K isomers in atomic nuclei
P. M. Walker, F. G. Kondev
Abstract
Abstract The properties of K isomers are reviewed. Energies and decay hindrance factors are considered in detail for selected isomers in the $$A \approx $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>A</mml:mi><mml:mo>≈</mml:mo></mml:mrow></mml:math> 160–190 region, focusing on pairing effects and the key K -mixing mechanisms that influence $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math> -ray decay rates. The $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> -decay of K isomers is studied, indicating that, far from the valley of $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> stability, high- K $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> -decaying isomers will populate high- K states in the daughter nuclei. The challenges of revealing predicted, but as-yet undiscovered, long-lived isomers in the neutron-rich $$N \approx 116$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>≈</mml:mo><mml:mn>116</mml:mn></mml:mrow></mml:math> prolate–oblate shape transition region are highlighted, and the occurrence of oblate high- K isomers is discussed. The 2015 multi-quasiparticle K -isomer table of Kondev, Dracoulis, and Kibédi is updated.