should be stressed that both approaches are completely phenomenological, since there is at present no proper theoretical description of the upbend structure.

For the first approach, the upbend is given by a low-lying resonance described by an SLO shape: $$f_{\mathrm{up1}}(E_\gamma)=\frac{1}{3\pi^2\hbar^2c^2} 
    \frac{\sigma_{\mathrm{up1}}E_\gamma\Gamma_{\mathrm{up1}}^2} {(E_\gamma^2-E_{\mathrm{up1}}^2)^2+E_\gamma^2\Gamma_{\mathrm{up1}}^2},
\label{eq:lorup}$$ located at a resonance energy of $E_{\mathrm{up1}}=1.5$ MeV with a full width at half maximum $\Gamma_{\mathrm{up1}}=1.5$ MeV and a peak cross section $\sigma_{\mathrm{up1}}=0.05$ mb. This resonance is added to the GLO-lo strength in order to make the total RSF fit with the low-energy data as well; this model is referred to as GLO-up1 and its Mo description is shown in Fig. \[fig02\].

For the second approach, we have modified the temperature-dependent width of the GLO model in the following way: $$\Gamma_{\rm up2}(E_{\gamma},T_f) = \frac{\Gamma_{E1}}{E_{E1}^2} \left[E_{\gamma}^2 + 
    \frac{4\pi^2T_f^2E_{E1}}{(E_{\gamma}+\delta)}\right], 
\label{eq:glowidthmod}$$ where the introduction of an $E_{\gamma}^{-1}$ dependence in the second term enables an increasing RSF for decreasing $E_{\gamma}$. The constant parameter $\delta = 0.05$ MeV is applied to ensure a finite value of $f_{\rm GLO}$ for $E_\gamma \rightarrow 0$. In this approach, the temperature $T_f $ has also been assumed to remain constant and the value of $T_f= 0.16$ MeV has been adjusted to reproduce at best the experimental 