Preparation of 225Ac by 226Ra(γ, n) photonuclear reaction on an electron accelerator, MT-25 microtron

225 Ac was prepared by the 226 Ra(γ, n ) reaction on an electron accelerator (MT-25 microtron) at FLNR. The radiation yield of 225 Ac was 550 Bq/(μA h mg 226 Ra). 225 Ac was isolated from the target material and radioactive impurities by the ion-exchange procedure. The 225 Ac: 227 Ac: 226 Ra activity ratio in the preparation was 1:∼2 × 10 −9 :≤6 × 10 −5 .