The k0 and Q0 Values for the Zr-Isotopes: A Re-Investigation

The k 0 and Q 0 values for 94Zr(n,)95Zr(E = 724.2+756.7 keV) and 96Zr(n,)97Zr(–) 97mNb (E = 743.4 keV) were re-investigated. The aim was to further improve the reliability of the neutron spectrum characterization (f and monitoring) in k 0-NAA, based on "bare monitor" methods with the use of these Zr radionuclides. So as to achieve this goal, experimental determinations were performed in three reactor centers: KFKI AEKI, Budapest (WWR-M reactor); INW, Gent (THETIS reactor); SCK·CEN, Mol (BR1 reactor). The results were: Q 0(94Zr) = 5.306; Q 0(96Zr) = 251.6; k 0(95Zr, 724.2+756.7 keV) = 2.000E-4; k 0(97Zr/97mNb, 743.4 keV) = 1.237E-5. This means that the newly evaluated k 0-values are about 4.7% lower than the formerly reported ones. It is also emphasized that the 97Zr half-life is 16.74 hours, contrary to the 1% higher values usually reported.