New Band Structures in Neutron-Rich $^{108}$Mo, and $^{108,110,112}$Ru

ORAL

Abstract

New insights into the structures of $^{108}$Mo, and $^{108,110,112}$Ru are identified in the spontaneous fission of $^{252}$Cf. The 5.7 x 10$^{11}$ triples and higher fold prompt gamma coincidences opened up the possibility to see new weakly populated band structures in these nuclei. Two phonon $\gamma $-bands that decay only to the one phonon $\gamma $-band were discovered in $^{108}$Mo and $^{110,112}$Ru. We discovered in $^{108}$Mo$^{ }$and$^{ 108,110,112}$Ru $\Delta $I=1, doublet bands. Our theoretical calculations indicate $^{108}$Ru is $\gamma $-soft and $^{110,112}$Ru are more rigid triaxial nuclei. The non-yrast band in $^{108}$Ru shows an energy level staggering not seen in its yrast partner band nor in $^{110,112}$Ru. This staggering is proposed to be related to its $\gamma $-soft shape perturbing its chiral structure. The doublet bands in $^{108}$Mo$^{ }$and $^{110,112}$Ru will be shown to have all the properties expected for chiral vibrational bands. Tilted axis cranking calculations for $^{110,112}$Ru stronly support the chiral vibrational interpretation of these bands but do not support their being accidentally degenerate energy doublets built on different configurations.

Authors

  • J.H. Hamilton

  • Y.X. Luo

  • A.V. Ramayya

  • C. Goodin

  • K. Li

  • J.K. Hwang

  • S. Liu

    • Vanderbilt Univ.
  • S.J. Zhu

  • H.-B. Ding

  • X.L. Che

    • Tsinghua Univ.
  • J.O. Rasmussen

  • I.Y. Lee

    • LBNL
  • D. Almehed

  • S. Frauendorf

  • V. Dimitrov

    • Univ. Notre Dame
  • J.Y. Zhang

  • N.J. Stone

    • Univ. of TN
  • G.M. Ter-Akopian

  • A.V. Daniel

    • JINR
  • M.A. Stoyer

    • LLNL
  • R. Donangelo

    • Univ. Fed. do Rio Janeiro
  • J.D. Cole

    • INL