PSPA, une Plateforme de Simulation en Physique des Accélérateurs

InformatiqueInternational audienceLa conception des accélérateurs modernes nécessite la simulation détaillée d’un nombre croissant de phénomènes liés àl’accélération et au transport de particules chargées.Un même phénomène peut être simulé selon différents modèles en utilisant différents algorithmes. La communauté desphysiciens des accélérateurs dispose aujourd’hui d’un ensemble important de logiciels de conception hétérogènes etdifficiles d’accès et il manque un ensemble coordonné de codes de simulation.Le projet de « plateforme » de simulation en physique des accélérateurs [PSPA], fournit l’accès à un ensemble évolutif delogiciels existants permettant de simuler complètement un accélérateur.Cette « plateforme » WEB offre la possibilité de construire interactivement une machine, de définir indépendamment lestraitements physiques à appliquer sur les différentes sections de cette machine, de vérifier la cohérence des logiciels misen oeuvre par l’utilisateur, de lancer l’exécution et d’effectuer une analyse des résultats produits

About the connection between the CℓC_{\ell} power spectrum of the Cosmic Microwave Background and the Γm\Gamma_{m} Fourier spectrum of rings on the sky

In this article we present and study a scaling law of the $m\Gamma_m$ CMB Fourier spectrum on rings which allows us (i) to combine spectra corresponding to different colatitude angles (e.g. several detectors at the focal plane of a telescope), and (ii) to recover the $C_l$ power spectrum once the $\Gamma_m$ coefficients have been measured. This recovery is performed numerically below the 1% level for colatitudes $\Theta> 80^\circ$ degrees. In addition, taking advantage of the smoothness of the $C_l$ and of the $\Gamma_m$, we provide analytical expressions which allow to recover one of the spectrum at the 1% level, the other one being known.Comment: 8 pages, 8 figure

HFI L2 DPC destripping and mapmaking modules

PoS(CMB2006)049International audienceThe data processing of the data from the High Frequency Instrument (HFI) of the Planck mission will use several modules. Destriping is expected to play a central role in the mapmaking stage. This paper outlines two existing HFI l2 DPC destriping modules together with estimations of their performances. MOKAPIX is a temperature data destriping tool based on scanning redundancies on the sky. We have developped another modules, BOGOPIX , based on the same philosophy, to perform simultaneously destriping and relative intercalibration

Results of the EUROTeV Beam-Beam Simulation (BBSIM) Task

This paper is the deliverable of the EUROTeV Beam-Beam Simulation (BBSIM) task and gives an overview of the published results

Modeling of the shared magnets of the ATF Extraction Line

After extraction from the ATF Damping Ring, the linear beam optics is matched before injection into a section dedicated to beam diagnostics. Experimentally, vertical emittances in this section have since several years been observed to be larger than expected, byfactors of two to three, with a seemingly strong dependence on intensity. This has motivated studies of the possible sources of emittance growth. One of these is thought to be the non-linearity experienced by the beam during the extraction, as it is transported off-axis through several magnets which are shared with the Damping Ring. Such non-linearity can generate a sensitivity of the emittance to the orbit parameters in the extraction, which would be very undesirable in the newly built ATF2 final focus system, where the same extraction line is used. In this report, a detailed calculation of the modeling of these shared magnets is presented, in order to quantify the magnitudes of both the linear and non-linear fields to be used in the evaluation of the optics and in tracking simulations of the performance of the extraction line

The 2mrad crossing angle scheme for the international linear collider

http://cern.ch/AccelConf/e08/papers/mopp005.pdfInternational audienceThe present baseline configuration of the ILC has a 14 mrad crossing angle between the beams at the interaction point. This allows easier extraction of the beams after col- lisions, but imposes on the other hand more constraints on the control of the beams prior to colliding them. More- over, some limitations to physics capabilities arise, in par- ticular because of the degraded very forward electromag- netic detector hermeticity and because calibration proce- dures for (gaseous) tracking detectors become more com- plex. To mitigate these problems, alternative configurations with very small crossing angles are studied. A new version of the 2 mrad layout was designed last year, based on sim- pler concepts and assumptions. The emphasis of this new scheme was to satisfy specifications with as few and feasi- ble magnets as possible, in order to reduce costs

Effect of the non-linear magnetic fields on the emittance growth in the ATF extraction line

WE6PFP075International audienceSince several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, has been significantly larger than that measured in the damping ring (DR) itself. The EXT line that transports the beam to the ATF2 Final Focus beam line has been rebuilt, but the extraction itself remains in most part unchanged, with the extracted beam transported off- axis horizontally in two of the quadrupoles, beyond the linear region for one of them. A few other nearby magnets have also modelled or measured non-linearity. In case of a residual vertical beam displacement, this can result in increased vertical emittance through coupling between the two transverse planes. Tracking studies as well as measurements have been carried out to study this effect and the induced sensitivity of beam optical parameters to the trajectory at injection, in view of deriving tolerances for reproducible and stable operation

GUINEA-PIG++ : an upgraded version of the linear collider beam-beam interaction simulation code GUINEA-PIG

http://cern.ch/AccelConf/p07/PAPERS/THPMN010.PDFInternational audienceGUINEA-PIG++ is a newly developed object-oriented version of the Linear Collider beam-beam simulation program GUINEA-PIG. The main goals of this project are to provide an reliable, modular, documented and versatile framework enabling convenient implementation of new features and functionalities

Iterative destriping and photometric calibration for Planck-HFI, polarized, multi-detector map-making

We present an iterative scheme designed to recover calibrated I, Q, and U maps from Planck-HFI data using the orbital dipole due to the satellite motion with respect to the Solar System frame. It combines a map reconstruction, based on a destriping technique, juxtaposed with an absolute calibration algorithm. We evaluate systematic and statistical uncertainties incurred during both these steps with the help of realistic, Planck-like simulations containing CMB, foreground components and instrumental noise, and assess the accuracy of the sky map reconstruction by considering the maps of the residuals and their spectra. In particular, we discuss destriping residuals for polarization sensitive detectors similar to those of Planck-HFI under different noise hypotheses and show that these residuals are negligible (for intensity maps) or smaller than the white noise level (for Q and U Stokes maps), for l > 50. We also demonstrate that the combined level of residuals of this scheme remains comparable to those of the destriping-only case except at very low l where residuals from the calibration appear. For all the considered noise hypotheses, the relative calibration precision is on the order of a few 10e-4, with a systematic bias of the same order of magnitude.Comment: 18 pages, 21 figures. Match published versio

Results of the EUROTeV Post Collision Line Design (PCDL) Task

This paper is the deliverable of the EUROTeV Post Collision Line Design (PCDL) task and gives an overview of the published results