14 MeV 中子在镓核激发态上的非弹性散射研究

The experimental studies of fast neutron scattering attract growing interest in the context of nuclear energy technology development and widespread use. Especially the precise data of inelastic scattering cross sections for the elements, which experimental data is scarce relatively. Gallium is one of such elements, which has important application in nuclear engineering, national defense, and nuclear astrophysics research. In this proposal, inelastic scattering of 14 MeV neutron from excited states in gallium will be studied based on D-T neutron source. The neutron and gamma ray were correlation measured by time-of-flight technique with scintillation detector and high-purity germanium or LaBr3(Ce) detector. The precise neutron energy spectra and gamma spectra of excited states will be acquired and the neutron inelastic scattering cross sections will be deduced from the experiment. The information of level cross sections for yrast states can be further studied from measured gamma spectra. The discrepancy between experimental data and evaluation database for neutron inelastic scattering cross sections in gallium can also be clarified. Theoretical models will be verified.

随着核能技术的发展与广泛应用，快中子散射实验研究成为国际热点问题。特别是许多核素的中子非弹性散射截面高精度实验数据缺乏。镓核在核能工程、国防及核天体物理中都有重要应用，但其相关实验数据极其缺乏。本项目拟基于氘氚中子源，研究14 MeV 中子在镓核激发态上的非弹性散射。实验采用飞行时间法，利用液体闪烁体探测器、高纯锗及溴化镧探测器进行中子和伽玛的关联测量。实验测量可以得到精确的中子能谱及镓核各个激发态的伽玛能谱，进而得到中子非弹性散射截面数据。利用伽玛谱可以进一步探究转晕态的能级截面相关信息，并澄清镓核中子非弹性散射数据中评价数据库与实验数据的分歧，对相关理论模型进行检验。

项目基于氘氚中子源，利用14MeV的中子轰击镓靶，采用中子飞行时间法，使用液体闪烁体探测器和溴化镧探测器测量了镓靶的泄漏伽玛能谱和中子能谱，得到了镓核分离能级即各个激发态的能级贡献，同时采用TALYS程序计算了该反应中的各个反应道及出射伽玛射线的数据。通过实验数据、TALYS程序理论计算数据与评价数据库中的中子反应道数据相比较，澄清了镓核中子非弹性散射数据中评价数据库与中子积分实验数据之间存在较大差异的原因。该套实验方法，验证了宏观检验系统的可靠性，同时校验了相关理论模型，并继续为中国CENDL数据库提供中子评价核数据宏观检验结果，并反馈与数据库，进一步优化改善评价数据。对于中国CENDL数据库的中子核数据宏观检验以及核工程相关的基础核数据的宏观检验有重要的意义。