Hit efficiency study of the BESIII drift chamber

The Beijing Spectrometer III (BESIII) on the Beijing Electron Positron Collider II (BEPCII) is a unique facility operating in the τ-charm region. The multilayer drift chamber (MDC), which plays a crucial role in the measurements of momentum and dE/dx for charged particles generated during electron-positron collisions, has been operating for around 15 years. Hit efficiency is a fundamental performance criterion of the MDC. To analyze the spatial distribution of the hit efficiency and the stability during the operation over the past decade, a track-based analysis was performed using Bhabha events collected from 2012 to 2023. Decreasing in hit efficiency due to the aging effect was observed in the first three layers. A position-dependent behavior was studied, which may be related to beam-induced background.