Characterization of neutron transmuted zinc traces in pure copper materials by isotope dilution mass spectrometry

The neutron transmutation doping (NTD) of highly pure copper with zinc was investigated as a promising means of achieving controlled gradation of the zinc content in the range 1-20 mug g(-1). The doping process leads to the e nrichment of two stable isotopes Zn-64 and Zn-66 in a ratio which differs f rom that of natural isotopic distribution. Mass spectrometric investigation s by thermal ionization mass spectrometry (TIMS) were performed to validate the results obtained by gamma spectrometry. The investigations included bo th determination of the isotopic ratios of the doped zinc isotopes and the analysis of the accumulated zinc contents by isotope dilution (ID) analysis . Thereby a sample-specific correction of the blank could be performed beca use the isotope Zn-68 was not influenced, because of the transmutation proc ess. The results obtained by TIMS prove the strict proportionality of the d oped zinc content, in the range 5 to 20 mug g(-1), to the neutron fluence. Comparison with gamma spectrometric results showed a very good agreement wi thin the uncertainties.