Alpha-burning of O-14

Level structure of18Ne and its importance in the14O(α,pTan1, Aprahamian2, Bucher3 et al. 2012Phys. Rev. C172150View full textAdd to dashboardCite

“…The one at E x = 5.09 MeV is just below the α-decay threshold while the other at E x = 5.15 MeV is slightly above the threshold. Wiescher et al [1] identified those states as the mirror levels of E x = 5.09 MeV and E x = 5.26 MeV in 18 O. According to this consideration it was assigned J π = 3 − and 2 + respectively without ruling out a swap in the spin-parity assignments.…”

“…These breakout reaction rates are very sensitive to the spins, energies, and the partial/total widths of the relevant resonances in 18 Ne. In fact, the direct reaction contribution to the 14 O(α,p) 17 F rate has been shown to be very small at relevant astrophysical temperatures in comparison to the resonance contributions [1].…”

“…In explosive astrophysical scenarios such as novae and X-ray bursts, when temperatures are T 9 ≥ 0.1, it is possible to bypass the β-decay of the waiting points in the HCNO cycle, such as the nuclei 14 O and 15 O, by α capture reactions leading directly to the αp-process and the rp-process [1]. The two breakout paths from the HCNO cycle are the reaction sequences 14 O(α,p) 17 F(p,γ) 18 Ne(α,p) and 15 O(α,γ) 19 Ne(p,γ) shown in Fig.…”

“…Reliable experimental information on these levels, despite various efforts in the past, is still largely missing, in part due to the radioactive nature of this nucleus and the complicated decay scheme of resonances. The properties of these levels and their contribution to the 14 O(α,p) 17 F reaction rate were first reported by Wiescher et al [1] where the widths and spin assignments of the relevant levels in 18 Ne were estimated from the properties of the mirror nucleus 18 O. Hahn et al [2] used a series of indirect measurements to study the 14 O(α,p) 17 F rate by populating and detecting the relevant levels in 18 Ne. However, the measurements on the indirect reactions did not yield any information on partial widths.…”

“…Information on the α-widths, in particular for the 6.15 MeV state, is critical for calculating the reaction rate since the proton decay channels dominate [1]. However, no direct measurements of the α-decay branching ratios have been made for these levels.…”