基于白光中子源的^(169)Tm辐射俘获截面测量和共振参数分析  

Radiative Capture Cross-section Measurement and Resonance Parameter Analysis for ^(169)Tm Based on White Neutron Source

作　　者：任杰[1] 阮锡超[1] 王金成 鲍杰[1] 栾广源 张奇玮[1] 黄翰雄[1] 聂阳波[1] REN Jie;RUAN Xichao;WANG Jincheng;BAO Jie;LUAN Guangyuan;ZHANG Qiwei;HUANG Hanxiong;NIE Yangbo(China Nuclear Data Center,Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院核数据重点实验室,中国核数据中心,北京102413

出　　处：《原子能科学技术》2022年第5期805-815,共11页Atomic Energy Science and Technology

基　　金：国家自然科学基金(11790321,11805282)。

摘　　要：中子辐射俘获截面及共振参数在核工程设计、核天体物理等研究领域中有重要的应用价值。在中国散裂中子源(CSNS)反角白光中子束线(Back-n)上,使用C_(6)D_(6)测量系统开展了^(169)Tm辐射俘获反应测量。通过脉冲高度权重技术、共振吸收法和饱和归一法得到^(169)Tm辐射俘获反应的产额。利用SAMMY程序拟合^(169)Tm的产额数据,得到^(169)Tm在1~100 eV能量区间的共振能量、中子宽度、辐射俘获宽度等共振参数。使用实验测得的共振参数和Reich-Moore近似计算了^(169)Tm在1~100 eV能量区间的辐射俘获截面。实验测量结果与ENDF/B-Ⅷ.0数据库的推荐值总体符合较好,部分共振参数和截面存在一定的差异。产生这些差异的原因与Back-n的源中子能谱结构、能量分辨率、实验本底的精度有关。Radiative neutron capture cross-section and the resonance parameter are very important nuclear data in the field of the R&D of accelerator driven systems,the transmutation of nuclear waste and nuclear astrophysics.In the recent years,radiative neutron capture cross-sections of important nuclides were mostly measured based on the white neutron source facilities,such as the CERN n_TOF,GELINA,LANSCE and so on.The back streaming white neutron beam line(Back-n)of China Spallation Neutron Source(CSNS)is the first white neutron facility in China,which can provide pulsed neutron beam with 25 Hz frequency in the energy region from thermal neutron to hundreds MeV.The main application of Back-n is to perform nuclear data measurement,such as cross-section,reaction yield,nuclear structure,and so on.The C_(6)D_(6) liquid scintillation detector is widely used for radiative neutron capture cross-section measurements on time-of-flight facilities,because of its low neutron sensitivity and good time response.A C_(6)D_(6) detection system with four detectors was installed at Back-n to perform radiative neutron capture cross-section measurement,especially in the resonance energy region.In this work,the measurement of ^(169)Tm(n,γ)^(170)Tm reaction was performed with the C_(6)D_(6) detection system at the Back-n.The stable isotope of thulium,^(169)Tm,is one of the fission product poisons,which makes the accurate neutron radiative capture cross-section of ^(169)Tm be of major significance for fission and fusion reactor design.Besides,the radioactivity induced by the reactions of ^(169)Tm(n,γ) ^(170)Tm and ^(170)Tm(n,γ)171 Tm makes the ^(169)Tm to be an ideal spectrum-sensitive activation detector for the neutron intensity diagnosis,in which the precise neutron capture cross-section is of critical importance.In the present measurement,the pulse height weighting technique was used to make detection efficiency be proportional to the excitation energy of the compound nucleus.The black filter method was used to determine the experimental

关 键 词：辐射俘获截面 共振参数 脉冲高度权重技术 白光中子源 

分 类 号：O571.552[理学—粒子物理与原子核物理]