Elsevier

Nuclear Physics A

Volume 542, Issue 3, 15 June 1992, Pages 375-409
Nuclear Physics A

Magnetic dipole spin excitations in rare-earth and actinide nuclei

https://doi.org/10.1016/0375-9474(92)90103-QGet rights and content

Abstract

Magnetic dipole spin excitations around Ex⋍6−8 MeV are described for rare-earth nuclei, ranging from 140Ce to 198Pt. Starting from an unperturbed basis of 1+ two-quasiparticle states, constructed within the Nilsson model and applying the BCS formalism, one can quantitatively estimate the total spin M1 strength. We include Coriolis mixing and residual quadrupole and spin separable forces and study the soin excitations in more detail for a number of representative examples. Far from closed shells, a double-humped structure in the spin M1 strength results from the calculations and is found to be related to separate proton and neutron spin-flip excitations. We furthermore show that quantitative discrepancies between theoretical and experimental M1 strength distributions are resolved to a large extent when accounting for fragmentation of the strength into a background of more complex configurations. Our results are compared with those of other theoretical studies and the different interpretations are evaluated, starting from a schematic model calculation.

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  • Cited by (0)

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    Research assistant of the NFWO.

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    Supported in part by the Bundesministerium für Forschung und Technologie under contract number 06DA1841.

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