Symmetry Energy II: Isobaric Analog States

Understand

Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, from a mass formula, on a nucleus-by-nucleus basis.

• Consistently with charge invariance, the coefficients vary weakly across an isobaric chain.
• However, they change strongly with nuclear mass and range from a_a~10 MeV at mass A~10 to a_a~22 MeV at A~240.
• Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects.