# Subpixel Mapping and Test Beam Studies with a HV2FEI4v2 CMOS-Sensor-Hybrid Module for the ATLAS Inner Detector Upgrade

## TL;DR

This paper investigates a high-voltage CMOS active pixel sensor with subpixel encoding for the ATLAS detector upgrade, demonstrating its potential as an alternative to traditional hybrid sensors through test beam validation.

## Contribution

It presents the design and testing of a novel HV CMOS sensor with subpixel encoding for particle tracking in high-energy physics experiments.

## Key findings

- Successful validation of subpixel encoding through test beam measurements
- Demonstrated compatibility with ATLAS read-out chip
- Potential for improved tracking resolution in collider upgrades

## Abstract

The upgrade to the High Luminosity Large Hadron Collider will pose unprecedented challenges to the tracking systems of all experiments. Recent advancement of active pixel detectors designed in CMOS processes provide attractive alternatives to the well-established hybrid design using passive sensors. This article presents studies with a high-voltage CMOS active pixel sensor designed for the ATLAS tracker upgrade. The sensor is glued to the read-out chip of the Insertable B-Layer. The device under test is structured in smaller pixels than those of the attached read-out chip with information on the hit CMOS pixel encoded in the output signal (subpixel encoding). Test beam measurements mapping recorded hits in the read-out chip to CMOS pixels, thus validating the subpixel encoding, are described.