Changes in the structure of nuclei between the magic neutron numbers 50 and 82 as indicated by a rotating-cluster analysis of the energy values of the first 2 excited states of isotopes of cadmium, tin, and tellurium.
Values of R, the radius of rotation of the rotating cluster, are calculated from the observed values of the energy of the lowest 2(+) states of the even isotopes of (48)Cd, (50)Sn, and (52)Te with the assumption that the cluster is alpha, p(2), and alpha, respectively. R shows a maximum at approximately N = 58, a minimum at approximately N = 62, and a second maximum at approximately N = 70. The increase to the first maximum is interpreted as resulting from the overcrowding of spherons (alphas and tritons) in the mantle (outer layer) of the nuclei, causing the cluster to change from rotating in the mantle to skimming over its surface; the decrease to the minimum results from the addition of three dineutrons to the core, expanding the mantle and permitting the rotating cluster to begin to drop back into it; and the increase to the second maximum results from the overcrowding of the larger mantle surrounding the core containing the semi-magic number 14 of neutrons rather than the magic number 8 for N = 50. The decrease after the second maximum results from the further increase in the number of core neutrons to 20, corresponding to the magic number 82. Some additional evidence for the change to an intermediate structure between N = 50 and N = 82 is also discussed.
Linus Pauling Institute of Science and Medicine, 440 Page Mill Road, Palo Alto, California 94306.
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