Study of antiproton annihilation in silicon with a hybrid pixel detector using the TimePix3 readout

The main goal of the AEgIS experiments is to measure the gravitational force for anti-hydrogen, testing Einstein's weak equivalence principle, which states that all bodies falls with the same acceleration, independently from their mass and composition. The measurement will be done using an anti-hydrogen beam sent trough a classical moire deflectometer. To measure the deflection of the beam from a straight path a position sensitive silicon detector followed by an emulsion detector and a scintillating fiber time-of-flight detector will be used. We present here a study performed using a novel hybrid pixel detector, employing the Timepix3 readout chip to tag and spatially resolve antiproton annihilations in silicon. In autumn 2014 we performed a test-experiment on a secondary beam line to the AEgIS experiment, where a pulsed beam of anti-protons of energy 5.3 MeV was delivered from the Antiproton Decelerator of CERN accelerator complex. Taking advantage of the high spatial resolution, ToA capabilities and extended energy range of the Timepix3, this study investigates unique features of antiproton annihilation events in silicon. We are for the first time able to set clear criteria to characterize an antiproton annihilation using a silicon detector.