An above-barrier narrow resonance in 15F

Abstract Intense and purified radioactive beam of post-accelerated 14 O was used to study the low-lying states in the unbound 15 F nucleus. Exploiting resonant elastic scattering in inverse kinematics with a thick target, the second excited state, a resonance at E R = 4.757 ( 6 ) ( 10 ) MeV with a width of Γ = 36 ( 5 ) ( 14 ) keV was measured for the first time with high precision. The structure of this narrow above-barrier state in a nucleus located two neutrons beyond the proton drip line was investigated using the Gamow Shell Model in the coupled channel representation with a 12 C core and three valence protons. It is found that it is an almost pure wave function of two quasi-bound protons in the 2 s 1 / 2 shell.