Speaker
Dr
Daniel Doherty
(CEA Saclay)
Description
The region surrounding the neutron number N = 60 for the Sr and Zr isotopic chains is an interesting example of shape evolution. Starting from the N = 50 closed spherical shell, and removing a few neutrons, the Sr and Zr isotopes become well deformed. On the neutron-rich side of these isotopic chains, N = 56 is observed to become an effective sub-shell closure with $^{96}$Zr exhibiting the properties of a doubly-magic nucleus. However, with the addition of only four more neutrons, $^{100}$Zr is observed to become strongly deformed. This sudden change from a spherical shape to one with large deformation, which is also observed for neighbouring N = 60 isotones such as $^{98}$Sr, has attracted many theoretical and experimental investigations over several decades and is probably the most sudden change from a spherical shape to one with large deformation of known nuclei. A stringent analysis of the nuclear structure and intrinsic shape of the nucleus $^{100}$Zr is, therefore, imperative. In order to shed new light on this phenomenon a Coulomb excitation experiment was performed with the aim of measuring reduced transition probabilities between low-lying excited states and quadrupole moments in order to determine the states’ intrinsic shapes.
The $^{100}$Zr beam was provided by the Californium Rare Isotope Breeder Upgrade (CARIBU) system, the only facility able to deliver intense beams of refractory elements such as zirconium. De-excitation $\gamma$-rays were detected with GRETINA detector array with the CHICO2 particle detector array employed for the detection of $^{100}$Zr projectiles and recoiling target nuclei. In this presentation, an overview of the recently performed experiment will be given and initial results presented.
Author
Dr
Daniel Doherty
(CEA Saclay)
