Speaker
Description
Pixel modules are currently being built for the ATLAS ITk Pixel detector upgrade.
Since the preproduction phase, recurring chip malfunctioning was observed during electrical testing, that was bypassed by disabling some pixel core columns in the ITkPix readout chip.
This issue is therefore called the "core column issue" which is a direct disqualifier for a pixel module.
A concerning number of cases has been observed in pixel modules with ITkPix v1.1 as well as v2 chips which would lead to unacceptable module yield.
However, the behaviour is erratic and there is no smoking gun hinting at the origin of this issue.
In this contribution we want to present our debugging process, highlight the electrical behaviour during testing, present findings in the data collected via our production database and through visual inspection, and point towards possible causes of the issue.
