Testing the limits of ITkPixV2: the ATLAS inner tracker pixel detector readout chip

TL;DR

This paper presents the first measurements of the ITkPixV2 chip, the final readout chip for the ATLAS Inner Tracker upgrade, demonstrating its performance at the high demands of the HL-LHC environment.

Contribution

It provides the first operational measurements of the ITkPixV2 chip under full design requirements, including activity-induced current at high hit rates.

Findings

Measured activity-induced current as a function of hit rate

Demonstrated chip operation at HL-LHC conditions

Validated design requirements for high-luminosity environment

Abstract

The ITkPixV2 chip is the final production readout chip for the ATLAS Phase 2 Inner Tracker (ITk) upgrade at the upcoming High-Luminosity LHC (HL-LHC). Due to the extraordinarily high peak luminosity at the HL-LHC of $5 \times 10^{34}$ cm$^{-1}$s$^{-1}$, ITkPixV2 must meet significant increases in nearly all design requirements compared to the current ATLAS Inner Detector (ID), including a 10x increase in trigger rate, a 7.5x increase in hit rate, a 3x increase in radiation tolerance, and a 12.5x decrease in pixel current draw per unit area, all while maintaining a similar power per unit area as present pixel detectors. Here we present the first measurements of the ITkPixV2 chip operated at the limits of the full chip design requirements, including in particular a measurement of the activity-induced current of the chip as a function of increasing hit rate.