Optical spectrum of bottom-up graphene nanoribbons: towards efficient atom-thick excitonic solar cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determining the oscillation parameters by solar neutrinos and KamLAND

The neutrino oscillation experiment KamLAND has provided us with the first evidence for e disappearance, coming from nuclear reactors. We have combined their data with all solar neutrino data, assuming two flavor neutrino mixing, and obtained allowed parameter regions which are compatible with the so-called large mixing angle MSW solution to the solar neutrino problem. The allowed regions in the plane of mixing angle and mass squared difference are now split into two islands at 99% C.L. We have speculated how these two islands can be distinguished in the near future. We have shown that a 50% reduction of the error on SNO neutral-current measurement can be important in establishing in each of these islands the true values of these parameters lie, We also have simulated KamLAND positron energy spectrum after I year of data taking, assuming the current best fitted values of the oscillation parameters, combined it the with current solar neutrino data and showed how these two split islands can be modified. (C) 2003 Published by Elsevier B.V. B.V.

Global analysis of the post-SNO solar neutrino data for standard and nonstandard oscillation mechanisms

What can we learn from solar neutrino observations? Is there any solution to the solar neutrino anomaly which is favored by the present experimental panorama? After SNO results, is it possible to affirm that neutrinos have mass? In order to answer such questions we analyze the current available data from the solar neutrino experiments, including the recent SNO result, in view of many acceptable solutions to the solar neutrino problem based on different conversion mechanisms, for the first time using the same statistical procedure. This allows us to do a direct comparison of the goodness of the fit among different solutions, from which we can discuss and conclude on the current status of each proposed dynamical mechanism. These solutions are based on different assumptions: (a) neutrino mass and mixing, (b) a nonvanishing neutrino magnetic moment, (c) the existence of nonstandard flavor-changing and nonuniversal neutrino interactions, and (d) a tiny violation of the equivalence principle. We investigate the quality of the fit provided by each one of these solutions not only to the total rate measured by all the solar neutrino experiments but also to the recoil electron energy spectrum measured at different zenith angles by the Super-Kamiokande Collaboration. We conclude that several nonstandard neutrino flavor conversion mechanisms provide a very good fit to the experimental data which is comparable with (or even slightly better than) the most famous solution to the solar neutrino anomaly based on the neutrino oscillation induced by mass.

Sintese e aplicação de filmes biocomponentes nanoestruturados de 'TI'/'TI''O IND.2'/'W''O IND.3' por template e 'SI'/'TI''O IND.2'/'PT' por heterojunção em conversão de energia solar e remediação ambiental

Pós-graduação em Química - IQ