APPLICATION OF A 6LiD THERMAL-14 MeV NEUTRON CONVERTER TO THE MEASUREMENT OF ACTIVATION CROSS SECTIONS
Research Reactor Institute, Kyoto University
Kumatori-cho, Sennan-gun, Osaka, 590-04 Japan
By means of the following two reactions; 6Li + nth → 4He + T + 4.8 MeV and D + T → 4He + n, 14 MeV neutrons can be generated from thermal neutrons, whose flux conversion rate is estimated about 2 × 10-4. A 6LiD converter, 10 × 10 cm square and 1 cm thick was prepared, and installed in a large thermal neutron irradiation facility of the Kyoto University Reactor, KUR, where the 14 MeV neutron flux of about 2.5 × 105 n/cm2/sec was obtained.
The characteristics of the 6LiD converters were measured: (1) energy of neutrons produced was determined to be 14.05 ± 0.07 MeV by the reaction rate ratio of 90Zr(n,2n)/93Nb(n,2n), and (2) the energy spectrum was obtained by unfolding multi-foil activation data using the NEUPAC code.
Making use of the 14.1 MeV neutrons, twenty three kinds of activation cross sections were measured relative to that for the 27Al(n,α)24Na reaction as a standard value. The present results have been compared with the evaluated data in ENDF/B-V and JENDL-2 and with the data in the IAEA Handbook and with the recent measurement by Ikeda et al.
KEYWORDS: 6LiD, D-T reaction, neutron converter, 14 MeV neutrons, Zr/Nb reaction ratio, spectrum unfolding, multi-foil, activation cross sections