Configurations and level structure of ²¹⁹Rn

The level structure of ²¹⁹Rn has been studied using the alpha decay of ²²³Ra and coincident gamma rays. While only modest changes are required in the level structure, and only above 342.8 keV, severe changes are required throughout the level scheme in the spin assigments. These changes allow the assignment of two sets of anomalous bands with K=5/2^± and K=3/2^±. The K=5/2^± bands have configurations intermediate between the reflection asymmetric configuration and the g_9/2 shell model configuration, while the K=3/2^± bands have configurations intermediate between the mixed reflection asymmetric configuration and the i_11/2 shell model configuration. Comparison of the systematics of ²¹⁹Rn with neighboring isotones, isobars, and isotopes shows clearly the collapse of the quadrupole-octupole-type configurations into the less degenerate shell model configurations.