19Ne(p,γ)20Naand19Ne(d,n)20Nareactions and its astrophysical implications for the transition of the hot CNO cycle to therpprocess

The population of the ${}^{20}\mathrm{Na}$ resonances at 448, 661, 797, and 887 keV above the proton threshold has been studied in measurements of the ${}^{19}\mathrm{Ne}(p,\gamma {)}^{20}\mathrm{Na}$ reaction with radioactive ${}^{19}\mathrm{Ne}$ 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 ${}^{19}\mathrm{Ne}(p,\gamma {)}^{20}\mathrm{Na}$ astrophysical reaction rate. The total cross section of the ${}^{19}\mathrm{Ne}{\mathrm{}(d,n)\mathrm{}}^{20}\mathrm{Na}$ 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 ${}^{19}\mathrm{Ne}(p,\gamma {)}^{20}\mathrm{Na}$ 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 ${}^{15}\mathrm{O}(\alpha ,\gamma {)}^{19}\mathrm{Ne}$ reaction and the photodisintegration of the produced ${}^{20}\mathrm{Na}$ nuclei will not impede the breakout.