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A fast pneumatic transfer facility was installed at the Nuclear Engineering Teaching Laboratory (NETL) of the University of Texas at Austin for the purpose of cyclic thermal and epithermal neutron activation analysis. In this work efforts were focused on the evaluation of cyclic epithermal neutron activation analysis (CENAA). Various NIST and CANMET certified materials were analyzed by the system. Experiment results showed 110Ag as one of the isotopes favored by the system. Thus, the system was put into practical application for identifying silver concentration in the Arctic atmospheres in air filters collected in 2009, and traces in metallic ores Comparison of silver concentrations via CENAA with the CANMET certified reference materials gave very good results. / text

A prompt-gamma, neutron-activation analysis facility earlier developed at the Nuclear Science Center of Texas A&M University could not be used successfully to analyze geologic samples due to high detection background, low neutron fluence rate and poor detection equipment . A systematic investigation into the performance capability of a prompt-gamma, neutron activation analysis facility was undertaken in this research project. The facility was reconstructed and used to obtain prompt-gamma spectra of chlorine and cadmium and from the spectra, the net peak area counts for the most intense prompt-gamma-ray energies were obtained. A theoretical model was developed which can predict the net peak area counts expected on these prompt-gamma-ray energies using the thermal neutron fluence rate at the sample position, the absolute efficiency of the detector, and the mass and partial gamma-ray production cross section data for the samples. The experimental and predicted results were compared to establish the performance capability of the reconstructed facility. Good agreements between experimental and predicted results were obtained for chlorine, but results from cadmium showed larger discrepancies due to self-shielding effects. Corrections for self-shielding effects were applied to results from cadmium and the experimental and predicted results were also in good agreement. The satisfactory results indicate that it is possible to implement the prompt-gamma, neutron-activation analysis technique at Beam Port #1 of the Nuclear Science Center Reactor. To be able to obtain excellent results from other samples, improvements in shielding materials to attain a lower detection background and a highly efficient detection system should be incorporated.

A prompt-gamma, neutron-activation analysis facility earlier developed at the Nuclear Science Center of Texas A&M University could not be used successfully to analyze geologic samples due to high detection background, low neutron fluence rate and poor detection equipment . A systematic investigation into the performance capability of a prompt-gamma, neutron activation analysis facility was undertaken in this research project. The facility was reconstructed and used to obtain prompt-gamma spectra of chlorine and cadmium and from the spectra, the net peak area counts for the most intense prompt-gamma-ray energies were obtained. A theoretical model was developed which can predict the net peak area counts expected on these prompt-gamma-ray energies using the thermal neutron fluence rate at the sample position, the absolute efficiency of the detector, and the mass and partial gamma-ray production cross section data for the samples. The experimental and predicted results were compared to establish the performance capability of the reconstructed facility. Good agreements between experimental and predicted results were obtained for chlorine, but results from cadmium showed larger discrepancies due to self-shielding effects. Corrections for self-shielding effects were applied to results from cadmium and the experimental and predicted results were also in good agreement. The satisfactory results indicate that it is possible to implement the prompt-gamma, neutron-activation analysis technique at Beam Port #1 of the Nuclear Science Center Reactor. To be able to obtain excellent results from other samples, improvements in shielding materials to attain a lower detection background and a highly efficient detection system should be incorporated.

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<p> The development of a unified system for the automatic neutron activation analysis of large numbers of samples is described. The realization of the system entailed the automation of a gamma ray spectrometer system by means of a data and control link to a small computer (PDP-15) and the development of a reliable and fast data reduction algorithm suited to the small computer system. A detailed study of the algorithm and the errors associated with it has been included. </p> / Thesis / Master of Science (MSc)

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