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A study of unbound states in 17C by means of one-neutron knockout from a fast moving 18C beam at an energy of 245 MeV/nucleon on a carbon target was performed at the RIKEN-RIBF laboratory utilizing SAMURAI. The energy spectrum of unbound 17C constructed from momentum vectors of the forward going beam velocity 16C fragment and neutron covered an energy range of the decay neutron below about 6 MeV in the center of mass of 17C*. The relative energy Erel spectrum was characterized by two resonances at about 1.92 and 3.24 MeV in Erel and a possible multiplet at around Erel ~ 0.7 MeV. Momentum distributions of the knockout residue for the Erel= 1.92 and 3.24-MeV states well matched to those of p-wave neutron removal, providing a model independent confirmation of negative parity assignments for these states. The proposed level scheme of 17C was compared with a range of different shell-model predictions; it turned out that the YSOX shell-model interaction, employing the monopole-based universal interaction for the cross-shell two-body matrix elements and incorporating larger ?! excitations, gave a consistent account of it, including the locations of the 1=21- and 3=21- cross-shell states. [ABSTRACT FROM AUTHOR]

Advanced nuclear structure models predict the presence of the shell closures N = 14, 16 in neutron-rich O isotopes rather than N = 20. Spectroscopic investigations performed at the neutron drip line have recently confirmed such predictions showing that the 24O is a doubly magic nucleus (Z = 8, N = 16). Predictions within the shell model calculation for the 23,24O ground state have been confirmed measuring their spectroscopic factors. Results obtained in one-neutron removal reactions performed by using in-flight radioactive ion beams produced at the Fragment Separator FRS of GSI are reported. [ABSTRACT FROM AUTHOR]

The nuclei 47Ca and 55Ti were populated in one-neutron knock-out reactions at relativistic energies. Momentum distributions of the residual nuclei as well as γ-ray spectra were measured at the GSI fragment separator (FRS). Preliminary results of the ongoing analysis including cross sections and spin/parity assignments are presented. [ABSTRACT FROM AUTHOR]

Spallation reactions are important due to their applications in various fields such as astrophysics, neutron sources, accelerator driven systems, and production of radioactive beams. To improve our understanding of the spallation mechanism a complete experiment, called SPALADIN, has been proposed, which aims at measuring as exclusively as possible the final states of the spallation reaction. This experiment has been performed at GSI using the spallation reactions 56Fe+p and 12C+p in reverse kinematics at 1 A GeV. The detection of the evaporation residues is performed with the ALADIN magnet and various detectors. The detection in coincidence of all the characteristics (type and energy) of the evaporation particles (neutrons and charged ones) and of the heavy residue should permit the reconstruction of the remnant prior to evaporation in mass, charge, and excitation energy. It will then be possible to test the modelisation of the first stage of the reaction. Furthermore it will allow study of the models describing the various decay modes of the primary residue like evaporation or Fermi break-up mechanisms for the lighter systems independently of the models of the first stage of the spallation reaction. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The ground state structure of the near drip-line 23O nucleus and neutron-rich 17,21O isotopes has been investigated at GSI via exclusive measurements of one-neutron Coulomb breakup reactions with a Pb target using secondary beams of the corresponding projectiles at 400–600 MeV/u. Differential cross sections for electromagnetic dissociation have been measured and compared with the calculated ones in a direct breakup model. The cross section dσ/dE* (excitation energy E*), further differentiated according to the observed (excited) states of the remaining nucleus, provides spectroscopic information on the ground state of these nuclei. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

One-nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of several neutron-rich isotopes in the sd-shell. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after one-nucleon removal cross-sections were measured. The relative contributions of the remaining fragments in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. The interesting case of 23O will be directly address. The interpretation of our experimental results in the framework of a simple theoretical model will favours a spin and parity assignment of 1/2+ for the 23O ground state in agreement with shell model predictions. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The availability of fast radioactive beams offers the possibility for studies of E1-strength in projectiles via Coulomb excitation. Theoretical calculations predict that a significant fraction of this strength is shifted towards lower excitation energies in neutron-rich systems (e.g., [1]). At the NSCL, virtual photon scattering was used to probe the discrete structure of both [sup 18]O and [sup 20]O for levels in the region between 1 and 8 MeV. Two 1[sup -] levels at 5.35(10) and 6.85(5) MeV were observed for the first time in [sup 20]O [2]. The observed γ-ray spectrum for [sup 20]O is, in fact, dominated by transitions resulting from E1 excitations to these states. The extracted B(E1) ↑ values of ∼0.062(16) e²fm² and ∼0.035(9) e&sup22fm² for the 5.35 and 6.85 MeV levels, respectively, are larger than shell model calculations predict [3, 4]. Such large dipole strengths are not observed for low-lying 1[sup -] states in [sup 18]O, indicating a shift of dipole strength towards lower energies as one approaches the neutron drip-line. [ABSTRACT FROM AUTHOR]

First coincidence data on the 56Fe+p reaction at 1 A.GeV in inverse kinematics obtained with the SPALADIN setup are presented. Data on charge correlations of cluster emissions occurring in the spallation reaction are shown and compared to spallation codes with the aim of discriminating between the various de-excitation mechanisms. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]