The geometric factor of high energy protons detector on FY-3 satellite

Abstract

Geometric factor is the key parameter for inversion of particle spectrum in space particle detection. Traditional geometric factor is obtained through the method of numerical calculation with the actual structure of the detector as the input condition. The degree of accuracy for data inversion is reduced since traditional geometric factor fails to take into account the physical process of interaction between the particle and substance as well as the influence of factors such as the particle interference between different energy channels on the measurement result. Here we propose an improved geometrical factor calculation method, the concept of which is to conduct actual structural modelling of the detector in the GEANT4 program, consider the process of interaction between the particle and substance, obtain the response function of the detector to particles of different energy channels through the method of Monte Carlo simulation, calculate the influence of contaminated particle on the geometrical factor, and finally get the geometrical factors for different energy channels of the detector. The imrpoved geometrical factor obtained through the method has carried out inversion for the data of high energy protons detector on China's FY-3 satellite, the energy spectrum after which is more in line with the power law distribution recognized by space physics. The comparison with the measured result of POES satellite indicates that the FY-3 satellite data are in good accordance with the satellite data, which shows the method may effectively improve the quality of data inversion. geometrical factor, response function, particle radiation, space detection, FY-3 Citation:The high energy protons detector (HPD) on FY-3 satellite (A/B) is developed by the Center for Space Science and Applied Research, Chinese Academy of Sciences. HPD is used to measure the energy spectrum of solar high energy protons during the high energy protons and solar burst within the radiation belt of the earth. The range of measurement is 3-300 MeV, which falls into six energy channels, and serves for space weather forecast and alarm of the National Weather Service (Huang et al., 2012).Important for the detector, the geometrical factor is the essential parameter for inversion of the direct measurement quantity of the detector to space physical quantity. The direct measurement quantity of HPD is the count N (s 1 ) of each energy channel recorded by the detector per unit time. The differential directional flux J (cm 2 sr 1 s 1 ) of space particle is required for more intuitive expression of the space environment in space physics. The conversion rela-

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Medium-Energy Proton Detector Onboard the FY-4B Satellite

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Medium Energy Proton Detector Onboard FY-4B Satellite

“…(5) Where σ F is Flux error, σ N is counting error, and σ G is geometry error. The calculation method of geometric factors can be referenced in reference [16]. Because this process is a calculation method based on random numbers, there will inevitably be computational errors.…”