Theoretical Study on the Estimation of Nuclear Resonance Fluorescence Cross Sections

Abstract

This thesis is concerned with theoretical estimation of the nuclear resonance fluorescence (NRF) cross-section, its Doppler broadening, and corresponding reaction rate using a semi-analytic method to facilitate NRF-based applications such as non-destructive material assay and nuclear transmutation. For the theoretical cross-section prediction, a modified single particle estimate (SPE) approach is introduced for more accurate estimation of the NRF reaction. Key point of this approach is to utilize experimental NRF cross-sections to correct the SPE model-based transition strength. The SPE model is used to analyze de-excitation process, which is categorized by a type and multipolarity of the NRF transition. Then, the reference data are divided into several subsets by certain criteria to correct the previous results. In each subset, scale down parameters are determined by the least-squares fitting method. In addition, the Doppler broadening of NRF cross sections has been analyzed for U-238 and its possible impact on cascade NRF reactions is also discussed in this work. Finally, the modified SPE approach is applied to estimate the production rate of $^{99m}Tc$ by irradiating a $^{99}Tc$ target with an LCS (laser Compton scattering) photon beam.