Impact of Triaxiality on the Emission and Absorption of Neutrons and Gamma Rays in Heavy Nuclei

For many spin-0 target nuclei neutron capture measurements yield information on level densities at the neutron separation energy. Also the average photon width has been determined from capture data as well as Maxwellian average cross sections for the energy range of unresolved resonances. Thus it is challenging to use this data set for a test of phenomenological prescriptions for the prediction of radiative processes. An important ingredient for respective calculations is the photon strength function for which a parameterization was proposed using a fit to giant dipole resonance shapes on the basis of theoretically determined ground state deformations including triaxiality. Deviations from spherical and axial symmetry also influence level densities and it is suggested to use a combined parameterization for both, level density and photon strength. The formulae presented give a good description of the data for low spin capture into 124 nuclei with 72<A<244 and only very few global parameters have to be adjusted when the predetermined information on ground state shapes of the nuclei involved is accounted for.Comment: Contribution to the Proceedings of Scientific Workshop on Nuclear Fission Theory-2, November 2012 at Biarritz, Franc

Breaking of axial symmetry in excited heavy nuclei as identified in Giant Dipole Resonance data

A recent theoretical prediction of a breaking of axial symmetry in quasi all heavy nuclei is confronted to a new critical analysis of photon strength functions of nuclei in the valley of stability. For the photon strength in the isovector giant dipole resonance (IVGDR) regime a parameterization of GDR shapes by the sum of three Lorentzians (TLO) is extrapolated to energies below and above the IVGDR. The impact of non-GDR modes adding to the low energy slope of photon strength is discussed including recent data on photon scattering and other radiative processes. These are shown to be concentrated in energy regions where various model calculations predict intermediate collective strength; thus they are obviously separate from the IVGDR tail. The triple Lorentzian (TLO) ansatz for giant dipole resonances is normalized in accordance to the dipole sum rule. The nuclear droplet model with surface dissipation accounts well for positions and widths without local, nuclide specific, parameters. Very few and only global parameters are needed when a breaking of axial symmetry already in the valley of stability is admitted and hence a reliable prediction for electric dipole strength functions also outside of it is expected.Comment: 21 pages, 21 figures, PACS: 26.50.+x, 25.20.Dc,27.60.+j Accepted by Europ. Phys. Journal

Comment on "Electromagnetic dissociation of ^8B and the astrophysical S-factor for ^7Be(p,gamma)^8B"

Recently, Davids and Typel recommended a "low" value of S_{17}(0) based on fits to published direct and Coulomb dissociation data, in which they excluded the precise result of Junghans et al. We show that their statistical analysis is incorrect, due to a substantial underestimate of the experimental uncertainties, and leads to conclusions that are not supported by a proper analysis.Comment: submitted to Phys. Rev.

Caracterização agronômica de genótipos clonais de abacaxizeiro resistentes à fusariose.

O abacaxi tem destaque no mercado internacional de frutos tropicais, pois é o terceiro fruto tropical mais comercializado no mundo. O Brasil é um dos três maiores produtores mundiais, mas na produção brasileira há predomínio de poucas cultivares e é destinada basicamente ao mercado interno

Variedades de abacaxi.

Todas as variedades de abacaxi cujo interesse é o fruto, seja para consumo in natura ou para processamento, pertencem à espécie Ananas comosus var. comosus. Alguns clones de Ananas comosus var. erectifolius, Ananas comosus var. ananassoides e Ananas comosus var. bracteatus são cultivados para produção de fibra ou para fins ornamentais. Recentemente, houve grande incremento nestas formas de utilização. A variedade de abacaxi predominantemente cultivada no mundo é a Smooth Cayenne, responsável por cerca de 70% da produção mundial de abacaxi. Contudo, outras variedades como Singapore Spanish, Queen, Red Spanish, Pérola e Perolera são muito cultivadas e difundidas em nível mundial (Leal, 1990). No Brasil, onde a área de plantio em 2002 foi de 62.597 ha, com produção de 1.430.018 mil frutos e rendimento de 22.845 frutos/ha (IBGE, 2003), a variedade mais plantada é a Pérola, responsável por cerca de 80% da produção brasileira de abacaxi havaiano, cujos plantios se concentram no Sudeste do país, principalmente em São Paulo e na região do Triângulo Mineiro.bitstream/item/81569/1/Circular-Tecnica-63-Variedade-Abacaxi-Renato-Cabral-2003.pdfMemória