Thin n-in-p planar pixel sensors and active edge sensors for the ATLAS upgrade at HL-LHC

TL;DR

This paper evaluates the performance of thin n-in-p planar and active edge silicon pixel sensors for the ATLAS upgrade at HL-LHC, focusing on radiation hardness, efficiency, and charge collection before and after irradiation.

Contribution

It presents the development and testing of novel thin and active edge silicon pixel sensors optimized for high radiation environments in collider experiments.

Findings

Sensors maintain high hit efficiency after irradiation.

Active edge technology maximizes sensitive area.

Performance varies with sensor thickness and bias voltage.

Abstract

Silicon pixel modules employing n-in-p planar sensors with an active thickness of 200 $\mu$m, produced at CiS, and 100-200 $\mu$m thin active/slim edge sensor devices, produced at VTT in Finland have been interconnected to ATLAS FE-I3 and FE-I4 read-out chips. The thin sensors are designed for high energy physics collider experiments to ensure radiation hardness at high fluences. Moreover, the active edge technology of the VTT production maximizes the sensitive region of the assembly, allowing for a reduced overlap of the modules in the pixel layer close to the beam pipe. The CiS production includes also four chip sensors according to the module geometry planned for the outer layers of the upgraded ATLAS pixel detector to be operated at the HL-LHC. The modules have been characterized using radioactive sources in the laboratory and with high precision measurements at beam tests to investigate the hit efficiency and charge collection properties at different bias voltages and particle incidence angles. The performance of the different sensor thicknesses and edge designs are compared before and after irradiation up to a fluence of $1.4\times10^{16}n_{eq}/cm^{2}$.