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[en] The various models that were successively developed for describing static nuclear deformations are reviewed. The properties of the nuclei in their ground state lead to the concept of ellipsoidal nuclei, the liquid drop model being intended to explain the deformations of the excited nucleus, the shell corrections explain the drawbacks of the liquid drop model and the Strutinski theory describes their effects on the fission barrier. The collective model, the deformed shell model and the unified model having been successively introduced to explain the rotational spectrum. The approximations involving infinite nuclear matter and effective interactions, and nuclear Hartree-Fock calculations are briefly outlined jointly with heavy ion excitation of yrast levels
[fr]Les differents modeles nucleaires qui ont successivement tente de decrire les deformations statiques du noyau sont evoques. Les proprietes des noyaux dans leur etat fondamental conduisent a la notion de noyaux de forme ellipsoidale, le modele de la goutte liquide etant destine a expliquer les deformations du noyau excite, les corrections de couches rendent compte des defauts du modele de la goutte liquide et la theorie de Strutinski decrit leurs effets sur la barriere de fission. Le modele collectif, le modele en couches deforme puis le modele unifie ont successivement ete introduits pour expliquer le spectre rotationnel. Les approximations de matiere nucleaire infinie et d'interaction effective et les calculs de Hartree-Fock pour le noyau sont evoques ainsi que les experiences d'excitation de niveaux yrast par les ions lourds
[en] We show that we may divide the nuclear current into a sum of an irrotational and a vortical current. The vortical current is a transverse current whose source is the vorticity density. Using specific examples we investigate hor to determine the vorticity density from the experimental data and hoe to calculate it theoretically. (author)
[en] An uncertainty propagation methodology relying on marginalization techniques was recently developed to produce covariance matrices between existing model parameters involved in describing neutron-induced reactions. This work has been implemented in the nuclear data assimilation tool CONRAD. The performance of the code was demonstrated through simplified test cases based on a Reich-Moore description of the 155Gd(n,γ) reaction. Results are compared with those produced via Monte Carlo techniques.
[en] Basic theoretical approaches to the explanation of the observed exponential nature of the decay law are discussed together with the hypothesis that it is not exponential. The significance of this question and its connection with fundamental problems of modern physics are considered. The results of experiments relating to investigation of the form of the decay law are given