Coexistence of low-Kprolate and high-Koblate πh11/2orbitals

Following theoretical predictions of competing prolate and oblate potential-energy minima, we present experimental evidence for the coexistence of prolate and oblate nuclear shapes which are associated in a given nucleus with the same single-quasiproton orbital. Prolate ΔI=2 and oblate ΔI=1 bands observed in the ${}_{}{}^{119}{}_{}{}^{}\mathrm{I}$ nucleus are proposed as built on an ${\mathrm{h}}_{11/2}$ proton with low K and high K, respectively.