Λ0-Fragment Decay in a Cloud Chamber

The decay in flight of a heavy nuclear fragment is described. The event is most reasonably interpreted as the decay of a Λ0 particle bound to a He3 nucleus, and is similar to examples previously observed in nuclear emulsions. The lifetime of the excited fragment in this single example is 5.4±0.6×10^-10 sec, and the binding energy of the Λ0 to He3 is probably less than 2 Mev.