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By use of secondary beams, nuclear-reaction studies can be extended considerably. Large variations of the N-over-Z ratio of the projectile, in many cases up to the drip lines, can be achieved. In one of the first secondary-reaction studies at the fragment separator of GSI, Thomas Brohm et al. investigated the total and the nuclear charge-changing cross sections for stable and neutron-deficient projectiles around mass number 60. The total nuclear charge-changing cross sections have been found to increase when the N-over-Z ratio of the projectile decreases. A closer look on the partial nuclear charge-changing cross sections, that means on the element distribution of the reaction products, revealed that this behaviour can be understood by the combined influence of the abrasion (the high-energy nucleus-nucleus collision) and the ablation (the statistical deexcitation phase) stages of the reaction. The studies were extended by Bertram Blank et al. with secondary products from a 58Ni beam. In another experiment, described by Marek Pfützner et al., even specific nuclides, produced in secondary reactions, have been identified. These results shed new light on previous findings, interpreted as evidence for "anomalons." Their existence had previously been deduced from unexpected, "anomalously" large cross sections of secondary reaction products, which are neutron-deficient on the average. The new experimental data gives a conservative interpretation of these findings.
T. Brohm et al., 1992 T. Brohm et al. , 1995 B. Blank et al., Z. Phys. A 352 (1995) 69-75 B. Blank et al., Z. Phys. A 352 (1995) 77-83 M. Pfützner et al., Nucl. Phys. A 587 (1995) 229-240 |
