Measurements of thermal-neutron capture cross-section and resonance integral of neptunium-237

• Published in: Journal of nuclear science and technology Vol. 56; no. 6; pp. 493 - 502
• Main Authors: Nakamura, Shoji, Kitatani, Fumito, Kimura, Atsushi, Uehara, Akihiro, Fujii, Toshiyuki
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis 03.06.2019; Taylor & Francis Ltd
• Subjects: Absorption cross sections; activation method; Aluminum base alloys; emission probability; Gadolinium; Gamma spectroscopy; gamma-ray spectroscopy; Irradiation; Monitors; Neptunium isotopes; Neptunium-237; Neutron flux; Neutrons; Nuclear capture; Position measurement; Protactinium-233; resonance integral; thermal-neutron capture cross-section
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/00223131.2019.1598304

The thermal-neutron capture cross-section (σ 0 ) and resonance integral (I 0 ) were measured for the 237 Np(n,γ) 238 Np reaction by an activation method. A method with a Gadolinium filter, which is similar to the Cadmium difference method, was used to measure the σ 0 with paying attention to the first resonance at 0.489 eV of 237 Np, and a value of 0.133 eV was taken as a cut-off energy. Neptunium-237 samples were irradiated at the pneumatic tube of the Kyoto University Research Reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as monitors to determine thermal-neutron fluxes and epi-thermal Westcott's indices at an irradiation position. A γ-ray spectroscopy was used to measure activities of 237 Np, 238 Np and neutron monitors. On the basis of Westcott's convention, the σ 0 and I 0 values were derived as 186.9 ± 6.2 barn, and 1009 ± 90 barn, respectively.