PARTIAL CHARGE-CHANGING CROSS-SECTIONS FOR NEUTRON-DEFICIENT ISOTOPESFROM NI-58 FRAGMENTATION

At the projectile-fragment separator FRS of GSI, relativistic secondar y beams of about 520 MeV/nucleon were produced by fragmentation of a p rimary beam of Ni-58 at 650 MeV/nucleon in a beryllium target. By mean s of a Delta E - B rho - TOF measurement, the fragments were identifie d and their charge-changing probabilities in targets of (CH2)(n), C, A l, and Pb placed at the exit of the FRS were determined. Whereas a fir st article dealt with the total charge-changing cross sections, we des cribe in this second article the element distributions of these second ary fragments, which are found to depend strongly on the isospin of th e secondary projectile as well as on the target material. In the case of the lead target, the influence of the electromagnetic dissociation is clearly visible in the one-proton and two-proton removal channels. The preference for the formation of even-Z fragments is much more pron ounced for exotic secondary projectiles than for projectiles close to stability. Calculations with a geometrical abrasion-ablation model all ow to understand the global features of the experimental data. However , far from stability, the discrepancies between calculations and exper imental data increase.