Valley of stability
= Valley of stability
{wiki}
The <valley of stability> is the region of nuclear <masses> near the minima with respect to proton-neutron imbalance. Its beta-stable band bends toward neutron excess for heavier <nuclei>, as <nuclear Coulomb energy> competes with the cost of neutron-proton asymmetry. The band is distinct from the particle-emission boundaries set by <nuclear separation energies>.