The 42Ca(α, γ)46Ti and 42Ca(α, p)45Sc cross sections and the mass-45 bottleneck

Abstract

The yield of γ-rays from the reaction 42Ca(α, γ)46Ti has been measured as a function of bombarding energy over the range Eα = 3.42-5.62 MeV and from 42Ca(α, pγ)45Sc over the range Eα = 4.06-5.92 MeV, and the yield of protons from the reaction 42Ca(α, p)45Sc has been measured over the range Eα = 4.78-5.92 MeV. Cross sections for all three reactions have been extracted from the data and compared with global statistical-model calculations. The agreement is good. Thermonuclear reaction rates under stellar conditions appropriate for silicon burning are calculated and their significance for the approach to and bridging of the mass-45 bottleneck in the upward flow of nucleosynthesis is discussed. ©..