The fine structure in C radioactivity of Ra was discussed for the first time by M. Greiner and W. Scheid in 1986.
The superconducting spectrometer SOLENO of IPN Orsay has been used since 1984 to identify C clusters emitted from Ra nuclei. Moreover, it was used to discover
the fine structure observing transitions to excited states of the daughter. A transition with an excited state of C predicted in Ref.  was not yet observed.
Surprisingly, the experimentalists had seen a transition to the first excited state of the daughter stronger than that to the ground state. The transition is favoured if the uncoupled nucleon is left in the same state in both parent and daughter nuclei. Otherwise the difference in nuclear structure leads to a large hindrance.
The interpretation
was confirmed: the main spherical component of the deformed parent wave function has an i character, i.e. the main component is spherical.