Planar n-in-n quad module prototypes for the ATLAS ITk upgrade at HL-LHC

TL;DR

This paper presents the development and characterization of planar n-in-n quad silicon pixel modules for the ATLAS ITk upgrade at HL-LHC, including tests on non-irradiated and irradiated devices.

Contribution

It introduces the design and testing of quad chip modules with special pixel cells to cover gaps, advancing detector technology for HL-LHC upgrades.

Findings

High hit efficiency achieved in non-irradiated modules

Charge collection performance characterized with radioactive sources

Initial results show promising radiation tolerance

Abstract

In order to meet the requirements of the High Luminosity LHC (HL-LHC), it will be necessary to replace the current tracker of the ATLAS experiment. Therefore, a new all-silicon tracking detector is being developed, the so-called Inner Tracker (ITk). The use of quad chip modules is intended in its pixel region. These modules consist of a silicon sensor that forms a unit along with four read-out chips. The current ATLAS pixel detector consists of planar n-in-n silicon pixel sensors. Similar sensors and four FE-I4 read-out chips were assembled to first prototypes of planar n-in-n quad modules. The main focus of the investigation of these modules was the region between the read-out chips, especially the central area between all four read-out chips. There are special pixel cells placed on the sensor which cover the gap between the read-out chips. This contribution focuses on the characterization of a non-irradiated device, including important sensor characteristics, charge collection determined with radioactive sources as well as hit efficiency measurements, performed in the laboratory and at testbeams. In addition, first laboratory results of an irradiated device are presented.