Research on ICCD for Space Observations of Cosmic Rays and Dark Matter

A semi-digital 3D-imaging calorimeter is proposed for the direct observation of cosmic rays and indirect observation of dark matter in space. Compared with traditional calorimeters composed of orthogonal scintillator strips, it needs no extra hodoscopes and can maintain accuracy of reconstructed energy despite partial energy leak of the shower. Therefore, a larger geometric factor and higher energy range can be achieved taking the advantages of the novel design. The semi-digital 3D-imaging calorimeter used as High Energy cosmic-Radiation Detection (HERD) facility onboard China’s Space Station is planned to be launched in about 2020. The low light level imaging and ultrafast detection system is an Image-intensified CCD (ICCD) for space observations of cosmic rays and dark matter, which is composed of an imaging intensifier and a high-frame-rate and large-area CCD. The readout system, with the functions of intensifying, delaying, imaging and memorizing, can make rapid response to the signals from tens of thousands of wavelength shifting fibers of the 3d-imaging calorimeter. Using the semi-digital information reconstruction method, the information of particle type, energy and direction can be obtained. By solving some key technologies including coupling between each optical part, a low noise imaging with high-frame-rate and large-area CCD, the high speed gating system of imager intensifier, the performance of ICCD has been improved significantly. The prototype of ICCD can meet the requirements: up to 400 frames per second, detection ability for low light about 10 photons, maximum linear dynamic range, low weight and power consumption. Performance verification of the prototype and the calorimeter is carried out by using the new semi-digital 3D-imaging method.