Direct Measurement of Resonances in ^{7}Be(α,γ)^{11}C Relevant to νp-Process Nucleosynthesis

Area of Science:

• Nuclear Astrophysics
• Particle Physics
• Cosmic Nucleosynthesis

Background:

• The ^{7}Be(α,γ)^{11}C reaction is vital for understanding nucleosynthesis in core-collapse supernovae.
• Previous measurements of resonance strengths were limited, introducing significant uncertainties.

Purpose of the Study:

• To perform the first direct measurement of two key resonance strengths in the ^{7}Be(α,γ)^{11}C reaction.
• To reduce uncertainties in the reaction rate relevant to the neutrino-driven (νp) process.

Main Methods:

• Utilized an intense radioactive ^{7}Be beam.
• Employed the DRAGON recoil separator for precise measurements.
• Measured resonance strengths at 1155 keV and 1110 keV.

Main Results:

• Reported the first measurement of resonance strengths: 1.73±0.25(stat)±0.40(syst) eV at 1155 keV and 125_{-25}^{+27}(stat)±15(syst) meV at 1110 keV.
• Reduced the uncertainty in the ^{7}Be(α,γ)^{11}C reaction rate to approximately 9.4%-10.7% for temperatures between 1.5-3 GK.

Conclusions:

• The new measurements provide crucial data for astrophysical models of supernovae.
• Despite improved accuracy, the constrained reaction rate did not alter predictions for νp-process nucleosynthesis.