PREPARATION OF ISOTOPICALLY ENRICHED SPUTTER TARGETS FOR THE PRODUCTION OF TANDEM ACCELERATED BEAMS OF CA-48 AND C-14

Due to its low consumption of target material a cesium beam hiconex type sputter ion source is well suited for the production of tandem accelerated beams of rare isotopes using isotopically enriched sputter targets. The present paper describes the preparation of 48Ca and 14C sputter targets. In the case of 48Ca, the sputter target consists of a nearly hemispherical stalactite, 20-50 mg in weight, which is prepared by a reduction distillation technique. The overall collection efficiency of this technique is (94 ± 1)%. With 20 mg of 69% enriched material, an analysed 48Ca beam of ∼250 nA can be supplied for 23 h. The 14C sputter target is a Fe3 14C pellet, which is produced by electron beam melting of adequate quantities of natural iron powder and amorphous,elemental 14C. The choice of Fe3 14C as a target material has been made for reasons of radiation protection. A Fe3 14C sputter target containing 0.6 mCi 14C supplied a 5 nA 14C beam for a period of more than 100 h. A higher enriched target with 80 mCi 14C produced an analysed 14C beam of 250 nA for a period of 350 h. © 1979.