Fernando Brenha Ribeiro

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In this study, a least squares procedure for calculating the calibration constants of a portable gamma-ray spectrometer using the general inverse matrix method is presented. The procedure weights the model equations fitting to the calibration data, taking into account the variances in the counting rates and in the radioactive standard concentrations. The(More)
A ground gamma-ray survey was conducted over part of a large granitic body located near the city of Campinas, eastern São Paulo State, Brazil. The dominant rock types are K-feldspar porphyries-rich granites, porphyritic biotite and hornblend-bearing granites, fine to medium-grained monzogranites and medium to gross grained, biotite and muscovite-bearing(More)
The radon emanation method was applied to measure the activity of 226Ra, dissolved and associated with suspended solids, in the ground waters from two wells drilled in the Morungaba Batholith fractured granites, intruded in the metamorphic basement, eastern border of the Paraná basin in São Paulo State, Brazil. The water samples were collected from March(More)
Activities of gamma-ray emitting members of the uranium (238U) and thorium (232Th) series were measured in a quaternary limestone deposit that outcrops in the southeastern Pantanal Matogrossense Basin and in quaternary tufas deposited at the drainage of the Serra da Bodoquena. It is a first step in a study of the mobilization of uranium and thorium series(More)
A detailed radiochemical procedure for alpha spectrometry measurements of uranium concentrations and of 234U/238U activity ratios in silicates is presented. The described chemical processing is characterized by relatively high uranium yields, in the range of 51-89%. The application of this chemical procedure to geological standards allowed estimating a(More)
In the city of Limeira, southeastern Brazil, an important exposure of Permian sediments of the Paraná basin was revealed by an open pit mine that exploits limestone for production of soil correction compounds and raw materials for the ceramic industry. The radioactivity of these sediments was investigated in some detail and the results provided a general(More)
A detailed radiochemical procedure for alpha spectrometry measurements of thorium concentrations and of 230Th/232Th activity ratios in silicates is presented. The Th behaviour, during each step of the chemical process, was investigated by using a 234Th tracer, which is a gamma-ray emitter. The described chemical processing provides relatively high thorium(More)
The assembling of a system for field sampling and activity concentration measurement of radon dissolved in groundwater is described. Special attention is given in presenting the calibration procedure to obtain the radon activity concentration in groundwater from the raw counting rate registered in a portable scintillation detector and in establishing the(More)
Uranium, thorium and potassium measurements and volumetric heat production rate calculations were made in Bambui Group Neoproterozoic sedimentary rocks from the São Francisco Basin, central Brazil. The measurements were made from drilling cuttings from two deep wells drilled near the cities of Alvorada do Norte, northeast Goiás State, and Montalvânia, north(More)
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