Using the SDvision 3D visualization software developed within the framework of IDL Object Graphics at CEA/IRFU, we have visualized the travel of charged particles in the IFMIFEVEDA accelerator. Simulations visualized here were made for a beam composed of 1 million macroparticles. To ensure that beam losses do not exceed 1W/m in the high energy part, simulations with 4,000,000,000 particles were performed, which lasted several weeks using fifty processors in parallel. Stereoscopic video sequences in 3D were achieved at IRFU and a 15-minute movie has been realized for outreach purposes. Keyword : visualization, numerical simulations, accelerator.

This paper describes the content of the movie "Computing the Universe", produced in August 2011 at IRFU, presenting to the general public the results of the numerical simulations in astrophysics produced by the COAST team.

The new generation of massively parallel mainframes enabled computational physics to make a quantum leap in complexity and size of numerical simulations, especially in the domain of astrophysics. The COAST project at CEA/IRFU at Saclay, started in 2005, involves astrophysicists and software engineers developing simulation codes in magneto-hydrodynamics and generic tools for data structuration and visualization. A dedicated software for visualizing the massive amounts of data produced by these simulation codes has been developed, the SDvision code, deployed in the framework of IDL Object Graphics. This code is suitable for interactive and immersive navigation for the analysis of 3D results and also for videos and stereoscopic movies productions for people at large.In this paper, we present the capabilities of the code SDvision and some applications in the domain of astrophysics simulations but also in the domain of fusion plasmas studies. In particular, two challenging simulations have been performed in the framework of the 'Grands Defis GENCI/CINES' on recent supercomputer Jade in CINES in 2010 and we present the visualization studies for such huge computation results.

Received 25 December 2007DOI:https://doi.org/10.1103/PhysRevLett.100.049902©2008 American Physical Society

The ability to interactively visualize the complex products of three-dimensional simulations is a key aspect in the validation and verification process of numerical algorithms and frameworks. Computational astrophysics, which benefits from the rapidly increasing computing resources offered by the use of massively parallel mainframes, is a challenging playground to scientific visualization. In this paper, we describe a graphical package developed in the framework of IDL Object Graphics. The requirements governing its design are defined in the context of the COAST software project which aims at providing an ensemble of enabling tools and techniques for the development and the validation of major simulation codes. This covers a wide range of applications, including cosmological formation of large-scale structures, turbulences in the interstellar medium, stellar magnetohydrodynamics, and formation of proto-planetary systems. The use of IDL Object Graphics provides an interactive and immersive visualization of complex scenes where various fields of different nature are entangled. Three-dimensional scalar and vector fields distributed over regular mesh grids or more complex structures such as Adaptive Mesh Refinement data, as well as N-body systems, can be visualized in a number of different, complementary ways.

Simulations conducted on high-performance, massively parallel mainframes have become a central tool in the study of astrophysical plasmas. Two parallelized codes, HERACLES and RAMSES, respectively dedicated to the simulation of the interstellar medium dynamics and the formation of cosmological structures, are described. Their algorithms implement a precise modelling of fundamental physical processes, including hydrodynamics, radiative transfer, gravitation, transport, turbulence, and diffusion. These algorithms are developed in Fortran 90 and parallelized with MPI. The RAMSES code benefits from the implementation of the AMR Adaptive Mesh Refinement technique, while the HERACLES code in its current implementation uses fixed, multi-geometrical grids. The technical software aspects of data handling and visualization are discussed. Data management is realized through the use of the HDF5 hierarchical data file format. A graphical interface, developed in the framework of IDL object programming, is presented. This application is optimized to provide interactive, three-dimensional representations of large data sets. Visualization of scalar and vector fields, as well as particles clouds, is obtained for AMR and cartesian grid geometries. Finally, prospects such as the introduction of a multigrid approach to overcome spatial resolution limitations, are presented. Application to other fields are discussed.

We present a measurement of the Zgamma production cross section and limits on anomalous ZZgamma and Zgammagamma couplings for form-factor scales of lambda = 750 and 1000 GeV. The measurement is based on 138 (152) candidates in the eegamma (mumugamma) final state using 320(290) pb(-1) of pp(-1) collisions at square root of s = 1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are /h(10,30)Z/ < 0.23, /h(20,40)Z/ < 0.020, /h(10,30)gamma/ < 0.23, and /h(20,40)gamma/ < 0.019 for lambda = 1000 GeV.

We present a measurement of the cross section for $Z$ production times the branching fraction to $\tau$ leptons, $\sigma \cdot$Br$(Z\to \tau^+ \tau^-)$, in $p \bar p$ collisions at $\sqrt{s}=$1.96 TeV in the channel in which one $\tau$ decays into $\mu \nu_{\mu} \nu_{\tau}$, and the other into $\rm {hadrons} + \nu_{\tau}$ or $e \nu_e \nu_{\tau}$. The data sample corresponds to an integrated luminosity of 226 pb$^{-1}$ collected with the D{\O}detector at the Fermilab Tevatron collider. The final sample contains 2008 candidate events with an estimated background of 55%. From this we obtain $\sigma \cdot$Br$(Z \to \tau^+ \tau^-)=237 \pm 15$(stat)$\pm 18$(sys)$ \pm 15$(lum) pb, in agreement with the standard model prediction.

We present a search for Wbb production in pp collisions at sqrt[s]=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb(-1) of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wbb production of 6.6 pb for b quarks with transverse momenta p(b)(T)>20 GeV and bb separation in pseudorapidity-azimuth space DeltaR(bb)>0.75. Restricting the search to optimized bb mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV.