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arXiv · 1410.0042

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

M. Tandecki·J. Zhang·S. Aubin·J. A. Behr·R. Collister·E. Gomez·G. Gwinner·H. Heggen·J. Lassen·L. A. Orozco·M. R. Pearson·S. Raeder·A. Teigelhöfer
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Abstract

We demonstrate a new technique to prepare an offline source of francium for trapping in a magneto-optical trap. Implanting a radioactive beam of $^{225}$Ac, $t_{1/2} = 9.920(3)$ days, in a foil, allows use of the decay products, i.e.$^{221}$Fr, $t_{1/2} = 288.0(4)$ s. $^{221}$Fr is ejected from the foil by the $\alpha$ decay of $^{225}$Ac. 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 $^{221}$Fr 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 $^{221}$Fr 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.

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M. Tandecki, J. Zhang, S. Aubin, J. A. Behr, R. Collister, E. Gomez, G. Gwinner, H. Heggen, J. Lassen, L. A. Orozco, M. R. Pearson, S. Raeder, A. Teigelhöfer. 2014-09-30. Offline trapping of $^{221}$Fr in a magneto-optical trap from implantation of an $^{225}$Ac ion beam. https://doi.org/10.1088/1748-0221/9/10/p10013

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