likely to depend more or less on the freeze-out conditions for which the $(n,\gamma$)–($\gamma,n$) competition comes out of equilibrium. Under such conditions, an accurate and reliable determination of all the ingredients of relevance in the calculation of the neutron capture rates, including in particular the $\gamma$-strength function, is required.

The nuclear physics group in Oslo has performed measurements on the $\gamma$-ray strength functions below neutron threshold of various light and medium-mass nuclei [@Fe_Alex; @Fe_Emel; @Mo_RSF; @V; @Sc]. These data have revealed an unexpected increase in the $\gamma$-decay probability at low $\gamma$-ray energies. This enhancement is seen to be present typically for $E_\gamma \leq 3 $ MeV. In contrast to other soft resonances observed previously such as the $M1$ scissors mode [@PragueM1; @SchillerM1], the physical origin of the enhancement remains unknown. There is, for the time being, no established theory that is able to explain this *upbend* phenomenon.

For nuclei close to the valley of stability, one might expect that the low-energy enhancement would have little influence on the neutron-capture cross section. Naturally, the most important energy region for the neutron-capture reaction is in the vicinity of the neutron separation energy $S_n$, and low-lying structures in the $\gamma$-ray strength function would 