Study of the Decay v n n m+v,

The branching ratios form — m 7r tr v, ands — m tr tr+(nn )v„n ~1, have been measured to be 0.078 + 0.005 + 0.008 and 0.047 + 0.005 + 0.008, respectively. The total three-prong tau branching ratio is 0.128+ 0.005+ 0.008. Study of the 3m — v, decay indicates that the three pions are predominantly from a J =1+ state which decays through a p vr — intermediate state in a rela