The preparation of thin radioactive sources by vacuum evaporation

An improved nethod for the production of thin (∼ 10 ng/cm2) sources of alpha- and beta-radiation is presented, which is based on a consecutive execution of the stages of electrodeposition of radioactive lanthanoides on a tantalic evaporator and high temperature evaporation of a radioactive sample in the vacuum onto a backing (source). The high temperature desorption of carrier-free radioactive isotopes of all lanthanoides, scandium and yttrium from the surface of polycrystalline tantal was systematically investigated. The values for the desorption heat were determined by the use of the data obtained by us. 28 refs.; 5 figs.; 1 tab