Experimentally Resolved Photo-Excitation Cross Sections Below the Neutron Separation Energy

Numerous nuclear resonance fluorescence experiments have been performed in recent years to study the photon strength function of nuclei up to $E_\gamma = S_n$ by measuring the photo-excitation cross section; however, accurate measurement of the total cross section remains an experimental challenge. A simple method of evaluating several aspects of experimentally resolvable photo-excitation cross sections below $E_x = S_n$ within a statistical model will be presented. The method used in the statistical code developed for this work differs from the widely-used DICEBOX algorithm [1] in that only transition widths of $\gamma$-rays which directly depopulate photo-excited states are sampled and converted into observable quantities, as production of a complete $\gamma$-ray intensity spectrum would be superfluous for this purpose. Available experimental data on the $N=50$ and $N=82$ isotonic chains will be compared with results using photon strength functions given by the standard Lorentzian and the model of Kadmenskii, Markushev, and Furman [2].\\[4pt] [1] F. Be\v{c}v\'{a}\v{r}, Nucl. Instrum. Meth. A 417, 434 (1998).\\[0pt] [2] S.G. Kadmenskii, V.P. Markushev, and V.I. Furman, Yad. Fiz. 37, 277 (1983).