Applications of CMOS technology at the ALICE experiment

TL;DR

This paper reviews the development and application of CMOS-based Monolithic Active Pixel Sensors (MAPS) in high energy physics, highlighting advances from initial detectors to upcoming cylindrical systems for LHC upgrades.

Contribution

It details the evolution of MAPS technology in high energy physics, including the design of the ALPIDE sensor and the new ITS3 project for future LHC runs.

Findings

Successful deployment of MAPS in the STAR experiment

Development of the ALPIDE sensor with improved performance

Design of the innovative cylindrical ITS3 detector for LHC Run 4

Abstract

Monolithic Active Pixel Sensors (MAPS) combine the sensing part and the front-end electronics in the same silicon layer, making use of CMOS technology. Profiting from the progresses of this commercial process, MAPS have been undergoing significant advances over the last decade in terms of integration densities, radiation hardness and readout speed. The first application of MAPS in high energy physics has been the PXL detector, installed in 2014 as the vertexer of the STAR experiment at BNL. In the same years, ALICE Collaboration started the development of a new MAPS with improved performances, to assemble a new detector to replace the Inner Tracking System used during LHC Run 1 and 2. This effort lead to the ALPIDE sensor, today successfully equipped in a large variety of systems. Starting from 2019, profiting from the experience acquired during the design of the ALPIDE sensor, the ALICE Collaboration embarked on a new development phase, the ITS3 project. Here the goal is to design the first truly cylindrical detector based on wafer-size sensors in 65 nm CMOS node. This new detector is expected to take data during LHC Run 4. ALICE Collaboration submitted a proposal for a new experiment, to be installed in place of the present detector system before the LHC Run 5. Building on the experience on MAPS acquired in the recent years, the idea is to design a compact all silicon detector, that will give unprecedented insight into the quark-gluon plasma characterization.