（n,xn<em>&gamma;</em>）反应截面测量的实验本底改进研究

王琦; 刘洋; 王朝辉; 侯龙; 鲍杰; 苏晓斌; 李霞

doi:10.11804/NuclPhysRev.34.02.195

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（n,xnγ）反应截面测量的实验本底改进研究

王琦, 刘洋, 王朝辉, 侯龙, 鲍杰, 苏晓斌, 李霞

文章导航 > 原子核物理评论 > 2017 > 34(2): 195-203

王琦, 刘洋, 王朝辉, 侯龙, 鲍杰, 苏晓斌, 李霞. （n,xnγ）反应截面测量的实验本底改进研究[J]. 原子核物理评论, 2017, 34(2): 195-203. doi: 10.11804/NuclPhysRev.34.02.195

引用本文:

WANG Qi, LIU Yang, WANG Zhaohui, HOU Long, Bao Jie, SU Xiaobin, LI Xia. Research for Improving the Background of the Experiment of (n, xnγ) Cross Section[J]. Nuclear Physics Review, 2017, 34(2): 195-203. doi: 10.11804/NuclPhysRev.34.02.195

Citation:

WANG Qi, LIU Yang, WANG Zhaohui, HOU Long, Bao Jie, SU Xiaobin, LI Xia. Research for Improving the Background of the Experiment of (n, xnγ) Cross Section[J]. Nuclear Physics Review, 2017, 34(2): 195-203. doi: 10.11804/NuclPhysRev.34.02.195

（n,xnγ）反应截面测量的实验本底改进研究

doi: 10.11804/NuclPhysRev.34.02.195

王琦¹,
刘洋²,
王朝辉¹,
侯龙¹,
鲍杰¹,
苏晓斌¹,
李霞¹

1.
中国原子能科学研究院核数据重点实验室, 北京 102413;
2.
中国原子能科学研究院反应堆物理研究室, 北京 102413

基金项目: 国防预研基金资助项目（41603030103）

详细信息

作者简介:
王琦(1981-),男,山东滨州人,助理研究员,硕士,从事粒子物理与原子核物理研究;E-mail:wangqi@ciae.ac.cn。

中图分类号: TL814

Research for Improving the Background of the Experiment of (n, xnγ) Cross Section

1.
Key Laboratory of Nuclear Data; China Institute of Atomic Energy, Beijing 102413, China;
2.
Reactor physics Laboratory; China Institute of Atomic Energy, Beijing 102413, China

Funds: National Defense Advanced Research Fund Subsidization Project(41603030103)

摘要: 瞬发γ射线法测量（n，xnγ）反应截面实验中，在线的实验本底对测量结果影响显著，是影响测量结果的关键因素。为了达到降低在线实验本底一个量级的目标，通过蒙特卡罗模拟程序给出了屏蔽体和准直器的改进方案，最终选取的屏蔽方案：在原有屏蔽体上加厚30 cm（C₂H₄）n+9 cmPb，原屏蔽墙加厚54 cm重混凝土，再在屏蔽体和屏蔽墙上共同加厚2 cm厚的铅（Pb）；准直孔开孔形状在圆柱形、圆锥形和对称双锥形这三种方案中准直效果和能量单一性方面对称双锥形准直孔最好。在屏蔽体改造完成后，利用尺寸为φ5.08cm×5.08 cm型液体闪烁体探测器（BC501）测量了改造后距准直孔右方径向距离70 cm处透射出来的中子和γ射线的相对强度，在扣除无束流天然本底后，有束流的中子本底降低了7.75倍，γ本底降低了38.5倍，改造效果达到了测量要求。

In the experiment of measuring (n,xnγ) reaction cross section with prompt γ ray method, the experiment background has a significant influence on the result and is the key factor. In order to achieve the goal of reducing a certain amount of the experiment background, the improvement scheme of shield and collimator was given through Monte Carlo method and the shielding scheme was finally selected: add 30 cm(C₂H₄)n+9 cm Pb on the original shield, 54 cm heavy concrete on the original shield wall and then 2 cm thick lead(Pb) on the shield and shield wall. The collimation effect and energy uniformity of symmetrical double cone collimation hole are the best among cylindrical, conical, and symmetrical double cone. After the completion of the transformation of shield, the relative intensities of the transmitted neutron and γ rays from the 70 cm in right radial of the transformed collimation hole were measured with ϕ5.08 cm×5.08 cm type liquid scintillator detector(BC501). After deducting the natural background of no beam current, the neutron background of the beam current is reduced by 7.75 times and the γ background is reduced by 38.5 times, which meets the requirement.
- （n,xn&gamma /
- ）反应截面 /
- 屏蔽 /
- 本底 /
- 准直器 /
- 模拟
Abstract: In the experiment of measuring (n,xnγ) reaction cross section with prompt γ ray method, the experiment background has a significant influence on the result and is the key factor. In order to achieve the goal of reducing a certain amount of the experiment background, the improvement scheme of shield and collimator was given through Monte Carlo method and the shielding scheme was finally selected: add 30 cm(C₂H₄)n+9 cm Pb on the original shield, 54 cm heavy concrete on the original shield wall and then 2 cm thick lead(Pb) on the shield and shield wall. The collimation effect and energy uniformity of symmetrical double cone collimation hole are the best among cylindrical, conical, and symmetrical double cone. After the completion of the transformation of shield, the relative intensities of the transmitted neutron and γ rays from the 70 cm in right radial of the transformed collimation hole were measured with ϕ5.08 cm×5.08 cm type liquid scintillator detector(BC501). After deducting the natural background of no beam current, the neutron background of the beam current is reduced by 7.75 times and the γ background is reduced by 38.5 times, which meets the requirement.
- (n,xn&gamma /
- )cross section /
- shield /
- background /
- collimator /
- simulation

[1]	FANG Jie. Introduction To Radiation Protection[M]. Beijing:Atomic Energy Press, 1991: 164. (in Chinese)(方杰. 辐射防护导论[M]. 北京: 原子能出版社, 1991: 164.)
[2]	WANG Qiang. MCNP Simulation And Design Of GTAF De-tector Shield System[D]. Lanzhou: Lanzhou University, 2007.(in Chinese) (王强. GTAF探测器屏蔽体系统的MCNP模拟计算设计[D]. 兰州: 兰州大学, 2007.)
[3]	HUTCHESON A, ANGELL C T, BECKER J A, et al. Nucl Instr and Meth B, 2007, 261: 369.
[4]	LU Xiting, JIANG Dongxing, YE Yanlin. Nuclear Physics[M]. 2nd Ed. Beijing: Atomic Energy Press, 2000:63. (in Chinese)(卢希庭, 江栋兴, 叶沿林. 原子核物理[M]. 第2版. 北京: 原子能出版社. 2000: 63.)
[5]	DING Dazhao, YE Chuntang, ZHAO Zhixiang, et al. Neu-tron Physics－Theory, Method and Application[M]. Beijing:Atomic Energy Press, 2001: VI. (in Chinese)(丁大钊, 叶春堂, 赵志祥, 等. 中子物理\|原理、方法与应用[M].北京: 原子能出版社, 2001: VI.)

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（n,xnγ）反应截面测量的实验本底改进研究

doi: 10.11804/NuclPhysRev.34.02.195

1. 中国原子能科学研究院核数据重点实验室, 北京 102413;

2. 中国原子能科学研究院反应堆物理研究室, 北京 102413

基金项目: 国防预研基金资助项目（41603030103）

作者简介:
王琦(1981-),男,山东滨州人,助理研究员,硕士,从事粒子物理与原子核物理研究;E-mail:wangqi@ciae.ac.cn。

收稿日期: 2016-04-14
修回日期: 2016-05-28
刊出日期: 2017-06-20

中图分类号: TL814

关键词:

（n,xn&gamma /

）反应截面 /

屏蔽 /

本底 /

准直器 /

模拟

摘要: 瞬发γ射线法测量（n，xnγ）反应截面实验中，在线的实验本底对测量结果影响显著，是影响测量结果的关键因素。为了达到降低在线实验本底一个量级的目标，通过蒙特卡罗模拟程序给出了屏蔽体和准直器的改进方案，最终选取的屏蔽方案：在原有屏蔽体上加厚30 cm（C₂H₄）n+9 cmPb，原屏蔽墙加厚54 cm重混凝土，再在屏蔽体和屏蔽墙上共同加厚2 cm厚的铅（Pb）；准直孔开孔形状在圆柱形、圆锥形和对称双锥形这三种方案中准直效果和能量单一性方面对称双锥形准直孔最好。在屏蔽体改造完成后，利用尺寸为φ5.08cm×5.08 cm型液体闪烁体探测器（BC501）测量了改造后距准直孔右方径向距离70 cm处透射出来的中子和γ射线的相对强度，在扣除无束流天然本底后，有束流的中子本底降低了7.75倍，γ本底降低了38.5倍，改造效果达到了测量要求。

In the experiment of measuring (n,xnγ) reaction cross section with prompt γ ray method, the experiment background has a significant influence on the result and is the key factor. In order to achieve the goal of reducing a certain amount of the experiment background, the improvement scheme of shield and collimator was given through Monte Carlo method and the shielding scheme was finally selected: add 30 cm(C₂H₄)n+9 cm Pb on the original shield, 54 cm heavy concrete on the original shield wall and then 2 cm thick lead(Pb) on the shield and shield wall. The collimation effect and energy uniformity of symmetrical double cone collimation hole are the best among cylindrical, conical, and symmetrical double cone. After the completion of the transformation of shield, the relative intensities of the transmitted neutron and γ rays from the 70 cm in right radial of the transformed collimation hole were measured with ϕ5.08 cm×5.08 cm type liquid scintillator detector(BC501). After deducting the natural background of no beam current, the neutron background of the beam current is reduced by 7.75 times and the γ background is reduced by 38.5 times, which meets the requirement.

English Abstract

Research for Improving the Background of the Experiment of (n, xnγ) Cross Section

1. Key Laboratory of Nuclear Data; China Institute of Atomic Energy, Beijing 102413, China;

2. Reactor physics Laboratory; China Institute of Atomic Energy, Beijing 102413, China

Funds: National Defense Advanced Research Fund Subsidization Project(41603030103)

Received Date: 2016-04-14
Rev Recd Date: 2016-05-28
Publish Date: 2017-06-20

Keywords:

Abstract: In the experiment of measuring (n,xnγ) reaction cross section with prompt γ ray method, the experiment background has a significant influence on the result and is the key factor. In order to achieve the goal of reducing a certain amount of the experiment background, the improvement scheme of shield and collimator was given through Monte Carlo method and the shielding scheme was finally selected: add 30 cm(C₂H₄)n+9 cm Pb on the original shield, 54 cm heavy concrete on the original shield wall and then 2 cm thick lead(Pb) on the shield and shield wall. The collimation effect and energy uniformity of symmetrical double cone collimation hole are the best among cylindrical, conical, and symmetrical double cone. After the completion of the transformation of shield, the relative intensities of the transmitted neutron and γ rays from the 70 cm in right radial of the transformed collimation hole were measured with ϕ5.08 cm×5.08 cm type liquid scintillator detector(BC501). After deducting the natural background of no beam current, the neutron background of the beam current is reduced by 7.75 times and the γ background is reduced by 38.5 times, which meets the requirement.