Recent Results of the ATLAS Upgrade Planar Pixel Sensors R&D Project

TL;DR

This paper reviews recent advancements in planar pixel sensor R&D for the ATLAS upgrade, focusing on radiation hardness, cost reduction, and new sensor technologies for HL-LHC conditions.

Contribution

It presents recent results on sensor performance, innovative edge designs, and cost-effective production techniques for the ATLAS pixel upgrade project.

Findings

Sensors maintain high efficiency after irradiation up to 2e16 neq/cm

Successful implementation of slim and active edge technologies

Cost-effective production methods for large-area sensors

Abstract

To cope with the higher occupancy and radiation damage at the HL-LHC also the LHC experiments will be upgraded. The ATLAS Planar Pixel Sensor R&D Project (PPS) is an international collaboration of 17 institutions and more than 80 scientists, exploring the feasibility of employing planar pixel sensors for this scenario. Depending on the radius, different pixel concepts are investigated using laboratory and beam test measurements. At small radii the extreme radiation environment and strong space constraints are addressed with very thin pixel sensors active thickness in the range of (75-150) mum, and the development of slim as well as active edges. At larger radii the main challenge is the cost reduction to allow for instrumenting the large area of (7-10) m^2. To reach this goal the pixel productions are being transferred to 6 inch production lines and more cost-efficient and industrialised interconnection techniques are investigated. Additionally, the n-in-p technology is employed, which requires less production steps since it relies on a single-sided process. Recent accomplishments obtained within the PPS are presented. The performance in terms of charge collection and efficiency, obtained with radioactive sources in the laboratory and at beam tests, is presented for devices built from sensors of different vendors connected to either the present ATLAS chip FE-I3 or the new Insertable B-Layer chip FE-I4. The devices, with a thickness varying between 75 mum and 300 mum, were irradiated to several fluences up to 2e16 neq/cm. Finally, the different approaches followed inside the collaboration to achieve slim or active edges are presented.