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3 He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235 U和239 Pu,并结合INAA可测量238 U/235 U同位素比值;5)14 MeV快中子活化分析技术(FNAA)可测量INAA和PGNAA不灵敏或不适合测量的元素如O、Si、P等.因此,中子活化分析技术(NAA)可有效解决月球样品中全元素、非破坏和精准测量问题,为我国深空探测珍贵样品研究提供核分析技术支撑.
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 the Earth-Moon system for human beings.However,some unsolved mysteries have been discovered and urgently needed to be answered by future exploration tasks and scientific research.China's Chang'E-5(CE-5)lunar soil is the first sample collected and returned by an extraterrestrial body in China,and it is also the lunar sample obtained by humans Forty-five years after the US and Soviet lunar exploration sampling missions.Given the preciousness and specificity of lunar samples,the use of advanced technologies for non-destructive and precise analysis of the total elemental contents in the lunar soil sample is of great significance for understanding the lunar evolution and the in-situ development and utilization of lunar resources.Based on the advantages of large-scale nuclear research reactors and accelerators neutron fluence rates,the non-destructive analysis of all natural elements in the lunar samples can be achieved using neutron activation analysis technology:1)over 60 elements between Na and U can be detected by the instrumental neutron activation analysis technology(INAA).2)The elements(e.g.,H,B,C and N)that are usually not suitable for INAA method can be measured by prompt gamma-ray neutron activation analysis(PGNAA).3)The depth of 3 He concentration in the near surface(micron level)of lunar sample could be analyzed by neutron depth profiling(NDP).4)Trace fission nuclides such as 235 U and 239Pu in the sample can be quantified by delayed neutron counting(DNC),and the 238 U/235 U isotope ratio was also obtained by combining with INAA method.5)Elements(e.g.,O,Si and P)that are not suitable for INAA and PGNAA methods can be measured by the 14 MeV fast neutron activation analysis(FNAA).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.