Speaker
Description
The RD50-MPW4, the latest HV-CMOS pixel sensor in the series from the CERN-RD50-CMOS group, advances radiation tolerance, granularity, and timing resolution for future experiments like HL-LHC and FCC. Fabricated by LFoundry in December 2023 using a 150nm CMOS process, it features a 64 x 64 pixel matrix with a $62 \times 62\mu m^2$ pitch and employs a column-drain readout architecture. The RD50-MPW3, its predecessor, faced noise coupling issues between the digital periphery and the pixels, limiting threshold settings to $\gtrsim 5ke^-$ and restricting operation to the matrix's top half.
The RD50-MPW4 solves these issues by separating the power domains for digital and analog components, enabling more sensitive threshold settings and full matrix operation. Additionally, a new backside biasing scheme and an improved guard ring structure support bias voltages up to 800V, enhancing radiation hardness.
Test with unirradiated samples showed >99.9% efficiency, ~16$\mu m$ spatial resolution, and ~10ns timing resolution. Several samples were irradiated at JSI to fluences from $1 \times 10^{14}$ up to $3 \times 10^{16}$ $1MeV n_{eq} cm^{-2}$. This presentation covers IV measurements, injection scans at varying temperatures before and after annealing, and results from the latest test beam campaign, allowing the comparison of irradiated and non-irradiated samples and demonstrating the technology's suitability for high-radiation environments.
