The reactions 32S+58Ni and 32S+64Ni are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even–odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this staggering appears hidden by the rapid variation of the production yields with the fragment size. Once this effect is accounted for, the staggering appears to be a universal feature of fragment production, slightly enhanced when the emission source is neutron poor. A closer look at the behavior of the production yields as a function of the neutron excess N−Z, reveals that odd–even effects cannot be explained by pairing effects in the nuclear masses alone, but depend in a more complex way on the de-excitation chain.

Reaction mechanisms and staggering in S+Ni collisions

GERACI, Elena Irene;
2011-01-01

Abstract

The reactions 32S+58Ni and 32S+64Ni are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even–odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this staggering appears hidden by the rapid variation of the production yields with the fragment size. Once this effect is accounted for, the staggering appears to be a universal feature of fragment production, slightly enhanced when the emission source is neutron poor. A closer look at the behavior of the production yields as a function of the neutron excess N−Z, reveals that odd–even effects cannot be explained by pairing effects in the nuclear masses alone, but depend in a more complex way on the de-excitation chain.
2011
measured fragment yield and charge distribution, deduced reaction mechanism features, odd–even effects; Comparison with GEMINI evaporation model; NUCLEAR REACTIONS, 58,64Ni(32S, X), E=463 MeV
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/46938
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