New Measurement of the Thermal-capture Cross Section for the Minor Isotope 180W

• Published in: Nuclear data sheets 2014-05, Vol.119, p.91-93
• Main Authors: Hurst, A.M., Firestone, R.B., Szentmiklósi, L., Révay, Zs, Basunia, M.S., Belgya, T., Escher, J.E., Krtička, M., Summers, N.C., Sleaford, B.W.
• Format: Article
• Language: English
• ISSN: 0090-3752; 1095-9904
• DOI: 10.1016/j.nds.2014.08.026

Tungsten occurs naturally in five isotopic forms; four of them, 182,183,184,186W, contribute significantly to the overall elemental abundance (with each contribution between 14 and 30 %), whereas 180W only occurs at the 0.12 % level and is a minor isotope. Given its very low abundance, a precise measurement of the thermal neutron-capture cross section is extremely challenging. This work reports a new value of the thermal neutron-capture cross section from a direct 180W(n,γ) measurement using a guided-thermal beam at the Budapest Research Reactor, incident upon an 11.35 % enriched sample to induce prompt γ-ray activation within the sample. The thermal-capture cross section was determined as the sum of experimentally observed partial neutron-capture γ-ray cross sections feeding the ground state directly, and, the modeled contribution from the (unobserved) ground-state feeding predicted from statistical-model calculations using the Monte Carlo program DICEBOX. The preliminary value of the 180W(n,γ) thermal neutron-capture cross section is 20.5(42) b.