Collinear laser spectroscopy of francium and rubidium with amplitude modulated light

A beamline has been developed to trap polarized francium ions to measure their nuclear g-factors. Francium, which has no stable isotopes, was created in a nuclear fusion reaction using the Stony Brook superconducting LINAC. Polarization of the nuclei can be achieved through optical pumping of the atomic beam with a suitable collinear laser beam.; We were able to convert 90% of a francium ion beam into an atomic beam by passing the beam through a short but dense region of Rb vapor. We determined the charge exchange cross section for 5 keV Fr ions with Rb atoms to be (9 +/- 3)x10-15 cm2.; Once neutralized we performed collinear laser spectroscopy on francium and rubidium atomic beams. With larger intensity Rb beams we were able to study their energy loss in passing through a Rb vapor. We modulated the exciting laser to increase the sensitivity in detecting the fluorescence from small francium beams, giving us a modest increase in the signal to noise by a factor of 2.5. Using this method we were able to detect the atomic resonances in 208-210Fr.; Two ion traps were developed to cool and trap polarized francium ions and provide an environment for the g-factor measurement. Accurate g-factor measurements in francium isotopes will provide a test of the calculated electron density at the nucleus in preparation for parity nonconservation experiments.