No description available.

No description available.

No description available.

In this study variations in Ortec and Hamner equipment with different types of detectors were utilized in coincidence circuits to receive the smallest lifetime values of nuclear states. Results from Ge(Li)-NaI(Tl) detectors were compared to results received when NaI(Tl)-NaI(Tl) detectors were combined in a coincidence circuit.Four different isotopes were investigated. Samples of 22Na and 60Co were utilized as prompt sources. The lifetimes of the 0.81 MeV energy level of i33Ba and the 0.124 MeV energy level of 154Eu were studied. These lifetimes have been reported as being 6.3 nsec and 1.18 nsec respectively.The best value received for the 154Eu energy state was a slope measurement of 5.85 ± 3.15 nsec. The smallest value for the 133Ba energy state was a centroid shift measurement of 6.93 nsec.

Previous studies of gamma ray spectra for different elements have been made by others using NaI(T1) (thallium activated, sodium iodide) detectors. This study has been done using a Ge(Li) (lithium drifted germanium) detector. Ge(Li) detectors feature much better energy resolution than do NaI(Tl) detectors. Using a Ge(Li) detector enables one to detect gamma rays closely spaced in energy that ordinarily would be unidentifiable due to the much poorer energy resolution of the NaI(Tl) detectors.Gamma ray spectra from 31 elements irradiated with 14-MeV neutrons have been examined, analyzed, and catalogued. These spectra can be used in the future as an aid in identifying elements using neutron activation analysis.

Thesis (Ph. D.)--University of Washington, 1993. / Vita. Includes bibliographical references (leaves [176]-189).

Thesis (M.S.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 62-64). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

The doublet level at E_p = 504 kev excited in the reaction Al²⁷(p, γ)Si²⁸ was investigated using a technique of nuclear resonance fluorescence. A silicon absorber was placed in a collimated beam of gamma rays from the reaction. The direction of collimation with reference to the direction of the bombarding protons governs the exact energy of the ground state games available for absorption. The energy deficit which appears in emission and absorption is made up by the kinetic energy of the compound nucleus recoiling from the proton bombardment. Variation of the angle between the collimator and the proton beam allows the measurement of the transmission of the absorber as a function of energy. Though the energy variation is small absorption by excitation of the energy levels mentioned was covered in the range of angle chosen. For the above transmission experiment measurement of the ratio of the number of transmitted ground state gamma rays and of the number of decaying nuclei is necessary. This was accomplished in one counter. The entire spectrum from the reaction was observed at each angle. The number of ground state games was stripped from each such spectrum and the number of gammas decaying to excited states thus determined. Thus the number of ground state gammas was normalized to the number of lower energy gammas. The low cross section of the reaction, the collimation and absorption all lead to an extremely low counting rate even though a thick target with proton energy just above resonance was used. The V.P.I. Van de Graaff was used as a source of protons. Detection of gammas was by a 3 x 3 Na I crystal giving spectra on a 512 channel analyser. The analysis of the data was accomplished on an IBM 1620 computer. The resulting transmission versus energy data were fit to a straight line (i.e. no resonant absorption) and a more complicated assumption of some eight closely spaced levels. The straight line fit is considerably poorer but a result of no resonant absorption seems the more likely. / Ph. D.

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. / This study developed a specific software for gamma ray spectra analysis for researchers of the Neutron Activation Laboratory (LAN), which was named SAANI (Instrumental Neutron Activation Analysis Software). The LAN laboratory of the Institute for Research and Nuclear Energy (IPEN-CNEN/SP), uses a multielementar analytical technique, based on irradiation of a sample by a flux of neutrons from a nuclear reactor, which induces radioactivity. The sample is then placed in a gamma-ray spectrometer, to obtain the spectrum. With free software philosophy in mind, this software will replace the existing software VISPECT / VERSION 2. The new software´s main features are: a friendlier interface; easier standardization procedure carried out by LAN staff and researchers; adapted to the use of plug technology; multiplatform and code free. The software was developed using the programming Python language, the library Trolltech Qt graphics and some of their scientific extensions. Preliminary results using the SANNI software were compared to those obtained with the existing software and were considered good. There were some errors in accuracy during the implementation of the software. The SAANI software has been installed in selected computers to be used for routine analysis in order to verify its strength, accuracy and usability.