Beta delayed particle decay of C-9 and the A=9, T = 1/2 nuclear system: R-matrix fits, the A=9 nuclear system, and the stellar reaction rate of He-4 (alpha n, gamma) Be-9
2001
16 pages
Published in:
- Phys.Rev.C 63 (2001) 034303
Citations per year
Abstract: (APS)
The decay of 9C (T1/2=126.5 ms) has been observed in two experiments at the TISOL facility at TRIUMF employing different detector configurations for each run. In the first of two papers [E. Gete et al., Phys. Rev. C 61, 064310 (2000)], the experimental technique and data analysis were described. Phenomenological branching ratios and Gamow-Teller strengths were then deduced. In this paper, the data are analyzed using a multichannel, multistate R−matrix approach which leads to a different interpretation of the spectra and therefore modified state energies, widths, branching ratios, and Gamow-Teller strengths. Difficulties in fitting the second excited state of 9B at 2.34 MeV and possible modifications to the penetrability are described. The existence of a Jπ=1/2− state at about 5 MeV excitation energy is suggested from the fits, as well as a considerable decay strength from the 9B ground state at high energies. Consequences for the properties of the A=9, T=1/2 nuclear system are then discussed; in particular, it is shown that the data agree qualitatively with shell model predictions without unusual Gamow-Teller strength present at high excitation energies. Finally, an estimate of the 4He(αn,γ)9Be stellar reaction rate is given.References(20)
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