Sensor response and radiation damage effects for 3D pixels in the ATLAS IBL Detector

TL;DR

This paper evaluates the radiation tolerance and performance of 3D pixel sensors in the ATLAS IBL detector during LHC Run 2 and Run 3, demonstrating their suitability for high-radiation environments in future collider upgrades.

Contribution

It provides comprehensive measurements and radiation damage simulations of 3D pixel sensors over multiple years of LHC operation, highlighting their robustness and potential for HL-LHC applications.

Findings

3D sensors show increased radiation tolerance compared to traditional sensors.

Sensor response degrades predictably with accumulated fluence.

Simulations align well with measured data, validating damage models.

Abstract

Pixel sensors in 3D technology equip the outer ends of the staves of the Insertable B Layer (IBL), the innermost layer of the ATLAS Pixel Detector, which was installed before the start of LHC Run 2 in 2015. 3D pixel sensors are expected to exhibit more tolerance to radiation damage and are the technology of choice for the innermost layer in the ATLAS tracker upgrade for the HL-LHC programme. While the LHC has delivered an integrated luminosity of $\simeq$ 235 fb$^{-1}$ since the start of Run 2, the 3D sensors have received a non-ionising energy deposition corresponding to a fluence of ${\simeq} 8.5\times10^{14}$ 1 MeV neutron-equivalent cm$^{-2}$ averaged over the sensor area. This paper presents results of measurements of the 3D pixel sensors' response during Run 2 and the first two years of Run 3, with predictions of its evolution until the end of Run 3 in 2025. Data are compared with radiation damage simulations, based on detailed maps of the electric field in the Si substrate, at various fluence levels and bias voltage values. These results illustrate the potential of 3D technology for pixel applications in high-radiation environments.