Testbeam results of irradiated ams H18 HV-CMOS pixel sensor prototypes

TL;DR

This study demonstrates that irradiated ams H18 HV-CMOS pixel sensors maintain high hit efficiency, showing promise for use in high-radiation environments like the HL-LHC upgrade.

Contribution

First testbeam characterization of irradiated ams H18 HV-CMOS sensors, confirming their radiation tolerance and suitability for future high-energy physics tracking detectors.

Findings

Hit efficiencies above 97% at 85 V bias voltage.

Achieved 99.7% efficiency at fluence of 1×10^{15} n_eq/cm^2.

Strong evidence of radiation tolerance for HL-LHC applications.

Abstract

HV-CMOS pixel sensors are a promising option for the tracker upgrade of the ATLAS experiment at the LHC, as well as for other future tracking applications in which large areas are to be instrumented with radiation-tolerant silicon pixel sensors. We present results of testbeam characterisations of the $4^{\mathrm{th}}$ generation of Capacitively Coupled Pixel Detectors (CCPDv4) produced with the ams H18 HV-CMOS process that have been irradiated with different particles (reactor neutrons and 18 MeV protons) to fluences between $1\cdot 10^{14}$ and $5\cdot 10^{15}$ 1-MeV-n$_\textrm{eq}$/cm$^2$. The sensors were glued to ATLAS FE-I4 pixel readout chips and measured at the CERN SPS H8 beamline using the FE-I4 beam telescope. Results for all fluences are very encouraging with all hit efficiencies being better than 97% for bias voltages of $85\,$V. The sample irradiated to a fluence of $1\cdot 10^{15}$ n$_\textrm{eq}$/cm$^2$ - a relevant value for a large volume of the upgraded tracker - exhibited 99.7% average hit efficiency. The results give strong evidence for the radiation tolerance of HV-CMOS sensors and their suitability as sensors for the experimental HL-LHC upgrades and future large-area silicon-based tracking detectors in high-radiation environments.