Resonant Rate for15O(α,γ)19Ne

Abstract

We have measured angular distributions for the "N(6Li, d)'9F and '60(6Li, d)20Ne reactions at a bombarding energy of 22 MeV. Distorted-wave Born-approximation and Hauser-Feshbach calculations were used to analyze the data. Ratios of n-transfer cross sections in ' F and Ne, plus isospin invariance, provide ratios of n widths in Ne and ONe. Using Ne (1,5.788 MeV) as a standard allows the determination of the n-particle width for the state at 4.033 MeV in ' Ne, and hence the resonant rate for the "O(n, y)'9Ne reaction, contributed from the 504 keV, -, resonance, at temperatures of astrophysical interest. PACS numbers: 25.70.Hi, 25.55.e, 27.20.+n, 97.10.CV One of the two links between the hot CNO (HCNO)

αcluster structures in unbound states in19Ne

“…Therefore, the α and 3 He cluster configurations are considered to be minor component in the threshold 3/2 + state. This result is consistent to the previous experimental result, which points out the dominance of the 5p-2h configuration in the threshold 3/2 + state [14], because the α and 3 He cluster configurations have the large overlap with the 4p-1h and 3p-0h shell model configurations, respectively, in the S = 0 limit. Therefore, we should include other cluster configuration, which has a large overlap of the 5p-2h state.…”

“…In the microscopic calculation, the coupled-channels calculation of ( 3 He+ 16 O) + (α+ 15 O) is performed on the basis of the generalized two-center cluster model (GTCM) [4]. In GTCM, the basis functions are constructed from the possible partitions of the valence neutrons around the 3 He and 14 O cores, and the anti-symmetrization among all the nucleons is completely taken into account. This model can produce the smooth connection of the weak coupling states and the strong coupling states in the adiabatic energy curves, which are the series of the energy eigenvalues as a function of the core distance.…”

“…The ψ( 3 He) and ψ( 14 O) represent the core wave functions of the 3 He and 14 O nuclei, respectively. The former part is described by the (0s) 3 configuration in the harmonic oscillator (HO) potential, while the latter part is constructed by the (0s) 4 (0p) 10 configuration.…”

“…Two centers are placed with the relative distance parameter S , which is treated as the generator coordinate. The single-particle wave function for the j-th valence neutrons ( j = 1, 2) localized around the 3 He or 14 O clusters is given by an atomic orbital (AO) ϕ m j , which is classified by a set of the AO quanta m j = (k, C, τ) with the labels of the HO orbitals k, the core C, and the neutron spin τ (= ↑ or ↓). The HO orbitals around the core C ( C = 3 He or 14 O) are k = 0s ( C = 3 He ) or k = 0p ( C = 14 O ).…”

“…The analyses in Ref. [14] have pointed out that the intrinsic structure of the resonance at 504 keV in 19 Ne is not the α + 15 O cluster structure, but the five particle-two hole (5p-2h) shell-model configuration with the 14 O g.s. core.…”