New Island of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">μ</mml:mi><mml:mi>s</mml:mi></mml:math>Isomers in Neutron-Rich Nuclei around the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">Z</mml:mi><mml:mspace/><mml:mo>=</mml:mo><mml:mspace/><mml:mn>28</mml:mn><mml:mn/></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">N</mml:mi><mml:mspace/><mml:mo>=</mml:mo><mml:mspace/><mml:mn>40</mml:mn><mml:mn/></mml:math>Shell Closures

New isomeric states in the neutron-rich nuclei near the $Z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}28$ and $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}40$ shell closures have been identified among the reaction products of a $60.3A$ MeV ${}^{86}\mathrm{Kr}$ beam on a ${}^{\mathrm{nat}}\mathrm{Ni}$ target. From the measured isomeric decay properties information about the excited states and their nuclear structure has been obtained. The isomerism is related mostly to the occupation of the neutron ${g}_{9/2}$ orbital, an intruder level in the $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3$ $\mathrm{fp}$ shell. It is illustrated with the decay properties of ${}^{69}{\mathrm{Ni}}^{m}$, ${}^{70}{\mathrm{Ni}}^{m}$, and ${}^{71}{\mathrm{Cu}}^{m}$ interpreted within the nuclear shell model.