3D silicon pixel sensors: Recent test beam results

The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension 50×400μm2. Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison.