| Mars is one of the planets closer to the Earth.Because its many physical properties are similar to Earth,research on Mars has been receiving attention of human since ancient times.The observations of Mars could data from 16 century.Only the appearance of Mars can be observed by means of optical telescope,at that time.Entering the spaceflight period,the Mars exploration has win a great success.With the development of technology,more and more advanced detector can be sent to space,which make the research on the origin and evolution of the solar system,the origin and evolution of life and the evolution of the Martian climate environment more deeper.Mars as one of the few planets that humans can reach,the detection of Mars is getting more and more attention of humans.At the end of 20 th century,led by United States and Soviet Union the Mars exploration has been set off to a new high level.The mind of today think that Mars was once a planet with mountains and water and the climate was warm and surrounded by the atmosphere.But the unknown reason caused the Mars to become what it is today.It is very important for protecting the Earth by studying how the energetic particles,especial the medium and low energetic particles,affect the escape of atmosphere of Mars having no the protection of a globally magnetic field.Mars-1 is the first detector of independent Mars exploration of China.It consists of a orbiter and a lander.And planning to sent to space in 2020 at Wen Chang Hai Nan.The main purposes of Mars-1 are to explore the geological features,the superficial soil characteristics,the distribution of water and ice,the surface material structure,the atmospheric climate and the internal structure of Mars.The orbiter that consists of seven scientific loads and a load controller is aimed to global and comprehensive detect the Mars.Mars Energetic Particle Analyzer(abbreviation EPA)is one of detector in seven scientific payload of orbiter and mainly responsible for the measurement of low-energy particles during the transportation between ground and Mars and the space environment of Mars,and plot the flux spectrum.The energetic particles that the EPA detected include the electron,proton,helium and heavy ions below iron ion.The energy scope of target particles ranged from 0.1 Me V to 300 Me V.The major work of this thesis is focus on the design of EPA,the process of manufacture,temperature effect,test and calibration,and it can be include as follows:· To reduce the weight and power consumption of the detector,the detector uses a single,compact design.In order to identify the incident particles and energy measurement simultaneous,the detector configuration adopts the ???? telescope system.The particle energy loss is measured segmented by two silicon detectors.In order to improve the discriminating ability of low-penetration particles,?? selected a silicon detector with a thickness of 15 ?m.In order to improve the energy loss of the particles with higher penetration ability,the second ?? detector uses silicon with a thickness of 300 ?m,and it can also be used as a full deposition detector for lower energy particles.For the particles with the strongest penetrating,a 32.5 mm thick cesium iodide crystal was selected for detection.In order to expand the dynamic range of the detector,the fluorescence photons of cesium iodide is readout by PD and SIPM simultaneously.At the same time,in order to completely cover the energy measurement ranged from 0.1 to 300 Me V,the output of each detector is divided into several parts and uses different gain circuits to measure it.In order to reduce the event rate and maintain the detection probability of rare events,the detector adopts two geometric factor design,combined with the electronic frequency division function,the detector can work in the environment of up to 105 cm-2s-1.It also adopts the data structure of the raw data of heavy ions mixed light particle spectrum to meet the data bandwidth limitation of 1.3kbps.· Some key technologies and technical difficulties were verified by radioactive source and beam testing during the development of unit components.Testing of silicon by radioactive sources has shown that energy measurements of a minimum energy of 0.1 Me V can be achieved,and beam measurements indicate that the highest energy can cover 300 Me V.And has good discriminating ability to incident particles· The temperature environment in deep space is much more complicated than the ground.In order to eliminate the temperature effect of the detector and ensure the normal operation of the detector in the orbit,the temperature effect of the cesium iodide coupled to PD and the cesium iodide coupled to Si PM are studied during the development process.And the relationship between the detector output amplitude and temperature is obtained.For the coupling of PD to cesium iodide,the numerical correction was used to eliminate the influence of temperature.Since the temperature effect of SIPM readout is very large,in order not to affect the dynamic range of the detector,the method of compensating SIPM voltage is used to eliminate the temperature effect of cesium iodide coupled to Si PM.The silicon detector and the anti-coincidence detector have no temperature correction due to the small temperature effect.· In order to verify the performance of the detector,the detector was calibrated by various secondary beams generated by bombarding the Be target with a carbon beam of 60 Me V/u during the experiment.The calibration results show that the detector's energy resolution of 270 Me V nitrogen and 100 Me V protons better than 3%.Due to the limitations of the experimental conditions,only the elements below nitrogen were identified,and the mass of the carbon elements was better than 3%.Under the condition of increasing the flow intensity,the FPGA performs a frequency division of 32,which can achieve a maximum count rate of 105 after the solar particle event in the Mars environment.The detector is calibrated by a known beam particles provided by the accelerator and get the performance parameters of the detector. |
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