Coincidence and correlation analysis for low spin states in 128Xe

Shape-driving effects in the triaxial nucleus,Xe128

“…In cases where transitions are too weak to be observed in this matrix or are considered to be contaminated, their intensity has been obtained from intensity balances in coincidence spectra. Column 5 of table I includes the measured R DCO values, which for previously known [3,4,19] J = 2 (590, 704, 775, 684, and 612 keV) and pure (δ = 0) J = 1 (303, 504, 846, and 1196 keV) transitions, respectively, average 1.01(2) and 0.56 (2), in agreement with the expected values of 1 and ∼0.56. The results for previously known transitions are in good agreement with earlier work [3,4,19].…”

“…The K π = 2 + γ band built on the 969 keV state was proposed up to the J π = 6 + level by Neuneyer et al [3]. It has been observed in the current experiment and an extension to the J π = 8 + state at 2973 keV is proposed.…”

“…The total Routhian surface calculations [1] for 128 Xe are compatible with other interpretations based on the O(6) limit of the interacting boson model [2] in suggesting a triaxial shape for the ground state. This is supported by the observation of the γ band at the relatively low excitation energy of 969 keV [3], indicating the softness of 128 Xe with respect to γ excitations and the necessity of including the triaxial degree of freedom in any theoretical approach.…”

“…It has been observed in the current experiment and an extension to the J π = 8 + state at 2973 keV is proposed. The 2973 keV state has been observed previously [3,4,20], but no J π value has been assigned to it. It decays via a 461 keV transition to the J π = 8 + member of the ground-state band and a 693 keV transition [3] to the J π = 6 + member of the K π = 2 + band.…”

O(6)-symmetry breaking in theγ-soft nucleusXe126and its evolution in the light stable xenon isotopes

“…The stable even-even xenon isotopes, 124−132 Xe, were considered to be part of this extensive O(6)-like region. Indeed, the low-spin structures of 128 Xe [11], 126 Xe [12] and 124 Xe [13] manifest O(6)-like arrangements of energy levels [10] and E2 branching ratios reflecting the selection rules of the O(5) symmetry, where O(5) is a subgroup of O(6). However, this interpretation was challenged very recently in the case of 124 Xe [14].…”