Calibration and alignment of the Belle II central drift chamber

Abstract

Abstract The Belle II central drift chamber (CDC) is crucial in the momenta measurements of charged particles. We present methods for calibration and alignment of the CDC. Using cosmic ray data acquired with and without a magnetic field , the CDC was calibrated and aligned, and its performance was evaluated. The position resolution is better than 120 μ m, depending on the layer and incident angles of the tracks. The alignment of the CDC improves the resolution of track parameters and reduces their systematic shifts. The transverse momentum ( P T ) resolution for charged tracks is 0 . 127 P T ⊕ 0 . 321 (%), P T is in GeV/ c .