Fragmentation of relativistic gold nuclei with energies between 0.92 and 4.0 A GeV in hydrogen

Modeling the propagation of ultraheavy (UH) cosmic-ray nuclei through the i nterstellar medium requires a knowledge of the fragmentation cross sections . The cross sections for the production of fragments from the interactions of relativistic gold nuclei in hydrogen have been measured from 0.56 to 10. 6 A GeV, using the Lawrence Berkeley Laboratory (LBL) Bevalac and the Brook haven alternating gradient synchrotron (AGS). The total charge-changing cro ss sections are found to be essentially independent of energy. The partial elemental cross sections vary significantly with energy but show a transiti on to energy independence at the highest energies. These cross sections can be scaled to apply to neighboring elements, corrected for the effects of r adio active decay, and applied to propagation models to deduce source abund ances of the heaviest UH elements from those observed near Earth. There are serious uncertainties involved in deducing the cross sections applicable i n space from those measured on Earth. Hence calculations of propagation mus t be regarded with caution.