This paper provides a specific study of the upgrade of the ATLAS pixel detector
in preparation for the upgrade of the Large Hadron Collider (LHC). The upgrade to High Luminosity-LHC (HL-LHC) is expected to start after the long shutdown in 2025-2027. The scheduled upgrade for ATLAS will be able to efficiently cope with the challenges caused by the high luminosity imposed by the HL-LHC. A new full-silicon Detector Inner Tracker (ITk) will replace the current ATLAS Inner Detector (ID). The ITk pixel detector will consist of more layers than in the current pixel detector. This study focuses on the Ring Oscillator (ROSC) sensors embedded in the ITkPix-V1 Front-End chip of the ATLAS ITk pixel detector. The paper reports the frequency response of the ROSC at various temperatures and voltage supply values. The results showed a high sensitivity of ROSCs frequencies to the applied voltage and the external temperatures which indicates the reliability of the ITkPix-V1 chip for the future ITk pixel modules.

This paper provides a specific study of the upgrade of the ATLAS pixel detector
in preparation for the upgrade of the Large Hadron Collider (LHC). The upgrade to High Luminosity-LHC (HL-LHC) is expected to start after the long shutdown in 2025-2027. The scheduled upgrade for ATLAS will be able to efficiently cope with the challenges caused by the high luminosity imposed by the HL-LHC. A new full-silicon Detector Inner Tracker (ITk) will replace the current ATLAS Inner Detector (ID). The ITk pixel detector will consist of more layers than in the current pixel detector. This study focuses on the Ring Oscillator (ROSC) sensors embedded in the ITkPix-V1 Front-End chip of the ATLAS ITk pixel detector. The paper reports the frequency response of the ROSC at various temperatures and voltage supply values. The results showed a high sensitivity of ROSCs frequencies to the applied voltage and the external temperatures which indicates the reliability of the ITkPix-V1 chip for the future ITk pixel modules.