Electron jumps reveal subtle changes in shape of francium nuclei:
As part of the commissioning process for the Francium Trapping Facility, precise measurements were carried out on the isotopic dependence of the 7s − 7p1/2 electronic transition in a chain of different francium isotopes. As reported in Physical Review A (2014) these data were combined with previously measured isotope shifts in the 7s - 7p3/2 transition. Isotope shifts are a sensitive measure of changes in the nuclear charge radius, or size of the nucleus, between isotopes of the same atom. Comparison of the two data sets provides insights into the change of electron behaviour as the number of neutrons in the nucleus varies. The results provide a sensitive gauge of the ability of the atomic many-body calculation to describe the francium atom at a level necessary for the interpretation of the Facility's future atomic-parity violation measurements with francium.