First sub-MeV nuclear reaction measurements in a heavy-ion storage ring

Area of Science:

• Nuclear astrophysics
• Experimental nuclear physics
• Atomic and molecular physics

Background:

• Studying nuclear reactions at astrophysically relevant energies is crucial for understanding stellar evolution and nucleosynthesis.
• Traditional experimental methods face limitations in achieving the extremely low center-of-mass energies required for certain astrophysical scenarios.
• Heavy-ion storage rings offer a novel platform for precise measurements of nuclear reactions at these low energies.

Purpose of the Study:

• To demonstrate the capability of heavy-ion storage rings for nuclear reaction studies at sub-MeV center-of-mass energies.
• To investigate the Nitrogen-15 (¹⁵N) proton scattering (p,p) and reaction (p,α) nuclear reactions in inverse kinematics.
• To establish a foundation for future research addressing key problems in nuclear astrophysics.

Main Methods:

• Utilized the CARME array within the CRYRING@ESR heavy-ion storage ring at GSI.
• Performed nuclear reaction measurements in inverse kinematics for ¹⁵N(p,p)¹⁵N and ¹⁵N(p,α)¹²C.
• Extended measurements down to an energy of 426 keV/u, corresponding to a center-of-mass energy of 403 keV.

Main Results:

• Achieved the lowest energy measurement of a nuclear reaction in a heavy-ion storage ring to date (403 keV).
• ¹⁵N(p,p) scattering results showed excellent agreement with theoretical R-matrix predictions.
• Successfully measured the ¹⁵N(p,α)¹²C reaction at 426 keV/u.

Conclusions:

• Heavy-ion storage rings are a viable and powerful tool for nuclear astrophysics research at sub-MeV energies.
• These measurements open new avenues for studying reactions critical to understanding stellar processes.
• The achieved low-energy frontier advances the field of experimental nuclear astrophysics.