Determination of the photodisintegration reaction rates involving charged particles: Systematic calculations and proposed measurements based on the facility for Extreme Light Infrastructure–Nuclear Physics

Abstract

Photodisintegration reaction rates involving charged particles are of relevance to the p-process nucleosynthesis that aims at explaining the production of the stable neutron-deficient nuclides heavier than iron. In this study, considering the compound and pre-equilibrium reaction mechanisms, the cross sections and astrophysical rates of (γ,p) and (γ,α) reactions for about 3000 target nuclei with 10 ≤ Z ≤ 100 ranging from stable to proton dripline nuclei are computed. To study the sensitivity of the calculations to the optical model potentials (OMPs), both the phenomenological Woods-Saxon and the microscopic folding OMPs are taken into account. The systematic comparisons show that the reaction rates, especially for the (γ,α) reaction, are dramatically influenced by the OMPs. Thus the better determination of the OMP is crucial to reduce the uncertainties of the photodisintegration reaction rates involving charged particles. Meanwhile, a γ-beam facility at Extreme Light Infrastructure-Nuclear Physics (ELI-NP) is being developed, which will open new opportunities to experimentally study the photodisintegration reactions of astrophysics interest. Considering both the important reactions identified by the nucleosynthesis studies and the purpose of complementing the experimental results for the reactions involving p-nuclei, the measurements of six (γ,p) and eight (γ,α) reactions based on the γ-beam facility and the Extreme Light Infrastructure Silicon Strip Array (ELISSA) for the charged particles detection at ELI-NP are proposed. Furthermore, the GEANT4 simulations on these (γ,p) and (γ,α) reactions are performed using the calculated cross sections and the features of the γ-beam facility and the ELISSA detector at ELI-NP. Simultaneously satisfying the minimum detectable limit of the experimental yield and the particle identification of proton and α particle, the minimum required energies of the γ-beam to measure the six (γ,p) and eight (γ,α) reactions are estimated. It is shown that the direct measurements of these photonuclear reactions based on the γ-beam facility at ELI-NP within the Gamow windows at the typical temperature of T9=2.5 for p-process are fairly feasible and promising. We believe that this pivotal work will guide the future photodisintegration experiments at ELI-NP. Furthermore, the expected experimental results will be used to constrain the OMPs of the charged particles, which can eventually reduce the uncertainties of the reaction rates for the p-process nucleosynthesis.

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