Cyclotron production of Ac from an electroplated Ra target.

PURPOSE

We demonstrate cyclotron production of high-quality Ac using an electroplated Ra target.

METHODS

Ra was extracted from legacy Ra sources using a chelating resin. Subsequent ion-exchange purification gave pure Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 37 MBq of Ra on a target box. Maximum activation was achieved using 15.6 MeV protons on the target at 20 µA for 5 h. Two functional resins with various concentrations of nitric acid purified Ac and recovered Ra. Cooling the intermediate Ac for 2-3 weeks decayed the major byproduct of Ac and increased the radionuclidic purity of Ac. Repeating the same separation protocol provided high-quality Ac.

RESULTS

We obtained Ac at a yield of about 2.4 MBq at the end of bombardment (EOB), and the subsequent initial purification gave 1.7 MBq of Ac with Ac/Ac ratio of < 3% at 4 days from EOB. Additional cooling time coupled with the separation procedure (secondary purification) effectively increased the Ac (4n + 1 series) radionuclidic purity up to 99 + %. The recovered Ac had a similar identification to commercially available Ac originating from a Th/Ac generator.

CONCLUSION

This procedure, which involves the Ra(p,2n)Ac reaction and the appropriate purification, has the potential to be a major alternative pathway for Ac production because it can be performed in any facility with a compact cyclotron to address the increasing demand for Ac.