Reactions Induced by Slow Neutron Irradiation of Europium

A sample of europium which had been subjected to slow neutron irradiation was analyzed using mass spectrometric techniques. By using a modified isotopic dilution technique, i.e., adding a standard containing known relative abundances of normal samarium, europium, and gadolinium the complete chemical and isotopic analysis of the irradiated sample was obtained. Combining this nuclide composition and certain radioactivity measurements the thermal neutron cross sections, half-lives and branching ratios of five of the europium isotopes were calculated. The results were σ₁₅₁=5200 barns, σ₁₅₂=3200 barns, σ₁₅₃=240 barns, σ₁₅₄=880 barns, σ₁₅₅=7900 barns, T1/2(152)=5.3 years, T1/2(154)=5.4 years, T1/2(155)=1.7 years, Kβ^- ratio for 9.2-hr. Eu¹⁵²=0.22, Kβ^- ratio for 5.3-year Eu¹⁵²=2.8, and Kβ^- ratio for 5.4-year Eu¹⁵⁴0.05. All these results are believed to be good to ±{}15 percent.