Taking individual heterogeneity in mortality risks into account in demographic studies of wild animal populations: development and use of statistical models.

The Cormarck-Jolly-Seber model incorporating frailty implemented in WinBUGS, using the 9000 kittiwake’s dataset monitorized during 22 years, showed that the convergence is very low over computational view. We developed different kind of multistate model, considering independence/dependence between random effect of breeding and survival probability. The last part of the work was dedicated to model selection with Bayesian framework

Towards Machine Wald

The past century has seen a steady increase in the need of estimating and predicting complex systems and making (possibly critical) decisions with limited information. Although computers have made possible the numerical evaluation of sophisticated statistical models, these models are still designed \emph{by humans} because there is currently no known recipe or algorithm for dividing the design of a statistical model into a sequence of arithmetic operations. Indeed enabling computers to \emph{think} as \emph{humans} have the ability to do when faced with uncertainty is challenging in several major ways: (1) Finding optimal statistical models remains to be formulated as a well posed problem when information on the system of interest is incomplete and comes in the form of a complex combination of sample data, partial knowledge of constitutive relations and a limited description of the distribution of input random variables. (2) The space of admissible scenarios along with the space of relevant information, assumptions, and/or beliefs, tend to be infinite dimensional, whereas calculus on a computer is necessarily discrete and finite. With this purpose, this paper explores the foundations of a rigorous framework for the scientific computation of optimal statistical estimators/models and reviews their connections with Decision Theory, Machine Learning, Bayesian Inference, Stochastic Optimization, Robust Optimization, Optimal Uncertainty Quantification and Information Based Complexity.Comment: 37 page

SHIRaC

Refroidisseur quadrupôle à radio-fréquences SHIRaC en place au LPC Caen. Ce dispositif sera au GANIL auprès de la future installation SPIRAL2

Le quadripole radio-fréquence refroidisseur d'ions (RFQ cooler) haute intensité au LPC Caen

Le rôle du RFQ cooler est de manipuler des faisceaux d'ions dans le but d'optimiser leur qualité optique. Cet instrument à la particularité d'être le premier RFQ cooler capable de traiter des faisceaux d'ions de forte intensité, il nécessite un développement particulier. Le RFQ cooler sera intégré sur l'installation SPIRAL2 au GANIL

Le quadripole radio-fréquence refroidisseur d'ions (RFQ cooler) haute intensité au LPC Caen

Le rôle du RFQ cooler est de manipuler des faisceaux d'ions dans le but d'optimiser leur qualité optique. Cet instrument à la particularité d'être le premier RFQ cooler capable de traiter des faisceaux d'ions de forte intensité, il nécessite un développement particulier. Le RFQ cooler sera intégré sur l'installation SPIRAL2 au GANIL

Le quadripole radio-fréquence refroidisseur d'ions (RFQ cooler) haute intensité au LPC Caen

Le rôle du RFQ cooler est de manipuler des faisceaux d'ions dans le but d'optimiser leur qualité optique. Cet instrument à la particularité d'être le premier RFQ cooler capable de traiter des faisceaux d'ions de forte intensité, il nécessite un développement particulier. Le RFQ cooler sera intégré sur l'installation SPIRAL2 au GANIL

Experimental study of a high intensity radio-frequency cooler

International audienceWithin the framework of the DESIR/SPIRAL-2 project, a radio-frequency quadrupole cooler named SHIRaC has been studied. SHIRaC is a key device of SPIRAL-2, designed to enhance the beam quality required by DESIR. The preliminary study and development of this device has been carried out at Laboratoire de Physique Corpusculaire de CAEN (LPC Caen), France. The goal of this paper is to present the experimental studies conducted on a SHIRaC prototype. The main peculiarity of this cooler is its efficient handling and cooling of ion beams with currents going up as high as 1  μA which has never before been achieved in any of the previous coolers. Much effort has been made lately into these studies for development of appropriate optics, vacuum and rf systems which allow cooling of beams of large emittance (∼80π  mm mrad) and high current. The dependencies of SHIRaC’s transmission and the cooled beam parameters in terms of geometrical transverse emittance and the longitudinal energy spread have also been discussed. Investigation of beam purity at optimum cooling condition has also been done. Results from the experiments indicate that an emittance reduction of less than 2.5π  mm mrad and a longitudinal energy spread reduction of less than 4 eV are obtained with more than 70% of ion transmission. The emittance is at expected values whereas the energy spread is not

Simulations of high intensity ion beam RFQ cooler for DESIR/SPIRAL 2: SHIRaC

International audienceSHIRaC is a buffer gas radiofrequency quadrupole cooler, part of SPIRAL 2 facility, at GANIL in France. It is designed to cool low energy ion beams with emittances up to 80 pi.mm.mrad and currents up to 1 mu A. It is devoted to reduce the beam parameters; less than 3 pi.mm.mrad of emittance and around 1 eV of spread energy, and to transmit more than 60% of ions. However, to achieve the least possible emittance, spread energy and ion transmission, the space charge has been overcome using high confining RF amplitude. Numerical simulations have been developed in order to study and evaluate the space charge effects on the beam parameters and the ion transmission. The simulation results have shown that the main degradations of these parameters stem from this effect. The ion transmission decreases progressively with the beam current and it nevertheless remains above 65%. The emittance and the spread energy increase with the beam current while staying below 2.4 pi.mm.mrad and 5.9 eV respectively