Tracking efficiency and charge sharing of 3D silicon sensors at different angles in a 1.4 T magnetic field

A 3D silicon sensor fabricated at Stanford with electrodes penetrating throughout the entire silicon wafer and with active edges was tested in a 1.4 T magnetic field with a 180 GeV/c pion beam at the CERN SPS in May 2009. The device under test was bump-bonded to the ATLAS pixel FE-I3 readout electronics chip. Three readout electrodes were used to cover the 400μm long pixel side, this resulting in a p-n inter-electrode distance of ∼71μm. Its behavior was confronted with a planar sensor of the type presently installed in the ATLAS inner tracker. Time over threshold, charge sharing and tracking efficiency data were collected at zero and 15 deg. angles with and without magnetic field. The latest is the angular configuration expected for the modules of the Insertable B-Layer (IBL) currently under study for the LHC phase 1 upgrade expected in 2014.