Research And The Simulation For Cosmic Ray Interactions With The Stable Elements On The Surface Of The Moon

Chang’E-1 gamma-ray spectrometer(CE1-GRS) is the Chinese first lunar gamma-ray spectrometer. In spectrum, some characteristic peaks which from the nature redioactive elements and the nuclear reactions between lunar stable elements and galaxy cosmic rays(GCR)can be seen. This thesis aims at developing a benchmark of simulation which is about GCR interactions with the lunar stable elements and the emission gamma-ray’s response on CE1-GRS, which can help developing new methods on CE1-GRS spectrum decomposition and getting more accurate analysis about lunar stable elements.In this paper, the main contributions of this simulation are as following: Analysing the physical process of nuclear interactions between GCR and the lunar stable elements in details. Caculating the GCR flux which is consistent with the timeframe of the CE1 mission by Giuliana Castagnoli method.A two steps simulation has been used to simulate GCR interactions within the surface of the moon and the emission gamma-ray’s response on CE1-GRS. Base on the result of simulation, gamma-ray probabilistic spectrum is converted to gamma-ray account spectrum by reasonable method.A procedure of data processing for level 3 spectra data is proposed and some peaks area of main elements are derived.Compare the simulate spectrum with CE1-GRS’s real measurement spectrum, whole energy peak’s area are not the same but the difference is within a reasonable range. The whole energy peak’s area could be the same by adjusting weight fractions of elements in simulation. It’s means this two-steps simulation is reliable. According to this simulation, relation between peak area and weight fractions of elements can be obtained.The innovative points in this paper includes:Two steps simulation is put forward based on unique conditions for moon: circular symmetry, isotropic cosmic rays and vacuum environment. Because the lunar surface are too huge and the effective area of the detector are too small, so one step simulation’s result is difficult to converge in the availability time. Two steps simulation can solve this problem.GCR’s flux which is consistent with the timeframe of the CE1 mission has been computed by Giuliana Castagnoli method for the first time. Based on this, a method of changing the probabilistic spectrum into count spectrum is putting forward.