Reexamination Of The Energy Levels Of F-15 By O-14+H-1 Elastic Resonance Scattering

The energy levels of F-15 have been measured by the p(O-14,p)O-14 reaction. The 120 MeV O-14 radioactive ion beam was produced by the BEARS coupled cyclotron system at an intensity averaging 1x10(4) particles/second on target. Energy calibration was obtained using resonances from the p(N-14,p)N-14 reaction. The two lowest resonances in F-15 were fitted with an R-matrix calculation. The fit to the ground state had J(pi)=1/2(+) at 1.23 +/- 0.05 MeV (width 0.5 - 0.84 MeV), and the first excited state was J(pi)=5/2(+) at 2.81 +/- 0.02 MeV (width 0.30 +/- 0.06 MeV), both relative to the mass-energy of the proton and O-14. The F-15 ground state energy supports the disappearance of the Z = 8 proton magic number for odd Z,T-z=-3/2 nuclei.