ИСТИНА

Terbium isotopes are considered as a perspective for nuclear medicine [1]. The aim of this work was to develop technique of isolation of radioactive terbium isotopes from europium target irradiated by 28 MeV alpha-particles. The method should be effective for separation of Tb from hundreds of mg of Eu and trace amounts of Gd formed during irradiation by 151Eu(α,pn)153Gd reaction. Several radioactive isotopes of Tb are formed during irradiation of Eu target by 28 MeV alpha particles on cyclotron according to nuclear reactions 153Eu(α,n)156Tb, 153Eu(α,2n)155Tb, 151Eu(α,n)154Tb, 151Eu(α,2n)153Tb. Also, in model experiments we used terbium radionuclides mixture obtained by irradiation of natural Tb with 55 MeV gamma quanta by reactions 159Tb(γ,3n)156Tb, 159Tb(γ,4n)155Tb, 159Tb(γ,5n)154Tb, 159Tb(γ,6n)153Tb on a race-track microtron. In order to separate terbium from bulk europium we used reduction to Eu(II) by zinc in concentrated HCl and subsequent precipitation of EuSO4 by ammonia sulphate. The optimal conditions for separation (the kinetics of the process and the concentration of reagents) were determined. Further separation of terbium from europium and traces of gadolinium was done by extraction chromatography. Sorbent LN-Resin [2] (TrisKem) was selected for separation. The chromatographic behavior of Tb, Eu, Gd, in HNO3 solutions was studied. Thus, the possibility of production of carrier-free terbium radionuclides 154,155,156Tb by alpha-particles irradiation of europium target was shown. The method of terbium separation from macro quantities of europium and trace amounts of gadolinium is developed.