Measurements of the $^{124}$Sn($\gamma$,n) and $^{169}$Tm($\gamma$,n) cross sections at E$_\gamma$ = 13 MeV*

Nuclear data for photo-nuclear reactions is scarce. By using the activation technique, ($\gamma$,n) cross sections can be measured to a high precision. $^{169}$Tm(n,2n) is a common neutron monitor reaction, but there is no available data on its photo-nuclear counterpart, the $^{169}$($\gamma$,n) reaction. Measurement of this reaction would allow use of thulium as a standard $\gamma$-ray monitor. The samples in this experiment were irradiated by monoenergetic $\gamma$-rays provided by the High Intensity $\gamma$-ray Source (HI$\gamma$S) located at Duke University. The resultant activity was quantified using $\gamma$-ray spectroscopy with high purity germanium detectors. The data confirmed the literature half-lives of $^{196}$Au, $^{123m}$Sn, and $^{169}$Tm as 6.16 d, 40.1 m, and 93.1 d, respectively. The first successful cross-section measurements of $^{124}$Sn($\gamma$,n)$^{123m}$Sn and $^{169}$Tm($\gamma$,n)$^{168}$Tm reactions were performed.