Parity-doublet structure in the _{57}^{147}La_{90} nucleus

J. Wiśniewski, W. Urban, T. Rząca-urban, A. G. Smith, J. F. Smith, G. S. Simpson, I. Ahmad, J. P. Greene

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Abstract

Excited states in 147La, populated in spontaneous fission of 252Cf have been reinvestigated by means of γ-ray spectroscopy, using high-fold γ-ray coincidences measured with Gammasphere array of Ge detectors. The 229.5-keV level, which has been assigned spin-parity 9/2− in a recent evaluation, is shown to have spin-parity 11/2−. Consequently, the ground state has spin-parity
5/2+. Excited levels in 147La have been arranged into a parity-doublet structure, showing that at medium excitation energy the 147La nucleus may have octupole deformation. The B(E1) rates in 147La, which are factor four lower than in 145La, suggest that the electric dipole moment in 147La is depressed by an extra mechanism, probably connected with the population of particular neutron orbitals.
Original languageEnglish
JournalPhysical Review C
Volume96
Issue number6
DOIs
Publication statusPublished - 1 Dec 2017

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Wiśniewski, J., Urban, W., Rząca-urban, T., Smith, A. G., Smith, J. F., Simpson, G. S., Ahmad, I., & Greene, J. P. (2017). Parity-doublet structure in the _{57}^{147}La_{90} nucleus. Physical Review C, 96(6). https://doi.org/10.1103/PhysRevC.96.064301