Francois Leblanc

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Iodine-131 and various other radionuclides were released into the atmosphere from the damaged Japanese reactors of Fukushima Dai-ichi from 12 to 22 March 2011. The contaminated air mass was detected in France after 24 March; samples of grass, vegetables, and milk have been analyzed for (131)I by the IRSN, considering the fact that few values of iodine-131(More)
Hyperboloid is a multi-directional mass spectrometer measuring ion distribution functions in the auroral and polar magnetosphere of the Earth in the thermal and suprathermal energy range. The instrument encompasses two analyzers containing a total of 26 entrance windows, and viewing in two almost mutually perpendicular half-planes. The nominal angular(More)
Global and three-dimensional hybrid simulations of the ionized environment of Mercury are used to investigate the effect of the quadrupolar component of the intrinsic planetary field on magnetic reconnection with the Interplanetary Magnetic Field (IMF), on the entry of solar wind ions in the Hermean magnetosphere and eventually their impacts on the(More)
We have designed and fabricated a new type of field electron source for a novel onboard mass spectrometer. The new electron source, which is a field effect emitter in a triode configuration, consists of a CNT-column array cathode and an extraction gate with holes that are aligned concentrically with respect to the cylindrical CNT columns. In triode mode(More)
The observed slow rotation and abundance peculiarities of certain blue horizontal branch (BHB) stars suggests that atomic diffusion can be important in their stellar atmospheres and can lead to vertical abundance stratification of chemical species in the atmosphere. To verify this hypothesis, we have undertaken an abundance stratification analysis in the(More)
Context. It is commonly believed that the observed overabundances of many chemical species relative to the expected cluster metallicity in blue horizontal branch (BHB) stars appear as a result of atomic diffusion in the photosphere. The slow rotation of BHB stars (with T eff > 11,500K), typically v sin i < 10 km s −1 , is consistent with this idea. Aims. In(More)
Context. The observed abundance peculiarities of many chemical species relative to the expected cluster metallicity in blue horizontal-branch (BHB) stars presumably appear as a result of atomic diffusion in the photosphere. The slow rotation (typically v sin i < 10 km s) of BHB stars with effective temperatures Teff > 11,500 K supports this idea since the(More)
Context. Atomic diffusion is believed to cause the abundance anomalies observed in AmFm stars. However, the detailed process has still not been well-established. For instance, two possible scenarios for the diffusion theory are presently envisaged. They differ mainly by the depth from which the abundance anomalies emanate. The first scenario predicts that(More)