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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 3087
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Ge Z G, Chen Y J 2015 Chin. Sci. Bull. 60 3087
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Ruan X C 2020 Scientia Sinica Physica, Mechanica & Astronomica. 55 5
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Ren J, Ruan X C, Chen Y Het al. 2020 Acta Phys. Sin. 69 172901
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Bao J, Chen Y H, Zhang X P, et al. 2019 Acta Phys. Sin. 68 080101
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图 1 C6D6 探测器实验光输出谱与模拟谱的比较
Figure 1. Comparison of C6D6 detector light output and Geant4 simulation results.
图 2 C6D6 探测器的能量刻度结果
Figure 2. Energy calibration of C6D6 detector.
图 3 (a) γ光输出谱; (b)权重函数; (c)原始探测效率曲线; (d)权重后的探测效率曲线
Figure 3. (a) Light output spectra; (b) weight function; (c) original detection efficiency; (d) weighted detection efficiency.
图 4 权重计数谱对比, 黑线、绿线和红线分别表示Au靶、空靶和空靶归一到小于0.3 eV能区Au靶的权重计数谱
Figure 4. Comparisons of weighted counts spectrum. Black, green and red lines indicate the spectrum of Au target, empty target and normalized empty target as Au target below 0.3 eV energy region, respectively.
图 5 (a)本底形状分析; (b) natLu靶加吸收片的权重计数谱
Figure 5. (a) Background shape analysis; (b) weighted counting spectrum of natLu with filters.
图 6 不同厚度natLu靶的中子俘获产额比较和SAMMY拟合结果
Figure 6. Comparison of capture yield with SAMMY fits of natLu targets with different thicknesses.
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
Figure 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
Figure 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.
图 9 不同厚度natLu靶的共振因子比例及其高斯函数拟合结果
Figure 9. Resonance kernel ratio and its gaussian function fitting of natLu targets with different thicknesses.
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 
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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 —
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[1] 葛智刚, 陈永静 2015 科学通报 60 3087
Google Scholar
Ge Z G, Chen Y J 2015 Chin. Sci. Bull. 60 3087
Google 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 Suppl
Google Scholar
Liu S L, Ge Z G, Ruan X C, Chen Y J 2020 Atomic Energy Sci. Tech. 54 Suppl
Google Scholar
[4] Chen G C, Cao W T, Yu B S, Tang G Y, Shi Z M, Tao X 2012 Chin. Phys. C 36 9
Google Scholar
[5] Chadwick M B, Herman M, Oblozinsk P, et al. 2011 Nucl. Data Sheets 112 2887
Google Scholar
[6] Barry D P, Leinweber G, Block R C, et al. 2013 Nucl. Sci. Eng. 174 188
Google Scholar
[7] Plompen A, Cabellos O, Jean C, et al. 2020 Eur. Phys. J. A 56 7
Google 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 062001
Google Scholar
[10] Tang J Y, An Q, Bai J B, et al. 2021 Nucl. Sci. Tech. 32 11
Google Scholar
[11] 李鑫祥, 刘龙祥, 蒋伟等 2020 核技术 43 080501
Google Scholar
Li X X, Liu L X, Jiang W, et al. 2020 J. Nucl. Tech. 43 080501
Google 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 126003
Google Scholar
[13] Yan J, Liu R, Li C, et al. 2010 Chin. Phys. C 34 993
Google Scholar
[14] Hu X R, Fan G T, Jiang W et al. 2021 Nucl. Sci. Tech. 32 101
Google Scholar
[15] 任杰, 阮锡超, 陈永浩等 2020 物理学报 69 172901
Google Scholar
Ren J, Ruan X C, Chen Y Het al. 2020 Acta Phys. Sin. 69 172901
Google Scholar
[16] Ren J, Ruan X C, Jiang W, et al. 2021 Nucl. Instrum. Methods A 985 164703
Google Scholar
[17] Lederer C, Colonna N, Domingo-Pardo C, et al. 2011 Phys. Rev. C 83 034608
Google Scholar
[18] Borella A, Aerts G, Gunsing F, et al. 2007 Nucl. Instrum. Methods A 577 626
Google Scholar
[19] 鲍杰, 陈永浩, 张显鹏等 2019 物理学报 68 080101
Google Scholar
Bao J, Chen Y H, Zhang X P, et al. 2019 Acta Phys. Sin. 68 080101
Google 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 165677
Google Scholar
[22] Li X X, Liu L X, Jiang W, et al. 2021 Phys. Rev. C 104 054302
Google Scholar
[23] Noguere G B, Heyse O J, Ebran A, Roig O 2019 Phys. Rev. C 100 065806
Google Scholar
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