Direct Evidence of Octupole Deformation in Neutron-Rich 144Ba

Brian Bucher, S. Zhu, C. Y. Wu, R. V. F. Janssens, D. Cline, A. B. Hayes, M. Albers, A.D. Ayangeakaa, P. A. Butler, C. Campbell, M. P. Carpenter, C. J. Chiara, J.A. Clark, H. Crawford, M. Cromaz, H.M. David, C. Dickerson, E. T. Gregor, J. Harker, C.R. HoffmanB. P. Kay, F. G. Kondev, A. Korichi, T. Lauritsen, A.O. Machiavelli, R.C. Pardo, A. Richard, M.A. Riley, G. Savard, Marcus Scheck, D. Seweryniak, M.K. Smith, R. Vondrasek, A. Wiens

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Abstract

The neutron-rich nucleus Ba144 (t1/2=11.5  s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV Ba144 beam on a 1.0−mg/cm2 Pb208 target. The measured value of the matrix element, ⟨31−∥M(E3)∥01+⟩=0.65(+17−23) eb3/2, corresponds to a reduced B(E3) transition probability of 48(+25−34)  W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.
Original languageEnglish
Article number112503
JournalPhysical Review Letters
Volume116
DOIs
Publication statusPublished - 17 Mar 2016

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Bucher, B., Zhu, S., Wu, C. Y., Janssens, R. V. F., Cline, D., Hayes, A. B., ... Wiens, A. (2016). Direct Evidence of Octupole Deformation in Neutron-Rich 144Ba. Physical Review Letters, 116, [112503]. https://doi.org/10.1103/PhysRevLett.116.112503