Measurement of high-energy prompt fission -ray emission in U ()

U中性子誘起核分裂における高エネルギー即発線の測定

牧井 宏之   ; 西尾 勝久   ; 廣瀬 健太郎  ; Orlandi, R.  ; Lguillon, R.*; 小川 達彦   ; Soldner, T.*; Kster, U.*; Hambsch, F.-J.*; 河野 俊彦*; Ache, M.*; Astier, A.*; Czajkowski, S.*; Frost, R. J. W.*; Guo, S.*; Mathieu, L.*; 大槻 勤*; Petrache, C. M.*; Pollitt, A.*; 関本 俊*; 高宮 幸一*; Tsekhanovich, I.*

Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, R.; Lguillon, R.*; Ogawa, Tatsuhiko; Soldner, T.*; Kster, U.*; Hambsch, F.-J.*; Kawano, Toshihiko*; Ache, M.*; Astier, A.*; Czajkowski, S.*; Frost, R. J. W.*; Guo, S.*; Mathieu, L.*; Otsuki, Tsutomu*; Petrache, C. M.*; Pollitt, A.*; Sekimoto, Shun*; Takamiya, Koichi*; Tsekhanovich, I.*

Prompt fission -ray spectra (PFGS) are important as they allow us to study the structure and de-excitation process of neutron-rich fission fragments. They are also required for the design of the Gen-IV fast reactors and advanced light-water reactors. For spontaneous fission of Cf, Cf(sf), prompt fission rays were observed up to energies of about 20 MeV. For neutron-induced fissions, however, the measured PFGS are limited below = 910 MeV. In this work we extended the measurement of the PFGS for cold neutron-induced fission of U up to 20 MeV by gaining a factor of about 10 in statistics compared to the measurements performed so far. The measurement was carried out at the PF1B cold-neutron facility of the ILL, Grenoble, France. The spectrum exhibits local bump structures at 4 MeV and 6 MeV and also a broad one at 15 MeV. In this contribution, we will discuss the origins of the bump structures in comparison with the statistical Hauser-Feshbach model calculation.