TOTAL CHARGE-CHANGING CROSS-SECTIONS FOR NEUTRON-DEFICIENT ISOTOPES FROM 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 have been iden tified and their charge-changing probabilities in targets of CH2, C, A l, and Pb have been determined. We describe the results for the total charge-changing cross sections in this first paper, whereas a second a rticle deals with the partial charge-changing cross sections. At the d rip line, the measured charge-changing cross sections exhaust close to 100% of the total interaction cross sections as calculated with semie mpirical models. The measurements at the proton drip line with low-Z t argets indicate that only a very small increase of p the cross section s may be observed, whereas the measurements with a lead target show th at no significant increase of the total charge-changing cross sections is present which would be a hint for low-lying dipole strength. Our e xperimental data are compared to Glauber-type calculations.