Studies On CVD Diamond Detectors For Pulsed Radiation Detection

Radiation detection is one of the key technologies in the pulsed radiation field diagnosis. The thesis conducted studies on CVD diamond film detectors for pulsed radiation detection in the purpose of developing new semiconductor detectors which have higher properties and great tolerance of atrocious environment.The possibility of CVD diamond film detectors for pulsed radiation detection is firstly researched. After times of material testing, detector preparing and researches on detector properties, the concept of"detector grade"diamond film which should have good lattice structures, especially have low impurity concentrations is concluded. Finally, high quality CVD diamond film detectors with good Ohmic contact and dark current as low as 10pA are prepared.Charge collecting properties of CVD diamond film detectors are studied. The relationship between detector charge collection efficiencies with the electric field and detector sizes is derived, and the relationship between detector charge collection efficiencies with diamond qualities is discussed. The charge collection efficiencies and charge carrier lives of the detectors developed in the thesis are obtained. The results show that, the charge collection efficiencies reach the saturate region when the electric field is higher than 2V/μm. The charge collection efficiencies of the detectors developed in the thesis are as high as 60%-70%, which reach the advanced level of the world.Pulsed radiation response properties of CVD diamond film detectors are systematically studied. Their time response waveforms are calculated using a physical mode, and the relevant experiments are finished on ultra-fast UV source, X rays and proton beams. Time response parameters of the detectors developed in the thesis and the relationship between the time response of diamond film detectors and diamond qualities are achieved. Basing on the Monte-Carlo calculations of the detectors'responses to radiation and n/γdiscrimination ability, their radiation response properties are experimentally investigated on pulsedγrays, X rays from Z-pinch processes, n/X mixed radiation fields of the DPF neutron generator, electron beams of BEPC II Testing Beam Facility. The results show that the best rise time of the detectors developed in the thesis is as fast as 440ps, their time response and sensitivities satisfy the requirements of pulsed radiation detection.The radiation hardness are studied on the 2×13MeV Beijing Tandem Accelerator HI-13. The results show that the radiation hardness of detectors developed in the thesis is 3 grade higher than that of Si-PIN detectors.It can be concluded that the CVD diamond film detectors developed in the thesis have high qualities of low dark currents, fast time response, high radiation hardness and they can be used as a better alternative detectors in the high intensity pulsed radiation diagnosis.