32 Si is the only long lived radio isotope of silicon which generated in small amount through primary or secondary cosmic-ray induced spallation of Ar in the atmosphere. It has very important applications in many aspects such as the research of global biogeochemical sillion cycle and the application in geochronometry in the range of 100-1000a. However, The precise value of its half-life are discrept and this decreased its applications to a great extent. This work measures the half-life of 32 Si by AMS at China Institute of Atomic Energy (CIAE). 32 Si was generated through radiated Mg2P2O7 and SiO2 sample was prepared according to certain procedure. The sample was divided into two parts,one for AMS measurement and the other for decay rate measurement. Then the absolute ratio of 32 Si/Si was measured by AMS method and its decay rate was measured by liquid scintillation detector. As a result, the half-life of 32Si is (182 + 16)a.%32Si是宇宙射线与空气中的Ar通过散裂反应产生的长寿命放射性核素,利用32Si可以开展广泛的应用研究.然而作为放射性核素关键数据的32Si半衰期数据仍然存在较大的偏差,这在很大程度上阻碍了32Si 的应用.本工作利用中国原子能科学研究院的加速器质谱系统开展了32 Si半衰期的测量.通过反应堆辐照Mg2 P2 O7生产32Si并制备出用于加速器质谱测量和活度测量的样品；利用加速器质谱技术进行了32Si/Si绝对比值的测定；通过液闪对样品进行了放射性活度测量,从而实现了32Si半衰期的测定,得到32Si的半衰期值为(182±16)a.
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