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

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).