Towards a satisfactory microscopic description of 21+ g factors

Davis E.D. ; Navratil P. (1994)


We investigate the possibility that microscopic boson g factor estimates may require revision and consider the impact on 21+ g factors of the difference v between the neutron and proton d boson energies found typically in microscopic evaluations of interacting boson model parameters. We recalculate microscopic estimates for both d and g boson g factors, this time using the similarity-transformed Dyson boson mapping approach. Modulo more pronounced variation at the beginning and end of shells, our results confirm previous estimates by other methods. Differences between d and g boson factors are too small for the inclusion of g bosons to have a significant effect on 21+ g factor predictions. Instead, we present qualitative and semiquantitative arguments in support of the contention that microscopic estimates of v (taken in conjunction with our microscopic boson g factors) can, by and large, account for the systematics of 21+ g factors in the Z=50-to-82 and N=82-to-126 shells. Detailed calculations for Sm148 and Sm154 are consistent with this assertion provided the Majorana interaction strength 2 is negligible. Our detailed calculations suggest substantial F-spin admixtures in the 21+ states of Sm148 (at the 20% level or more) and the members of ground-state band of Sm154 (9% or so), and point to the existence of a mixed-symmetric bandhead in Sm154 at below 2 MeV. © 1994 The American Physical Society.

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