Ne-19(p,gamma)Na-20 and Ne-19(d,n)Na-20 reactions and its astrophysical implications for the transition of the hot CNO cycle to the rp process

The population of the Na-20 resonances at 448, 661, 797, and 887 keV above the proton threshold has been studied in measurements of the Ne-19(p,gamma)Na-20 reaction with radioactive Ne-19 beams. The data have been analyzed fully in terms of resonance strengths, enabling a comparison with theoretical estimates and the extraction of upper and lower limits on the resonant part of the Ne-19(p, gamma)Na-20 astrophysical reaction rate. The total cross section of the Ne-19(d,n)Na-20 reaction has been measured from 0.6 to 1.8 MeV (c.m.). On the basis of the results of a subsequent distorted-wave Born approximation analysis the direct component of the Ne-19(p,gamma)Na-20 astrophysical reaction rate has been calculated in a potential model. The astrophysical implications of the resulting total reaction rate have been investigated: the conditions for the breakout from the hot CNO cycle into the rapid-proton capture process are determined by the preceding O-15(alpha, gamma)Ne-19 reaction and the photodisintegration of the produced Na-20 nuclei will not impede the breakout. [S0556-2813(98)05305-9].