MAPS-based vertex detectors for collider experiments: from the STAR HFT to the next generation

The PiXeL detector (HFT PXL) of the STAR experiment at RHIC is the first application of the thin
Monolithic Active Pixel Sensors (MAPS) technology in a collider environment. It is based on 50 μm-thin
MAPS sensors with a pitch of 20.7 μm. Each sensor includes an array of nearly 1 million pixels, read out
in rolling shutter mode in 185.6 μs. The 170 mW/cm 2 power dissipation allows for air cooling and
contributes to reduce the global material budget to 0.4% radiation length on the innermost layer.
Detector performance and lessons learned from the construction and the 3-years of operations will be
presented in the first part of this talk.
Following the successful experience in STAR, the next-generation MAPS sensor will be used to upgrade
the ALICE Inner Tracking System (ITS) at LHC. Compared to the STAR PXL detector, the integration time
for the future ALICE ITS Upgrade has been reduced down to <20 μs. This allows high reconstruction
efficiency, especially for low momentum tracks in high luminosity heavy-ion collisions. The same
technology and a similar design have been proposed for the vertex detector (MVTX) for sPHENIX, the
future nuclear physics experiment for the study of the QGP planned for RHIC. A general description of
the ITS Upgrade and the MVTX systems will be given in the second part of this presentation, with
particular focus on some specific technical aspects and the project schedules.