THE EFFECT OF LARGE ANGULAR MOMENTA ON MULTIFRAGMENTATION OF HOT NUCLEI

Multifragmentation of highly-excited nuclei with large angular momenta is analyzed as an example of microcanonical thermodynamics. The equip artition of the available phase space under the constraint of a given (large) angular momentum gives interesting new effects which cannot be studied in conventional thermodynamics. It is shown that momentum- an d energy distributions of the fragments are considerably changed from the non-rotational case. Especially, a large slope parameter of the ki netic energy distribution is established which is up to ten times larg er than the thermodynamic temperature. This, commonly attributed to no nequilibrium effects, can be used to identify high angular momenta. In this way ''nonthermal'' collective motion of nuclear matter (flows) o bserved in some experiments in which one would not expect any compress ions may be understood as fully equilibrized thermal motion under larg e angular momentum.