Shapes of the 192,190^{192,190}Pb ground states from beta decay studies using the total absorption technique

The beta decay of $^{192,190}$Pb has been studied using the total absorption technique at the ISOLDE(CERN) facility. The beta-decay strength deduced from the measurements, combined with QRPA theoretical calculations, allow us to infer that the ground states of the $^{192,190}$Pb isotopes are spherical. These results represent the first application of the shape determination method using the total absorption technique for heavy nuclei and in a region where there is considerable interest in nuclear shapes and shape effects

Teaching experienced developers to design graphical user interfaces

Five groups of developers with experience in the design of character-based user interfaces were taught graphical user interface design through a short workshop with a focus on practical design exercises using low-tech tools derived from the PICTIVE method. Several usability problems were found in the designs by applying the heuristic evaluation method, and feedback on these problems constituted a way to make the otherwise abstract usability principles concrete for the designers at the workshop. Based on these usability problems and on observations of the design process, we conclude that object-oriented interactions are especially hard to design and that the developers were influenced by the graphical interfaces of personal computers with which they had interacted as regular users

Advanced Model for SBS of a Randomized Laser Beam and Application to Polarization Smoothing Experiments with Preformed Underdense Plasmas

An advanced statistical model is presented, which describes the SBS of a randomized laser beam interacting with an underdense, expanding plasma. The model accounts for the self-focusing of speckles and for its influence on the speckles SBS reflectivity in the regime where the effect of plasma heating is important. Plasma heating has an important effect on speckle self-focusing and it decreases the SBS threshold and also decreases the SBS reflectivity. The model exhibit a good agreement with the measured SBS levels at the LULI multi-beam facility for a broad range of the laser and plasma parameters and both types of beam smoothing--RPP and PS. Both the model and the experiments confirm that the PS technique allows to control the SBS level more efficiently than RPP

Laser-Plasma Interaction Physics at LULI

Laser-plasma interaction physics is studied in the context of laser fusion using the six-beam laser facility at LULI. Interaction between RPP laser beams and well-characterized preformed plasmas has been performed to study various aspects of stimulated Brillouin and Raman scattering (SBS and SRS), self-focusing and filamentation. Thomson scattering of a short wavelength probe laser beam was used to provide a complete characterization of the plasma (electron temperature, density, flow velocity) and measurements of the density fluctuations associated with ion acoustic waves and electron plasma waves, with temporal, spatial, frequency and wavenumber resolution. Among the different studies, they will present results on the effect of polarization smoothing, target material, multi-species plasmas, and Langmuir decay on parametric instabilities

Coherence properties of high-order harmonics : Application to high-density laser-plasma diagnostic

We present two interferometry schemes in the extreme ultraviolet, based on either the wave-front division of a unique harmonic beam (1st scheme) or two spatially separated, phase-locked harmonic sources (2nd scheme). In the first scheme using a Fresnel bimirror interferometer, we measure the degree of spatial coherence of the 13 th harmonic generated in xenon, as a function of different parameters. A high degree of coherence, larger than 0.5, is found for the best conditions in almost the full section of the beam. Then, we demonstrate that the second scheme can be used for interferometry measurements with an ultrahigh time resolution. The 11th harmonic is used to study the spatial variation of the electron density of a laser-produced plasma. Electronic densities higher than 2.10 20 cm -3 are measured