Thermal Neutrons
Mostrando 1-12 de 25 artigos, teses e dissertações.
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1. Evaluation of a Metal-Organic Composite (Tungsten-Lignin) for Attenuation of Gamma Radiation
The objective of this work was to use tungsten and lignin as precursors to obtain a metal-organic composite tungsten-lignin (W-Lig) using different sintering temperatures. Tungsten is a refractory metal and it was selected for the composite since it is widely used for high-energy radiation shielding as it has an excellent absorption cross section for thermal
Mat. Res.. Publicado em: 02/09/2019
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2. Condições de contorno albedo para cálculos globais de reatores nucleares térmicos com o modelo de ordenadas discretas a dois grupos de energia / Albedo boundary conditions for thermal nuclear reactors global calculations with two energy group discrete ordinates formulations
Como eventos de fissão induzida por nêutrons não ocorrem nas regiões nãomultiplicativas de reatores nucleares, e.g., moderador, refletor, e meios estruturais, essas regiões não geram potência e a eficiência computacional dos cálculos globais de reatores nucleares pode portanto ser aumentada eliminando os cálculos numéricos explícitos no interior
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 28/11/2011
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3. Pequenos polarons ligados e centros de cor em topázio
In the present work we studied the color beneficiation processes of colorless topaz, an abundant gemstone in Brazil. Blue topaz is the most internationally traded gemstone in the gem and market, reaching about 100 million carats per year. Almost 100% of blue topaz received some treatment to improve the color that, generally, involves some type of irradiation
Publicado em: 2010
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4. DOSIMETRIC EVALUATION OF SPECTROPHOTOMETRIC RESPONSE OF ALANINE GEL SOLUTION FOR GAMMA, PHOTONS, ELECTRONS AND THERMAL NEUTRONS RADIATIONS / Avaliação dosimétrica da resposta espectrofotométrica da solução gel de Alanina para radiação gama, de fótons, de elétrons e de nêutrons térmicos
O dosímetro alanina gel é um novo material na forma de gel desenvolvido pelo IPEN, que apresenta uma melhora significativa em relação ao sistema a base de Alanina desenvolvido por Costa. A DL-Alanina (C3H7NO2) é um aminoácido tecido equivalente que favorece a produção de íons Férricos na solução. Este trabalho visa analisar as principais caracter
Publicado em: 2009
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5. Neutron induced radiography: a technique to inspect the internal structure of thin samples
The present paper describes a radiography technique to inspect low thickness samples, on the order of micra. The penetrating radiation are charged particles generated by a lithium fluoride screen irradiated by thermal neutrons. The film used to register the images is a solid state nuclear track detector and the experimental conditions to obtain the best radi
Brazilian Journal of Physics. Publicado em: 2008-09
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6. Caracterização do campo de nêutrons na instalação para estudo em BNCT no Reator IEA-R1 / NEUTRON FIELD CHARACTERIZATION IN THE INSTALLATION FOR BNCT STUDY IN THE IEA R1 REACTOR.
This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the convention
Publicado em: 2008
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7. Calibração dos canais nucleares do Reator IPEN/MB-01, obtida a partir da medida da distribuição espacial do fluxo de nêutrons térmicos no núcleo do reator através da irradiação de folhas de ouro infinitamente diluídas / CALIBRATION OF THE NUCLEAR POWER CHANNELS OF THE IPEN/MB-01 REACTOR OBTAINED FROM THE MEASUREMENTS OF THE SPATIAL THERMAL NEUTRON FLUX DISTRIBUTION IN THE REACTOR CORE THROUGH THE IRRADIATION OF INFINITELY DILUTED GOLD FOILS
Several nuclear parameters are obtained through the gamma spectrometry of targets irradiated in a research reactor core and this is the case of the activation foils which make possible, through the measurements of the activity induced, to determine the neutron flux in the place where they had been irradiated. The power level operation of the reactor is a par
Publicado em: 2008
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8. Estudo de traços de fissão em vidro utilizando-se microscopias de força atomica e eletronica de varredura : inferencia da estrutura de traços latentes a partir de traços atacados / Glass fission track analysis by AFM and SEM : inferring latent track structure trough etched tracks
A study on the geometric evolution of 235U induced fission tracks in a soda-lime glass was made. It was necessary to know about the geometric model for structure evolution of fission tracks in isotropic materials. This model is based on the competition of two chemical etching rates: one in the bulk material (VB) and another in each fragment trajectory (VT).
Publicado em: 2008
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9. Thermal neutron computed tomography at the Argonauta Reactor
Since 1985 the Argonauta Reactor at the Instituto de Engenharia Nuclear - IEN/CNEN has been used as a source of thermal neutrons to acquire transmission-generated radiographic images. From that time until the end of the last century, some Universities and Research Institutions have as well used the irradiation facilities of this reactor for that purpose and
Brazilian Journal of Physics. Publicado em: 2005-09
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10. Evaluation of the fluence to dose conversion coefficients for high energy neutrons using a voxel phantom coupled with the GEANT4 code
Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the male adult voxels phan
Brazilian Journal of Physics. Publicado em: 2005-09
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11. A direct measurement of the neutron-neutron scattering length
A direct measurement of nn-scattering by colliding free neutrons has never been performed. Indirect measurements continue to provide inconsistent results, leaving the issue of charge symmetry in the nuclear force unresolved. At present the Russian pulsed reactor YAGUAR is the best neutron source for such a measurement. A neutron moderator is installed in the
Brazilian Journal of Physics. Publicado em: 2005-09
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12. Development of a CCD-based image acquiring system for neutrons at the Argonauta Reactor
A thermal neutron image acquiring system is being developed at the Instituto de Engenharia Nuclear-IEN (CNEN). This system would be capable to perform non-destructive assays after 2D images acquired on a real or quasi real time basis as well as 3D tomographic images reconstructed from the two-dimensional ones. The source-detector set is constituted by the Ar
Brazilian Journal of Physics. Publicado em: 2005-09