Calibration for Belle II Central Drift Chamber

Belle II Central Drift Chamber (CDC) plays an important role in measuring momentum of charged particles, in addition to the particle identification using energy loss per ionization, dE/dx. We present a method used to calibrate the time offset, the time walk, the time to space relation, and the position resolution. This method is established using cosmic data taken during March 2017 and confirmed with data taken during summer 2017. The position resolution obtained is better than 120 μm, depending on the layer and the incident angles of track. The performances of CDC after calibration, using a cosmic data sample taken under a 1.5 T magnetic field, are also shown.