Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions. The strategy explored here is to leverage the network of fiber optic seafloor telecom cables already in place and that criss-cross the oceans. This is made possible by the metrological approach called Distributed Acoustic Sensing (DAS) which analyze the properties of the light back-propagated to infer strain variations of the fiber. I will present results of measurements performed on the 41.5 km-long MEUST-NUMerEnv telecom cable deployed offshore Toulon, France. Our observations demonstrate the capability of the approach to turn the cable into a dense network of seismo-acoustic sensors; here we recorded at 2kHz over more than 6500 sensors. With these sensors we can monitor with unprecedented details the ocean-solid earth interactions from the coast to the abyssal plain, the propagation of waves generated by regional micro-earthquakes or simply track passing boats. The ability of DAS to provide a dense sampling of the seismo-acoustic wavefield over large distances is unique and paves the way to many more applications and new discoveries.
Anthony Sladen: https://asladen.github.io
In the Standard Model, Yukawa-like interactions are short-range interactions between the fermions and the Higgs boson. Even though these interactions have important macroscopic consequences, only a subset of them could be observed directly and their origin remains unclear. At the LHC, the top and the b-quark are very sensitive probes for particles with Yukawa-like interactions, due to their large mass. This includes Higgs bosons, but also new scalar particles predicted by theories beyond the standard model and connected to the dark sector. By virtue of the t→bW branching ratio being close to 100%, both b- and top quarks are inferred by the presence of hadronic jets initiated by b-quarks, called b-jets, in the final state. I will introduce b-jet identification at the LHC and demonstrate its crucial role to study the coupling of the Higgs boson to third-generation fermions and probe the dark sector. I will highlight the importance of b-jet identification for the future steps of the LHC physics program and discuss the main experimental challenges.
5 last Seminars
Ce séminaire présentera le Centre de Calcul de l’IN2P3 et les services informatiques qu’il propose aux personnels IN2P3. Après un aperçu des missions fondamentales du Centre de Calcul et du rôle qu'il joue aujourd'hui aux niveaux national et international, nous décrirons plus précisément son offre de service. Cette offre répondant aux besoins scientifiques quotidiens de stocker des données, les traiter, partager la connaissance, travailler en collaboration etc., ce séminaire s'adresse à tous les acteurs de la recherche de votre unité. Nous terminerons la présentation par une session de discussion avec laquelle nous pourrons aller plus en profondeur sur certains aspects et recenser vos besoins.
The study of the de-excitation of 8Be through the emission of e+e- pairs found an anomaly in the angular correlation spectrum of the electrons [Phys. Rev. Lett. 116, 052501 (2016)]. One that can possibly be explained by the existence of a yet unknown (bosonic) particle. A new measurement, with a re-built experimental setup, studying the angular correlation of e+e- pairs coming from the de-excitation of 4He provided a similar anomaly [arXiv:1910.10459 (nucl-ex)]. One that may be explained by the existence of the same mXc2 = 16.84 ± 0.16 (stat) ± 0.20 (syst) (X17) particle. The talk will review the experiments performed at the Institute for Nuclear Research (Atomki, http://www.atomki.hu/en/), describe the data analysis, and discuss the possible interpretations of the results.
. TWEPP 2019, ASICS (M. Menouni)
Next few decades will be extremely exciting in Astronomy. New telescopes will enter in operation on Earth and in space; at the same time a new generation of Gravitational Wave detectors will be so powerful that they will detect the merging of black-holes binaries in the whole visible universe, up to a redshift of one hundred. Studying high energy events with a true Multi-Messenger Astronomy will give us a fantastic opportunity to discover new objects and new physics.
After a short introduction on the science case for a new generation of GW detectors, the presentation will be focused on the many challenges that scientists need to face to reduce the internal noise of the interferometers by a factor 10 with respect the current generation of instruments. Both the collaborations of Virgo and LIGO have prepared conceptual design and design studies that are attracting new scientists every day.
In Europe a collaboration has started to be formed around the project called Einstein Telescope. Details will be given on this observatory made of several interferometers working at cryogenic as well as at room temperatures. The CNRS is already involved in the whole field of GW but many scientists in France can find opportunities in this new field, applying their expertise on the detector development as well as on data analysis or astrophysics.