Overview of Silicon Pixel Sensor Development for the ATLAS Insertable B-Layer (IBL)

The ATLAS Pixel Detector is the innermost part of the ATLAS tracking system and is critical for track and vertex reconstruction. In order to preserve the tracking performance notwithstanding the increasing instantaneous luminosity delivered by the LHC, ATLAS plans to introduce a new pixel layer (IBL) mounted directly on a reduced diameter beam pipe. The IBL will have to sustain an estimated radiation dose, including safety factors, of $5 imes 10^{15}$~n$_{eq}$/cm$^2$. Two sensor technologies are currently being considered for the IBL, planar n-on-n slim edge and 3D double sided designs. Results of the characterization, irradiation and beam test studies of IBL pixel devices are presented.