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C6D6闪烁体探测系统结合脉冲权重技术被广泛应用于中子俘获反应截面测量研究. 实验中采用的样品厚度直接影响中子束流时间, 同时也影响实验数据的可靠性. 本文基于中国散裂中子源反角白光束线(CSNS Back-n) C6D6探测系统, 对比研究了不同厚度的镥(Lu)样品中子俘获反应截面的实验测量. 利用GEANT4蒙特卡罗程序模拟了考虑样品厚度的探测系统光响应, 计算出精确的脉冲权重函数. 实验中, 通过采用较长中子飞行距离和本底测量, 得到了高精度的共振区产额分布. 通过R矩阵理论分析产额分布, 得到了相应的实验共振参数. 结果发现, 较厚Lu样品因其厚度效应导致共振曲线发生变化, 实验共振参数与ENDF/B-VIII.0评价数据库差距较大; 然而, 较薄Lu样品实验结果能够很好地再现ENDF/B-VIII.0评价数据.The C6D6 detection system coupling with the pulse height weighting technique is widely used for experimentally measuring the neutron capture cross section. The thickness of sample used in the experiment directly affects the neutron beam time and the reliability of the experimental data. In the present work, we compare the lutetium (Lu) neutron capture reaction cross sections among the samles with different thickness, obtained by the C6D6 detection system of the back-streaming white neutron beam line at China spallation Neutron Source (CSNS back-n). The light response of the detection system is simulated with the consideration of the sample thickness by GEANT4 Monte Carlo simulation code. The 4th order polynomial pulse weight functions for different samples are determined by using the above light response function. In the experiment, the high precision capture yield distributions in the resonance energy region are obtained by measuring the longer flight distance and background. The experimental resonance parameters are deduced by analyzing the capture yield distribution with the R-matrix theory. The comparisons of the results of capture yield and the resonance parameters between the two groups show that the resonance curve of 1.06mm natLu sample changes due to its thickness effect, and there is a large difference between the experimental resonance parameters and ENDF/B-VIII.0 database. However, the experimental results of 0.207mm natLu sample can well accord with the ENDF/B-VIII. 0 data.
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Keywords:
- neutron capture cross section /
- china spallation neutron source /
- resonance parameter analysis
[1] 葛智刚, 陈永静 2015 科学通报 60 3087Google Scholar
Ge Z G, Chen Y J 2015 Chin. Sci. Bull. 60 3087Google Scholar
[2] 阮锡超 2020 中国科学: 物理学 力学 天文学 55 5
Ruan X C 2020 Scientia Sinica Physica, Mechanica & Astronomica. 55 5
[3] 刘世龙, 葛智刚, 阮锡超, 陈永静 2020 原子能科学技术 54 SupplGoogle Scholar
Liu S L, Ge Z G, Ruan X C, Chen Y J 2020 Atomic Energy Sci. Tech. 54 SupplGoogle Scholar
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[7] Plompen A, Cabellos O, Jean C, et al. 2020 Eur. Phys. J. A 56 7Google Scholar
[8] Ignatyuk A V, Fursov B I 2007 Proc. Int. Conf. on Nuclear Data for Science and Technology Nice, France, April 22–27, 2007 vol 2, p759
[9] Tang J Y, Liu R, Zhang G H, et al. 2021 Chin. Phys. C 45 062001Google Scholar
[10] Tang J Y, An Q, Bai J B, et al. 2021 Nucl. Sci. Tech. 32 11Google Scholar
[11] 李鑫祥, 刘龙祥, 蒋伟等 2020 核技术 43 080501Google Scholar
Li X X, Liu L X, Jiang W, et al. 2020 J. Nucl. Tech. 43 080501Google Scholar
[12] Zhang S, Chen Z Q, Han R, Liu X Q, Wada R, Lin W P, Jin Z X, Xi Y Y, Liu J L, Shi F D 2013 Chin. Phys. C 37 126003Google Scholar
[13] Yan J, Liu R, Li C, et al. 2010 Chin. Phys. C 34 993Google Scholar
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[15] 任杰, 阮锡超, 陈永浩等 2020 物理学报 69 172901Google Scholar
Ren J, Ruan X C, Chen Y Het al. 2020 Acta Phys. Sin. 69 172901Google Scholar
[16] Ren J, Ruan X C, Jiang W, et al. 2021 Nucl. Instrum. Methods A 985 164703Google Scholar
[17] Lederer C, Colonna N, Domingo-Pardo C, et al. 2011 Phys. Rev. C 83 034608Google Scholar
[18] Borella A, Aerts G, Gunsing F, et al. 2007 Nucl. Instrum. Methods A 577 626Google Scholar
[19] 鲍杰, 陈永浩, 张显鹏等 2019 物理学报 68 080101Google Scholar
Bao J, Chen Y H, Zhang X P, et al. 2019 Acta Phys. Sin. 68 080101Google Scholar
[20] Larson N M Oak Ridge National Laboratory Report No. ORNL/TM-9179/R6
[21] Jiang B, Han J L, Jiang W, et al. 2021 Nucl. Instrum. Methods A 1013 165677Google Scholar
[22] Li X X, Liu L X, Jiang W, et al. 2021 Phys. Rev. C 104 054302Google Scholar
[23] Noguere G B, Heyse O J, Ebran A, Roig O 2019 Phys. Rev. C 100 065806Google Scholar
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图 7 1.25—1.85 eV范围内 natLu中子俘获产额分布, 其中, 黑色实心点为实验数据、红色实线为SAMMY拟合结果、绿色实线为ENDF/ B-VIII.0评价数据的SAMMY计算. 图(a)和(b)分别为0.207和1.06 mm厚的natLu结果
Fig. 7. Neutron capture yield of natLu. Black solid circles indicate the experimental data, red and green lines indicate SAMMY fit of experimental data and SAMMY calculations of ENDF/B-VIII.0 evaluation data from 1.25 eV to 1.85 eV. Panel (a) and panel (b) show 0.207 and 1.06 mm thickness of natLu, respectively.
图 8 1.85—6.5 eV范围内natLu中子俘获产额分布, 其中, 黑色实心点为实验数据、红色实线为SAMMY拟合结果、绿色实线为ENDF/ B-VIII.0评价数据的SAMMY计算. 图(a)和(b)分别为0.207和1.06 mm厚的natLu结果. 红色、粉色和蓝色箭头分别表示175Lu, 176Lu和 181Ta的共振能量
Fig. 8. Neutron capture yield of natLu. Black solid circles indicate the experimental data, red and green lines indicate SAMMY fit of experimental data and SAMMY calculations of ENDF/B-VIII.0 evaluation data from 1.85 eV to 6.5 eV. Panel (a) and panel (b) show 0.207 and 1.06 mm thickness of natLu, respectively. Red, pink, and blue arrows indicate the energies of the 175Lu, 176Lu, and 181Ta resonances, respective.
表 1 实验样品信息
Table 1. Sample information.
靶 厚度/mm 直径/mm 质量/mg 面密度/(atom·b–1) natLu 1.06 30 7373.11 3.58820 × 10–3 natLu 0.207 30 1439.84 7.00715 × 10–4 197Au 0.1 30 1357.17 5.86721 × 10–4 natPb 0.53 30 4249.75 1.74678 × 10–3 59Co 0.4 80 17894.51 3.63240 × 10–3 natAg 0.4 80 21091.40 2.34173 × 10–3 表 2 本实验结果与ENDF/B-VIII.0数据库及Noguere等[23]的共振因子对比
Table 2. Comparisons of resonance kernels of present experiment, ENDF/B-VIII.0 libraries and Noguere et al.[23].
ER/eV Element I J g ENDF/B-III.0 $ {R}_{\rm{k}} $ natLu-0.207 mm $ {R}_{\rm{k}} $ natLu-1.06 mm $ {R}_{\rm{k}} $ Noguere-2019[23] $ {R}_{\rm{k}} $ 1.56 176Lu 7.0 7.5 0.53 0.252 0.257 ± 0.005 0.242 ± 0.002 — 2.59 175Lu 3.5 4.0 0.56 0.100 0.111 ± 0.004 0.073 ± 0.006 0.117 ± 0.005 4.28 181Ta 3.5 4.0 0.56 2.034 2.821 ± 0.004 0.647 ± 0.003 — 4.75 175Lu 3.5 4.0 0.56 0.145 0.167 ± 0.005 0.104 ± 0.002 0.167 ± 0.006 5.22 175Lu 3.5 3.0 0.44 0.690 0.730 ± 0.004 0.735 ± 0.007 0.732 ± 0.017 6.13 176Lu 7.0 7.5 0.53 0.709 0.792 ± 0.012 0.807 ± 0.016 — -
[1] 葛智刚, 陈永静 2015 科学通报 60 3087Google Scholar
Ge Z G, Chen Y J 2015 Chin. Sci. Bull. 60 3087Google Scholar
[2] 阮锡超 2020 中国科学: 物理学 力学 天文学 55 5
Ruan X C 2020 Scientia Sinica Physica, Mechanica & Astronomica. 55 5
[3] 刘世龙, 葛智刚, 阮锡超, 陈永静 2020 原子能科学技术 54 SupplGoogle Scholar
Liu S L, Ge Z G, Ruan X C, Chen Y J 2020 Atomic Energy Sci. Tech. 54 SupplGoogle Scholar
[4] Chen G C, Cao W T, Yu B S, Tang G Y, Shi Z M, Tao X 2012 Chin. Phys. C 36 9Google Scholar
[5] Chadwick M B, Herman M, Oblozinsk P, et al. 2011 Nucl. Data Sheets 112 2887Google Scholar
[6] Barry D P, Leinweber G, Block R C, et al. 2013 Nucl. Sci. Eng. 174 188Google Scholar
[7] Plompen A, Cabellos O, Jean C, et al. 2020 Eur. Phys. J. A 56 7Google Scholar
[8] Ignatyuk A V, Fursov B I 2007 Proc. Int. Conf. on Nuclear Data for Science and Technology Nice, France, April 22–27, 2007 vol 2, p759
[9] Tang J Y, Liu R, Zhang G H, et al. 2021 Chin. Phys. C 45 062001Google Scholar
[10] Tang J Y, An Q, Bai J B, et al. 2021 Nucl. Sci. Tech. 32 11Google Scholar
[11] 李鑫祥, 刘龙祥, 蒋伟等 2020 核技术 43 080501Google Scholar
Li X X, Liu L X, Jiang W, et al. 2020 J. Nucl. Tech. 43 080501Google Scholar
[12] Zhang S, Chen Z Q, Han R, Liu X Q, Wada R, Lin W P, Jin Z X, Xi Y Y, Liu J L, Shi F D 2013 Chin. Phys. C 37 126003Google Scholar
[13] Yan J, Liu R, Li C, et al. 2010 Chin. Phys. C 34 993Google Scholar
[14] Hu X R, Fan G T, Jiang W et al. 2021 Nucl. Sci. Tech. 32 101Google Scholar
[15] 任杰, 阮锡超, 陈永浩等 2020 物理学报 69 172901Google Scholar
Ren J, Ruan X C, Chen Y Het al. 2020 Acta Phys. Sin. 69 172901Google Scholar
[16] Ren J, Ruan X C, Jiang W, et al. 2021 Nucl. Instrum. Methods A 985 164703Google Scholar
[17] Lederer C, Colonna N, Domingo-Pardo C, et al. 2011 Phys. Rev. C 83 034608Google Scholar
[18] Borella A, Aerts G, Gunsing F, et al. 2007 Nucl. Instrum. Methods A 577 626Google Scholar
[19] 鲍杰, 陈永浩, 张显鹏等 2019 物理学报 68 080101Google Scholar
Bao J, Chen Y H, Zhang X P, et al. 2019 Acta Phys. Sin. 68 080101Google Scholar
[20] Larson N M Oak Ridge National Laboratory Report No. ORNL/TM-9179/R6
[21] Jiang B, Han J L, Jiang W, et al. 2021 Nucl. Instrum. Methods A 1013 165677Google Scholar
[22] Li X X, Liu L X, Jiang W, et al. 2021 Phys. Rev. C 104 054302Google Scholar
[23] Noguere G B, Heyse O J, Ebran A, Roig O 2019 Phys. Rev. C 100 065806Google Scholar
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