Lowest energy state of the nucleus.
Discrete energetic nuclear state above the ground state (level 1).
Discrete energetic nuclear state above the ground state (level 2).
Discrete energetic nuclear state above the ground state (level 3).
Discrete energetic nuclear state above the ground state (level 4).
Long-lived excited state with a measurable half-life.
Energy state of an atomic nucleus relative to its lowest potential.