Small Momentum Widths in Heavy-Ion Fragmentation at 20 MeV/amu and Below

Abstract
The widths of the momentum distributions for quasielastic fragments produced by Ne20 on Au197 at 20 MeV/amu and below are found, in contrast to a previous similar measurement, to be much smaller than at 2 GeV/amu. This contradicts a rapid change of reaction mechanism near 20 MeV/amu, in particular, the sudden onset of fragmentation or the decay from a nonequilibrated high-temperature subsystem.