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Le réacteur Orphée.

Les neutrons permettent de sonder la matière et leur sensibilité aux éléments légers et au magnétisme en font une sonde unique et originale. A l'IRAMIS , l’utilisation de la spectrométrie neutronique dans divers domaines de la recherche fondamentale et appliquée est développée au Laboratoire mixte CEA-CNRS Léon Brillouin à Saclay. L'activité scientifique propre du laboratoire peut se regrouper en trois secteurs sensiblement d'égale importance: la physico-chimie, les études structurales et de transition de phases, le magnétisme et la supraconductivité.



Neutron diffusion make possible to probe the matter and its sensitivity to the light elements and to magnetism make it a single and original probe. Within IRAMIS, neutron spectrometry is used in various fields in fundamental and applied research and is developed at the CEA-CNRS Laboratory Leon Brillouin (LLB) in Saclay. Neutrons are mainly intended for the study of condensed matter. The scientific activity of the laboratory belongs to three sectors of equal importance: physicochemistry, structural studies and phase transitions, magnetism and supraconductivity.



The Orphée reactor.

#110 - Last update : 06/28 2020
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  DREAM: A versatile powder diffractometer with single crystal capabilities   Brief description DREAM is a time-of-flight diffractometer that is mainly dedicated to powder diffraction, but also offers single crystal capabilities.
Eros a versatile reflectometer
Reflectivity experiments have been performed on the Eros reflectometer at Saclay on very small pieces of glass. During this measurement, we did demonstrate our ability to obtain reflectivity curves down to values of 10-5 within a few hours. The curve obtain in this measurement is given on the first picture in red. The calculated Fresnel curve is represented in blue.
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden) This is the Bifrost web page
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden) This is the Cspec web page
LLB is engaged in the upgrade of IN6 through a CRG contract of type A. This upgrade will be performed during the 2019 shutdown of ILL, but LLB is already in charge of the IN6 spectrometer. The IN6-Sharp LLB team will welcome users as soon as the ILL reactor restarts (March 1st 2018). Details of the upgrade could be find in the following pdf file : Sharp_lancement fédération 16 mai_2017-V2.pdf
LLB is engaged at various levels in the construction of five spectrometers around ESS (European Spallation Source in Sweden) This is the Skadi web page : presentation of the project.
TiNi alloy is polymorphic. It exhibits a martensitic transition near room temperature between a cubic CsCl-type (austenite) and a monoclinic TiNi-type (martensite) structure. This transformation is at the origin of its shape memory effect. In addition, TiNi has good hydrogen storage properties under normal conditions of pressure and temperature. In austenic form, TiNi absorbs 1.4 H/f.u. under atmospheric pressure.
The improvement of the mechanical properties of polymer films by inclusion of mineral particles is a well known industrial practice used since the end of the XIX century. A classical example is the rubber industry for which the addition of carbon black as fillers permits to increase the elastic modulus of the pneumatics. Nevertheless, the mechanisms which govern the reinforcement properties are still not completely described by experiments and theory.
I.V. Golosovsky1, I. Mirebeau2, G. André2, D. A. Kurdyukov3, Yu. A. Kumzerov3,
1: St. Petersburg Nuclear Physics Institute, 188350, Gatchina, St. Petersburg, Russia 2: Laboratoire Léon Brillouin, CE-Saclay, F-91191, Gif-sur-Yvette, France 3: A. F. Ioffe Physico-Technical Institute, 194021, St. Petersburg, Russia 4: Rostov State University, 344090, Rostov/Don, Russia The properties of magnetics confined in nanometer scale cavities drastically differ from those in the bulk material.
The strongly interacting conduction electrons can be accurately represented as a gas of weakly interacting electron-like excitations. This description, known as Fermi liquid theory, works for many metallic systems. However, over the past two decades, new types of metallic materials with strongly correlated electrons have been discovered that do not fit this standard description. The list includes the superconducting copper oxides and many other materials. More...
Hidden degrees of freedom in aperiodic crystals.
Following the synthesis by the ribosome, to carry out its biological function, a protein much fold into a single, well defined conformational state: the native state. Protein folding is thus the physico-chemical process by which a polypeptidic chain undergoes a structural change from an ensemble of coil like structure up to the unique structure encoded in its amino-acid sequence. This process is fascinating and remains one of the most challenging problems of structural biology.
This study investigates the long term behavior of glasses used for confinement of nuclear wastes. The results have been obtained from a fruitful collaboration between different CEA laboratories (LLB, LIONS, CEA Marcoule) and the Ecole Polytechnique. The corrosion process of the glasses by water creates at the glass surfaces, an alteration porous layer, hydrated and amorphous, called "gel".
In 1893 Sir William Armstrong reported a remarkable experiment: if a high voltage is established between two wine-glasses filled to the brim with pure water and connected by a cotton  thread, a rope of water is formed and remains suspended between the lips of the two glasses. This "water bridge" can subsist for a few seconds even once the thread has been removed [1].
  In the pyrochlore compounds R2Mo2O7, both rare earth R3+ and M4+ transition metal ions form a threedimensional network of corner sharing tetrahedra. The pyrochlore lattice is geometrically frustrated both for antiferromagnetic (AF) and ferromagnetic (F) nearestneighbour exchange interactions, leading to intriguing magnetic states such as spin liquids, spin ices or chemically ordered spin glasses.
The use of agricultural resources for industrial purposes will undoubtly be one of the major challenges of the 21 st century. Organic biosynthons used in chemistry should progressively replace those coming from fossil fuels. Our work on dispersions of fatty acids and hydroxylated derivatives forms part of these efforts in that it seeks to demonstrate the potential contribution of fatty acids (which may be extracted from plants) as a new class of surface active agents.
This work is part of a theoretical project which aims to unravel the mechanism at work in the high temperature cuprate superconductors. In the recent article [1] we have studied the role of spin fluctuations, and namely of the collective spin mode, for the superconducting pairing and numerous electronic anomalies observed in cuprates.
Le magnétisme est un domaine d’intérêt majeur, car combiné à l’électronique, il a modifié en profondeur notre vie quotidienne : sous forme de capteurs, d’actionneurs, de dispositifs nomades (téléphones, tablettes, ordinateurs portables), de matériaux aux capacités de stockage accrues pour l'enregistrement magnétique de toutes nos données informatiques., etc...
The pseudogap region of the phase diagram is an important unsolved puzzle in the field of hightransition-temperature (Tc) superconductivity, characterized by anomalous physical properties below a certain temperature, T*[1]. In contrast to the superconducting temperature Tc which exhibits a dome-like shape, the pseudogap phase is observed only at low doping in the underdoped region of the cuprates phase diagram.


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