A new study for 16O(γ, α)12C at the energies of nuclear astrophysics interest : The inverse of key nucleosynthesis reaction 12C(α,γ)16O

Abstract The key reaction 12 C ( α , γ ) 16 O in nuclear astrophysics is difficult to be performed experimentally at low energy because of the Coulomb barrier. But it is different if we use its inverse reaction 16 O ( γ , α ) 12 C because the cross-section of 16 O ( γ , α ) 12 C is almost 100 times larger than the cross-section of 12 C ( α , γ ) 16 O at the same center of mass energy ( E c . m . ) based on our study. In the present work, we study the angular distributions and total cross-sections of 16 O ( γ , α ) 12 C which are induced by polarized photon using the resonance theory of low energy reaction. The differential cross-sections as well as E1 and E2 transition cross-sections at low nuclear astrophysics energies are also calculated. The feature of the future Shanghai Laser Electron Gamma Source (SLEGS) facility, a low energy γ -ray beam line with a high photon flux, is presented. The experiments of 16 O ( γ , α ) 12 C are simulated with a time projection chamber (TPC) and a realistic SLEGS layout. The lowest ( E c . m . ) , which can be obtained from the simulation, is 0.8 MeV with the 20–30% uncertainty for the one-month beam time of SLEGS. The extracted S factors of 12 C ( α , γ ) 16 O and their statistical uncertainties from the simulation are compared with the existing data and some theoretical calculations. It is shown that the promising 16 O ( γ , α ) 12 C experiment at SLEGS can largely reduce the statistical uncertainties of the 12 C ( α , γ ) 16 O experiment at low energies.