Search for K/sub L//sup O/. --> mu. e at the 10/sup -13/ level

A few of the experimental problems of searching for the lepton non-conserving decay K/sub L//sup O/ ..-->.. ..mu..e are discussed in the light of the experience of BNL E791. This experiment was designed to have high rate capability and excellent background rejection; as such it provides information useful in evaluating designs for similar experiments at high-intensity facilities. The conclusion is that a level of a few times 10/sup -13/ may be reachable, but requires careful design and makes significant demands on the accelerator, particularly as regards beam time structure. Development of precise positron-sensitive detectors with shorter resolving times is also necessary. 4 refs., 1 fig.