Investigating the astrophysically important Ex = 2.646 MeV state in 20Na

Abstract

Observations of neon lines in the spectra of energetic novae have prompted a renewed look at explosive hydrogen burning. The 19Ne(p, γ) 20Na reaction is expected to play a major role in the breakout of the hot CNO cycle to the rp-process, which can process CNO nuclei to heavier elements. The reaction rate is dominated by the lowest resonance in the 19Ne + p system, corresponding to the E x = 2.646 MeV state in 20Na. A large variety of nuclear experimental techniques have been used to study this state; e.g. charge exchange reactions, β-delayed proton decay and radioactive beams. Their results have lead to a J π = 3 + assignment for this state [B. Brown et al., Phys. Rev. C 48 (1993) 1456], allowing an estimate of the proton width ( Γ p). This leaves the gamma width ( Γ γ ) to be determined. We have performed 20Ne( 3He, experiments to measure the branching ratio ( Γ γ Γ ) of the E x = 2.646 MeV excited state in 20Na.