[Application of direct demodulation technique in analysis of ground verification test of x-ray spectrometer for Chang'e mission].

An X-ray fluorescence imaging spectrometer based on silicon PIN photodiodes was designed and constructed for the Chang'E mission, the first lunar spacecraft, and will be in operation at a 200 km circular lunar orbit with one year lifetime. The X-ray fluorescence spectrometer consists of two silicon PIN photodiodes modules, each holds two low energy detector units to analyze the distribution of useful elements and to estimate the abundance on the moon, which is one of the objectives of the X-ray fluorescence spectrometer experiment. The low energy detector unit is 25 mm2, 500 microm thick, with the energy band of 1-10 keV, and energy resolution of: approximately 5% at 5.9 keV. The ground verification tests of the X-ray spectrometer for Chang' E mission were introduced in the present paper. Taking the energy response matrix of the spectrometer as the foundation and using the direct demodulation technique and fundamental parameter method, the authors performed some quantitative and qualitative analysis of these scientific data which came from the ground verification tests, especially for Mg, Al and Si elements.