICRU operational quantities Hp(10), Hp(0.07), H′(0.07) and H*(10) were calculated using monoenergetic conversion coefficients at zero angle of incidence. The results are discussed with respect to ISO 4037-4, and compared with published results for low-energy X-ray spectra. [ABSTRACT FROM AUTHOR]

A periodic multilayer waveguide for X-rays with an air gap serving as a guiding layer is considered. The propagation of hard X-ray guided modes through such a waveguide has been investigated with the help of numerical modeling. The propagation lengths of the guided modes are analyzed thoroughly with respect to their dependence on the reflectivity of the periodic multilayers forming the waveguide. It is shown that the guided modes can be generated even in a waveguide composed of low-reflectivity multilayers. The influence of a standing wave inside the reflecting multilayers on the transmission of the guided waves by the waveguide is demonstrated. Conditions which are favorable for the excitation of the guided modes are discussed. [ABSTRACT FROM AUTHOR]

Abstract: We report on a study of field emission accompanied by emission of visible light and by emission of characteristic X-rays in a 5 and a 20 cell superconducting niobium 3GHz accelerating cavity of the S-DALINAC injector. The nearly absorption free measurement of characteristic niobium X-rays inside the beam pipe allowed for the first time an estimate of the field emission current during the normal operation of superconducting accelerating cavities within their cryostat. The field emission current for different accelerating field strengths is well described by the law of Fowler and Nordheim. Hence the field enhancement factors for the observed field emission sites could be determined. For electron tracking calculations based on the Leap-Frog method the field strength distribution of the 5 cell cavity was determined. Due to these calculations it can be assumed that light emitting spots are electron emitters too and that the characteristic niobium X-rays are emitted from the same areas. We additionally report on the cleaning method and heat treatment of the superconducting niobium accelerating cavities at the S-DALINAC with particular application to the 5 cell cavity. After that, up to the maximum applied field strength of field emission as well as the emission of visible light and characteristic X-rays were not observed anymore. [Copyright &y& Elsevier]

We obtain contemporaneous observations of the surface and corona of AB Doradus (AB Dor), a young single cool star, using ground-based circularly polarized spectra from the Anglo-Australian Telescope and X-ray light curves and spectra from the Chandra satellite. The ground-based data are used to construct surface magnetic field maps, which are extrapolated to produce detailed models of the quiescent corona. The X-ray data serve as a new test for the validity of these coronal models. We find that AB Dor's X-ray corona must be concentrated close to its surface, with a height, ; this height is determined by the high coronal density and complex multipolar magnetic field from the surface maps. There is also significant correlation between the positions of surface and coronal active longitudes as determined from the surface spot and magnetic field maps and the X-ray light curve. At this epoch (2002 December) AB Dor appears to possess one very large active longitude region, covering almost half the star; displaying enhanced activity in the form of large dark spots, strong magnetic fields and chromospheric emission. This is unusual as previous surface maps of AB Dor typically display more active regions that span a wider range of longitudes. Finally, the level of rotational modulation and shape of the X-ray light curve depend on the distribution of magnetic field in the obscured hemisphere (AB Dor is inclined by 60°). The models that best reproduce the rotational modulation observed in the contemporaneous Chandra X-ray light curve and spectra require the magnetic field in the obscured hemisphere to be of the same polarity as that in the observed hemisphere. The Sun shows different behaviour, with the leading polarity reversed in the opposite hemisphere. The X-ray observations provide a unique constraint on the magnetic structure in the obscured hemisphere. [ABSTRACT FROM AUTHOR]

We perform Monte Carlo simulations of cosmic ray-induced hard X-ray radiation from the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range 25–300 keV is mainly determined by Compton scatterings and photoabsorption, and is almost insensitive to the incident cosmic ray spectrum. We provide a fitting formula for the hard X-ray surface brightness of the atmosphere as would be measured by a satellite-borne instrument, as a function of energy, solar modulation level, geomagnetic cut-off rigidity and zenith angle. A recent measurement by the INTEGRAL observatory of the atmospheric hard X-ray flux during the occultation of the cosmic X-ray background by the Earth agrees with our prediction within 10 per cent. This suggests that Earth observations could be used for in-orbit calibration of future hard X-ray telescopes. We also demonstrate that the hard X-ray spectra generated by cosmic rays in the crusts of the Moon, Mars and Mercury should be significantly different from that emitted by the Earth's atmosphere. [ABSTRACT FROM AUTHOR]

We present an X-ray study of the massive edge-on Sa galaxy, Sombrero (M 104; NGC 4594), based on XMM–Newton and Chandra observations. A list of 62 XMM–Newton and 175 Chandra discrete X-ray sources is provided, the majority of which are associated with the galaxy. Spectral analysis is carried out for relatively bright individual sources and for an accumulated source spectrum. At energies ≳2 keV, the source-subtracted X-ray emission is distributed similarly as the stellar K-band light and is primarily due to the residual emission from discrete sources. At lower energies, however, a substantial fraction of the source-subtracted emission arises from diffuse hot gas extending to ∼20 kpc from the galactic centre. The galactic disc shows little X-ray emission and instead shadows part of the X-ray radiation from the bulge. The observed diffuse X-ray emission from the galaxy shows a steep spectrum that can be characterized by an optically thin thermal plasma with temperatures of ∼0.6–0.7 keV, varying little with radius. The diffuse emission has a total luminosity of in the 0.2–2 keV energy range. This luminosity is significantly smaller than the prediction by current numerical simulations for galaxies as massive as Sombrero. However, such simulations do not include the effect of quiescent stellar feedback (e.g. ejecta from evolving stars and Type Ia supernovae) against the accretion from intergalactic medium. We argue that the stellar feedback likely plays an essential role in regulating the physical properties of hot gas. Indeed, the observed diffuse X-ray luminosity of Sombrero accounts for at most a few per cent of the expected mechanical energy input from Type Ia supernovae. The inferred gas mass and metal content are also substantially less than those expected from stellar ejecta. We speculate that a galactic bulge wind, powered primarily by Type Ia supernovae, has removed much of the ‘missing’ energy and metal-enriched gas from the region revealed by the X-ray observations. [ABSTRACT FROM AUTHOR]

A bent-crystal Laue {or Cauchois [J. Phys. Radium 3, 320 (1932)] geometry} spectrograph is a good compromise between sensitivity and spectral resolution for measuring x-ray spectra (15

Energy-dispersive X-ray spectrometry offers the opportunity for a fast and reliable determination of the composition of a specimen. For fundamental parameter based quantification, detailed knowledge of the X-ray generation cross sections and of the detection system’s efficiency is required. The detection efficiency is determined comparing the measured and calculated spectrum of undispersed synchrotron radiation (SR) from the electron storage ring BESSY II in the spectral range from 0.1 keV to 100 keV. Alternatively, monochromatized SR in the spectral range from 0.1 keV to 60 keV is used to determine the detection efficiency with a typical relative uncertainty of 1% to 2% by direct comparison with a reference detector. Employing well-calibrated detectors and monochromatized SR of well-known radiant power and high spectral purity, fluorescence yields have been investigated and resonant Raman scattering was studied as an example of a basic effect creating spectral background. [ABSTRACT FROM AUTHOR]

Some of the results of X-ray observations of the Sun in the energy interval from 3 to 31.5 keV using a semiconductor spectrometer are reported. A brief description is given of the instrument, in which a not deeply cooled cadmium telluride detector is used for the first time for spectrometric measurements under cosmic conditions. The main parameters of the instrument and the technique employed for processing the data are described as well. The capabilities of the spectrometer made it possible to track the evolution of the X-ray spectra of weak solar flares registered under favorable background conditions. It is also shown that the intensity and hardness of the radiation of the quiet Sun increases with the level of its activity. [ABSTRACT FROM AUTHOR]

The structures of deoxypeganine (DOP) hydrochloride and oxalate were solved by x-ray structure analysis. An infinite chain along the crystallographic c axis was formed in the crystal structure of DOP oxalate. A molecular framework consisting of Cl anions and DOP cation protonated at N1 was found in the structure of unhydrated DOP hydrochloride. The molecular packing of the “host” (DOP cation) was pseudoisostructural in the studied ion-molecular crystals but differed from other known DOP salts. The “guest” molecules (acid anions) in the studied and known DOP salts formed different intermolecular contacts. [ABSTRACT FROM AUTHOR]

Starting from the basic photon detection process in semiconductors, the function, principles and properties of sophisticated silicon detectors are discussed. These detectors are based on, or inspired by, the semiconductor drift detector. They have already shown their potential in X-ray astronomy (pn-CCD) and in X-ray spectroscopy (silicon drift diode), and further detector types (DEPFET pixel detector and macro-pixel detector) are under development for several other future experiments. The detectors seem to be very well suited for synchrotron radiation experiments. [ABSTRACT FROM AUTHOR]

New possibilities are opened up utilizing position-sensitive germanium detectors in the X-ray spectroscopy of highly charged heavy ions at GSI-Darmstadt. The recent experiments revealed the need for two-dimensional strip detectors with their inherent advantages concerning spectroscopy and imaging capabilities as well as polarization sensitivity. For the first prototype a germanium diode (70 mmtimes41 mm, 11 mm thick) with a boron implanted contact and an amorphous Ge contact was prepared. A 128-strip structure on an area of 32 mmtimes56 mm with a pitch of 250 mum on the front contact (implanted) and a 48-strip structure with a pitch of 1167 mum on the rear contact (amorphous Ge) are realized with the help of plasma etching. The detector is mounted in a cryostat which will enable any orientation of the detector with respect to a photon source. The results of laboratory tests and planned applications at the ESR storage ring in Darmstadt are presented [ABSTRACT FROM PUBLISHER]

Some applications of gated x-ray imagers, pulsed x-ray spectroscopy, for example, benefit if image capture is simultaneous and gain is uniform over the frame. Simultaneity and uniformity are both improved when the voltage gate pulse propagation distance is as short as practical across the micro-channel-plate. This article describes a micro-channel-plate intensifier that captures a 40×100 mm2 image in <300 ps. A simple transmission line loss model is proposed to explain voltage loss across the micro-channel-plate. The voltage loss exponent was measured to be 0.05/cm±20%, and used to predict spatial and temporal gain dependence. The spatial and temporal gain profile was measured in detail by capturing images of ∼1 ps x-ray bursts created with a short pulse laser. The measured profile is consistent with that predicted using the loss model. [ABSTRACT FROM AUTHOR]

‘Long’ γ-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which give rise to highly relativistic jets. Inhomogeneities in the expanding flow result in internal shock waves that are believed to produce the γ-rays we see. As the jet travels further outward into the surrounding circumstellar medium, ‘external’ shocks create the afterglow emission seen in the X-ray, optical and radio bands. Here we report observations of the early phases of the X-ray emission of five GRBs. Their X-ray light curves are characterised by a surprisingly rapid fall-off for the first few hundred seconds, followed by a less rapid decline lasting several hours. This steep decline, together with detailed spectral properties of two particular bursts, shows that violent shock interactions take place in the early jet outflows. [ABSTRACT FROM AUTHOR]

It is analytically shown that X-ray Bragg reflections from periodical multilayer structures can be used for the excitation of guided modes. The X-ray guided modes in (i) a guiding film embedded in a periodical multilayer and (ii) an air gap between two space-separated multilayers have been considered. In the former case, analytical expressions have been obtained which describe a resonant X-ray intensity enhancement taking place inside the guiding film under the guided mode excitation. Optimal parameters of the waveguide have been found, which are needed to achieve a maximum intensity gain. In the latter case, eigen guided modes arising in the air gap have been determined. Properties of the eigen modes have been studied. [ABSTRACT FROM AUTHOR]

Abstract: The X-ray spectra produced by K-shell ionization in collisions of Li-like (U89+) uranium ions at an energy of 397MeV/u with gaseous N2 target have been measured. The very high level selectivity during such collision has been found. The effect allows us to measure undistorted two-photon energy distribution from a decay of the 1s2s1S0 state in He-like uranium. [Copyright &y& Elsevier]

The formation of a volume discharge in an open gas diode with coaxial electrodes was accompanied by hard X-ray emission. The conditions of supershort avalanche electron beam formation are retained at a pulse repetition rate up to 1.5 kHz. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

Many inorganic species are now recognized as being essential for life, including many forms of sulfur, phosphate and numerous classes of metal ions. For example, recent progress in the fields of biochemistry and biology has pointed out the critical importance of sulfur in the biosynthesis of vital cofactors and active sites in proteins, and in the complex reaction mechanisms often involved. Special attention has also been drawn to the diverse roles of alkaline (Na+, K+) and alkaline earth (Mg2+, Ca2+) metal ions in mediating the activity of RNA, proteins and many processes in living cells. While the general effect of these ions in biology is mostly understood, information on their detailed role is deficient. Here the application of softer X-ray absorption spectroscopy (XAS) to probe the local structural and electronic environment of such ions within their biological complexes and during physiological reactions is discussed. In addition, the required experimental set-up and the difficulties associated with conducting softer XAS experiments on biological samples are presented. [ABSTRACT FROM AUTHOR]

Abstract: Narrow X-ray lines from helium-like argon emitted from a dedicated ECR source have been used to determine the response function of a Bragg crystal spectrometer equipped with large area spherically bent silicon (111) or quartz crystals. The measured spectra are compared with simulated ones created by a ray-tracing code based on the expected theoretical crystal''s rocking curve and the geometry of the experimental set-up. [Copyright &y& Elsevier]

High-velocity outflows from active galactic nuclei are a well-known phenomenon in terms of the broad absorption lines seen in the ultraviolet/optical. More recently, similar, possibly related, outflows have been reported in the X-ray. The most extreme example is seen in the nearby, luminous QSO PDS 456, which displays a massive, high-velocity (50 000 km s−1), high-ionization X-ray outflow of . Here we present the ultraviolet spectrum of PDS 456 as observed by the Hubble Space Telescope. We find that the ultraviolet spectrum is also extreme, displaying very broad emission lines, with C ivλ1549 blueshifted by 5000 km s−1 and a broad Lyα absorption trough blueshifted by 14 000–24 000 km s−1. No strong, broad high-ionization absorption features are seen. We interpret the combined ultraviolet and X-ray spectrum of PDS 456 as the signature of a decelerating, cooling outflow, which may be driven by radiation and/or magnetic field. This outflow may be the source of some of the broad emission- and absorption-line gas. [ABSTRACT FROM AUTHOR]

A high pressure/high temperature cell dedicated to x-ray absorption spectroscopy, small angle x-ray scattering, and inelastic x-ray scattering techniques is presented. The P and T parameters are controlled independently and their range allow the study of aqueous solutions (T<=500 °C and P<=2000 bar) and liquid metals and glasses (T<=1700 °C and P<=2000 bar). The autoclave technology is inspired from previous high pressure/high temperature equipments but great improvements are achieved. Original high pressure windows have been developed to ensure both pressure resistance and low absorbance combined with large angular aperture. Different configurations are available for the internal cell that contains the sample whether it is aqueous or not. As an example of the efficiency of the set-up, we present preliminary x-ray absorption results on 0.01 m FeCl3 aqueous solutions from ambient to supercritical conditions (375 °C and 300 bar). These low concentrations samples and low energy spectra (Fe K-edge is at 7112 eV) represent challenging experimental conditions. [ABSTRACT FROM AUTHOR]