Speaker
Description
The current inner detector of the ATLAS experiment was designed to operate under the conditions of the Large Hadron Collider (LHC). In the forthcoming High-Luminosity LHC (HL-LHC) era, particle densities and radiation levels will increase by approximately an order of magnitude. The instantaneous luminosity is expected to reach unprecedented levels of $7 \times 10^{34}\,\mathrm{cm^{-2}\,s^{-1}}$, resulting in up to 200 proton-proton interactions per bunch crossing. These conditions impose stringent requirements on the tracking detector upgrade. The new system must provide faster readout and significantly higher granularity, while maintaining robust performance in a harsh radiation environment. At the same time, increased power delivery to the front-end electronics is required, without introducing excess material that would degrade tracking performance. To meet these challenges, the ATLAS experiment will replace its current inner detector with an all-silicon Inner Tracker (ITk) of extended coverage. The ITk comprises multiple layers of silicon sensors: pixel detectors in the innermost region, surrounded by a large-area strip detector. The ITk strip detector consists of four layers in the central tracker region (barrel) and six disks in each endcap region, covering a pseudorapidity range of $|\eta| < 2.7$. Silicon sensors, front-end ASICs, and power distribution are integrated into silicon strip modules mounted on lightweight support structures (staves and petals), which also provide common electrical, optical, and cooling services. The 256-channel ABCStar ASIC performs front-end readout of silicon strip signals. The scale of this upgrade is substantial, requiring the assembly of approximately 11,000 silicon strip modules in the barrel and 7,000 modules in the endcap regions. An overview of the ITk strip detector and its underlying technologies is provided. Current production status, performance results, and integration plans are presented, together with challenges encountered during pre-production and early production and their successful resolution, paving the way for large-scale international production.