Speaker
Description
Development of CMOS monolithic active pixel sensors for the ALICE ITS3 and ALICE3 Tracker upgrades
Walter Snoeys1,*, on behalf of the ALICE collaboration
- EP-ESE-ME, CERN, Esplanade des Particules 1, 1211 Geneva 23, Switzerland
- Corresponding author, walter.snoeys@cern.ch
Monolithic active pixel sensors (MAPS) in commercial CMOS technologies, integrating sensor matrix and readout in one piece of silicon, have received continued interest for use in high energy physics. Used for the first time in high energy physics in the STAR experiment, MAPS are now taking data in the Inner Tracker System 2 (ITS2) of the ALICE experiment (Fig. 1). It is instrumented with 24120 ALPIDE sensor chips covering a sensitive area of 10 m2.
In synergy with the R&D program on Detector Technologies of the CERN EP department, the ALICE experiment is developing two further upgrades based on MAPS: the first is the Inner Tracker System 3 or ITS3 [1], replacing the three inner layers by wafer-scale stitched sensors bent around the beam pipe. The MOSAIX sensor chip [2], a first full scale prototype just came back from foundry and is presently under test (Fig. 2). It is implemented in the TPSCo 65nm CMOS imaging process, modified in collaboration with the foundry in several iterations to improve charge collection and reduce sensor capacitance [3,4].
A major upgrade of the experimental apparatus, ALICE3 [5], is also being proposed, including a new tracker covering several tens of square meter. It foresees a three-layer vertex detector in the center to be integrated inside the beam pipe, subject to increased particle hit rates and radiation levels (100 Mhits/cm2/s, several hundred Mrad and ~3 ×x 1015 neq/cm2 for the innermost layer). It requires a 2.5 µm spatial resolution compatible with a 10 µm pixel pitch.
This contribution will give an overview of the ongoing MAPS development for these upgrades through different phase, including the optimization of the sensor and the technology, and the use of stitching for the design of the sensors.
[1] https://cds.cern.ch/record/2890181?ln=en, TDR of the ALICE Inner Tracking System 3 – ITS3
[2] P. Vicente Leitao on behalf of the ALICE collaboration, 2025 JINST 20 C06001
[3] W. Snoeys et al https://doi.org/10.22323/1.420.0083
[4] Giulio Borghello et al 2025 JINST 20 C07053
[5] Letter of intent for ALICE 3: https://doi.org/10.48550/arXiv.2211.02491