Search for D-0-D-0 mixing with double-layer TOF at BESIII

The decay of D-0 -> K-pi(+) is a golden channel in the study of D-0-D-0 mixing at psi(3770). The requirements of excellent K/pi separation will play an essential role in the mixing search. A technique was developed to precisely extract event start time (t(0)) with TOF measurements in multiple charged tracks event at BESIII. After the t(0) extracting algorithm, the time resolution of double-layer TOF reduced from similar to 78ps to similar to 64ps, the upper limit of D-0-D-0 mixing rate at 95% CL can be improved by a factor of 7% in 20fb(-1) psi(3770) data.