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Robust and sensitive tools to characterise local structure are essential for investigations of granular or particulate matter. Often local structure metrics derived from the bond network are used for this purpose, in particular Steinhardt's bond-orientational order parameters ql. Here we discuss an alternative method, based on the robust characterisation of the shape of the particles' Voronoi cells, by Minkowski tensors and derived anisotropy measures. We have successfully applied these metrics to quantify structural changes and the onset of crystallisation in random sphere packs. Here we specifically discuss the expectation values of these metrics for simple crystalline unimodal packings of spheres, consisting of single spheres on the points of a Bravais lattice. These data provide an important reference for the discussion of anisotropy values of disordered structures that are typically of relevance in granular systems. This analysis demonstrates that, at least for sufficiently high packing fractions above [lowercase_phi_synonym] > 0.61, crystalline sphere packs exist whose Voronoi cells are more anisotropic with respect to a volumetric moment tensor than the average value of Voronoi cell anisotropy in random sphere packs. [ABSTRACT FROM AUTHOR]

A fusion-evaporation experiment has been performed with a SPIRAL 76Kr radioactive beam in order to study the deformation of rare-earth nuclei near the proton drip-line. The experimental setup consisted in the EXOGAM γ-array, coupled to the light-charged particles (LCP) DIAMANT detector and to the VAMOS heavy-ion spectrometer. The difficulties inherent to such measurements are enlightened. The coupling between EXOGAM and DIAMANT has been used to decrease the huge background caused by the radioactivity of the beam. It further permits assigning new γ-ray transitions to specific residual nuclei. A γ-ray belonging to the 130Pm level scheme has thus been observed for the first time. [ABSTRACT FROM AUTHOR]

An experiment has been performed using a SPIRAL 76Kr radioactive beam at GANIL to investigate rare-earth nuclei near the proton drip-line. The EXOGAM gamma array was coupled with the DIAMANT light charged-particle detector and the VAMOS spectrometer. We report here on the powerful of this setup to extract fusion-evaporation γ-rays from a large beam contamination. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]