Multi-column Compton Camera of stacked Si pixel sensors for sub-degree angular resolution

The Compton camera is a sensitive imaging detector for soft gamma-rays. Compton Reconstruction can not only give imaging capability but also remove background events to achieve good sensitivity. However, the angular resolution is in principle limited to several degrees. In this paper, we propose a novel concept of Compton camera incorporating shadow effects. We consider multi-column Compton camera (MCCC), consisting of stacked Si pixel sensors. Each of columns is separated each other to create shadow effects. This design achieves an angular resolution of less than 1 degree within around 1 degree from the center of the field-of-view by just modifying a conventional Si-stacked Compton camera and keeping advantages (wide field-of-view and good sensitivity) of conventional Compton camera. Here we validated the concept of proposed Compton camera through Monte-Carlo simulation. MCCC with 1 m column height, 0.5 mm pixel size, 100 layers, and 10 columns for the 1-D direction can distinguish two sources separated by 0.1 degree with 0.6M Compton-reconstructed events.