ALICE Experiment to Install Revolutionary ITS3 Silicon Vertex Detector During LHC Upgrade
The ALICE experiment at CERN will replace its three innermost tracking layers with the ITS3, a groundbreaking fully cylindrical silicon vertex detector using ultra-thin, bent monolithic sensors during the LHC's Long Shutdown 3. The detector uses 50-micrometer-thick sensors bent to 19mm radii with wafer-scale stitching to create seamless 27cm-long sensors, eliminating traditional support structures and flexible circuits. This upgrade significantly reduces material interference in particle detection, improving measurement precision for studying quark-gluon plasma and other fundamental physics phenomena.
The ALICE collaboration has designed the ITS3 upgrade to replace its innermost tracking detector with an innovative silicon vertex detector featuring monolithic active pixel sensors (MAPS) fabricated in 65nm CMOS technology. The key innovation involves ultra-thin sensors (50 micrometers) that are bent to small radii (as small as 19mm) and stitched together at the wafer scale to create seamless 27cm-long detector elements with integrated power and signal distribution. This design eliminates the need for traditional support material and flexible printed circuits within the active detection volume, reducing the material budget to less than 0.09% radiation lengths per layer. The detector will use air-convection cooling instead of water cooling, further simplifying the system. Extensive R&D validation through full-scale prototypes (MOSS and MOST) has demonstrated the feasibility of wafer-scale stitching, high manufacturing yield, radiation hardness, and effective thermal management, paving the way toward final qualification.
What's missing
The study does not discuss the expected physics improvements or scientific reach enabled by the reduced material budget, nor does it provide a timeline for installation or estimated costs of the upgrade.
What different sources said
- arXiv physicsCenter
Overview of the ALICE ITS3 Upgrade
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