5 last Seminars
Distributed Computing was the response of the High Energy Physics community to the challenge of managing unprecedently large volumes of data produced by the LHC experiments. The resulting grid computing infrastructure is now largely considered to be one of the pillars of the LHC success. The grid middleware provides common interfaces for accessing computing and storage resources. On top of it, all the LHC experiments developed their solutions for managing complex workflows of computing tasks. DIRAC is the product of the LHCb experiment which is now adopted by multiple other scientific communities for distributed computing. DIRAC services are now also provided by large grid infrastructures such as France-Grilles, GridPP or EGI, the services are available for user communities from various scientific domains. DIRAC provides solutions for both workload and data management on a large scale.
In the seminar, we will introduce distributed computing grid systems and illustrate their architecture and operations based on the example of the DIRAC Interware project. Opportunities offered by the DIRAC services to research communities will be discussed.
The seminar will be followed on Tuesday by a Tutorial session from 9 to 12 at the CPPM library:
The DIRAC Tutorial is devoted to a practical introduction into the use of DIRAC services. The participants will learn how to prepare and submit computational tasks, monitor their execution and retrieve the results. The system algorithms behind the scene will be explained. Participants will also see how to create and store new data files in a distributed computing system and make them available either locally or in remotely executing tasks. The tutorial will use a production DIRAC service which will be accessible even afterwards. The goal is to provide enough information for the participants to consider using distributed computing resources, e.g. European Grid Infrastructure (EGI) DIRAC service, for their practical research work.
Ultralight bosons are compelling dark-matter candidates and arise in a variety of beyond-Standard-Model scenarios. These fields can tap energy and angular momentum from spinning black holes through a process known as "black hole superradiance", during which a macroscopic bosonic condensate develops around the black hole. Striking signatures of this phenomenon that have been studied over the past few years include for example: gaps in the spin-mass distribution of astrophysical black holes, the emission of continuous gravitational-wave signals and signatures in the gravitational waves emitted by binary black holes, opening the exciting possibility to search for extremely light particles using current and future observations of black holes and gravitational waves. In this talk I will give an overview of the status of this research program.
The MICROSCOPE mission allowed for an unprecedented precision on the test of the Weak Equivalence Principle (WEP). The WEP states that all bodies fall at the same rate, independently of their mass and composition, and is the cornerstone of General Relativity (GR). MICROSCOPE’s measurement concept relied on comparing the free fall of two test masses of different compositions as they orbited the Earth.
Beside testing GR’s foundation, it allowed us to shed light on modified gravity models involving the existence of a putative fifth force. For instance, the test of the equivalence principle in the Earth orbit sets constraints on long-range (of order a thousand kilometres and more) fifth force, while the interaction of MICROSCOPE’s test masses with each other provides clues on a shorter (of order 0.1 m) fifth force.
In this talk, I will first present the MICROSCOPE experiment and test of the WEP. I will then discuss how MICROSCOPE could set new constraints on fifth force models such as a Yukawa deviation from Newtonian gravity, a light dilaton and a chameleon field.
2007 : thèse au CEA Saclay, “Les lentilles gravitationnelles faibles vers la cosmologie de haute précision”, sous la direction d’Alexandre Réfrégier
2008 – 2011 : postdoc au JPL et Caltech sur le weak lensing (phénoménologie et analyse de données)
2011 – 2012 : postdoc à l’ETH Zurich sur le weak lensing (analyse de données, simulations, Euclid)
2013 – présent : ingénieur-chercheur à l’ONERA (DPHY -- Département de Physique, Instrumentation, Environnement, Espace). Travail sur MICROSCOPE (segment sol et analyse de données) et concepts de tests de la gravitation dans l’espace.
Because of their weak interactions, neutrinos can traverse matter like no other known particle. These elusive messengers can therefore be turned into a new probe to investigate the structure and composition of the deep Earth.
In this seminar, I will present the different methodological approaches to neutrino tomography, focusing on recent efforts exploiting either the oscillation or the absorption of atmospheric neutrinos in the Earth. I will then describe how these methods can be used and combined to investigate open questions in deep-Earth science.
The advent of a new generation of large-scale atmospheric neutrino detectors such as KM3NeT and IceCube, and in the future HyperKamiokande and even DUNE, might finally bring these ideas into a concrete possibility that can be investigated with real data. The seminar will conclude with a discussion of the expected performances of these detectors for neutrino tomography, while paving the way to a next-generation instrument fully optimised for Earth tomography.
Since summer 2019, the national computing center of the CNRS for high performance computing and artificial intelligence is hosting the supercomputer « Jean Zay ». With more than 1500 scalar CPU nodes and 600 accelerated GPU nodes the peak performance reaches 28 PFLOPs. This equipment is available for research communities, either private or academic, relying on extrem computing. Getting
hours to run on the supercomputer is free at the condition that results are published.
During this talk we will cover the important administrative steps to be able to use the machine then describe the hardware and software environment. You will have all you need to get started on « Jean Zay ».
Myriam Peyrounette: CV