Systematic study of micro-discharge characteristics of ATLAS barrel silicon microstrip modules

Among the 981 silicon microstrip modules fabricated by the ATLAS SCT Japan group, 111 modules showed a micro-discharge, a rapid leakage current increase when the bias is raised, below 500 V bias at least once in the series of the quality assurance testing. We have conducted a systematic study to understand the causes, including the hot spot localization using an infrared sensitive camera, and measurement of leakage current decay time.