Simultaneous Microscopic Description of Nuclear Level Density and Radiative Strength Function

The nuclear level density (NLD) and radiative strength function (RSF) are simultaneously described within a microscopic approach, which takes into account the thermal effects of the exact pairing as well as the giant resonances within the phonon-damping model. The good agreement between the results of calculations and experimental data extracted by the Oslo group for ${}^{170,171,172}\mathrm{Yb}$ isotopes shows the importance of exact thermal pairing in the description of NLD at low and intermediate excitation energies. It also invalidates the assumption based on the Brink-Axel hypothesis in the description of the RSF.

Figure 1

Neutron and proton pairing gaps $\mathrm{\Delta }$ [(a)–(c)] as functions of $T$ and total level densities $\rho$ [(d)–(f)] as functions of $E^{*}$ obtained within the $\mathrm{EP}+\mathrm{IPM}$ in comparison with predictions of HFBC calculations for the positive and negative parities and the experimental data for ${}^{170,171,172}\mathrm{Yb}$ nuclei.

Figure 2

Radiative strength functions [(a)–(c)] obtained within the $\mathrm{EP}+\mathrm{PDM}$ in comparison with experimental data for ${}^{170,171,172}\mathrm{Yb}$ nuclei, and the corresponding total strength functions [(d)–(f)] together with their components for $E1$, $E2$, and $M1$ excitations as functions of $E_{\gamma }$ at different temperatures.