Mixed Configurations in Nuclei

The role of mixed configurations in nuclear states is discussed and illustrated by various examples; it is discussed in particular for $\beta$ transitions with anomalous $\mathrm{ft}$ values and as a qualitative explanation of the empirically-found smooth variations of the first excited states of even-even nuclei. It is shown by various examples that a nucleon of one kind (neutron or proton) with a given $j$ has a "stabilizing" influence on pairs of the other kind with a given $j^{\prime }$. This stabilization effect is calculated on simplified assumptions for different $j$ and $j^{\prime }$.