Experiment 780 is a search for the rare K decays K/sub L//sup 0/ ..-->.. ..mu..e and K/sub L//sup 0/ ..-->.. e/sup +/e/sup -/. We will be sensitive to these decays if the branching ratio is above 10/sup -10/. To achieve this in a 1000 hr experiment will require an intense beam with about 2 x 10/sup 5/ K decays/sec in the three meter decay region and over 10/sup 7/ counts/m/sup 2//sec in the apparatus. We will need a multilevel event selection sequence which will accept good events with high efficiency but quickly reject most of the background events. 1 ref
