Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force

Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ($\beta_2\beta_3$) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and octupole collective structure fairly well, and turns out to be consistent with GCM results obtained with the Gogny force.Comment: 17 pages, 12 figures, 4 table

Structural evolution in germanium and selenium nuclei within the mapped interacting boson model based on the Gogny energy density functional

The shape transitions and shape coexistence in the Ge and Se isotopes are studied within the interacting boson model (IBM) with the microscopic input from the self-consistent mean-field calculation based on the Gogny-D1M energy density functional. The mean-field energy surface as a function of the quadrupole shape variables $\beta$ and $\gamma$, obtained from the constrained Hartree-Fock-Bogoliubov method, is mapped onto the expectation value of the IBM Hamiltonian with configuration mixing in the boson condensate state. The resultant Hamiltonian is used to compute excitation energies and electromagnetic properties of the selected nuclei $^{66-94}$Ge and $^{68-96}$Se. Our calculation suggests that many nuclei exhibit $\gamma$ softness. Coexistence between prolate and oblate, as well as between spherical and $\gamma$-soft, shapes is also observed. The method provides a reasonable description of the observed systematics of the excitation energy of the low-lying energy levels and transition strengths for nuclei below the neutron shell closure $N=50$, and provides predictions on the spectroscopy of neutron-rich Ge and Se isotopes with $52\leq N\leq 62$, where data are scarce or not available.Comment: 16 pages, 20 figure

Effective 4D propagation of a charged scalar particle in Visser brane world

In this work we extend an analysis due to Visser of the effective propagation of a neutral scalar particle on a brane world scenario which is a particular solution of the five dimensional Einstein-Maxwell equations with cosmological constant having an electric field pointing in the extra spatial dimension. We determine the dispersion relations of a charged scalar particle to first order in a perturbative analysis around those of the neutral particle. Since depending on whether the particle is charged or not the dispersion relations change, we could collect bulk information, namely the presence of the electric field, by studying the 4D dynamics of the particles.Comment: 12 pages, 5 figure

Structure of krypton isotopes within the interacting boson model derived from the Gogny energy density functional

The evolution and coexistence of the nuclear shapes as well as the corresponding low-lying collective states and electromagnetic transition rates are investigated along the Krypton isotopic chain within the framework of the interacting boson model (IBM). The IBM Hamiltonian is determined through mean-field calculations based on the several parametrizations of the Gogny energy density functional and the relativistic mean-field Lagrangian. The mean-field energy surfaces, as functions of the axial $\beta$ and triaxial $\gamma$ quadrupole deformations, are mapped onto the expectation value of the interacting-boson Hamiltonian that explicitly includes the particle-hole excitations. The resulting boson Hamiltonian is then used to compute low-energy excitation spectra as well as E2 and E0 transition probabilities for $^{70-100}$Kr. Our results point to a number of examples of the prolate-oblate shape transitions and coexistence both on the neutron-deficient and neutron-rich sides. A reasonable agreement with the available experimental data is obtained for the considered nuclear properties.Comment: 13 pages, 9 figures, 2 table

La educación como desarrollo de la cultura : experiencia en una comunidad quechua en Bolovia

In 1970, a literacy process was started in Bolivia by INDICEP, and is presently continued in the Integrated Educational Center for Adults in the Rural Areas (Centro de Educación Integrada para Adultos en el Area Rural). The context where this experience is realized is characterized by the existence of a culturally plural population in which a dominantly native society live together (principally composed of Quechuas and Aymaras), which is oppressed and ignored by a minority group of occidental character. Any educational project and in this case, that of alphabetization, should consider this fact to avoid the indifference of those to whom the project is directed. The literacy efforts carried out unti1 now by oficial entities have not endeavoured to integrate in the native communities, but impose the occidental model with a paternalistic perspective of the problem. An image of this situation is the language (with all its cultural contents) which has been utilized was not that of the natives but the Castillan language, producing the loss of the cultural identity of the subject. The new project which is being experimented in the Quechua community is based on the AYNI RUWAY system, which among other aspects is characterized by a simple institutionalization, a non competitive participation and promotion of the own personality of its members and a continuous evaluation. The target which this project pursue is expressed concretely in four points: a) Study of the wheat and its commercialization. b) Production stimulus and commercialization of traditional handicrafts. c) Starting a health programme and correct nutrition. d) Emergency in the formation of native teachers. The main educational instrument which is being used for this literacy campaign is the newspaper in the Quechuan language, in order to answer to the necessities and problems of cultural development in the subjects and in so doing would have a motivating character for those who have not yet attained this basic level of instruction. The formation of rural teachers <coutsiders>in> the community is being developped, while the basis is being prepared to be able to start soon the formation of the native educators