Cosmic-ray nuclei have been observed to produce 2072 secondary fragments in nuclear interactions detected in nuclear emulsions. These fragments produce 557 further interactions. Previous reports that these secondary nuclei show anomalously short mean free paths near their point of origin are confirmed. This effect can be interpreted as being due to all fragments having cross sections about twice normal for some ${10}^{-10\mathrm{}}$ sec after creation, or to a small fraction having cross sections an order of magnitude greater than normal.

• Received 11 January 1982

DOI:https://doi.org/10.1103/PhysRevLett.48.856