The half-life of a $K^{\pi }={12}^{+}$ isomer in ${}^{164}$Er has been measured to be 68(2) ns, and new decay pathways have been identified. These include highly $K$-forbidden $\gamma$-ray transitions directly to the ground-state rotational band, with reduced hindrance values that can be compared with those found for heavier nuclides. The new data support the interpretation that the level density is a key variable in determining $K$-forbidden transition rates.

• Received 9 August 2012

DOI:https://doi.org/10.1103/PhysRevC.86.044307