SYMPOSIA PAPER Published: 01 January 1994

Measurements of Thermal Neutron Cross Section and Resonance Integral for the Np(n,γ) Np Reaction


Making use of a standard neutron spectrum field with a pure Maxwellian distribution at the heavy water thermal neutron facility of the Kyoto University Reactor (KUR), the thermal neutron cross section for the 237Np(n,γ)238Np reaction was measured by the activation method, using a high purity Ge detector. The result is 158±3 b, which is obtained relative to the reference value of 98.65±0.09 b for the 197Au(n,γ)198Au reaction. The present value is lower by about 13% than that of the ENDF/B-VI data. The data given by Mughabghab and obtained from JENDL-3 are larger by 11 to 14% than the present measurement.

The resonance integral for the 237Np(n,γ)238Np reaction was measured with a 1/E standard neutron spectrum in the cavity of the central graphite reflector region between the two-divided cores of the Kinki University Reactor (UTR-KINKI), relative to the reference value of 1550±28 b for the 197Au(n,γ)198Au reaction. By defining the Cd cut-off energy as 0.5 eV, the present resonance integral is 652±24 b, which is in good agreement with the JENDL-3, ENDF/B-VI and Mughabghab data. However, most of the old experimental data are, in general, larger by 24 to 38% than the present measurement.

Author Information

Kobayashi, K
Research Reactor Institute, Kyoto University, Osaka, Japan
Yamanaka, A
Hitachi Works, Hitachi, Ltd., Ibaraki, Japan
Kimura, I
Kyoto University, Kyoto, Japan
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Developed by Committee: E10
Pages: 711–719
DOI: 10.1520/STP15167S
ISBN-EB: 978-0-8031-5281-6
ISBN-13: 978-0-8031-1899-7