High-spin structure in the transitional nucleus 131Xe:Competitive neutron and proton alignment in the vicinity of the N = 82 shell closure

International audienceThe transitional nucleus Xe131 is investigated after multinucleon transfer in the Xe136+Pb208 and Xe136+U238 reactions employing the high-resolution Advanced γ-Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA at the Laboratori Nazionali di Legnaro, Italy, and as an elusive reaction product in the fusion-evaporation reaction Sn124(B11,p3n)Xe131 employing the High-efficiency Observatory for γ-Ray Unique Spectroscopy (HORUS) γ-ray array coupled to a double-sided silicon strip detector at the University of Cologne, Germany. The level scheme of Xe131 is extended to 5 MeV. A pronounced backbending is observed at ℏω≈0.4MeV along the negative-parity one-quasiparticle νh11/2(α=−1/2) band. The results are compared to the high-spin systematics of the Z=54 isotopes and the N=77 isotones. Large-scale shell-model calculations employing the PQM130, SN100PN, GCN50:82, SN100-KTH, and a realistic effective interaction reproduce the experimental findings and provide guidance to elucidate the structure of the high-spin states. Further calculations in Xe129−132 provide insight into the changing nuclear structure along the Xe chain towards the N=82 shell closure. Proton occupancy in the π0h11/2 orbital is found to be decisive for the description of the observed backbending phenomenon

SÉLECTIVITÉ SPECTRALE PAR EFFET DE STRUCTURE DES COUCHES MINCES DÉPOSÉES DE NICKEL ET DE CHROME

L'efficacité de nombreux absorbeurs solaires demeure liée à la réalisation de surfaces sélectives stables à des températures de plus en plus élevées (~ 500°C). De telles surfaces spectralement sélectives ont été développées par un revêtement d'un film mince de métaux tels que Ni et Cr créant ainsi une topologie de structure satisfaisante à de bonnes conditions de sélectivité (α = 0,9 ε = 0,2). Ces surfaces sont obtenues par condensation sous vide de vapeurs métalliques à plus ou moins grande concentration pour lesquelles la taille et la forme des cristallites sont influencées par la vitesse et la température de déposition. Les propriétés thermo-optiques des films ont été mesurées après traitement à 300°C et 500°C et leur stabilité a été vérifiée après 1200 à 1800 heures d'application. Ces surfaces n'impliquent pas de procédés de fabrication complexes. Elles présentent une bonne tenue mécanique, une forte résistance à l'auto-diffusion, une bonne stabilité à la corrosion, de ce fait elles semblent devoir apporter une solution satisfaisante au problème des surfaces absorbantes sélectives employées à des températures élevées.The efficiency of numerous solar absorbers is still closely linked to the manufacture of selective surfaces which remain stable at high temperatures (~ 500°C). Such spectral selective surfaces have been developed by covering plates with thin layers of metal, such as Ni and Cr leading to good selectivity (α = 0.9 and ε = 0.2) by the microstructure of the surfaces. These layers are obtained by vacuum deposition of metal vapour at different concentrations. The dimensions and the shape of the cristallites formed are determined by the deposition rate and the substrate temperature. The thermo-optical properties of the layers are measured after treatments at 300°C and 500°C and their stability is checked after 1200 hrs to 1800 hrs. Those surfaces do not require complex production procedures. The surfaces show good mechanical properties, a low coefficient for self-diffusion and good corrosion resistance. They, therefore, apparently provide a satisfactory solution to the problem of spectral selective surfaces for high temperature use

Integrated design of a lightweight positioning system

In this paper a new approach to the design of positioning systems is introduced. The approach aims at the design of fast and accurate systems that are lightweight compared to classical designs. The new design reduces peak power requirements and thermal effects that deteriorate performance of the whole system

Integrated design of a lightweight positioning system

In this paper a new approach to the design of positioning systems is introduced. The approach aims at the design of fast and accurate systems that are lightweight compared to classical designs. The new design reduces peak power requirements and thermal effects that deteriorate performance of the whole system