SESAME, un laboratoire d’excellence multidisciplinaire au service des scientifiques du Moyen-Orient

Le 16 mai 2017, le centre de rayonnement synchrotron de troisième génération SESAME a été officiellement inauguré par le roi Abdallah II de Jordanie sur le site d’Allan, au nord d’Amman. C’est l’aboutissement de deux décennies d’une collaboration internationale ayant pour objectif de créer un centre de recherche scientifique interdisciplinaire ouvert à tous les pays de la région. Cette inauguration marque le début d’une ère nouvelle pour la recherche scientifique, le développement technologique, l’éducation et la coopération au Moyen-Orient. Nous proposons de retracer ici la genèse et l’état actuel de ce projet créé, à l’image du CERN, sous les auspices de l’UNESCO

Horizontal Emittance Reduction on a Synchrotron Radiation Light Source with a Robinson Wiggler

The performance of synchrotron light facilities are strongly influenced by the photon beam bright- ness, that can be further increased by reducing the beam emittance. A Robinson Wiggler can be installed in a non-zero dispersion straight section to reduce the horizontal beam emittance. It is composed of an array of magnets of alternated polarities, whose both magnetic field and gradient are of opposite signs. It provides a compact solution to reduce by 50% the horizontal emittance. How- ever, it increases the energy spread by 40%. The concept of the Robinson Wiggler (RW) is described here, the first experimental observation of the Robinson effect in a synchrotron light source on the transverse and longitudinal beam properties by the means of four existing undulators is presented and the impact on the photon flux density is studied

Le rayonnement synchrotron, une source de lumière dédiée à la recherche

Les électrons relativistes qui circulent dans les accélérateurs de particules produisent un rayonnement intense. Ce rayonnement synchrotron couvre un domaine en énergie allant des ondes millimétriques aux rayons X durs avec une brillance exceptionnelle, des polarisations linéaires ou circulaires, et une structure temporelle exploitable. En France, deux centres de ce type sont enfonctionnement [1] : l'Éuropean Synchrotron Radiation Facility (ESRF), situé à Grenoble, et SOLEIL(a

Study of Higher-Order Achromat Lattice as an Alternative Option for the SOLEIL Storage Ring Upgrade

International audienceA ring composed of 20 symmetrical 7BA cells in which of a pair of chromaticity correcting sextupoles placed around horizontal dispersion bumps à la ESRF-EBS was developed as a baseline lattice for the SOLEIL storage ring upgrade (presented at IPAC2018). The strict phase relation between the two dispersion bumps provides an efficient way of optimizing the (on-momentum) nonlinear optics with a limited number of sextupoles. As an alternative, a scheme known as Higher-Order Achromat (HOA) develops a MBA (Multi-Bend Achromat) lattice where chromaticity correcting sextupoles are distributed in each M unit cell with a strict phase relation cell-wise such as to cancel basic geometric and chromatic resonance driving terms. The beam dynamics in a 20-fold 7BA HOA ring is compared with those of the baseline lattice, with focus on off-momentum properties such as Touschek lifetime, which are important for medium energy rings like SOLEIL. The robustness against errors, the reduction of the ring symmetry by introducing 4 longer straight sections, as well as a horizontal dispersion bump to cope with longitudinal on-axis injection scheme are also presented

Baseline Lattice for the Upgrade of SOLEIL

International audiencePrevious MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV

TDR Baseline Lattice for the Upgrade of SOLEIL

International audiencePrevious CDR studies for the SOLEIL Upgrade project have converged towards a lattice alternating 7BA and 4BA HOA type cells providing a low natural horizontal emittance value in the 80 pm.rad range at an energy of 2.75 GeV. This lattice adapts to the current tunnel geometry as well as to preserve as much as possible the present beamline positions. The TDR lattice is an evolution of the CDR one including longer short straight sections, better relative magnet positioning, and the replacement quadrupole triplets by quadruplets for improving flexibility of optics matching in straight section. The SOLEIL upgrade TDR lattice is then composed of 20 HOA cells with a two-fold symmetry, and provides 20 straight sections having four different lengths of 3.0, 4.2, 8.0, and 8.2 m. This paper reports the linear and the non-linear beam dynamic optimization based on intense MOGA investigations, mainly to improve the energy acceptance required to keep a large enough Touschek beam lifetime. Some future directions for performance improvement are discussed

Contribution a l'etude d'un selecteur de charge pour le nouvel accelerateur Vivitron

SIGLECNRS RP 195 (52) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc