Neutron-rich nucleus shapeshifts between a rugby ball and a discus

There are two coexisting, competing quantum shapes at low energy in 98Kr, never before seen for neutron-rich Kr isotopes, report scientists. The team also showed that these isotopes experience a gentle onset of deformation with added neutrons, in sharp contrast with neighboring isotopes of rubidium, strontium, and zirconium, which change shapes suddenly at neutron number 60. This study marks a decisive step towards an understanding of the limits of this quantum phase transition region.