MATISSE, perspective of imaging in the mid-infrared at the VLTI

International audienceMATISSE is foreseen as a mid-infrared spectro-interferometer combining the beams of up to four UTs/ATs of the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory. The related science case study demonstrates the enormous capability of a new generation mid-infrared beam combiner. MATISSE will constitute an evolution of the two-beam interferometric instrument MIDI. MIDI is a very successful instrument which offers a perfect combination of spectral and angular resolution. New characteristics present in MATISSE will give access to the mapping and the distribution of the material (typically dust) in the circumstellar environments by using a wide mid-infrared band coverage extended to L, M and N spectral bands. The four beam combination of MATISSE provides an efficient UV-coverage : 6 visibility points are measured in one set and 4 closure phase relations which can provide aperture synthesis images in the mid-infrared spectral regime

MATISSE, the VLTI mid-infrared imaging spectro-interferometer

GalaxiesStars and planetary systemsInstrumentatio

IRAN - Interferometric remapped array nulling

European symposium on astronomical telescopes, SPIE 5491, p. 86 (2004)International audienc

Modifications of structural and physical properties induced by swift heavy ions in Gd2Ti2O7 and Y2Ti2O7 pyrochlores

International audienceThe structural transformations induced by ionization processes in Gd2Ti2O7 and Y2Ti2O7 pyrochlores irradiated with swift heavy ions have been studied using XRD and Raman experiments. Results show that irradiation induces amorphization and that the phase transformation build-up can be accounted for in the framework of a model involving a single-impact mechanism. The radiation induced amorphization build-up is faster in Gd2Ti2O7 than in Y2Ti2O7. Moreover, a decrease of the thermal conductivity (measured by the laser flash method) is induced by irradiation both in Gd2Ti2O7 and Y2Ti2O7

Dynamical and ozone measurements by constant volume balloons in the low troposphere during ESCOMPTE experiment

The objectives of the ESCOMPTE program concern the study of emission of the primary pollutants in industrial and urban areas, their transport and their diffusion in the atmosphere. This experiment, realized in the southeast of France on a 120km*120km, can be used to validate and to improve chemical transport numerical models. One major aim of this experiment is to follow the pollutant plume, and to investigate its thermodynamical and chemical time evolution. This is realized with constant volume balloons (CVB), operated by the Centre National d'Etudes Spatiales (CNES) and instrumented by the Laboratoire d'Aérologie (LA) and Météo France. The CVBs, located by GPS and equipped with thermodynamical and ozone sensors, fly at a constant density level in the atmospheric boundary layer. These CVBs constitute a way to validate the high resolution trajectories against in situ measurements. During the ESCOMPTE campaign which took place in June and July 2001, thirty-three CVB flights were made, fifteen of them with ozone measurements. We present (i) the experimental system including CVB, radiosonde and balloon tracking stations, (ii) the first results of the different flights, in particular the time evolution of the ozone along the CVB trajectories

IRAN: Interferometric Remapped Array Nulling

IRAN is a method of beam-combination in the hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. We propose to observe the interferometric image in the pupil plane, performing multi-axial pupil plane interferometry. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. The image is concentrated into the limited support of the output pupil of the individual telescopes, in which the object-image convolution relation is conserved. Specific deconvolution algorithms have been developped for IRAN hypertelescope imagery, based upon Lucy-like iterative techniques. We show that the classical (image plane) and IRAN (pupil plane) hypertelescope imaging techniques are equivalent if one uses optical fibers for beam transportation. An application to the VLT/VIDA concept is presented

Demande d'Observation, Extra-solar planets with the VLTI in the mid-infrared - First attempt of direct detection with MIDI-Perspective in L and N band with MATISSE, VLTI ESO

n/a, pages (2006

X-ray absorption spectroscopy investigations on radioactive matter using MARS beamline at SOLEIL synchrotron

International audienceThe MARS beamline at the SOLEIL synchrotron is dedicated to the characterization of radioactive material samples. One great advantage of the beamline is the possibility to characterize about 380 radionuclides by different X-ray techniques in the same place. This facility is unique in Europe. A wide energy range from around 3.5 keV to 36 keV K-edges from K to Cs, and L3 edges from Cd to Am and beyond can be used. The MARS beamline is optimized for X-ray absorption spectroscopy techniques (XANES/EXAFS), powder diffraction (XRD) but x-ray fluorescence (XRF) analysis, High Energy Resolution Fluorescence Detected -XAS (HERFD-XAS), X-ray Emission (XES) and μ-XAS/XRD are also possible. A description of the beamline as well as its performances are given in a first part. Then some scientific examples of XAS studies from users are presented which cover a wide variety of topics in radiochemistry and nuclear materials

Key role of the short-range order on the response of the titanate pyrochlore Y 2 T i 2 O 7 to irradiation

International audienc