Breakout from the hot CNO cycle via the Ne(α,p)Na reaction. II. Extended-energy range E ∼1.7-2.9 MeV

We have extended the experiment reported in Bradfield-Smith et al. [Phys. Rev. C 59, 3402 (1999)] concerning the Ne(α,p)Na reaction, which is of importance to nuclear astrophysics. This study covered an energy region ∼ 1.7-2.9 MeV in the center of mass frame of the Ne+α system. A change in the detector geometry resulted in an increase in the detection efficiency and significantly reduced the proton background that hindered the previous measurement. A direct measurement of the energy loss of the Ne beam, as it passed through He gas, was undertaken to reduce a major source of uncertainty in the determination of the stellar reaction rate. Eight states have been identified in the compound nucleus, Mg. These resonances were used to calculate an enhanced stellar reaction rate which shows good agreement with theoretical predictions [Görres, Wiescher, and Thielemann, Phys. Rev. C 51, 392 (1995)] at and above a temperature of 1.5 GK. The impact of this enhanced stellar reaction rate upon the nucleosynthesis that occurs during the peak phase of an x-ray burst has been investigated.