Angular distributions and mechanisms for light fragment formation in relativistic heavy-ion collisions

Angular distributions are reported for ³⁷Ar and ¹²⁷Xe produced by the interaction of 8-GeV ²⁰Ne and 25-GeV ¹²C ions with Au. A shift from a forward to a sideward peaked distribution is observed for ³⁷Ar, similar to that known to occur for incident protons over the same energy interval. Analysis of these data and those for Z=8 fragments indicate that reactions leading to heavy fragment emission become more peripheral as bombarding energies increase. A mechanistic analysis is presented which explores the ranges of applicability of several models and the reliability of their predictions to fragmentation reactions induced by both energetic heavy ions and protons.