An above-barrier narrow resonance in 15F

Intense and purified radioactive beam of post-accelerated 14O was used to study the low-lying states in the unbound 15F nucleus. Exploiting resonant elastic scattering in inverse kinematics with a thick target, the second excited state, a resonance at ER=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 12C core and three valence protons. It is found that it is an almost pure wave function of two quasi-bound protons in the 2s1/2 shell.