An interferometric method is used to improve the accuracy of the 7S-7P transition frequencies of three francium isotopes by 1 order of magnitude. The deduced isotope shifts for 209-211Fr confirm the ISOLDE data. The frequency of the D2 transition of 212Fr--the accepted reference for all Fr isotope shifts--is revised, and a significant difference with the ISOLDE value is found. Our results will be a benchmark for the accuracy of the theory of Fr energy levels, a necessary step to investigate fundamental symmetries.

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We study the rubidium magneto-optical trap (MOT) population changes induced by a laser beam interacting with the trapped atoms and resonant with different transitions from both the ground and the excited trap levels. Laser excitation outside the cooling scheme induces losses in the MOT population, while the laser increases the trap population when tuned to transitions linked to the trapping cycle. The experiment is performed with a small number of trapped atoms (100 to 10 000). A discussion of our ability in manipulating the atomic population of different hyperfine states is reported.

A brief review of the Francium trapping experiments at the INFN-LNL facility is presented in the wide context of Atomic Parity Non-Conservation, which, as long as acquiring more precise and new spectroscopic data on the Francium isotopes, is the ultimate goal of the experiment. Due to its instability, Francium atoms must be produced continuously by a nuclear fusion-evaporation reaction into a heated Gold target hit by a beam of accelerated Oxygen ions. Francium is then extracted in the ionic form and guided by an electrostatic line to the actual science chamber, where the ions are neutralized. Atoms are then cooled down and trapped in a Magneto-Optical Trap to ensure both the availability of a sufficiently populated and stable atomic sample and to eliminate the Doppler broadening which would affect the precision of the measurements. A review of the recent improvements to the experimental apparatus and to the detection techniques that led to a sensitivity better than 5 atoms is presented. The final part of this article deals with a summary of the recent results obtained by our collaboration and a short outlook for the immediate future

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