An apparatus used to make 22Na sources for use in low-energy positron beams

The 22Na nuclide, having a relatively long half-life (2.6 year) and high branching ratio for positron emission (90%), is often the preferred nuclide for producing low-energy positron beams. Suitable commercial 22Na sources are, however, relatively expensive and are sometimes subject to delay in supply. To circumvent such problems in the long-term maintenance of our positron beam a radioactive source deposition apparatus, capable of preparing up to 20 mCi 22Na sources from aqueous solution, has been designed and constructed. The 22NaCl solution is deposited onto a platinum substrate, dried and remotely capped with 3 μm of titanium. The apparatus has been safely employed to produce both 10 mCi and 20 mCi 22Na sources both of which are now in use in our magnetically guided positron beam.