3D sensor modules for the innermost layer of the ATLAS ITk Pixel Detector

by Niraj Kakoty (IFAE)

Wednesday 28 May 2025, 13:00 → 14:00 Europe/Madrid

IFAE Seminar Room (In-person)

The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will push the ATLAS detector to handle an increased luminosity of \(5 \times 10^{34} \text{cm}^{-2} \text{s}^{-1}\) and up to 200 proton-proton collisions per bunch crossing. To meet this challenge, the current ATLAS Inner Detector will be replaced with the new silicon-based Inner Tracker (ITk), consisting of a Pixel detector at a small radius and a surrounding Strip detector.  

The ITk Pixel detector uses hybrid pixel sensors bump-bonded to ITkPix readout chips (65 nm CMOS). Planar sensors will be used for the outer layers, while radiation-hard 3D sensors are chosen for the innermost layer (L0), which faces fluences up to about \(2 \times 10^{16} \text{n}_{eq} \text{cm}^{-2}\). L0’s basic unit, the "triplet" module, consists of three 3D sensors individually hybridized to readout chips and mounted on a flexible PCB for biasing and communication. Three designs exist: linear triplets for the barrel and two ring geometries (R0, R0.5) for the end-cap sections.  

IFAE will handle triplet module assembly and quality control of L0 linear triplets. This talk presents the current status of linear triplet production, detailing assembly, testing procedures, bump connectivity checks and sensor stability. Additionally, recent findings on the time resolution of 3D sensors obtained through the Transient Current Technique (TCT) will be discussed.