Elsevier

Nuclear Physics A

Volume 718, 5 May 2003, Pages 131-134
Nuclear Physics A

The key reactions in Stellar helium burning: 12C(α,γ)16O and 22Ne(α,n)25Mg

https://doi.org/10.1016/S0375-9474(03)00690-0Get rights and content

Abstract

The excitation functions of 12C(α,γ)16O and 22Ne(α,n)25Mg have been determined with a yet unequaled experimental sensitivity of 10−11 b. From γ-angular distributions the SE1-and SE2-factors for 12C(α,γ)16O have been deduced and extrapolated into the range of helium burning temperatures using the R-matrix method. An improved reaction rate has been calculated: NAσν〉=(7.9±2.5)x10−15cm3(mols)−1 at T9 = 0.2. For a more precise extrapolation the excitation function has to be measured with better statistics. Therefore a new experiment on 12C(α,γ)16O with a better suited setup has been started recently.

The accuracy of the 22Ne(α,n)25Mg reaction rate could be improved considerably compared to previous compilations: NAσν〉 = (0.88−0.3+2.6) x 10−16cm3(mols)−1 at T9 = 0.2.

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