γ-Particle coincidence technique for the study of nuclear reactions

a b s t r a c t The Saci-Perere γ ray spectrometer (located at the Pelletron AcceleratorLaboratory -IFUSP) was employed to implement the γ-particle coincidence technique for the study of nuclear reaction mechanisms. For this, the Pd has been extracted and compared to coupled channel calculations using the São Paulo Potential (PSP), being reasonably well described by it

Bedrock and Detrital Zircon Thermochronology to Unravel Exhumation Histories of Accreted Tectonic Blocks: An Example from the Western Colombian Andes

The Northern Andes are the result of multiple tectonic phases, which include extensional and compressional volcanic arcs, strike-slip fragmentation, and accretion of exotic terranes. The alternations of these tectonic settings have overprinted and fragmented the geological record, which has hindered precise paleogeographic and tectonic reconstructions. In the western segment of the Colombian Andes, the oceanic-cored Western Cordillera (WC) and the continental Central Cordillera (CC) are separated by the Romeral Fault Zone (RFZ). This segment of the Andes preserves the record of Cretaceous back-arc extension, the onset of compression, and the accretion of the Caribbean plateau during the Late Cretaceous-Paleocene. To refine the tectonic evolution of the Western Colombian Andes, this study documents new detrital zircon fission-track (ZFT) data from the Meso-Cenozoic sedimentary cover in the CC, the RFZ, and the WC; new ZFT and zircon helium (ZHe) bedrock data from the CC and the RFZ; and new U–Pb detrital data from the Miocene sedimentary cover of the RFZ. Within the RFZ, we obtained bedrock ZFT ages of 239.0 ± 11.0 Ma and 111.1 ± 4.3 Ma, and detrital ZFT data from the Abejorral Formation are interpreted as the result of post-magmatic cooling and Cretaceous rifting. Late Cretaceous to Eocene ZFT and ZHe ages (~61–50 Ma) in the CC and detrital ZFT data in the WC record exhumation and deformation of the CC during and after the collision of the Caribbean plateau with the continental margin. Finally, detrital U–Pb and ZFT data from the Amagá Formation record the formation of a Miocene intermountain basin. This study reconstructs the basin geometries and the deformation patterns before, during, and after the collision of the Caribbean plateau with the South American margin. We highlight that in accretionary orogens, in which prolonged deformation and erosion have removed the sedimentary cover, the quantification of differential basement exhumation is key to reconstruct thick-skin deformation and to define major tectonic boundaries

Future perspectives for neutron beam utilization in Brazil

Sem informação[No abstract available]The production of radioisotopes in the Brazilian research reactors has a limited capacity leading to a high dependence on external supply. In order to overcome this issue and due to the high age of these research reactors, in 2010 the Brazilian Nuclear Commission decided to develop a new research reactor for radioisotope production, nuclear materials and fuel irradiation testing and neutron beam science. Regarding the last purpose, the Brazilian Multipurpose Reactor (RMB) has been designed to provide thermal and cold neutron beams using neutron guides to transport neutrons to a large hall of instruments. This article describes the main characteristics of the RMB project.25435Sem informaçãoSem informaçãoSem informaçã

Instrumental Neutron Activation Analysis (INAA) As-sessment of REE of Soil from Mining Site Umuahia, Abia State, South East, Nigeria

In this work, the main goal was to examine the REE concentration and distribution pattern in soil from Umuahia, Abia State, Southeast, Nigeria, in a clay mining site compared with a non-contaminated site approximately 3 km away. The REE were determined by Instrumental Neutron Activation Analysis (INAA) at IPEN, Brazil. The main mineralogy of the samples was determined by XRD. The following REE were determined: Ce, Eu, La, Lu, Nd, Sm, Tb and Yb. Soil samples from the mining area present quartz and kaolinite as their main constituents, with REE concentrations comparable with that of the Upper Continental Crust and the North American Shale Composite. The calculated Geoaccumulation index (IGeo) indicate that REE have natural origin and ∑LREEN/∑HREEN ratio show an enrichment of the light over heavy REE, in samples of the clay mining area