CHEMICAL-SEPARATION PROCEDURE FOR THE NUCLIDE ANALYSIS OF A TANTALUM TARGET IRRADIATED FOR 500 DAYS WITH 800 MEV PROTONS

A rapid radiochemical separation procedure has been developed for the determination of long-lived and stable nuclides produced by spallation and activation in a tantalum target irradiated for 500 days with 800 MeV protons. In this procedure the matrix element tantalum and simulta neously the Ta-182 activity, built-up by activation of the matrix with thermalized spallation neutrons is removed from many elements. About 50 mg of the tantalum sample is dissolved in a mixture of concentrated nitric and hydrofluoric acid. After dilution tantalum is extracted wi th a solution of 0.2M tetrahexylammonium bromide in methyl isobutyl ke tone (MIBK). The residual amount of tantalum and the remaining Ta-182 activity are 0.0003% and the recoveries of 27 investigated elements ar e in the range of 96.0-99.9%. A further 22 elements are quantitatively separated according to their chemical behavior. In the final aqueous fraction the separated long-lived and stable nuclides of 49 elements c an be measured with high sensitivity by gamma-ray spectrometry and mas s spectrometry (ICP-MS).