| Abstract: |
Samples irradiated at the core of a nuclear reactor are activated with thermal and epithermal neutrons. The spectrum of the thermal neutrons has approximately a Maxwellian distribution of the neutron velocity. Its peak position varies according to the temThe present work can be summarized as:1-Study of k0 Parameters f, ? and Q0 for the Thetis Reactor (INW/Gent):The thermal to epithermal neutron flux ratio f. ? is the deviation of the power of the reciprocal of the neutron energy E of the epithermal neutron spectrum from the ideal 1/E law. Q0 is the ratio of the resonance integral to thermal neutron cross sectiona- “Cd-covered multi-monitor” method.b- “Cd-ratio for multi-monitor” method.c- “Bare multi-monitor” method.The conversion of Q0 value to Q0(?) can be determined. Also the value of f factor can be determined by the “Cd-ratio method”. In cases where the maxwellian neutron temperature (Tn) plays a role, formalism (such as Westcott’s) is needed. It may be implemen2-Determination of Irradiation Parameters of the ET-RR-2 ReactorThe high precision of the k0 standardization requires a precise determination of the irradiation parameters (f, ?) at the irradiation positions. Standard samples of (Fe, Au, Zr, Co, and W) with the aluminum foil sample as well as the iron ore samples were3-Investigation of an Aluminum Foil sampleAn aluminum foil for food packaging during cooking produced by the Egyptian Copper Works at Alexandria was investigated by thermal and epithermal neutron activation analysis (NAA). The gamma-ray spectrum of the sample was measured several times for period4-Investigation of Egyptian Iron Ore SamplesAn iron ore sample from Umm-Nar and other three samples from Wadi-Kareim in the eastern desert of Egypt. The gamma-ray spectrum of each sample was measured several times for periods between 3600 and 5000 sec. during eight weeks post irradiation. Iron was The thesis contains six chapters which including details of the work:In chapter one, a general introduction is given. The history of different methods for neutron activation analysis with the contribution of the epithermal activation parameters (f, ?, ?r, Q0) is reported. An outline of the different applications as well asIn chapter two, the principal of theoretical basis for neutron activation analysis (absolute, relative, single-comparator, k0-standardization) are reported in details.In chapter three, short description of the irradiation facilities [Thetis reactor (Gent) and the second Egyptian research reactor (ET-RR-2)] is given where the irradiation positions were shown. Also the Ge detection systems with energy, efficiency calibraIn chapter four, the experimental determination of the parameters (f, ?, Q0) for the Thetis reactor at the irradiation sites (channels 3, 15) are given with a temperature determination by applying Westcott’s formalism for 166Lu).In chapter five, the sensitivity concept was introduced to the activation equation. The cadmium ratio, the k0 and the Q0 were expressed in terms of the sensitivity concept. The high precision of the k0 standardization led to an acceptable precision in theIn chapter six, the experimental determination of the parameters (f,?) for the ET-RR-2 is given. Also investigations of the Al-foil sample and the iron ore samples by using the k0-standardization are given.A conclusion of this work is given.Lists of 138 references are included at the end of this thesis.
|
|
|