高级检索

s-/r-过程及0\nu\beta\beta 能区锗同位素链中子俘获截面高精度测量方案

Precision Measurement Proposal of Neutron Capture Reaction in Ge Isotopes for s-/r-process and Neutrino-less Double-beta Decay Within Its Relevant Energy Range

  • 摘要: 74Ge(n,\gamma)反应是大质量恒星氦核心和碳燃烧壳层弱s-过程中的关键反应,76Ge(n,\gamma)反应是弱r-过程中的重要反应。两反应决定了宇宙中74,76Ge的丰度。同时74,76Ge(n,\gamma)反应又是国际上正在开展的GERDA组和MAJORANA组76Ge无中微子双\beta衰变实验中需要精确测量的中子诱导的主要本底反应。当前已有的实验数据受实验条件或中子能区的限制,存在精度不高且部分能区缺失的情况。本工作计划基于中国散裂中子源(CSNS)反角通道白光中子源实验终端很宽的能谱以及优异的时间结构特性,应用C_6D_6探测器开展74,76Ge中子俘获反应的高精度测量研究,给出10 keV\thicksim 5 MeV能区的截面值。特别是天体物理最关注的30 keV附近能区反应截面的直接测量工作,将为理解大质量恒星s-/r-过程提供关键的核物理输入量,帮助解决美国国家科学委员会于2002年在《发现》杂志上提出的21世纪尚未解决的11个重大物理问题之三,“从铁到铀的元素是如何产生的?”这一重大物理问题。同时,为正在开展的分别位于意大利格兰萨索地下实验室GERDA合作组和位于美国桑福德地下实验室MAJORANA合作组76Ge核0\nu \beta \beta实验、以及锦屏深地实验室(CJPL)清华大学中国暗物质实验合作组(CDEX)未来吨量级的高纯锗探测器0\nu \beta \beta实验研究,提供精确的本底反应数据。

     

    Abstract: The reaction of 74,76Ge(n,\gamma) is the key reaction of weak s-process in massive stars during He Core burning, and later during C Shell burning. And, in order to more accurately predict the neutron-induced internal background in the 76Ge based 0\nu \beta \beta decay searches GERDA and MAJORANA, the neutron-capture cross section of 76Ge and 74Ge must be known. Because the present nuclear data library is limited by experimental condition and energy range, the precision of some nuclear data is low, some nuclear data are blank. The back streaming white neutron beam (Back-n) at China Spallation Neutron Source has very wide energy spectrum and excellent time structure. A high precision measurement of 74,76Ge neutron capture reaction will be carried out using C_6D_6 detector from 10 keV\thicksim 5 MeV energy. In particular, the direct measurement of the 74,76Ge neutron capture reaction at 30 keV will be given, which is the most concerned with astrophysics. The work will provide key input of nuclear physics for understanding weak s-/r- process in massive stars. In year 2002, American National Research Council ranked “How were the heavy elements from iron to uranium made?” on the Discover magazine as one of the 11 Greatest Unanswered Questions of Physics of this century. The experiment is crucial to solve the key scientific questions. At the same time, accurate nuclear data of neutron-induced internal background is provided for GERDA, located at Italy’s Gran Sasso underground laboratory, the MAJORANA Demonstrator, at the US’s Sanford Underground Research Facility, and the 0\nu \beta \beta decay of CDEX collaboration in China Jinping Underground Laborotory (CJPL).

     

/

返回文章
返回