This is NOT what the nucleus is doing.

Rotational spectra are insanely complex and properly the study of so-called “nuclear chemistry.” We will not say much about the details.

Deformed nuclei occupy the regions of “half-filled” shells, in other words the regions around halfway between “magic numbers.”

The Dy isotopes offer a gorgeous example of rotational symmetry breaking... as more and more pairs of neutrons are added, the spectrum shifts from pure vibrational to pure rotational!

For low-lying states, the extracted rotational inertia for deformed nuclei is neither that of a rigid ellipsoid, nor that of an “irrotational” superfluid, but about halfway between. The importance of pairing in nuclear matter makes the nucleus very much like a superfluid or superconductor, in general, however. Drastic things happen to the rotational bands when the excitation is great enough to break a significant number of pairs.

Walter Greiner (1935 - 2016) was the best-known German theoretical physicist of the last half of the 20th Century. In his long and active career, he worked in just about every field of theoretical physics, but particularly in nuclear theory and elementary particle theory. He also co-wrote a long series of textbooks covering pretty much all of theoretical physics at the graduate level. One of his mid-1960 papers had a major impact on my own research!  Tamura and I called the method SMART.

Sabine Hossenfelder, famous for her weekly YouTube series Science Without the Gobbledygook, was one of Greiner's graduate students.