板状Bi样品泄漏中子和γ谱实验测量与模拟计算

Measurement and Calculation of Leakage Neutron andγSpectra from Bi Slab Sample

通过飞行时间法,测量了氘氘脉冲中子与不同厚度209 Bi样品作用后61°和119°方向的泄漏中子飞行时间谱和泄漏γ能谱,样品尺寸分别为30 cm×30 cm×5 cm、30 cm×30 cm×10 cm和30 cm×30 cm×15 cm。采用BC501A液体闪烁体探测器测量0.8~3.2 MeV能区的泄漏中子飞行时间谱,钾冰晶石探测器(CLYC)测量0.2~0.8 MeV的泄漏中子飞行时间谱和泄漏γ能谱。用MCNP-4C程序对泄漏中子飞行时间谱和泄漏γ能谱进行了模拟计算,209 Bi的评价中子核数据分别采用了CENDL-3.1库、ENDF/B-Ⅷ.0库、JENDL-4.0库以及JEFF-3.3库中的数据,模拟结果分别与实验结果进行比较分析,研究结果表明,泄漏中子谱CENDL-3.1库的模拟结果在119°方向弹性峰位置有较严重的低估现象,JENDL-4.0库在1.5 MeV附近(第二非弹能区)有一定高估,而在低能区有明显低估;泄漏γ能谱JENDL-4.0库和JEFF-3.3库的模拟结果与实验结果偏差明显,而CENDL-3.1库符合较好。

The leakage neutron andγspectra from 209 Bi slab samples with different thicknesses(30 cm×30 cm×5 cm,30 cm×30 cm×10 cm and 30 cm×30 cm×15 cm)were measured by time-of-flight method at 61°and 119°using a D-D neutron source.A BC501A liquid scintillation detector was chosen to measure the leakage neutron spectra from 0.8 to 3.2 MeV,and CLYC(Cs 2LiYCl 6:Ce)scintillator detector was used to measure the leakage neutron spectra from 0.2 to 0.8 MeV andγspectra.Theoretical calculations were carried out by Monte Carlo neutron transport code MCNP-4C,using the evaluated nuclear libraries of 209 Bi from the CENDL-3.1,ENDF/B-Ⅷ.0,JENDL-4.0 and JEFF-3.3.The experimental results were compared with the corresponding calculated ones.From the comparison,it is found that the calculated results of neutron spectra with the CENDL-3.1 library are underestimated in the elastic peak region at 119°,and the results with JENDL-4.0 are overestimated near 1.5 MeV but underestimated in the 0.2-1 MeV range at both 61°and 119°.Theγspectra with the JENDL-4.0 and JEFF-3.3 libraries are significantly different from the experimental results,while those from CENDL-3.1 library well reproduce the experimental ones.