Speaker
Description
The neutron-rich lanthanides are expected to exhibit octupole collectivity, which can lead to asymmetric nuclear shapes. The study of low-lying negative-parity states in the even-even nuclei in this region is key to understanding the magnitude of collectivity and whether the nucleus adopts a static or dynamic asymmetric shape. Lifetimes of these states are particularly sensitive to electric-dipole transition strengths, where an enhancement can signify octupole deformation.
The fast-timing technique can be used to measure lifetimes of short-lived states in radioactive nuclei by analysing γ-γ and β-γ coincidences following β-decay. In this work, the lifetimes of low-lying states in barium, cerium, and neodymium isotopes with A = 146, 148, and 150 have been measured using the GRIFFIN spectrometer based at the ISAC-I facility at TRIUMF, Vancouver.
Primary beams of $^{146,148,150}$Cs were delivered on to a moving tape collector at the centre of the GRIFFIN spectrometer, which consists of an array of 16 HPGe clover detectors, supplemented with an array of 8 LaBr$_{3}$ scintillator detectors for fast timing, and a zero-degree scintillator for the detection of electrons emitted during β-decay. This poster will present preliminary results of these measurements obtained using both the convoluted decay-curve method and the generalised centroid-shift method.
