Planar and aplanar tilted bands in the odd–odd nucleus¹³²Cs

Abstract

High-spin states in the doubly odd N = 77 nucleus 132Cs have been studied. Gamma-ray linear polarization and angular correlation measurements have been performed to determine the spin and parity of the states. A rotational sequence of enhanced dipole transitions was established. This band can be described within the framework of the the tilted axis cranking (TAC) model as a band based on a weakly deformed structure in which the total angular momentum vector does not coincide with any of the principal axes of the triaxial nucleus but still is in the plane defined by the short and long axes. The theoretical description of the previously proposed chiral bands in 132Cs was extended in the framework of the core–particle coupling model (CPCM) confirming that the total angular momentum for the πh11/2 ⊗ νh11/2 configuration is well outside any planes defined by the principal axes of the nucleus and revealing the important role of the residual proton–neutron interaction between the valence particles.

Excited states and signature inversion inCs116

“…[28,29], which are thus also in agreement with the measurements of Refs. [16,26,27]. Clearly, a smooth trend is observed, which continues for 116 Cs, given the spin assignments on the level scheme.…”

“…Over the range 118 A 132, the spins of these bands have been unambiguously measured in five cases: 120 Cs [13]; 122 Cs [15]; 124 Cs [16]; 130 Cs [26]; and 132 Cs [27]. Systematic spin assignments have also been made for these isotopes in Refs.…”

“…These systematic spin assignments are consistent with each other and with the spins measured in Refs. [16,26,27].…”

“…Unless there is a discontinuity in the excitation energy systematics, it would appear that the measurements of Moon et al are not consistent with those of Refs. [16,26,27].…”

Transitional nuclei near shell closures

“…In some cases, chiral partner bands were also observed [7,8,9] for this configuration. In 132 Cs, several band structures have been observed by Rainovski et al [13,14] and the band built on the above configuration was interpreted as a chirallike band. A four-quasiparticle band in this nucleus with πh 11/2 ⊗ ν[d 5/2 (h 11/2 ) 2 ] configuration was interpreted as a magnetic rotational band.…”