In a recent experiment, carried out at the Radioactive Isotope Beam Factory/RIKEN, the ${}^{25}\mathrm{F}(p,2p){}^{24}\mathrm{O}$ reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of ${}^{25}\mathrm{F}$ significantly differs from a free ${}^{24}\mathrm{O}$ nucleus. We interpret these results within the particle-rotor model and show that the experimental level scheme of ${}^{25}\mathrm{F}$ can be understood in the rotation-aligned coupling scheme with its $5/2_1^{+}$ ground state as the bandhead of a decoupled band. The excitation energies of the observed $1/2_1^{+}$ and $9/2_1^{+}$ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its $2^{+}$ energy at $\approx 3.2\mathrm{MeV}$ and a moderate quadrupole deformation ${\epsilon }_2\approx 0.15$. The measured fragmentation of the $\pi d_{5/2}$ single-particle strength is discussed, and some further experiments suggested.

• Received 3 August 2020
• Accepted 14 September 2020

DOI:https://doi.org/10.1103/PhysRevC.102.041301