M-C Simulation Of Heavy Ion Track And Experiment Study Of A Heavy Ion Track Imaging Detector

For unique irradiation biological effect and the superiority of the dose distribution, Heavy ion therapy is considered to be an ideal radiotherapy method. Besides, with the development of manned space of our country, spacecrafts and astronauts may take a longer time in the space environment in future. The irradiation effect of the heavy ions from space for spacecrafts and spacemen should not be ignored. Study of heavy ions track may help explain the irradiation biological effect.Under a TEA gas chamber model considered the relevant physics reaction, the tracks of protons, a particles, carbon ions and argon ions are simulated using Geant4code for the pressure of4mbar,10mbar and40mbar. The simulated results show that protons, a particles, carbon ions and argon ions can all form single-particle-track in the TEA gas chamber under the pressure scope of4to40mbar. When the energy of per nuclei energy remain constant, secondary electrons number increases with the mass number and charge state of the incident particle, and the track structure becomes more complicated. When the pressure in gas chamber remains constant, with the energy of incident particle decreasing, ionization of TEA molecule goes up, and’ secondary electrons density-around track core increases, but the spread of the secondary electrons decreases.A heavy ion track imaging detector system was developed. The detector system consists of the gas avalanche chamber system, the power supply system, the CCD imaging acquiring system, the plastic scintillator detector system, working gas supply system and the vacuum system. Preliminary experimental test was performed, in which α particle radiated from39Pu was used as the incident particle. In the experiments, the pressures of5mbar,10mbar,15mbar,30mbar and35mbar were selected respectively, and the exposure time of the CCD camera is respectively set to be1ms,10ms,100ms,1s and10s. Visual field of the CCD camera only is Φ50mm. The experiment results show that a particle track imaging can be successfully achieved, even more the single particles incident. Under the condition of the gas pressure of35mbar and the exposure time greater than10s, a particle scattering track was successfully achieved. It is found that a particle track is closely related to the gas pressure in the avalanche chamber and the exposure time of the CCD camera. According to analyzing the data of a particle track, it is proved that the track structure show axial-symmetry. With incident depth increasing, the track spread decreases gradually, and the image points density increases. It indicates that in the visual field of Φ50mm, energy deposition per unit length stays essentially unchanged, while energy deposition per unit surface density gradually increases with the penetration depth.