Development of a monolithic pixel sensor based on SOI technology for the ILC vertex detector

SOI detector SOFIST is a pixel sensor optimized for the International Linear Collider vertex detector. SOFIST stores both position and timing information of charged particles. Our aim is to achieve 3 μm single-point resolution with a 20 × 20 μm 2 pixel. The first prototype sensor SOFIST Ver.1 was evaluated with a 120 GeV proton beam at the FermiLab Test Beam Facility. The position resolution was about 1.3 μm. We are currently evaluating the next version of sensor, SOFIST Ver.2, which has an in-pixel comparator and timestamp.