Laboratoire Léon Brillouin

UMR12 CEA-CNRS, Bât. 563 CEA Saclay

91191 Gif sur Yvette Cedex, France

+33-169085241 llb-sec@cea.fr

BD diffusons les neutrons

CRG SHARP: contract signed between LLB and ILL !  
Following the agreement to strengthen the Franco-Swedish cooperation in the field of neutron scattering, the Laboratoire Léon Brillouin (LLB) is involved in the construction of an inelastic time-of-flight spectrometer. After the announcement of the Orphée reactor shutdown in 2020, the project originally planned at Saclay could be transferred to the Laue Langevin Institute (ILL). This renaissance takes the form of an A type CRG contract concluded on September 29th 2017 between the DRF of the CEA, the INP of the CNRS, and the ILL.
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Signature of the contract on 29/10/17 at the ILL
From left to right : Alain Schuhl CNRS/INP,
Maria Faury CEA/DRF, Helmut Schober director ILL,
Alexandre Durand ILL
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3D drawing of the SHARP instrument

The new project SHARP (Spectromètre Hybride Alpes Région Parisienne) consists of a complete rebuilding of the IN6 secondary spectrometer: sample environment, time-of-flight chamber and detection. The work will last one year and is scheduled to coincide with the ILL's 2019 long shutdown. The spectrometer will be equipped with 240 PSD (Position Sensitive Detector) detectors under 5 bars of 3He. Beyond the gain of a factor four in detection coverage solid angle, these new detectors will allow a spectacular gain in the definition and mapping of the (Q, w).

Finally, the third improvement will concern the time-of-flight chamber itself. It will now be under vacuum. A removable foil between the sample and the inlet of the chamber will enable to operate either with a sample under vacuum or under a controlled atmosphere. In the first configuration, the vacuum of the chamber also serves as the cryostat isolation vacuum. The number of windows between the sample and the detector will be minimized and offer a very positive gain in background. The second configuration will make it possible the study of samples to be kept under controlled atmosphere or in complex environment (laser or electrical excitation for example).

Endurance program, a longer-term project (starting in 2023) would be to merge the SHARP spectrometers and the ILL RAMSES project at the end of a new doubly elliptical guide (gain of a factor five in incident flux). A bandwidth chopper positioned upstream of a horizontally and vertically focusing monochromator would also allow to combine i) an additional gain of the order of five in brightness and ii) a decrease in background noise of an order of magnitude. Finally, an extended experimental area would make possible a wide take-off range giving access to the entire range of incident wavelengths between 2 and 5.9 Å. This new high brilliance spectrometer would allow studies in extreme conditions (very high pressures) and/ or experiments on samples only available in very small quantities.

For more details, see : http://www-llb.cea.fr/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=2766.

A. Menelle, dépêche du 14/10/2017

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