NUCLEAR CHARGE-CHANGING REACTIONS OF SECONDARY BEAMS IN THE MASS RANGE 50-LESS-THAN-OR-EQUAL-TO-A-LESS-THAN-OR-EQUAL-TO-62

At the fragment separator FRS at GSI, relativistic secondary beams with nuclear mass numbers 50 less-than-or-equal-to A less-than-or-equal-to 62 were produced by the fragmentation of a 1 A . GeV Kr-86 beam in a Be-9 production target. The nuclear charge and mass numbers of the secondary-beam particles were determined by a DELTAE-t.o.f.-Brho measurement. The fragmentation of stable and neutron-deficient manganese, iron, cobalt and nickel isotopes in a composite carbon-hydrogen target, placed behind the separator, was investigated. The element distributions of the secondary-fragmentation products were found to depend strongly on the neutron-to-proton ratio of the projectile. Calculations with a statistical abrasion model allow an explanation of the observed features by means of the different influences of the neutron-to-proton ratio of the projectile on the abrasion and ablation steps of the fragmentation reaction.