F*

Nuclei with extreme proton-to-neutron ratios are key to testing shell-model and other theoretical approaches.  One isotopic chain which has received considerable attention is the O isotopes, which are accessible for ab-initio theoretical approaches, and have proven sensitive to details of the fundamental NN and 3N interactions employed.

One proton above oxygen, the evolution of core-excitations in the ground-states of the neutron-rich F isotopes provides direct insight into the effect of the single valence proton outside the O core.  In particular, we present results of a proton-knockout measurement performed at the NSCL with GRETINA and the S800, with an emphasis on the case of ²⁵F(-1p)²⁴O.  The nature of the effective ²⁴O core in ²⁵F is discussed in the context of this and other recent experimental results [1].

[1] T. L. Tang et al., Phys. Rev. Lett. 124, 212502 (2020).