Quadrupole moment of Fr 203

Abstract

The spectroscopic electric quadrupole moment of the neutron-deficient francium isotope Fr203 was measured by using high-resolution collinear resonance ionization spectroscopy (CRIS) at the CERN Isotope Separation On-Line Device (ISOLDE) facility. A remeasurement of the Fr207 quadrupole moment was also performed, resulting in a departure from the established literature value. A sudden increase in magnitude of the Fr203 quadrupole moment, with respect to the general trend in the region, points to an onset of static deformation at N=116 in the Fr87 isotopic chain. Calculation of the static and total deformation parameters show that the increase in static deformation only cannot account for the observed departure of its relative charge radius from the Pb82 chain.