1. General Seminars

Recent advances in CMOS pixel sensors, towards more applications

by jerome Baudot (IPHC - IN2P3)

Aula Bruno Touschek (LNF INFN)

Aula Bruno Touschek


Pixel sensors built directly from the CMOS integrated circuit technology, as known as CPS or MAPS, are gaining more and more enthusiasts for vertexing and tracking in subatomic physics. Indeed CMOS pixel sensors feature genuinely spatial resolution in the micrometers range and material budget well below 1% of radiation length, which are key assets for these applications. It was less straightforward, and took some developments, to bring MAPS in the realm of nanosecond range time resolution or microsecond integration time, and radiation tolerance matching 10^15 neutron (1 Mev equivalent) per cm2. These last achievements required the depletion of the sensitive volume, which in turn yield an interesting byproduct in term of energy resolution. For instance, 6 keV X-rays can be reconstructed with about 300 eV resolution, roughly just a factor 3 from the absolute Fano limit. Such a performance opens up perspectives for spectroscopy in a broad range of applications, well beyond high energy physics. A less well recognised but nonetheless very strong point of MAPS is their ability to be easily integrated in a system. This stems from two main reasons: these sensors rely on an industrial technology widely used on the consumer market and they can reach extremely low power dissipation, since there is not much amplification required. This seminar intends to introduce briefly the basic operational concept of CMOS pixel sensors and then to cover the latest developments pushing performances (energy, timing, smartness) to their current limits. These discussions will embark us on a journey through the applications driving these developments: from high energy physics (STAR, ALICE, ATLAS, ILC, ...) to low energy physics with hadron-therapy (FIRST, FOOT, ...) passing by soft X-ray detection or molecular imaging in freely moving rat brain. A good fraction of the described projects comes from the Strasbourg group, who proposed charged particle tracking with MAPS about 20 years ago, but not only, demonstrating the current vividness of the field, still full of promises.