Particle tracking using CMOS monolithic active pixel sensor

A novel monolithic active pixel sensor for charged particle tracking has been designed and fabricated in a standard CMOS technology. The device architecture is identical to a CMOS camera, recently being proposed as an alternative to CCD sensors for visible light imaging. The partially depleted thin epitaxial silicon layer is used as a sensitive detector volume. The sensor is a photodiode having a special structure, which allows the high detection efficiency required for tracking applications A first prototype was made of four arrays each containing 64×64 pixels, with a readout pitch of 20 μm in both directions. An architecture allowing serial readout of the analogue information from each pixel has been implemented. To evaluate the tracking performance of such a device, series of tests have been performed using a high-energy particle beam. A detailed analysis of the beam test data presented in this work demonstrate close to 100% minimum ionising particle detection efficiency and a good enough signal-to-noise ratio of more than 30.