[en] We report on the study of a magnetic dislocation in pure chromium. Coherent X-ray diffraction profiles obtained on the incommensurate Spin Density Wave (SDW) reflection are consistent with the presence of a dislocation of the magnetic order, embedded at a few micrometers from the surface of the sample. Beyond the specific case of magnetic dislocations in chromium, this work may open up a new method for the study of magnetic defects embedded in the bulk.

[en] As the production of electricity by concentration solar power (CSP) installations is said to be a source of energy for the future, the author discusses past experiments (notably the French Thermis project), and the different techniques which are currently being used. He indicates the regions which appear to be the most appropriate for this technique. He presents the three main techniques: parabolic cylinder, tower, and Stirling cycle installations. He discusses the issue of intermittency. He proposes an assessment of prices and of their evolution, and indicates the investments made in different installations (in Italy, Spain, Germany and Portugal). He comments the case of hybrid installations (sun and gas), evokes the Desertec project proposed by the German industry which comprises a set of hybrid installations. He notices that there is no significant technological evolution for this process

[en] The author shows the needs of the sea water desalination for the dry countries. The main technique is the reverse osmosis. It requires electricity and its development needs big electric power plants. For economical and ecological reasons, the nuclear energy seems well appropriate. Libya is for instance very interested in this technique, because of their water shortage problem. (A.L.B.)

[en] Coherent X-ray-scattering measurements were performed in the type-I antiferromagnetic phase of UAs at the M_IV uranium absorption edge. Speckle patterns from a magnetic reflection were followed up through the magnetic transition. The origin of the speckles is discussed in terms of antiferromagnetic domain configuration and fluctuations

[en] Short communication. 1 ref

No abstract available

[en] The precipitation structure in a model nickel-based superalloy was examined by using anomalous X-ray small-angle scattering. Preliminary results are presented on the temporal power law of the precipitation growth and the partitioning of the solute atoms between the precipitates and the matrix. In the present experiment, the concentration of nickel was the same in the matrix and the precipitates, giving no contrast change near the nickel K edge. (orig.)

[en] The microstructure of the 2091 alloy (Al-Li-Cu-Mg-Zr) has been studied and compared to that of two simpler Al-Li and Al-Cu-Mg alloys. The SAXS, in situ SAXS, and TEM techniques have been used for heat treatments at room temperature and at 150 C. The time evolution of the size and of the volume fraction of the delta-prime precipitates and of the Cu-rich GPB zones have been determined. The delta-prime precipitates are shown to follow a classical Lifschitz-Slyosov-Wagner law. Their interfacial energy has been estimated. S and S-prime precipitates have also been characterized on grain boundaries and on helical dislocations, respectively, by TEM. 16 refs

[en] The use of charge-coupled devices (CCDs) under direct illumination of X-rays for two-dimensional position-sensitive detectors in high-resolution diffraction experiments is discussed. Two detectors are compared: a standard CCD and a 'deep depletion' CCD. These give position resolution close to the pixel size (∼22 μm), and energy resolution close to the theoretical resolution of a Si detector. These detectors can be used for photon-counting and an algorithm for electronic noise suppression is presented. This algorithm is useful for experiments with frequent readouts and low intensity. Examples demonstrating the advantages of this algorithm for diffraction experiments are given

[en] Small-angle coherent X-ray scattering measurements on a polymer gel and on a single crystal of Al-9at.% Li are reported. Speckle structures were recorded using a direct-illumination CCD camera. A speckle intensity fluctuation of ∝20% was observed. Time and space statistics for the signal provided estimates of the coherence effects and the measurements demonstrate the wavevector dependence of the coherence effects. Preliminary intensity-fluctuation spectroscopy was performed for Al-Li. (orig.)