Speaker
Description
The ATLAS experiment inner detector will undergo a complete replacement with the all-silicon Inner Tracker (ITk) during the 2027–2029 shutdown, in preparation for operation at the High-Luminosity Large Hadron Collider. The ITk pixel detector, forming the innermost tracking system, is designed to operate under unprecedented radiation levels and particle densities. Its innermost layer (Layer 0) will employ radiation-hard 3D silicon sensor technology capable of withstanding fluences up to 1.7×10^16 " " "n" _"eq" /〖"cm" 〗^2, while the outer layers (L1–L4) will utilize thin n-in-p planar hybrid modules with sensor thicknesses of 100 µm (L1) and 150 µm (L2–L4).
Test-beam campaigns play a crucial role in evaluating sensor and module performance before and after irradiation to HL-LHC levels. In recent years, a broad range of sensor designs from multiple vendors has become available for systematic studies. The 2025 test-beam campaigns introduced new module configurations, including triplet and quad assemblies equipped with the final ITkPixV2 readout chip. Triplet modules integrating 3D sensors with pixel geometries of 50×50" " μ"m" ^2and 25×100" " μ"m" ^2were tested under beam conditions, both before and after irradiation.
Measurements were performed over a range of incident angles to probe charge-collection efficiency under realistic detector operating conditions. The 2025 dataset therefore provides significant new insights into sensor performance, particularly in irradiated scenarios, and contributes to the ongoing qualification of ITk pixel technologies. A subset of these data is currently under detailed analysis.
This contribution presents an overview of the ITk pixel sensor and module qualification program based on test-beam studies, highlighting the latest results from the 2025 and 2026 campaigns.