Reactor neutron activation analysis by using multi-elemental comparators: Problems of nuclear constants of128I,175Yb and several other nuclides

A simple method has been developed for evaluating the neutron spectrum and the temperature by using U, Sb, Cr, Co and Lu as monitors and successfully applied to the routine analysis. For most of nuclides, amounts determined by the method showed reasonable agreements with those added. However, there have been found several nuclides which gave erroneous results beyond the permissible limits. In the case of128I, the reason for the deviation was found to lie on the normalization factor of γ-ray abundances that are in common use. This was confirmed by using I2 doped polyacethylene which is a material highly resistant to ionizing radiations.46Sc,175Yb and several other rare earth nuclides are discussed as well.