The anisotropy of the potential is such that the length of an equipotential along the z is greater than the length on the transverse axes in the ratio ω ω ⊥ ⊥ / ω ω z . This is conventionally expressed in terms of a deformation parameter δ so that the harmonic oscillator part of the potential can be written as the sum of a spherically symmetric harmonic oscillator and a term proportional to δ. Positive values of δ indicate prolate deformations, like an American football. Most nuclei in their ground states have equilibrium shapes such that δ ranges from 0 to 0.2, while superdeformed states have δ δ ≈ ≈ 0.5 (a 2-to-1 axis ratio).