中子俘获反应截面在线测量技术研究

利用γ全吸收型4π BaF₂探测装置，对中子俘获反应截面进行了在线测量。基于HI-13串列加速器提供的脉冲化质子束，通过⁷Li(p，n) ⁷Be反应产生中子，构建了keV能区中子源实验条件，经屏蔽准直后的中子轰击样品，应用4π BaF₂装置在线测量(n，γ)反应复合核退激时释放的瞬发γ射线级联，测量了Au、C、Nb、空白等样品。通过计算⁹³Nb(n，γ)⁹⁴Nb和¹⁹⁷Au(n，γ)¹⁹⁸Au两个反应的截面数据比值并与文献数据比对，检验了4π BaF₂探测装置和(n，γ)反应截面在线测量技术，为在中国散裂中子源（CSNS）上顺利开展(n，γ)反应截面数据测量工作提供了技术支持。

Online Method for Neutron Capture Reaction Cross-section Measurement

The γ-ray total absorption BaF₂ facility was used to measure the neutron capture reaction cross section with high precision. An experimental neutron source condition of keV energy region was set up through the ⁷Li(p,n)⁷Be reaction, based on the HI-13 tandem accelerator providing the pulsed proton beam. By using the total absorption BaF₂ facility and online method, the prompt γ-ray cascades were detected when the neutron bombarded sample after shielding and collimation. Samples of Au, C, Nb and the blank were measured. The facility was checked and the online method for the (n,γ) reaction cross-section measurement was tested by comparing the deduced reaction cross-section ratio of ¹⁹⁷Au(n,γ)¹⁹⁸Au to ⁹³Nb(n,γ)⁹⁴Nb with the reference data. It also provides technical support for the implementation of (n, γ) reaction cross-section measurement at China Spallation Neutron Source (CSNS).