Search for free decay of negative pions in water and light materials

We report on a search for the free-decay component of {pi}{sup -} stopped in water and light materials. A nonzero value of this would be an indication of anomalous {nu}{sub e} contamination to the {nu}{sub e} and {nu}{sub {mu}} production at stopped-pion neutrino facilities. No free-decay component of {pi}{sup -} was observed in water, Beryllium, and Aluminum, for which upper limits were established at 8.2x10{sup -4}, 3.2x10{sup -3}, and 7.7x10{sup -3}, respectively.