Speaker
Description
The ITS3 upgrade of the ALICE experiment at CERN will introduce ultralight, bent monolithic pixel sensors using the TPSCo 65 nm CMOS process. This design reduces the material budget to 0.09% X0 per layer and the innermost layer radius to 19 mm, improving the impact parameter resolution by a factor of 2 for momenta < 1 GeV/c.
As part of the ITS3 R&D effort, multiple prototype sensors were developed
and characterized, with extensive testing conducted using radioactive sources, particularly 55-Fe. Unlike charge deposition from minimum-ionizing particles, 55-Fe X-ray spectra offer a more stringent probe of charge collection dynamics and subtle detector effects, but are correspondingly harder to model precisely.
Accurately reproducing these spectra indicates a deep understanding of the
sensor’s internal processes. Although the sensors have met the radiation hardness requirements of 4 x 10^12 1 MeV neq cm^−2, higher irradiation levels (up to 10^16 1 MeV neq cm^−2) lead to notable degradation in the 55-Fe spectral response, due to radiation-induced effects in silicon. To investigate this, simulations were carried out using TCAD for electric field modeling and Garfield++ for charge transport. This presentation
will highlight the simulation approach, its role in understanding sensor
performance post-irradiation, and will showcase the excellent compatiblity with experimental data.
These results not only support the ongoing optimization of sensor performance for ITS3, but also lay the groundwork for developing next-generation monolithic sensors capable of operating reliably in even harsher radiation environments.
