학술논문
Direct Evidence of Octupole Deformation in Neutron-Rich Ba144
Document Type
article
Author
Bucher, B; Zhu, S; Wu, CY; Janssens, RVF; Cline, D; Hayes, AB; Albers, M; Ayangeakaa, AD; Butler, PA; Campbell, CM; Carpenter, MP; Chiara, CJ; Clark, JA; Crawford, HL; Cromaz, M; David, HM; Dickerson, C; Gregor, ET; Harker, J; Hoffman, CR; Kay, BP; Kondev, FG; Korichi, A; Lauritsen, T; Macchiavelli, AO; Pardo, RC; Richard, A; Riley, MA; Savard, G; Scheck, M; Seweryniak, D; Smith, MK; Vondrasek, R; Wiens, A
Source
Physical Review Letters. 116(11)
Subject
Language
Abstract
The neutron-rich nucleus ^{144}Ba (t_{1/2}=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 ^{144}Ba beam on a 1.0-mg/cm^{2} ^{208}Pb target. The measured value of the matrix element, ⟨3_{1}^{-}∥M(E3)∥0_{1}^{+}⟩=0.65(+17/-23) eb^{3/2}, 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.