Research for Improving the Background of the Experiment of (n, xn<em>&gamma;</em>) Cross Section

WANG Qi; LIU Yang; WANG Zhaohui; HOU Long; Bao Jie; SU Xiaobin; LI Xia

doi:10.11804/NuclPhysRev.34.02.195

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.

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

Key words:

(n,xn&gamma /

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.

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Reference (5)

[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.)

[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.)

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

doi: 10.11804/NuclPhysRev.34.02.195

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通讯作者: 陈斌, bchen63@163.com

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

doi: 10.11804/NuclPhysRev.34.02.195

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

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

doi: 10.11804/NuclPhysRev.34.02.195

Abstract

References

Proportional views

通讯作者: 陈斌, bchen63@163.com

Article Metrics

Proportional views

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

doi: 10.11804/NuclPhysRev.34.02.195

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

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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