A re-evaluation of k0 and related nuclear data for the 555.8 keV gamma-line emitted by the 104mRh- 104Rh mother–daughter pair for use in NAA

Abstract

A re-evaluation is made of the k 0-factor and related nuclear data for the 555.8 keV gamma-ray of the 104mRh- 104Rh mother–daughter pair that are important in neutron activation analysis (NAA). This study considers that the relevant level is also fed by the 4.34 min 104mRh mother (with an absolute gamma-ray emission probability γ 2=0.13%) and not only, as assumed in former work, by the 42.3 s 104Rh daughter isotope (with γ 3=2.0%). In view of this, generalised equations were developed for both the experimental determination and the analytical use of the k 0-factor and of the associated parameters k 0(m)/ k 0(g), Q 0(m) and Q 0(g) [(m): 104mRh; (g): 104Rh], requiring the introduction of the γ 2 and γ 3 data and also of the 104mRh→ 104Rh fractional decay factor F 2(=0.9987). The experimental determinations were based on irradiations performed in the BR1 reactor in Mol and the WWR-M reactor in Budapest. Furthermore, considering the special formation of the 555.8 keV gamma-ray, the procedure for true-coincidence correction was revised as well. All this led to the compilation and recommendation of a new set of ‘ k 0-NAA’ data.