Calculation of neutron cross sections on Nb for JENDL-4

JENDL-4のためのNb中性子断面積の理論計算

市原 晃 ; 国枝 賢  ; 柴田 恵一

Ichihara, Akira; Kunieda, Satoshi; Shibata, Keiichi

JENDL-4開発に向けて、JENDL-3.3のNb核データを、中性子入射エネルギーが10keVから20MeVの領域において理論計算により再評価した。4種類の核反応模型(球対称光学模型,歪曲波Born近似,Kalbach前平衡及びHauser-Feshbach統計模型)を適用して断面積,微分断面積、及び二重微分断面積を計算した。その結果、JENDL-3.3と比較して放出エネルギー1MeVにおける中性子スペクトルの実験データが、本計算によってよりよく再現できた。計算で得た全断面積,弾性及び非弾性散乱,(,), (,3), (,), (,), (,), (,), (,)及び(,)反応に対する断面積は、実験値と定量的に一致した。

Nuclear data of Nb in JENDL-3.3 were reexamined in the incident neutron energy range from 10 keV to 20 MeV toward JENDL-4. Cross sections, differential and double-differential cross sections were calculated on the basis of the nuclear reaction models such as the spherical optical model, the distorted wave Born approximation, the Kalbach preequilibrium model, and the Hauser-Feshbach statistical model. It was found that experimental neutron emission spectra were reproduced well by the present calculation compared with the JENDL-3.3 evaluations for emission energies 1 MeV. Calculated cross sections are almost consistent with the experimental data for total, elastic and inelastic scattering, (,), (,3), (,), (,), (,), (,), (,) and (,) reactions. An appreciable change from the JENDL-3.3 evaluation was not seen for the (,2) reaction, which was about 20% larger than the experiments for incident energies 14 MeV.