Production cross-sections of protactinium and thorium isotopes produced in fragmentation of 238U at 1 A GeV

The production cross-sections of proton-rich protactinium and thorium isotopes have been investigated for the fragmentation of 1 A GeV 238U in a beryllium target at the SIS/FRS facility at GSI Darmstadt. The experimental results are compared with the predictions of an abrasion–ablation model of nuclear fragmentation yielding good overall agreement. Weak evidence for first observation of the new isotopes 208Th and 211Pa is presented.