大学物理 ›› 2019, Vol. 38 ›› Issue (6): 55-.doi: 10.16854 /j.cnki.1000-0712.180444

• 大学生园地 • 上一篇    下一篇

抑制NaI( Tl) 谱仪中反散射峰的简便实验方法

魏凡,李根,楼建玲   

  1. 北京大学物理学院核物理与核技术教学实验室,北京100871
  • 收稿日期:2018-08-08 修回日期:2018-11-03 出版日期:2019-06-20 发布日期:2019-07-02
  • 通讯作者: 楼建玲,E-mail: jllou@ pku.edu.cn
  • 作者简介:魏凡( 1997—) ,男,辽宁锦州人,北京大学物理学院,2014 级本科生.
  • 基金资助:
    国家自然科学基金资助项目( 11775004) ; 理科基地( J1103206) 资助

Simple experimental approach to suppress the backscattering peak in NaI( Tl) spectrometer

GUAN Shu-yue,ZHANG Ming,ZHANG Shi-ping,WU Ping   

  1. School of Mathematics and Physics,University of Science and Technology,Beijing 100083,China
  • Received:2018-08-08 Revised:2018-11-03 Online:2019-06-20 Published:2019-07-02

摘要: 本文通过控制变量的对比实验方法,系统研究了NaI( Tl) 谱仪中反散射峰产生的原因以及影响其大小的因素. 结果发现衬底材料、衬底厚度、源仪距、源衬底距、闪烁体的包装材料和闪烁体的尺寸均对反散射峰有不同程度的影响. 经过对比分析,找到了几种抑制反散射峰的简便易行的实验方法.

关键词: 康普顿散射, 反散射峰, 立体角, 反散射材料

Abstract: In Millikan's oil-drop experiment,if the oil drop is chosen too small,it shows obvious Brownian motion,which causes the measured dropping time to deviate from the ideal dropping time. In this article,through practical experiment and theoretical study,the stochastic differential equation of the movement of the oil drop is established by solving the Langevin equation. By introducing single and multiple time deviation,both the Brownian motion and the time deviation are quantitatively analyzed. As being indicated by the result,when the oil drop is relatively small,the influence of Brownian motion should be taken into account because of the limit of experiment times.

Key words: Millikan's oil-drop experiment, Brownian motion, Langevin equation, moving trail