Analytical possibilities of epithermal neutron activation in routine in NAA of mineral materials

The epithermal neutron activation analysis (ENAA), as compared with the pile reactor or thermal neutron activation, offers advantages in the non-destructive determination of a number of trace elements above all in mineral samples. By means of special repeatedly utilizable can, provided with Cd or Cd-B filters, the advantage factors of epithermal neutron activation were experimentally established for a wide range of elements. The highest values were obtained for such elements as Ga, As, Se, Br, Rb, Sr, Zr, Mo, Ag, Cd, In, Sb, Cs, Ba, Sm, Tb, Tm, Ta, W, Pt, Au, Th and U. A great number of mineral and organic samples, including standard reference rocks and minerals were analyzed by the ENAA method. Samples were irradiated for 20 hrs in the VVR-S reactor of the Nuclear Research Institute in Rez. Semiconductor γ-ray spectrometry was used for the measurement of irradiated samples and standards. (T.I.)