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Electric monopole transitions from excited Kπ = 0+ levels in 172Yb and 174Yb

1978; Elsevier BV; Volume: 309; Issue: 1-2 Linguagem: Inglês

10.1016/0375-9474(78)90539-0

1873-1554

J. Larysz, K. Schreckenbach, W.F. Davidson, H. G. Börner, D.D. Warner, R. F. Casten, W. Gelletly,

Nuclear Physics and Applications

Electric monopole transitions in 172Yb and 174Yb have been studied following thermal neutron capture on 171Yb and 173Yb. It is found that the second excited 0+ state in 172Yb at 1405 keV has a very large X = B(E0; 02+−0g+)B(E2; 02+−2g+ value of 2.81±0.31. The E0 decay branches for the other 0+ states in 172Yb were also measured. In the case of 174Yb no E0 conversion lines were observed from the corresponding 0+ states but upper limits were placed on their intensities. These results indicate that none of the known 0+ states in 174Yb exhibit such a large X-value. Various interpretations are discussed and it is concluded that the 1405 keV level in 172Yb may contain large amplitudes of proton pair excitations. A model based on such excitations is presented which accounts qualitatively for the large X(1405) value in 172Yb as well as for the systematics of large X-values in the rare-earth region.