Longitudinal momenta and production cross-sections of isotopes formed by fragmentation of a 500 A×MeV ⁸⁶Kr beam

At the projectile-fragment separator FRS at GSI, longitudinal momentum distributions and production cross-sections were investigated for reactions between a 500 A×MeV ⁸⁶Kr beam and beryllium, copper and tantalum targets. Fragments in a wide A Z range were studied. For fragments close to the projectile the measured longitudinal momentum distributions agree qualitatively with a semi-empirical parametrization. Deviations from this simple picture are found, however, for the momentum widths of light fragments and for the momentum transfer to those fragments that differ in their A Z ratio from the most probable value. The experimental data on production cross-sections are used for testing the predictions obtained from a semi-empirical parametrization, a geometrical abrasion model and an intranuclear-cascade model. The cross-section for the formation of the doubly magic nucleus ⁷⁸Ni in ⁸⁶Kr fragmentation is estimated to be 17 pb.