ALPIDE, the Monolithic Active Pixel Sensor for the ALICE ITS upgrade

A new 10 m 2 inner tracking system based on seven concentric layers of Monolithic Active Pixel Sensors will be installed in the ALICE experiment during the second long shutdown of LHC in 2019–2020. The monolithic pixel sensors will be fabricated in the 180 nm CMOS Imaging Sensor process of TowerJazz. The ALPIDE design takes full advantage of a particular process feature, the deep p-well, which allows for full CMOS circuitry within the pixel matrix, while at the same time retaining the full charge collection efficiency. Together with the small feature size and the availability of six metal layers, this allowed a continuously active low-power front-end to be placed into each pixel and an in-matrix sparsification circuit to be used that sends only the addresses of hit pixels to the periphery. This approach led to a power consumption of less than 40mWcm−2 , a spatial resolution of around 5 μm, a peaking time of around 2 μs, while being radiation hard to some 10131MeVneq/cm2 , fulfilling or exceeding the ALICE requirements.