MARCELO FRANCIS MADUAR

MARCELO FRANCIS MADUAR

(Fonte: Lattes)

Resumo

Doctorate (2010) and Master (2000) degrees in Nuclear Technology at São Paulo University, Physics Bachelorate at São Paulo University (1996) and Technologist in Data Processing at Universidade Estadual Paulista Júlio de Mesquita Filho (1989). Experience in Experimental Physics, focusing on Experimental Methods and Instrumentation for Elementary Particles and Nuclear Physics. (Text obtained from the Currículo Lattes on November 16th 2021)

Doutorado (2010) e Mestrado (2000) em Tecnologia Nuclear pela Universidade de São Paulo, Bacharelado em Física pela Universidade de São Paulo (1996) e graduação em Tecnologia Em Processamento de Dados pela Universidade Estadual Paulista Júlio de Mesquita Filho (1989). Tecnologista senior do Instituto de Pesquisas Energéticas e Nucleres (IPEN), órgão da Comissão Nacional de Energia Nuclear (CNEN). Gerente adjunto (desde julho/2018) do Serviço de Gestão de Radiometria Ambiental (SEGRA) do IPEN. Tem experiência na área de Física, com ênfase em Métodos Experimentais e Instrumentação para Detectores de Radiação, atuando principalmente nos seguintes temas: espectrometria gama, radioatividade ambiental e aplicação de métodos computacionais na avaliação de espectros gama, em modelos de dispersão ambiental e em dose externa decorrente de radiação gama. Orientador de Mestrado do Programa de Pós-Graduação em Tecnologia Nuclear do IPEN - área de Aplicações (TNA) a partir de maio de 2019 e docente das disciplinas TNA5754, Radioatividade no meio ambiente e avaliação de impacto radiológico ambiental, e TNA5733, Tópicos Avançados de Medidas Nucleares. (Texto extraído do Currículo Lattes em 16 nov. 2021)

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Counting efficiency in gamma-ray spectrometry with different sample volumes for the same geometry
2022 - NISTI, M.B.; MADUAR, M.F.; DAMATTO, S.R.; ALENCAR, M.M.
The aim of this study is to determine an easy and fast method to calculate efficiencies in different volumes, in the same counting geometry, for gamma-ray spectrometry technique. Reference Material Soil IAEA 326 was packed in a 100 mL capacity polyethylene bottle with different masses and volumes, and sealed for about four weeks, prior measurement, in order to ensure that radioactive equilibrium had been reached between 226Ra and its progeny. After this time, they were measured by gamma-ray spectrometry with a hyper-pure germanium detector. The masses of the reference material used were 25, 60, 80, 95 and 128g. The energies of gamma-rays used in this paper are recommended due to the considerations: gamma intensity value, peak quality, spectral region without interference and the gamma- ray energies of the 238U and 232Th series very important for determining the natural radioactivity. The efficiency values obtained compared to the adjusted efficiency values were similar and presented a good correlation coefficient. The performance was acceptable for all different masses studied, indicating results consistent for the method. The proposed method could be useful as a tool for laboratories, dealing with of samples on a routine basis, by reducing the cost on the purchase of another counting geometry and optimizing the use of the detection system, thus improving their performance.
Radiological implications of using phosphogypsum as building material
2020 - MAZZILLI, B.P.; CAMPOS, M.P.; NISTI, M.B.; SAUEIA, C.H.R.; MADUAR, M.F.
Phosphogypsum, a waste byproduct derived from the production of phosphoric acid, is being worldwide stock-piled, posing concerns about the environmental problems originating from this practice. Considerations about the viability of the safe reuse of this material have been raised, among them its potential use as building material. However, as phosphogypsum can contain natural radionuclides in significant concentrations, using it as a build-ing material has radiological implications, which presently prevent such application. In order to evaluate the feasibility of using phosphogypsum in the manufacturing of building elements such as bricks and plates, a com-prehensive research was undertaken in Brazil, following a multiple approach. This research included studies related to: Brazilian phosphogypsum characterization; experimental determination of radon exhalation rate; and application of theoretical models to forecast both radon exhalation and external doses in dwellers. In this paper, a comprehensive review of the research carried out in Brazil is presented.
Optimization of the gamma-ray spectrometry counting time based on uncertainties of radionuclides concentration in samples
2020 - NISTI, M.B.; MADUAR, M.F.; SAUEIA, C.H.R.; CAVALCANTE, F.; MAZZILLI, B.P.
This paper aims to propose an easy and fast method of optimization of the gamma-ray spectrometry counting time in determining natural radionuclides (210Pb, 212Pb, 214Pb, 212Bi, 214Bi and 228Ac) in order to minimize uncertainties in the concentration. The samples were measured by gamma-ray spectrometry with a hyper-pure germanium detector Canberra, 25% relative efficiency, effective resolution of 1.9 keV on the 1332.5 keV 60Co with associated electronics and coupled to a microcomputer. Multichannel Maestro A65-I model was used for spectrum acquisition and peak net area determination, and WinnerGamma/Interwinner 6.01 software was used for gamma-ray spectra analysis and to calculate the concentrations and associated uncertainties. The counting times used were 86,000 s and 150,000 s.
Radiation hazard indices in the application of phosphogypsum mixtures as a building material
2019 - MADUAR, M.F.; MAZZILLI, B.P.; NISTI, M.B.
Phosphogypsum (PG), a by-product from the phosphoric acid industry, is being worldwide stockpiled, posing environmental problems. Viability of the PG safe re-use in civil construction has been studied, as PG can contain natural radionuclides in significant concentrations. We propose a policy for using PG as a building material, limiting the total concentration of 226Ra plus 228Ra by mixing PG with natural gypsum. It was concluded that PG from the largest Brazilian deposits could be used without any dilution, when the sum of the activity concentrations of 226Ra and 228Ra does not exceed 150 Bq kg-1. For higher values, the approach is to mix PG with increasing amounts of natural gypsum, so that the final concentration does not exceed 1000 Bq kg-1. We show that PG re-use in such a way is feasible in terms of radiological protection and recommended to minimize PG piles environmental impact.