High spin states in57135La78

Abstract

High spin states in ${}^{135}$La have been investigated using the ${}^{128}$Te(${}^{11}$B,$4n$)${}^{135}$La reaction at a beam energy of 50.5 MeV using the Indian National Gamma Array (INGA). The level scheme has been confirmed and extended both for low and high spin states with the observation of several new transitions. The Directional Correlations of Oriented states (DCO) ratios and linear polarization measurements have been performed to assign spin-parity for most of the reported $\ensuremath{\gamma}$ transitions. A new positive parity band has been observed and identified as a decoupled band ($\ensuremath{\Delta}I=2$). Two negative parity dipole bands ($\ensuremath{\Delta}I=1$) have been established and for one of the dipole bands the crossover $E2$ transitions have been identified for the first time. On the basis of the Tilted Axis Cranking (TAC) calculations, a three quasiparticle (qp) $\ensuremath{\pi}{({h}_{11/2})}^{1}\ensuremath{\bigotimes}\ensuremath{\nu}{({h}_{11/2})}^{\ensuremath{-}2}$ configuration and 5qp $\ensuremath{\pi}{({h}_{11/2})}^{1}{({g}_{7/2}/{d}_{5/2})}^{2}\ensuremath{\bigotimes}\ensuremath{\nu}{({h}_{11/2})}^{\ensuremath{-}2}$ configuration have been assigned to these two dipole bands. The comparison with experimental observables supports the configuration assignments for both the dipole bands.