Production of new neutron rich isotopes of heavy elements in fragmentation reactions of ²³⁸U projectiles at 1 AGeV

The production of heavy neutron-rich nuclei has been investigated using cold-fragmentation reactions of U 238 projectiles at relativistic energies. The experiment performed at the high-resolving-power magnetic spectrometer Fragment Separator at GSI made it possible to identify 40 new heavy neutron-rich nuclei: Pt 205 , Au 207−210 , Hg 211−216 , Tl 214−217 , Pb 215−220 , Bi 219−224 , Po 223−227 , At 225−229 , Rn 230,231 , and Fr 233 . The production cross sections of these nuclei were also determined and used to benchmark reaction codes that predict the production of nuclei far from stability.