The variations of nuclear potential radii, obtained by fitting the last particle binding energies, are investigated for nuclei in the isotopic and the isotonic sequences. It is found that while the neutron (proton) potential radii increase as $A^{\frac{1}{3}}$ for nuclei in isotonic (isotopic) sequences in accordance with the universally adopted procedure in shell model and optical model studies, these radii do not show the expected behavior in the case of nuclei in isotopic (isotonic) sequences. Possible interrelationship between the variations of the potential radii and those of the nucleon separation energies and also between the potential radii and the density distribution radii in such sequences is investigated. The anomalous variations of the neutron potential radii in the isotopic sequences are found to be related with the fact that the charge distribution radii in such sequences do not increase as rapidly as $A^{\frac{1}{3}}$. The consequences of and the possible physical explanations for such a behavior are discussed.

NUCLEAR STRUCTURE Searched potential radius to fit last particle binding energy, studied its variations in isotopic and isotonic sequences; $A=40-150\mathrm{}$.

• Received 6 November 1974

DOI:https://doi.org/10.1103/PhysRevC.11.2056