Phase Transitions of Nuclear Matter

Abstract

THE distribution of capture cross-sections of slow neutrons reveals a surprising concentration of strongly absorbing elements in the region of the rare earths¹. As has been pointed out², this fact may be explained in the simplest way by the supposition that the mean spacings between the resonance capture levels of slow neutrons have a minimum in this region of the periodic system. A more detailed study of the connexion between the distribution of the capture cross-sections and the variation of resonance level density carried out by me seems to prove definitely the non-monotonic shift of the resonance level spacings with a minimum in the region of the rare earths (mean atomic weight 160).