Shape of the Nucleus

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Science  13 Feb 1959:
Vol. 129, Issue 3346, pp. 361-367
DOI: 10.1126/science.129.3346.361


The gross features of nuclear morphology can be summarized as follows. Nuclei have shapes similar to a diffusesurfaced, liquid drop. The interior density is rather uniform, and also constant from nucleus to nucleus. The constancy of nuclear density implies an A law for the mean nuclear radius, the proportionality constant being 1.07 x 1O–13 centimeter. The surface region is diffuse, the nuclear density falling from 90 to 10 percent of the central value in a distance of about 2.4 x 10–13 centimeter, independently of nuclear mass number.

Nuclear shapes can vary rather widely, with doubly magic nuclei preferring spherical symmetry. Some nuclei execute volume-preserving oscillations about spherical shape, while others possess permanent spheroidal deformations. The values of the deformation parameter, ε, for such spheroids possibly attains 0.85 for some light nuclei and 0.4 for some intermediate weight nuclei.

There is some evidence, based on the occurrence of "inversion" spectra and asymmetrical fission, that pear-shaped nuclei may also exist.