No description available.

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In recent years, there have been several research endeavors to increase the ability to identify and quantify special nuclear material in field measurements. These have included both gamma spectroscopy and neutron coincidence systems that are portable and work in a variety of environments. In this work, a Monte Carlo Neutral Practicle X (MCNPX) model was used to design an instrument that includes four gamma detection slabs placed within four neutron detection slabs. The combination of gamma spectroscopy and neutron coincidence counting in a single instrument allows for direct measurement of plutonium (Pu) mass without need for assumptions or operator declarations. A combined neutron-gamma instrument was designed for use in characterizing and quantifying Pu in field samples. This detector consists of a plastic scintillator containing LaBr3 nanoparticles and a polyethylene slab containing four 3He tube detectors. The system was tested via simulation with MCNPX for four Pu samples of known quality and quantity. These samples had masses ranging from 100-300 g of Pu. It was found that the designed detector system could be used to determine 240Pu-effective mass to within 3.5% accuracy and to characterize the isotopic content of the Pu to within 2% accuracy for all isotopes except for 238Pu and 242Pu. The system could determine 238Pu isotopic content to within 14% accuracy but is completely unable to determine 242Pu content. This system has the ability to Four Plutonium (Pu) samples of known quantity were modeled and tested to determine what data was available from each individual signature. Each model included a separate MCNPX deck for each individual isotope that contributes to the gamma signature in photon mode and a spontaneous fission and (alpha,n) deck for the neutron signature. The first three samples were used to create spectrums and efficiency curves for each odd isotope as well as for a Pu effective mass for the neutron signature. The data from these simulations were then used to identify the isotopics in the fourth sample to within acceptable accuracy. From this data, a total Pu mass was obtained as well as an ability to determine the ratio of (alpha,n) to spontaneous fission neutrons without additional simulations. This provides a new method to detect and identify the Pu content within a sample without producing requiring supplemental additional information since isotopics can be determined with the combined use of the gamma and neutron systems.

Made available in DSpace on 2014-10-09T12:55:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:56Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:37:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:26Z (GMT). No. of bitstreams: 1 11277.pdf: 1195463 bytes, checksum: 8dc42e0617e56d7a2b38c99f8b1ce4ff (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:55:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:56Z (GMT). No. of bitstreams: 0 / O Laboratório de Análise por Ativação com Nêutrons (LAN) do Instituto de Pesquisas Energéticas e Nucleares (IPEN), utiliza esta técnica analítica multielementar, baseada na irradiação de uma amostra por um feixe de nêutrons oriundos de um reator nuclear, que induz a radioatividade; que é medida em um espectrômetro de raios gama, para a obtenção dos espectros de raios gama. Neste trabalho é implementado um software denominado de SAANI (Software Análise por Ativação com Nêutrons Instrumental) para análise de espectros de raios gama, desenvolvido para os usuários do laboratório LAN-IPEN, com a filosofia de software livre, para a substituição do software existente VISPECT/VERSÃO 2, e tem como características principais: tornar a interface mais amigável; facilitar a padronização dos procedimentos realizados pelos pesquisadores, estudantes e técnicos; ser extensível com a utilização da tecnologia de plugins; multiplataforma; código livre. O software foi desenvolvido utilizando a linguagem de programação Python, a biblioteca gráfica Trolltech Qt e algumas de suas extensões científicas. Os resultados preliminares obtidos utilizando o software SAANI foram comparados aos obtidos com o software existente e foram considerados bons. Algumas diferenças encontradas foram verificadas oriundas de erros de precisão na implementação do software. O software SAANI está instalado nos computadores de usuários selecionados para a execução de rotinas de análise para uma maior verificação de sua robustez, precisão e usabilidade. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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No description available.

The international project KATRIN (KArlsruhe TRItium Neutrino experiment) is a next- generation tritium beta decay experiment. It is designed to measure the electron antineutrino mass by means of a unique electron spectrometer with sensitivity of 0.2 eV/c2 . This is an improvement of one order of magnitude over the last results. Important part of the measurement will rest in continuous precise monitoring of high voltage of the KATRIN main spectrometer. The monitoring will be done by means of conversion electrons emitted from a solid source based on 83 Rb decay. Properties of several of these sources are studied in this thesis by means of the semiconductor gamma-ray spectroscopy. Firstly, measurement of precise energy of the 9.4 keV nuclear transition observed in 83 Rb decay, from which the energy of conversion electrons is derived, is reported. Secondly, measurement of activity distribution of the solid sources by means of the Timepix detector is described. Finally, a report on measurement of retention of 83 Rb decay product, the isomeric state 83m Kr, in the solid sources is given.