High angular momentum states populated in fragmentation reactions

The population of metastable states produced in relativistic-energy fragmentation of a 238U beam has been measured. For states with angular momentum ≳20ℏ, a much higher population than expected has been observed. By introducing a collective component to the generation of angular momentum the experimental data can be understood. This is the first time that a collective degree of freedom has be shown to play a major role in such high-energy collisions.