Photo-induced nucleosynthesis: Current problems and experimental approaches

Abstract

Photon-induced reactions play a key role in the nucleosynthesis of rare neutron-deficient p-nuclei. The paper focuses on (γ,α), (γ,p), and (γ,n) reactions which define the corresponding p-process path. The relation between stellar reaction rates and laboratory cross sections is analyzed for photoninduced reactions and their inverse capture reactions to evaluate various experimental approaches. An improved version SC(E) of the astrophysical S-factor is suggested which is based on the Coulomb wave functions. SC (E) avoids the apparent energy dependence which is otherwise obtained for capture reactions on heavy nuclei. It is found that a special type of synchrotron radiation available at SPring-8 that mimics stellar blackbody radiation at billions of Kelvin is a promising tool for future experiments. By using the blackbody synchrotron radiation, sufficient event rates for (γ,α) and (γ,p) reactions in the p-process path can be expected. These experiments will provide data to improve the nuclear parameters involved in the statistical model and thus reduce the uncertainties of nucleosynthesis calculations.

High precision113In(α,α)113In elastic scattering at energies near the Coulomb barrie

“…However, by using the detailed balance theorem, information on the photodisintegration cross sections can be obtained from the experimental study of the inverse capture reactions. This approach provides more relevant astrophysical information than the direct study of the γ -induced reactions since often the influence of thermally excited states is smaller in this direction, compared to photon-induced reactions [16,[22][23][24]. In recent years several α-capture cross sections have been measured using the well known activation technique [25][26][27][28][29][30][31][32][33], and the results were compared with the H-F predictions.…”

Cd110,116(α,α)Kiss1, Mohr2, Fülöp3 et al. 2011Phys. Rev. CSelf Cite

“…However, in such an experiment the target nucleus is always in its ground state, whereas in stellar environments thermally populated excited states also contribute to the reaction rate. Thus theoretical considerations cannot be avoided [7]. Alternatively, the (γ ,α) rates can be determined experimentally by measuring the inverse (α,γ ) reaction cross section and converting the results by using the detailed balance theorem.…”

“…Alternatively, the (γ ,α) rates can be determined experimentally by measuring the inverse (α,γ ) reaction cross section and converting the results by using the detailed balance theorem. In this direction the influence of thermally excited states remains relatively small [7,8]. In recent years a range of (α,γ ) reaction cross sections on 70 Ge, 96 Ru, 106 Cd, 112,117 Sn, 113 In, 144 Sm, 151 Eu, and 169 Tm has been measured using the activation method, and the results have been compared with model predictions [9][10][11][12][13][14][15][16][17].…”

Measurement of alpha-induced reaction cross sections on erbium isotopes for γ process studies

“…However, by using the detailed balance theorem, information on the photodisintegration cross sections can be obtained from the experimental study of the inverse capture reactions. This approach provides more relevant astrophysical information than the direct study of the γ-induced reactions since often the in uence of thermally excited states is smaller in this direction, compared to photon-induced reactions [1,5,6,7]. In recent years several α-capture cross sections have been measured using the well-known activation technique [8,9,10,11,12,13,14,15,16,17], and the results were compared with the H-F predictions [18].…”