Offline trapping of ²²¹Fr in a magneto-optical trap from implantation of an ²²⁵Ac ion beam

We demonstrate a new technique to prepare an offline source of francium for trapping in a magneto-optical trap. Implanting a radioactive beam of ²²⁵Ac, t_1/2 = 9.920(3) days, in a foil, allows use of the decay products, i.e. ²²¹Fr, t_1/2 = 288.0(4) s. ²²¹Fr is ejected from the foil by the α decay of ²²⁵Ac. This technique is compatible with the online accumulation of a laser-cooled atomic francium sample for a series of planned parity non-conservation measurements at TRIUMF. We obtain a 34 % release efficiency for ²²¹Fr from the recoil source based on particle detector measurements. We find that laser cooling operation with the source is 8⁺¹⁰_-5 times less efficient than from a mass-separated ion beam of ²²¹Fr in the current geometry. While the flux of this source is two to three orders of magnitude lower than typical francium beams from ISOL facilities, the source provides a longer-term supply of francium for offline studies.