[en] The Generalized Parton Distributions (GPDs) provide a new description of the nucleon structure in terms of its elementary constituents, the quarks and the gluons. The GPDs give access to a unified picture of the nucleon, correlating the information obtained from the measurements of the Form Factors and the Parton Distribution Functions. They describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark of the nucleon eN → e'N'γ, is the most straightforward exclusive process allowing access to the GPDs. A dedicated experiment to study DVCS with the CLAS detector of Jefferson Lab has been carried out using a 5.883 GeV polarized electron beam and an unpolarized hydrogen target, allowing to collect DVCS events in the widest kinematic range ever explored in the valence region: 1 < Q² < 4.6 GeV², 0.1 < x_B < 0.58, 0.09 < -t < 3 GeV². In this work, we present the extraction of three different DVCS observables: the unpolarized cross section, the difference of polarized cross sections and the beam spin asymmetry. We present comparisons with GPD model. We show a preliminary extraction of the GPDs using the latest fitting code procedure on our data, and a preliminary interpretation of the results in terms of parton density. (author)

[en] Model complexity in amplitude analyses is often a priori under-constrained since the underlying theory permits a large number of possible amplitudes to contribute to most physical processes. The use of an overly complex model results in reduced predictive power and worse resolution on unknown parameters of interest. Therefore, it is common to reduce the complexity by removing from consideration some subset of the allowed amplitudes. This paper studies a method for limiting model complexity from the data sample itself through regularization during regression in the context of a multivariate (Dalitz-plot) analysis. The regularization technique applied greatly improves the performance. An outline of how to obtain the significance of a resonance in a multivariate amplitude analysis is also provided

[en] The exclusive electroproduction of π ⁺ above the resonance region was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory by scattering a 6GeV continuous electron beam off a hydrogen target. The large acceptance and good resolution of CLAS, together with the high luminosity, allowed us to measure the cross section for the γ^*p→nπ ⁺ process in 140 (Q ²,x_B,t) bins: 0.16< x_B<0.58, 1.6 GeV²< Q²<4.5 GeV ² and 0.1 GeV²<-t<5.3 GeV². For most bins, the statistical accuracy is on the order of a few percent. Differential cross sections are compared to four theoretical models, based either on hadronic or on partonic degrees of freedom. The four models can describe the gross features of the data reasonably well, but differ strongly in their ingredients. In particular, the model based on Generalized Parton Distributions (GPDs) contain the interesting potential to experimentally access transversity GPDs. (orig.)

[en] A first document reports an in-situ experiment which aimed at the realisation of a tight tank for a possible storage of radioactive effluents, and at the study of possibilities of quick intervention in case of accidental contamination of the groundwater table. The next ones report various observations made by the BRGM on the hydrogeological conditions of the CEA Pierrelatte industrial site during the site reconnaissance period, during site construction, and during its operation. These studies aimed at determining characteristics of exploitation and protection of underground waters contained by alluvial formations of the Rhone plain within the limits of the Centre and at its vicinity. The last one reports a sampling campaign performed in order to acquire a better knowledge of the geological nature of soils under deposits where hydraulic circulation presented a risk which could become critical in case of accidental pollution of ground water tables. Four samplings have been performed, followed by correlation tests, chemical analyses, tritium analyses and piezometry measurements