Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Offline trapping of $^{221}$Fr in a magneto-optical trap from
  implantation of an $^{225}$Ac 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
$^{225}$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.

7
The categories of this paper are: hep-th
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The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
18
The categories of this paper are: econ