Tuesday, June 18, 2013

1306.3734 (J. Hu et al.)

A confirmative spin-parity assignment for the key 6.15 MeV state in
$^{18}$Ne of astrophysical importance

J. Hu, J. J. He, S. W. Xu, H. Yamaguchi, K. David, P. Ma, J. Su, H. W. Wang, T. Nakao, Y. Wakabayashi, T. Teranishi, J. Y. Moon, H. S. Jung, T. Hashimoto, A. Chen, D. Irvine, S. Kubono
Proton resonant states in $^{18}$Ne have been investigated by the resonant elastic scattering of $^{17}$F+$p$. The $^{17}$F beam was separated by the CNS radioactive ion beam separator (CRIB), and bombarded a thick H$_2$ gas target at 3.6 MeV/nucleon. The recoiled light particles were measured by using three sets of ${\Delta}$E-E Si telescope at scattering angles of $\theta$$_{lab}$$\approx 3^\circ$, 10$^\circ$ and 18$^\circ$, respectively. Four resonances, {\it i.e.}, at $E_{x}$=6.15, 6.30, 6.85, and 7.05 MeV, were observed clearly. By $R$-matrix analysis of the excitation functions, $J^{\pi}$=1$^-$ was firmly assigned to the 6.15 MeV state which is a key state in calculating the reaction rate of $^{14}$O($\alpha$,$p$)$^{17}$F reaction. This reaction was thought to be one of the most probable key reactions for the breakout from the hot-CNO cycle to the $rp$-process in type I x-ray bursts In addition, a new excited state observed at $E_{x}$=6.85 MeV was tentatively assigned as 0$^{-}$, which could be the analog state of 6.880 MeV, 0$^{-}$ in mirror $^{18}$O.
View original: http://arxiv.org/abs/1306.3734

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