The branching ratio [formula omitted] of the 4.033 MeV state in 19Ne

Abstract

The 15O(α,γ) 19Ne reaction is an important pathway from the hot CNO cycle to the rp process that leads to the synthesis of heavier nuclei. At lower temperatures, the reaction rate is dominated by the transition to the 4.033 MeV 3/2 + state in 19Ne, the first level above the 15O(α,γ) threshold at 3.534 MeV. We have performed an indirect measurement of the ratio Λ α Λ γ by populating the 3/2 + state via the 3He( 20Ne,α) 19Ne reaction in inverse kinematics. The α particles were detected in a double-sided Si strip detector telescope while the heavy reaction products, 19Ne and 15O, were identified in the focal plane of a magnetic spectrograph. For the 4.033 MeV state in 19Ne an upper limit Λ α Λ γ of ≤ 7×10 −4 has been obtained.