On the sensitivity of extracting the astrophysical cross section factor of the 12C(a,g) reaction from existing data [Comment on Schuermann et al. Phys. Lett. B711(2012)35]
Abstract
We address a conflicting report on the value and uncertainty of the astrophysical cross section factor of the 12C(a,g) reaction extracted from existing data. In sharp contrast to previously reported ambiguities (by up to a factor 8), Schuermann et al. suggest an accuracy of 12%. We demonstrate that the so claimed "rigorous data selection criteria" used by Schuermann et al. relies on the s-factors extracted by Assuncao et al. But these results were shown in a later analysis (by this author) to have large error bars (considerably larger than claimed by Assuncao em et al.) which render these data not appropriate for a rigorous analysis. When their "rigorous data selection" is adjusted to remove the results of Assuncao et al. the astrophysical cross section factor cannot be extracted with 12% accuracy, or even close to it. Such data on the SE2 values at low energies deviate by up to a factor two from their fit and exhibit a sharper slope rising toward low energies, leading to strong doubt on their extrapolated SE2(300) value and the quoted small error bar. Contrary to their claim the small value of SE1(300) ~10 keVb cannot be ruled out by current data including the most modern gamma-ray data. As previously observed by several authors current data reveal ambiguities in the value of SE1(300) ~10 keVb or ~80 keVb, and the new ambiguity that was recently revealed (by this author) of SE2(300) ~60 keVb or ~154 keVb, appear to be a more reasonable evaluation the status of current data.