<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>66</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Co</mml:mi><mml:mo>,</mml:mo></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>68</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Co</mml:mi><mml:mo>,</mml:mo></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>70</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Co</mml:mi></mml:math>

The neutron-rich nuclei, ${}^{66}\mathrm{Co},$ ${}^{68}\mathrm{Co},$ and ${}^{70}\mathrm{Co}$ were produced using a laser-ionization isotope-separation on-line method. The resulting $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$ decay was studied. The half-life of ${}^{66}\mathrm{Co}$ is measured to be 0.18(1) s. Two $\ensuremath{\beta}$-decaying states are identified in ${}^{68}\mathrm{Co}$ with half-lives of 0.23(3) and 1.6(3) s. In addition, two $\ensuremath{\beta}$-decaying states are observed in ${}^{70}\mathrm{Co}$ with half-lives of 0.12(3) and 0.50(18) s. From the $\ensuremath{\beta}$ decay of these states in ${}^{66,68,70}\mathrm{Co},$ many new excited levels are established in ${}^{66}\mathrm{Ni},$ ${}^{68}\mathrm{Ni},$ and ${}^{70}\mathrm{Ni}.$ These results are compared to the valence mirror nuclei in the $N=50$ region as well as with shell-model calculations. It can be concluded that collective excitations appear to play an increasingly important role with increasing occupation of the $\ensuremath{\nu}{g}_{9/2}$ orbital.

Перевод пока недоступен