核物理领域的双β衰变测量、粒子物理领域的中微子测量及新物理学中的暗物质测量对环境提出了极为苛刻的要求,需要环境造成的放射性本底尽可能低,可统称为极低本底实验。这类实验的放射性本底来源有两大类:一类是宇宙射线本底,另一类是地球的环境本底。地球环境本底分为两大类:一类是伽玛射线,一类是中子。环境的快中子本底(能量为几MeV)主要来源于地球 Double beta decay measurements in nuclear physics, neutrino measurements in the field of particle physics, and dark matter measurement in new physics place extremely stringent requirements on the environment, requiring as little as possible radioactive background to the environment, collectively referred to as extremely low Background experiment. There are two main sources of radioactive background for such experiments: one is the background of cosmic rays and the other is the environmental background of the Earth. The background of the Earth’s environment is divided into two broad categories: one is a gamma ray, one is a neutron. The environment’s fast neutron background (energy MeV) comes mainly from Earth