Speaker
Description
Neutron-rich nuclei in the mass region A~100 exhibit large variety of interesting nuclear
structure phenomena. The nuclei having neutron number N ≤ 58 has a nearly spherical ground
state, but they undergo a rapid shape transition from nearly spherical to well-deformed prolate
deformation as N = 60 is approached. This abrupt shape change was correctly described by largescale Monte Carlo shell model (MCSM) calculations which pointed out the proton-neutron
interaction between π(1?/?) and ν(1??/?) orbitals. Lying in the intermediate position between
the spherical 96Zr and the deformed 100Zr, it is expected that the level structure of 98Zr should
exhibit the multifaceted excitation features arising out due to the strong competition between
single particle and collective behaviors.
As these neutron rich nuclei are difficult to populate through conventional fusion evaporation
reaction, the previous investigations on these nuclei were mostly carried out using the
spontaneous fission (SF) data from 252Cf and 248Cm radioactive sources. The present study
attempts an investigation of nuclear structure phenomena associated with the 98Zr nucleus, in the
low- and medium spin regimes, incorporating the new spectroscopic results obtained from an
experiment employing thermal neutron induced fission of 235U. The experiment was performed
at the PF1B line of the high-flux reactor facility at the Institut Laue-Langevin (ILL), Grenoble,
France. The γ- rays from the 98Zr nucleus and its complimentary fragment nuclei were detected
by an array consisting of eight EXOGAM large clovers, six large single-cryatal coaxial detectors
and two unsuppressed clovers from ILL. Evidence of shape-coexistence phenomenon with all its
complexities and consequences, and possibilities of other exotic modes of excitations in this
nucleus will be presented.
