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中国物理学会期刊

14 MeV附近191Ir(n,2n)190Ir反应截面实验研究

CSTR: 32037.14.aps.71.20220776

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

CSTR: 32037.14.aps.71.20220776
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  • 铱元素是测量中子能谱的优质活化探测器. 本文围绕191Ir(n,2n)190Ir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191Ir(n,2n)190Ir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191Ir (n,2n) 190Ir第2激发态截面σm2, 191Ir(n,2n)190Ir基态与第1激发态之和的反应截面σg+m1、总反应截面σg+m1+m2和截面比σm2/σg+m1等实验数据, 实验不确定度在3.4%—3.5%, 其中, 14 MeV对应σm2 = (136.05 ± 4.93) mb, σg+m1 = (1972.35 ± 67.06) mb, σg+m1+m2 = (2108.40 ± 71.99) mb, 截面比σm2/σg+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σg+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191Ir(n,2n)190Ir总反应截面σg+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 191Ir(n,2n)190Ir 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 191Ir(n,2n)190Ir, σm2 and σg+m1, are measured carefully. The 191Ir(n,2n)190Ir cross sections: σm2, σg+m1, σg+m1+m2 and cross section ratio of σm2/σg+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 191Ir(n,2n)190Ir at 14 MeV are σm2 = (136.05 ± 4.93) mb, σg+m1 = (1972.35 ± 67.06) mb, σg+m1+m2 = (2108.40 ± 71.99) mb, and σm2/σg+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 σg+m1, the evaluated data from JEFF3.0/A are underestimated by 5%–20% in comparison with the present data for σm2, the evaluated data from ENDF/B-VIII.0 are underestimated by 10% in comparison with the present data for σm2, and the ENDF/B-VIII.0 data are consistent with the present data for σg+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.

     

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