Research On Simulation And Experiment Of Proportional Counter For Monitoring The Space Neutron Radiation

During space activities, space radiation is a vital aspect of hazards, especially in manned space-flight. One of the space radiation particles, neutron get much attention, because it can cause remarka-ble biological effectiveness. Therefore, its radiation monitoring is essential. Neutron-sensitive propor-tional counter is one of the gaseous detectors used aboard spacecrafts. The electric field and propertyof gas filled in the detector determines its performance. The simulation of working condition, physicprogress and out-put signal could provide support and reference for design of new high-performancegaseous detectors.Based on the analysis of electric field and gas quality, this thesis simulates the prime ionization,avalanche multiplication and out-put signal of a Boron-lined proportional counter. Electric fields ofdifferent models are analyzed by finite element software. The properties of P10gas under differentpressure are calculated. The physic process and out-put signals are simulated by Garfield. Experi-ments are carried out to verify the conversion of Boron coat by using CR-39solid state nuclear trackdetector and the detector was tested at an Am-Be neutron source. It shows that, the hole in tube-wallhas great effect on out-put signal, which could vary by30%most. The simulation result of multiplica-tion and output signal curves fit in with the proportional region character. In the proportional workingvoltage range of800V~1000V, the detector was tested.In general, this thesis gets progress especially in two aspects. First, under the radiation ofhigh-energy electron, the dielectric might be charged. The model of deep dielectric charging was em-ployed. The charge density and the distortion effect of the charged dielectric are calculated, it showsthat Charged Teflon under high-energy electron has great effect on electric field inside detector, theelectric strength increases5times most. Methods of reduce the induced charge are proposed and dis-cussed. Secondly, a proper gas-cycle system of vacuum and gas-filling for the detector was designedand deployed for the detector.