The nuclear pseudospin symmetry along an isotopic chain

We investigate the isospin dependence of pseudospin symmetry in the chain of tin isotopes (from $^{120}$Sn until $^{170}$Sn). Using a Woods-Saxon parametrization of the nuclear potential for these isotopes we study in detail the effect of the vector-isovector $\rho$ and Coulomb potentials in the energy splittings of neutron and proton pseudospin partners in the isotopic chain. We conclude that the realization of nuclear pseudospin symmetry does not change considerably with the mass number, and is always favored for neutrons. We also find that the $\rho$ potential accounts for essentially all the pseudospin isospin asymmetry observed and that the Coulomb potential plays a negligible role in this asymmetry. This can be explained by the dynamical nature of pseudospin symmetry in nuclei, namely the dependence of the pseudospin splittings on the shape of the nuclear mean-field potential.Comment: 4 pages, 4 figures, to be published in Brazilian Journal of Physic

Tensor coupling and pseudospin symmetry in nuclei

In this work we study the contribution of the isoscalar tensor coupling to the realization of pseudospin symmetry in nuclei. Using realistic values for the tensor coupling strength, we show that this coupling reduces noticeably the pseudospin splittings, especially for single-particle levels near the Fermi surface. By using an energy decomposition of the pseudospin energy splittings, we show that the changes in these splittings come by mainly through the changes induced in the lower radial wave function for the low-lying pseudospin partners, and by changes in the expectation value of the pseudospin-orbit coupling term for surface partners. This allows us to confirm the conclusion already reached in previous studies, namely that the pseudospin symmetry in nuclei is of a dynamical nature.Comment: 11 pages, 5 figures, uses REVTeX macro

Dynamical nature of the nuclear pseudospin and its isospin asymmetry

Pseudospin symmetry in nuclei is investigated by solving the Dirac equation with Woods-Saxon scalar and vector radial potentials. We relate the pseudospin interaction with a pseudospin-orbit term in a Schroedinger-like equation for the lower component of the Dirac spinor. We show that this term gives a large contribution to the energy splittings of pseudospin partners, so that the near pseudospin degeneracy arises from a significant cancellation among the different terms in that equation. This is a manifestation of the dynamical character of this symmetry in the nucleus. We analyze the isospin dependence of the pseudospin symmetry in a nuclear isotope chain by including a vector-isovector potential V_rho and a Coulomb potential and conclude that V_rho gives the main contribution to the observed pseudospin isospin asymmetry.Comment: 4 pages, 2 figures, uses World Scientific style file. Contribution presented at the VIII International Workshop on Hadron Physics, Bento Goncalves, RS, Brazil, April 14-19, 2002. To be published by World Scientific in the proceedings of the "International Workshop on Hadron Physics 2002

Pseudoexfoliation: the diagnosis at first sight

info:eu-repo/semantics/publishedVersio

Potencialidades das rochas graníticas no concelho de Nisa

O presente texto visa dar a conhecer os resultados obtidos a respeito das potencialidades das rochas graníticas existentes na área do município. Estes resultados foram obtidos no âmbito de um trabalho mais vasto de inventariação, caracterização e avaliação das potencialidades em recursos minerais do concelho de Nisa, o qual foi objecto de um protocolo de colaboração com carácter pioneiro entre a autarquia e o LNEG

Resposta a NPK por seringueiras em viveiros nas condicoes do estado de Rondonia.

Procurou-se verificar as resposta a adubacao e definir niveis mais adequados nitrogenio, fosforo e potassio para viveiros de seringueira em Rondonia. Os experimentos foram instalados em alguns solos representativos nos municipios de Porto Velho e Ariquemes: Latossolo Amarelo textura pesada; Ouro Preto D'Oeste: Podzolicos. Os delineamentos foram do tipo fatorial incompleto em blocos ao acaso, com tres repeticoes. Utilizou-se: ureia com 45% de N, superfosfato triplo com 46% de P2O5 e cloreto de potassio com 60% de K2O.Mediu-se o diametro do caule a 5cm do solo consideradosos diametros de 1,2cm para plantas de 7 meses e de 2cm para plantas de 12 meses de idade no calculo da porcentagem de plantas aptas a enxertia. Resultados demonstram que nao ha resposta significativa a adubacao de ate 90kg de N, 250kg P2O5 e 120kg K2O/ha. O manejo adequado da materia organica, calagem e adubacao de testituicao, deverao ser praticas observadas para a garantia da producao de viveiros de seringueira. Sugere-se que enquanto nao se tem determinacao segura de teores exportados palas plantas em diversos locais do Estado, a aplicacao de 1,0g de P2O5 e K2O por planta deve ser suficiente para a produçãobitstream/item/23946/1/11-jul88.pd

Relating pseudospin and spin symmetries through charge conjugation and chiral transformations: the case of the relativistic harmonic oscillator

We solve the generalized relativistic harmonic oscillator in 1+1 dimensions, i.e., including a linear pseudoscalar potential and quadratic scalar and vector potentials which have equal or opposite signs. We consider positive and negative quadratic potentials and discuss in detail their bound-state solutions for fermions and antifermions. The main features of these bound states are the same as the ones of the generalized three-dimensional relativistic harmonic oscillator bound states. The solutions found for zero pseudoscalar potential are related to the spin and pseudospin symmetry of the Dirac equation in 3+1 dimensions. We show how the charge conjugation and $\gamma^5$ chiral transformations relate the several spectra obtained and find that for massless particles the spin and pseudospin symmetry related problems have the same spectrum, but different spinor solutions. Finally, we establish a relation of the solutions found with single-particle states of nuclei described by relativistic mean-field theories with scalar, vector and isoscalar tensor interactions and discuss the conditions in which one may have both nucleon and antinucleon bound states.Comment: 33 pages, 10 figures, uses revtex macro