Investigation of the 19Na nucleus via resonance elastic scattering

The structure of the unbound proton-rich isotope 19Na was studied in resonance elastic scattering of a radioactive 18Ne beam on a proton target using the thick-target inverse-kinematics method. The experiment covered the excitation energy range from 0.5 to 2.7 MeV in c.m.s. Only one state of 19Na (the second excited state) was observed. A combined R-matrix and potential model analysis was performed. The spin and parity assignment of this second excited state was confirmed to be 1/2+. We show that the position of the 1/2+ state significantly affects the reaction rate through that state, but the total reaction rate remains unchanged since the 18Ne(2p, γ) proceeds mostly via the ground and first excited states in 19Na at stellar temperatures.