Production of neutron-rich heavy residues and the freeze-out temperature in the fragmentation of relativistic U projectiles determined by the isospin thermometer

Isotope yields of heavy residues produced in collisions of U with lead at 1⋅A GeV show indications for a simultaneous break-up process. From the average N-over-Z ratio of the final residues up to Z = 70, the average limiting temperature of the break-up configuration at freeze out was determined to T -thermometer method. Consequences for the understanding of other phenomena in highly excited nuclear systems are discussed.