Electron Pattern Recognition using trigger mode SOI pixel sensor for Advanced Compton Imaging

Compton imaging is a useful method for localizing sub MeV to a few MeV gamma-rays and widely used for environmental and medical applications. The direction of recoiledelectrons in Compton scatteringprocess provides the additional information to limit the Compton cones and increases the sensitivity in the system. The capability of recoiledelectron tracking using trigger-mode Silicon-On- Insulator(SOI) sensor is investigated with various radiation sources. The trigger-mode SOI sensor consists of 144 by 144 active pixels with 30 μm cells and the thickness of sensor is 500 μm. The sensor generates the digital output when it is hit by gamma-rays and 25 by 25 pixel pattern of surrounding the triggered pixel is readout to extract the recoiledelectron track. The electron track is successfully observed for 60Co and 137Cs sources, which provides useful information for future electron tracking Compton camera.