This talk will address nuclear structure studies in two critical regions of the nuclear chart; the neutron-deficient selenium isotopes around mass A~70 and the mass A~100 region in the vicinity of the neutron number N~60. Both regions display sudden evolution of nuclear shapes, shape coexistence phenomena and, furthermore, state-of-the-art theoretical calculations suggest that possible non-axially deformed (or triaxial) nuclear shapes may be present in these mass regions. Coulomb excitation is an ideal experimental probe of such phenomena owing to the well-understood interaction between collision partners and the relatively large reaction cross sections.
Beams of the radioactive isotope 72Se were delivered by new the HIE-ISOLDE facility, CERN where the newly increased beam energy means that it is now possible to probe states further from the nuclear ground state. However, many of the most interesting nuclei in the neutron-rich A~100 region are examples of so-called ‘refractory’ elements which cannot be extracted from traditional ISOL targets. Instead, therefore, these studies take place primarily at ANL’s CARIBU (CAlifornium Rare Isotope Breeder Upgrade) facility where beams of refractory isotopes can be produced from thermalized fission fragments. The recent results on 110Ru represent the very first successful post-acceleration of a beam of an unstable refractory isotope.
In addition, I will also briefly address our new plans to perform Coulomb excitation studies at LNL which in the first instance will focus on our accepted proposal to study type-II shell evolution in 94Zr with the SPIDER array coupled to GALILEO.
