The Core of ${}^{25}$F in the Rotational Model

Abstract

In a recent experiment, carried out at RIBF/RIKEN, the ${}^{25}$F$(p,2p)$${}^{24}$O reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of ${}^{25}$F significantly differs from a free ${}^{24}$O nucleus. We interpret these results within the Particle-Rotor Model and show that the experimental level scheme of ${}^{25}$F can be understood in the rotation-aligned coupling scheme, with its $5/2_1^{+}$ ground state as the band-head 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 MeV and a moderate quadrupole deformation, $\hat{I}{\mu }_2\approx 0.15$. The measured fragmentation of the $\ddot{I}€d_{5/2}$ single-particle strength is discussed and some further experiments suggested.

5 pages, 3 figures. Submitted to Physical Review C