PROMPT AND SEQUENTIAL DECAY PROCESSES IN THE FRAGMENTATION OF 40 MEV NUCLEON NE-20 PROJECTILES/

The fragmentation of E/A = 40 MeV Ne-20 projectiles into exit channels containing only p, d, t, He-3, alpha, He-6, Li-6, and Li-7 fragments has been investigated. Relative shifts between the average longitudina l velocity of each fragment type were measured with Sn-120 and Au-197 targets. A post-breakup Coulomb acceleration component of these shifts was isolated. Its magnitude indicates that the projectile broke up wh ile in near contact with the target. On the other hand, correlations b etween projectile fragments indicate that a significant fraction of th ese fragments are produced by the sequential decay of long- and short- lived unstable intermediates. A fully sequential decay process, althou gh consistent with the experimental relative angle distributions, fail s to reproduce the correlation function. Thus, a picture emerges of a prompt breakup step producing stable and unstable particles with the s ubsequent decay of the latter extending over a long time period.