14 MeV附近^(191)Ir(n,2n)^(190)Ir反应截面实验研究  

Measurement of^(191)Ir(n,2n)^(190)Ir cross section near 14 MeV

作　　者：朱传新[1] 秦建国[1] 郑普[1] 蒋励[1] 朱通华[1] 鹿心鑫[1] Zhu Chuan-Xin;Qin Jian-Guo;Zheng Pu;Jiang Li;Zhu Tong-Hua;Lu Xin-Xin(Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621999,China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,绵阳621999

出　　处：《物理学报》2022年第19期45-52,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11775200)资助的课题。

摘　　要：铱元素是测量中子能谱的优质活化探测器.本文围绕^(191)Ir(n,2n)^(190)Ir反应截面开展了实验研究,在PD-300中子发生器DT中子源上采用活化法以93Nb(n,2n)92mNb反应截面为标准进行了14 MeV附近9个能点的^(191)Ir(n,2n)^(190)Ir反应截面测量,活化产物采用高纯锗探测器进行了测量,获得了13.40-14.86 MeV范围内^(191)Ir(n,2n)^(190)Ir第2激发态截面sm2,^(191)Ir(n,2n)^(190)Ir基态与第1激发态之和的反应截面sg+m1、总反应截面sg+m1+m2和截面比sm2/sg+m1等实验数据,实验不确定度在3.4%-3.5%,其中,14 MeV对应sm2=(136.05±4.93)mb,sg+m1=(1972.35±67.06)mb,sg+m1+m2=(2108.40±71.99)mb,截面比sm2/sg+m1=0.0690±0.0024.实验结果与文献数据及ENDF/B-VIII.0和JEFF3.0/A数据库评价数据进行了比较,结果表明:第1激发态与基态截面之和sg+m1实验结果与文献数据取得了较好的一致性,ENDF/B-VIII.0数据库评价数据与本工作所得^(191)Ir(n,2n)^(190)Ir总反应截面sg+m1+m2实验数据较好地符合,对文献数据分歧情况进行了分析和澄清;本实验结果与文献数据相较有更高的测量精度,本研究结果可为核数据评价相关工作提供重要参考.Natural iridium acts as a high-quality activated detector for probing the energy components of a neutron fluence.Measurements of^(191)Ir(n,2n)^(190)Ir cross sections are carried out near 14 MeV by the activation method based on 93Nb(n,2n)92mNb reaction cross section standard by PD-300 neutron generator DT neutron source.The(n,2n)products are measured by using a calibrated high pure Ge detector.The cross sections of^(191)Ir(n,2n)^(190)Ir,sm2 and sg+m1,are measured carefully.The^(191)Ir(n,2n)^(190)Ir cross sections:sm2,sg+m1,sg+m1+m2 and cross section ratio of sm2/sg+m1 are obtained in an energy range of 13.40-14.86 MeV.Experimental uncertainties are in a range of 3.4%-3.5%.The measured cross sections for the reaction of^(191)Ir(n,2n)^(190)Ir at 14 MeV are sm2=(136.05±4.93)mb,sg+m1=(1972.35±67.06)mb,sg+m1+m2=(2108.40±71.99)mb,and sm2/sg+m1=0.0690±0.0024.The present data are compared with the previous experimental data and the ENDF/B-VIII.0 and JEFF3.0/A evaluated data,showing that the experimental data from the literature are in good agreement with the present data for sg+m1,the evaluated data from JEFF3.0/A are underestimated by 5%-20%in comparison with the present data for sm2,the evaluated data from ENDF/B-VIII.0 are underestimated by 10%in comparison with the present data for sm2,and the ENDF/B-VIII.0 data are consistent with the present data for sg+m1+m2.The discrepancies between the data from the literature and the present data are analyzed and clarified.The present data show significant improvement in accuracy in comparison with data from the literature,these results provide more reliable nuclear data for improving the future evaluation.

关 键 词：反应截面 IR 活化法 DT中子源 

分 类 号：TL816[核科学技术—核技术及应用]