The charge sensitivity calibration of the upgraded ALICE Inner Tracking System

Abstract

The ALICE detector is undergoing an upgrade for run 3 at the LHC. A new Inner Tracking System (ITS) is part of this upgrade. The upgraded ALICE ITS features the ALPIDE, a monolithic active pixel sensor. Due to IC fabrication variations and radiation damage, the threshold values for the ALPIDE chips in the ITS need to be measured and adjusted periodically to ensure the quality of data. The calibration is implemented within the ALICE Online-Offline (O2) computing system, thus it runs in the same framework as the normal operations. This paper describes the concept and first implementation of the charge sensitivity scanning procedures for the upgraded ALICE ITS in the ALICE O2 system, and demonstrates the first results of the scanning of the data taken from the installed ITS.