月球样品的中子活化分析技术研究

月球的起源是月球研究的核心问题。月球探测任务返回的数据和样品极大地提高了人类对地月系统的认知，同时也发现了更多未解之谜，亟待未来的探测任务和科学研究来解答。嫦娥五号月壤是我国首次地外天体采集返回的样品，也是继美国和苏联探月采样任务45年后人类再次获得的月球样品。鉴于月球样品的珍贵性和特殊性，利用先进技术开展其全元素含量的非破坏精准分析对于认识月球演化和月球资源就地开发利用具有重要的意义。依托大型核反应研究堆和加速器中子注量率优势，利用中子活化分析技术可实现月球样品中的全元素非破坏分析：1)仪器中子活化分析技术(INAA)可测量Na—U元素之间的60余种元素；2)瞬发γ中子活化分析技术(PGNAA)可补充测量INAA不适合测量的元素如H、B、C、N等；3)中子深度剖面分析技术(NDP)可测量样品近表面(微米级)聚变能源³He的浓度深度分布；4)缓发中子测量技术(DNC)可定量样品中痕量裂变核素如²³⁵U和²³⁹Pu,并结合INAA可测量²³⁸U/²³⁵U同位素比值；5)14 Me...

Research of the crucial techniques on neutron activation analysis for lunar samples

The origin of the Moon is a core issue of lunar research. The data and samples returned by the lunar exploration missions have greatly improved the knowledge of human beings for the Earth-Moon system. However, some unsolved problems have been discovered and needed to be answered by future exploration tasks and scientific research. Forty-five years after the Apollo and Luna missions, China’s Chang’E-5 (CE-5) returned samples can further understand our celestial neighbor. Moreover, China’s research teams have revealed important information on the CE-5 lunar soil using advanced technologies for the basic properties, the formation age, and source characteristics of mare basalt and so on. The non-destructive analysis of the elemental contents in the lunar soil sample is of great significance for understanding the lunar evolution and the development and utilization of lunar resources. Based on the advantages of large-scale nuclear research reactors and accelerators, the China Institute of Atomic Energy (CIAE) can realize the non-destructive analysis of all natural elements in the lunar samples. For examples, (1) the instrumental neutron activation analysis technology (INAA) can detect over 60 elements between Na and U. (2) Prompt gamma-ray neutron activation analysis (PGNAA) can measure the elements (e.g., H, B, C and N) that are usually not suitable for INAA method. (3) Helium-3, one of the most ideal fuels for nuclear fusion, is very scarce on Earth but abundant on the Moon, which is of far-reaching significance for the sustainable development of human energy in the future. The depth of 3He concentration in the near surface (micron level) of lunar sample could be analyzed by neutron depth profiling (NDP). (4) Delayed neutron counting (DNC) was applied in quantitative determination of 235U and 239Pu in the sample, and the 238U/235U isotope ratio is also obtained by combining with INAA method. (5) The 14MeV fast neutron activation analysis (FNAA) can be used to measure elements (e.g., O, Si, and P) that are not suitable for INAA and PGAA methods. Therefore, the neutron activation analysis (NAA) technology can effectively solve the problem of non-destructive, high-precision measurement for the natural elements in the lunar sample, and provide a nuclear technology supporting for the China’s deep-space exploration samples.