On the Excited States of Nuclei Beyond Oxygen

Abstract

If spin-orbit coupling and the difference between neutron-neutron, neutron-proton, and proton-proton forces are neglected, the energies of the ground states of the nuclei beyond oxygen can be expressed in terms of the symmetry character of the wave functions and a smoothly varying function of atomic weight. With the same assumptions, the energies of the excited states of these nuclei can be expressed in similar terms. Thus the difference in energy of the ground states and the excited states of the same symmetry would be expected to vary smoothly as a function of mass number. Since each state is a supermultiplet of states which will be split under the influence of spin-orbit coupling, it will not in general be possible to observe this behavior of the energy levels. However, in the case of the alpha-particle nuclei, the low-lying excited states are singlets so the regularity should be observable. Unfortunately there are insufficient experimental data on the excited states of these nuclei to make a positive statement as to agreement, but those data which are available do not disagree with the suggested behavior.