Giant quadrupole resonance: capture amplitude analysis of the 14C(p,γ)15N and 15N(p,γ)16O reactions

The (p,γ) reaction on 14C and 15N was studied and a phase shift analysis of the results was performed. The analysis allows a determination of the quadrupole capture strength in the 15N and 16O nuclei. No evidence for quadrupole capture strength in excess of that due to direct capture alone is found in 15N. For 16O a resonance-like enhancement of quadrupole strength is found at about 24 MeV in excitation with a width of 4 MeV. In 15N the quadrupole strength integrated from 20.5 MeV to 28 MeV excitation exhausts greater than or equal to 7% of the isoscalar quadrupole sum rule. In 16O the strength integrated from 19 MeV to 29 MeV exhausts greater than or equal to 28% of the isoscalar quadrupole sum rule