α -cluster structure in F19 and Ne19 in resonant scattering

Abstract

The nuclear structure of $^{19}\mathrm{F}$ and $^{19}\mathrm{Ne}$ is important for understanding of $\ensuremath{\alpha}$ clustering in the $A=20$ mass region and in questions related to astrophysics. However, the only high-resolution broad angular and energy range study of the $^{19}\mathrm{F}$ resonance structure in $\ensuremath{\alpha}+^{15}\mathrm{N}$ scattering was published over 60 years ago, and a detailed analysis of complex excitation functions of overlapping resonances with several decay channels was simply impossible at that time. We performed a modern $R$-matrix analysis of these old data to assign spins and specify resonant parameters of levels up to excitation energy of 8.2 MeV in $^{19}\mathrm{F}$. We successfully tested our $R$-matrix parameters in a fit of the recent data on $\ensuremath{\alpha}+^{15}\mathrm{N}$ obtained by thick target inverse kinematics (TTIK) method at 180 degrees. We used the new parameters for $^{19}\mathrm{F}$ to fit TTIK data for $\ensuremath{\alpha}+^{15}\mathrm{O}$, the mirror resonant reactions. The comparison of the data for isobaric mirror resonant reactions provides an interesting insight into the nuclear structure.