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Lv, Bingfeng
Universite Paris-Saclay, Ecole doctorale no. 576, particules hadrons energie et noyau instrumentation, image, cosmos et simulation - Pheniics, Espace Technologique, Immeuble Discovery, Route de l'Orme aux Merisiers RD 128 91190 Saint-Aubin (France); Universite Paris-Sud, Centre de Sciences Nucleaires et de Sciences de la Matiere - CSNSM - UMR8609 (France)2019
Universite Paris-Saclay, Ecole doctorale no. 576, particules hadrons energie et noyau instrumentation, image, cosmos et simulation - Pheniics, Espace Technologique, Immeuble Discovery, Route de l'Orme aux Merisiers RD 128 91190 Saint-Aubin (France); Universite Paris-Sud, Centre de Sciences Nucleaires et de Sciences de la Matiere - CSNSM - UMR8609 (France)2019
AbstractAbstract
[en] The exotic collective excitation mode called chirality has been investigated and long-lived isomers have been searched for in the 136Nd and 135Nd nuclei. Five pairs of nearly degenerate ΔI = 1 bands with the same parity have been identified at high spins in 136Nd. The observed bands were investigated by the constrained and tilted axis cranking covariant density functional theory and a new developed four single-j shells particle-rotor model. It was found that the properties of these doublet bands are in good agreement with results of the model calculations. Therefore, the multiple chiral doublets (MχD) phenomenon in the nucleus 136Nd was confirmed. This was the first experimental evidence for the MχD bands in even-even nuclei. The five pairs of chiral doublet bands is the largest observed in a single nucleus until now. In addition, the level scheme of the 136Nd has been extended significantly at low, medium, and very high spins. Possible configurations of all rotational bands have been assigned by using the cranked Nilsson-Strutinsky model. The band structure of 136Nd was clarified and the various types of single-particle and collective excitations were well understood. A new pair of positive-parity chiral doublet bands has been identified in 135Nd. The characteristics of the doublet bands support the chiral interpretation. Together with the previously reported negative-parity chiral doublet bands show the presence of MχD bands in 135Nd. The observed doublet bands were compared with constrained covariant density functional theory and particle-rotor model calculations which nicely reproduce the experimental data, confirming the MχD phenomenon in this nucleus. The newly observed MχD bands in 135Nd represents an important milestone in supporting the existence of MχD in nuclei. The search for long-lived isomeric states in 135Nd and 136Nd has also been performed. This did not lead to the identification of new isomers, but we could confirm the existence of the previously reported isomers in the nuclei 138Nd, 134Ce, 136Pr, and 137Pr in our data. (author)
[fr]
Le mode d'excitation collective exotique appele chiralite a ete etudie et des isomeres de longue duree de vie ont ete recherches dans les noyaux 136Nd et 135Nd. Cinq paires de bandes ΔI = 1 presque degenerees et de meme parite ont ete identifiees a des spins eleves dans 136Nd. Les bandes observees ont ete etudiees en utilisant la theorie de la fonctionnelle de densite covariante contrainte et rotation autour d'une axe incline, et par un nouveau modele de rotor plus particules developpe pour decrire le couplage de particules dans quatre couches j a un rotor triaxial. Les proprietes de ces bandes doublet sont en bon accord avec les resultats des calculs theoriques. Par consequent, l'existence de bandes chirales multiples (MχD) dans le noyau 136Nd a ete etablie. Il s'agit de la premiere preuve experimentale de l'existence de bandes chirales dans des noyaux pairs. Les cinq paires de bandes chirales constituent le plus grand ensamble de bandes chirales observe jusqu'a present dans un seul noyau. De plus, le schema de niveaux de 136Nd a ete considerablement etendu aux spins bas, moyens et tres eleves. Les configurations possibles de toutes les bandes rotationnelles ont ete attribuees a l'aide du modele Nilsson-Strutinsky en rotation. La structure de 136Nd a ete clarifiee et les divers types d'excitations uni-particule et collectives ont ete bien compris. Une nouvelle paire de bandes chirales a parite positive a ete identifiee dans 135Nd. Les caracteristiques des bandes soutiennent leur interpretation en termes de bandes chirales. Des bandes chirales a parite negative ayant ete identifiees precedemment, la presence de multiple bandes chirales dans 135Nd est ainsi etablie. Les bandes chirales observees ont ete etudiees en utilisant la theorie avec fonctionnelle de densite covariante contrainte et avec le modele rotor plus particules; elles reproduisent fidelement les donnees experimentales, confirmant ainsi le phenomene MχD dans ce noyau. Les bandes chirales nouvellement observees dans 135Nd representent une etape importante dans la confirmation de l'existence du phenomene MχD dans les noyaux. La recherche d'etats isomeriques a longue duree de vie dans 135Nd et 136Nd a ete aussi effectuee, mais n'a pas permis d'identifier de nouveaux isomeres. Cependant, nous avons pu confirmer la presence des isomeres deja identifies dans les noyaux 138Nd, 134Ce, 136Pr, et 137Pr dans nos donnees. (auteur)Original Title
Chiralite dans les noyaux 136Nd et 135Nd
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Source
11 Oct 2019; 164 p; 137 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses; These de doctorat de l'Universite Paris-Saclay, Specialite: Structure et reactions nucleaires
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Miscellaneous
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Thesis/Dissertation
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BETA DECAY RADIOISOTOPES, BETA-PLUS DECAY RADIOISOTOPES, ELECTRON CAPTURE RADIOISOTOPES, ENERGY LEVELS, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, INTERMEDIATE MASS NUCLEI, ISOTOPES, MINUTES LIVING RADIOISOTOPES, NEODYMIUM ISOTOPES, NUCLEI, PARTICLE PROPERTIES, RADIOISOTOPES, RARE EARTH NUCLEI, SPECTROSCOPY
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