Particle configurations of giant e 1 states in the N14(γ, p2) and N14(γ, p0) processes

Angular distributions and absolute cross sections have been measured for the N14(γ, p2) and N14(γ, p0) reactions, at giant resonance energies. The angular distributions are shown to be consistent with a model in which exclusively (p12)-1 (2s 1d) giant dipole states populate the C13 ground state by proton decay, and predominantly (p32)-1 (2s 1d) giant dipole states feed the 32- state of C13 at 3.68 MeV. Branching calculations based on established spectroscopic factors further support this model. It is inferred that the N14 dipole states of (p32)-1 (2s 1d) character, which carry ∼90% of the E 1 strength and which dominate the (γ, p2) process studied, do not contribute significantly to the (γ, p0) process which has often previously been treated as representative of E 1 absorption. NUCLEAR REACTIONS N14(γ, p2), (γ, p0), Eγ=19-25 MeV; measured σ(Eγ;Ep;θ). Deduced E 2, M 1 excitation strength. Inferred parent E 1 configurations. © 1974 The American Physical Society.