Lifetime measurements in $A\simeq 96$ isotopes via the fast-timing technique.

Gamba E.R., Bottoni S., Iskra L.W., Zavaglia C., Leoni S., Fornal B., Cieplicka-Oryńczak N., Crespi F., Köster U., Kim Y.H., Jentschel M., Michelagnoli C., Regis J.
  Giovedì 15/09   15:00 - 18:30   Aula B - Maria Goeppert-Mayer   I - Fisica nucleare e subnucleare   Presentazione
Shape coexistence is a fundamental phenomenon found in atomic nuclei. It consists in some states displaying different intrinsic deformations while having relatively similar excitation energies. Neutron-rich nuclei belonging to the $A\simeq 100$ region of the nuclear chart are known to show a large degree of deformation. Due to the interplay between these spherical and deformed configurations, shape coexistence is expected in nuclei lying at the border between the two regions. Nuclei belonging to the low-$Z$ edge of the $A\simeq 100$ deformed region of the nuclear chart were produced in the thermal-neutron--induced fission of a $^{233}U$ target. Lifetime measurements of excited states in $^{96}Rb$, $^{93\mbox{-}96}Y$ and $^{94\mbox{-}95}Sr$ were measured using the fast-timing technique with $LaBr_{3}:Ce \gamma$-ray detectors, which is able to provide precise measurements down to the picosecond regime. From these measurements, $B(E2)$ and $Q_{0}$ values were extracted to provide information on nuclear deformation in this region. In this contribution, preliminary results of the fast-timing analysis on several excited states in the mentioned nuclei will be discussed, together with some still tentative insight of their physical interpretation.