The magic nature of 132Sn explored through the single-particle states of 133Sn

Atomic nuclei have a shell structure where nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lie outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn.Comment: 19 pages, 5 figures and 4 table

Por um olhar inverso: prismas e questões de pesquisa sobre a economia solidária

A Economia Solidária constitui hoje um tema de pesquisa cuja expansão em várias disciplinas vizinhas à Sociologia é nítida e profícua. Nesse contexto, e tendo em vista as novas alternativas de investigação propiciadas pelo "Mapeamento Nacional da Economia Solidária no Brasil", o artigo discute algumas frentes de trabalho ainda merecedoras de investigação e consolidação teórica, no âmbito do que considera como pauta de pesquisa já em evidência. A seguir, chama atenção para aspectos do padrão de pesquisa vigente nesse campo, uma vez que seu entrelaçamento com a práxis política da Economia Solidária tende a resultar em renúncias a tratar determinados problemas e em lacunas de conhecimento. Diante disso, propõe bases para um delineamento investigativo com maior amplitude cognitiva, em especial no sentido de reconhecer os fatores primordiais de impulsão da Economia Solidária e a sua irredutibilidade ao econômico.<br>The Solidarity Economy constitutes, nowadays, a research theme whose expansion into Sociology's neighboring disciplines is clear and fruitful. In this context, in view of the new investigation alternatives brought about by the "Brazilian Solidarity EconomyNational Mapping", the article first discusses some work fronts that still deserve investigation and theoretical consolidation, within what the considered research agenda in working process. The article, then, questions the existing research pattern in this field, sustaining that its connections with the political praxis of the Solidarity Economy may result in avoiding problems and renouncing knowledge. Due to these findings, the article proposes bases for an investigative design with larger cognitive amplitude, especially regarding the recognition of the main impulsion factors of the Solidarity Economy and its irreducibility to the economic