Feb 21 – 25, 2022
Vienna University of Technology
Europe/Vienna timezone

ALICE ITS3 - a bent, wafer-scale CMOS detector

Feb 22, 2022, 5:15 PM
Vienna University of Technology

Vienna University of Technology

Gusshausstraße 27-29, 1040 Wien
Live Presentation Semiconductor Detectors Large Detector Systems


Alex Kluge (CERN)


ALICE is developing the ITS3 (inner tracker system) as upgrade of the inner layers of the presently installed ITS with the aim to improve the pointing resolution by factor of two and to lower the material budget to an unprecedented value of 0.05% X0 per layer.

Its three layers are based on Monolithic Active Pixel Sensors (MAPS) thinned down to 20-40 µm. The configuration employs half-cylinders, which are bent around the beam pipe with bending radii of 18, 24 and 30 mm, respectively. The sensors are produced using stitching techniques allowing to reach a length of 28 cm. As consequence, the detector consists of six MAPS sensors only. The material budget is kept to a minimum using carbon foam elements to hold the stitched sensors in place, as well as by employing airflow cooling.

The ITS3 R&D has already passed important milestones of proving that bent MAPS are a viable technology option, and that thin wafer-scale silicon can be reliably integrated into true half-cylinders of target radii. A full scale mechanical integration prototype has already been produced. First prototype ASICs in 65 nm target technology are under test and are showing excellent in-beam performances.

This contribution summarises the achieved R&D results on bending and thinning, the mechanical prototype, beam tests and the 65 nm prototype ASIC test, as well as the path towards the last remaining milestone: the implementation of a wafer-scale, stitched sensor design.

Primary experiment ALICE

Primary authors

Presentation materials