Towards atomic parity violation at the francium trapping facility

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Collister, Robert
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The development of the Francium Trapping Facility at TRIUMF, Canada and progress towards an atomic parity violation measurement in francium are underway. Francium (Z = 87) is the heaviest alkali. Its simple atomic structure and large number of nucleons make it an attractive system for weak interaction studies. For this reason, atomic parity violation in francium is an active area of study, and recent years have seen significant progress towards that end. Laser trapping of francium at Triumf has only recently been achieved, and several useful physics measurements for the future atomic parity violation experiment have been performed. The future measurement is of the highly forbidden 7S - 8S optical transition amplitude, which is suppressed by ~ 10^10 compared to an allowed transition amplitude. This will be achieved by interference with an allowed Stark transition, similar to the 6S - 7S optical atomic parity violation measurement in cesium. The commissioning of the two-chamber trapping apparatus as well as the development of the electric field plates for the Stark interference will be reported on. The physics measurements include the photoionization cross-section from the 7P_3/2 states, and isotope shifts of the D1 line. The cross-section must be known to evaluate a potential atom loss mechanism from the 506 nm light of the 7S - 8S excitation, negatively impacting the trapped population. Atomic theory calculations, which are required for the extraction of the weak coupling constants from the atomic measurement, may be benchmarked against these isotope shifts, allowing theorists to refine their techniques for the more sensitive evaluations.
Atomic parity violation, Francium, Atom trapping, Isotope shifts, Photoionization cross-section