β-delayed α emission of N18: Broad Jπ=1- states in the C14 +α system
Abstract
The β-delayed α-spectrum of N18 has been measured at the TISOL facility at TRIUMF resolving the structure of a broad α-particle distribution at α-energies of 1.5 5.5 MeV into several states that show a distinct interference pattern. R-matrix fits assuming a solely Jπ=1- partial wave confirm this finding. The extrapolated low energy part of this structure constitutes the natural parity background in a possible experiment to observe the parity forbidden α-decay of the Ex=6.880 MeV, Jπ=0- state in O18 that is estimated from the fit to be 2×10-8 of the intensity of the Eα=1081 keV peak. In addition, the tails of the broad 1- states observed likely contribute to the astrophysical C14 (α,γ)O18 reaction rate though the experimental information available is too incomplete to allow precise predictions. The β-delayed α-spectrum of N18 also excludes complex β-feeding amplitudes at a significant level. The states seen in the β-delayed α-decay produce a pattern of approximately equally spaced 1- states in O18 consistent with Jπ=1- states seen at the same and higher excitation energies of O18.
- Publication:
-
Physical Review C
- Pub Date:
- January 2007
- DOI:
- 10.1103/PhysRevC.75.012804
- Bibcode:
- 2007PhRvC..75a2804B
- Keywords:
-
- 23.60.+e;
- 25.55.Ci;
- 27.20.+n;
- Alpha decay;
- Elastic and inelastic scattering;
- 6<
- =A<
- =19