Low-energy Coulomb excitation

In this Wiki, "low-energy Coulomb excitation" is defined as Coulomb excitation below the Coulomb barrier.  A more conservative constraint is "safe" Coulomb excitation.  For collisions involving nuclei with atomic number greater than ~6, the safe bombarding energy is defined as the energy for which the classical nuclear surfaces are separated by 5 fm.  That is,

<math>E_{max}[MeV] = 1.44 fm ((A_1 + A_2)/A_2) (Z_1 Z_2/(1.25(A_1^{1/3} + A_2^{1/3}) + 5)</math>