Experimental cross sections of 165Ho(α,n)168Tm and 166Er(α,n)169Yb for optical potential studies relevant for the astrophysical γ-process

Abstract

Background: Optical potentials are crucial ingredients for the prediction of nuclear reaction rates needed in simulations of the astrophysical γ-process. Associated uncertainties are particularly large for reactions involving α-particles. This includes (γ,α) reactions which are of special importance in the γ-process. Purpose: The measurement of (α,n) reactions allows for an optimization of currently used α-nucleus potentials. The reactions 165Ho(α,n) and 166Er(α,n) probe the optical model in a mass region where γ-process calculations exhibit an underproduction of p nuclei which is not yet understood. Method: To investigate the energy-dependent cross sections of the reactions 165Ho(α,n) and 166Er(α,n) close to the reaction threshold, self-supporting metallic foils were irradiated with α-particles using the FN tandem Van de Graaff accelerator at University of Notre Dame. The induced activity was determined afterwards by monitoring the specific β-decay channels. Results: Hauser-Feshbach predictions with a widely used global α-potential describe the data well at energies where the cross sections are almost exclusively sensitive to the α-widths. Increasing discrepancies appear towards the reaction threshold at lower energy. Conclusions: The tested global α-potential is suitable at energies above 14 MeV, while a modification seems necessary close to the reaction threshold. Since the γ- and neutron width show non-negligible impact on the predictions, complementary data are required to judge whether or not the discrepancies found can to be solely assigned to the α-width.

References in corpus (19)

• Nucleosynthesis in Massive Stars With Improved Nuclear and Stellar Physics
• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• The s Process: Nuclear Physics, Stellar Models, Observations
• Constraining the astrophysical origin of the p-nuclei through nuclear physics and meteoritic data
• Type Ia Supernovae as Sites of p-process: Two-Dimensional Models Coupled to Nucleosynthesis
• Sensitivity of p-Process Nucleosynthesis to Nuclear Reaction Rates in a 25 Solar Mass Supernova Model
• The Path to Improved Reaction Rates for Astrophysics
• Relevant energy ranges for astrophysical reaction rates
• Sensitivity of astrophysical reaction rates to nuclear uncertainties
• Alpha-induced cross sections of 106Cd for the astrophysical p-process
• Complementary optical-potential analysis of alpha-particle elastic scattering and induced reactions at low energies
• Determination of 141Pr(alpha,n)144Pm cross sections at energies of relevance for the astrophysical p-process using the gamma-gamma coincidence method
• ${}^{92}$Mo($\alpha ,\alpha$)${}^{92}$Mo scattering,the ${}^{92}$Mo--$\alpha$ optical potential, and the ${}^{96}$Ru($\gamma ,\alpha$)${}^{92}$Mo reaction rate at astrophysically relevant energies
• Production of the p-Process Nuclei in the Carbon-Deflagration Model for Type Ia Supernovae
• Determining reaction cross sections via characteristic X-ray detection: α-induced reactions on 169Tm for the astrophysical γ -process
• Investigation of alpha-induced reactions on the p nucleus 168Yb
• Challenges in nucleosynthesis of trans-iron elements
• Solution of the alpha-potential mystery in the gamma-process and its impact on the Nd/Sm ratio in meteorites
• Astrophysical analysis of the measurement of (alpha,gamma) and (alpha,n) cross sections of 169Tm

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