Accelerator Laboratory Department of Engineering Physics Tsinghua University Beijing 100084 China;
Key Laboratory of Particle and Radiation Imaging of Ministry of Education Tsinghua University. Beijing 100084 China;
Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense Beijing 100084 China;
Accelerator Laboratory Department of Engineering Physics Tsinghua University Beijing 100084 China;
Key Laboratory of Particle and Radiation Imaging of Ministry of Education Tsinghua University. Beijing 100084 China;
Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense Beijing 100084 China;
