Description of yrast traps inHf176

Abstract

The yrast traps in ${}_{72}{}^{176}{}_{}{}^{}\mathrm{Hf}_{104}^{}{}_{}{}^{}$ with angular momenta $J=K=14\mathrm{} \mathrm{to} 22$ are studied in a cranked Hartree-Fock-Bogoliubov approach with particle number projection before the variation of the important degrees of freedom. It is shown that the bands formed on the $J=K$ bandheads corresponding to rotation around the prolate symmetry axis intersect the ground state rotational band ($K=0\mathrm{}$) to form these yrast traps. The main reason for the low energy of the $K=J$ bandheads is the concentration of Nilsson levels with a large angular momentum projection $\Omega$ on the symmetry axis near the Fermi surface in this nucleus.