Proton activation analysis of trace impurities in purified cobalt

Nondestructive activation analysis by proton beam bombardment has been applied to cobalt specimens. Thick target yields were measured on 18 elements for the purpose of quantitative analysis. In order to detect precisely the radionuclides with different half-lives, gamma-ray spectrometry was repeated three times after different cooling times of 1, 15 and 250 hrs from the finish of bombardment for 1 hrby 10.4 MeV proton beam. It was found that Ti, Cr, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Zr, Nb, Mo, Cd, Sn, Sb, and Te of the order of ppm or less could be detected accurately. Using the proton activation analysis developed, the purification effects of anion exchange, electrolytic extraction, and floating zone-refining have been examined. It was confirmed that the concentrations of the impurity elements contained in the starting material decreased stepwise upon the application of each purification method.