Non-destructive proton activation analysis for nitrogen in refractory metals

The non-destructive determination of nitrogen in some refractory metals was studied by activation analysis with the ¹⁴N(p, n)¹⁴O reaction. The samples were irradiated with 12-MeV protons from a cyclotron. The proton beam intensity was normalized by means of a copper flux monitor. After chemical etching, the ¹⁴O activity (E_γ = 2313 keV, T_{$\text{1}\text{2}$} = 70.5 s) of the sample was measured by means of a Ge(Li) or NaI(Tl) detector. Standardization was carried out by the “average cross-section” method with nylon 6 as a nitrogen standard. The method gives a sensitivity of 0.4–30 μg g^?1 for analysis of Ta, W, Nb, and Ti, and 2000–4000 μg g^?1 for Zr, Ni and Mo.