K_L reconstruction for the Belle experiment at KEK B-factory

摘要

We report the K_L reconstruction algorithm and its performance for the Belle experiment at KEK B-factory. We select the K_L candidates using the dedicated K_L detector and electromagnetic calorimeter by detecting the hadron shower caused by K_L. Simple cut criteria with K_L detector shows the detection efficiency over 50% for the K_L momentum above 1.2 GeV/c. Likelihood method is used to discriminate the hadron shower and other events in the K_L selection with the electromagnetic calorimeter. Using K_L'S selected by these methods, we measured the B~0→ J/ψ + K_L events, and obtained the CP-violation parameter, sin 2φ_1 = 0.80 +- 0.13(stat).