Fabrication of Radioactive Samples for Cross-Section Measurements

For measurements of neutron cross sections as a function of energy by the fast-chopper technique, uniform samples are required. Intensely radioactive materials present difficult problems of sample fabrication. A method of fabricating such samples, applicable to a wide range of radioactive materials, consists of preparing the radioactive nuclide in the form of a finely divided chemically stable oxide, followed by mixing the oxide with aluminum powder and compacting into a solid bar. Special sealed containers for such samples provide tight containment of the radioactive material with a minimum of surface contamination.