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Intermediate energy single-neutron removal from 31 Mg has been employed to investigate the transition into the N = 20 island of inversion. Levels up to 5 MeV excitation energy in 30 Mg were populated and spin-parity assignments were inferred from the corresponding longitudinal momentum distributions and γ -ray decay scheme. Comparison with eikonal-model calculations also permitted spectroscopic factors to be deduced. Surprisingly, the 0 2 + level in 30 Mg was found to have a strength much weaker than expected in the conventional picture of a predominantly 2 p − 2 h intruder configuration having a large overlap with the deformed 31 Mg ground state. In addition, negative parity levels were identified for the first time in 30 Mg, one of which is located at low excitation energy. The results are discussed in the light of shell-model calculations employing two newly developed approaches with markedly different descriptions of the structure of 30 Mg. It is concluded that the cross-shell effects in the region of the island of inversion at Z = 12 are considerably more complex than previously thought and that n p − n h configurations play a major role in the structure of 30 Mg. [ABSTRACT FROM AUTHOR]

Abstract: The fragmentation of neutron-rich nuclei produced in the fission of projectiles at 950 A MeV has been investigated at the FRagment Separator (FRS) at GSI. This work represents the first investigation of fragmentation of medium-mass radioactive projectiles with a large neutron excess. The measured production cross sections of the residual nuclei are relevant for the possible use of a two-stage reaction scheme (fission+fragmentation) for the production of extremely neutron-rich medium-mass nuclei in future rare-ion-beam facilities. Moreover, the new data will provide a better understanding of the “memory” effect in fragmentation reactions. [Copyright &y& Elsevier]

The fragmentation of neutron-rich Sn isotopes obtained from the fission of 238U projectiles at 950 MeV/u has been investigated at the FRagment Separator (FRS) at GSI. In order to study the feasibility of a two-step reaction scheme for the production of medium-mass neutron-rich nuclei, fragments with masses A ≈ 130 have been isotopically resolved in the first part of FRS and their fragmentation residues identified in the second part. [ABSTRACT FROM AUTHOR]

The production cross sections of neutron-rich fission residues in reactions induced by 238U projectiles at 950A MeV impinging on Pb and Be targets are investigated at the Fragment Separator at GSI. These two targets allow us to investigate fission processes induced by two reaction mechanisms, Coulomb and nuclear excitations, and to study the role of these mechanisms in the neutron excess of the final fragments. [ABSTRACT FROM AUTHOR]

Abstract: The radial evolution of the matter distributions with neutron excess has been investigated at GSI measuring total interaction cross sections for long isotopic chains of medium-mass nuclei. Comparisons with different model calculations show a clear increase of the total interaction cross sections for the most neutron-rich nuclei that we interpret as a signature for a larger matter radius of those nuclei. [Copyright &y& Elsevier]