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Träfflista för sökning "WFRF:(Schrieder G.) srt2:(2000-2004)"

Sökning: WFRF:(Schrieder G.) > (2000-2004)

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1.
  • Habs, D., et al. (författare)
  • The REX-ISOLDE project
  • 2000
  • Ingår i: Hyperfine Interactions. - 0304-3843. ; 129:1-4, s. 43-66
  • Tidskriftsartikel (refereegranskat)abstract
    • The Radioactive Beam Experiment REX-ISOLDE [1-3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.
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2.
  • Aleksandrov, D., et al. (författare)
  • Halo excitations in fragmentation of He-6 at 240 MeV/u on carbon and lead targets
  • 2000
  • Ingår i: Nuclear Physics A. - 0375-9474. ; 669:1-2, s. 51-64
  • Tidskriftsartikel (refereegranskat)abstract
    • Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while the dipole mode is dominating in Coulomb dissociation. Neither theoretically predicted new resonance states in He-6 nor nuclear excitation of a dipole mode were found. Direct evidence has been obtained for strong suppression of Coulornb post-acceleration in direct Coulomb breakup in a lead target.
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3.
  • Nilsson, T, et al. (författare)
  • RES-ISOLDE - Post-accelerated radioactive beams at CERN-ISOLDE
  • 2001
  • Ingår i: APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY. - American Institute of Physics. - 1551-7616 .- 0094-243X. ; 576, s. 265-268
  • Konferensbidrag (refereegranskat)abstract
    • The ISOLDE RIB-facility at CERN has today been producing a vast range of radioactive beams since more than 30 years. The low-energy beams of ISOLDE will be complemented by a post-accelerator, REX-ISOLDE, currently being assembled. In order to convert the pseudo-DC, singly-charged beam from the ISOLDE mass separators into a cooled and bunched beam at higher charge states, a novel scheme of trapping, cooling and charge-state breeding has been devised, using a linear Penning trap and an Electron Beam Ion Source (EBIS). This allows for subsequent acceleration by a short, cost-effective LINAC consisting of an RFQ, an IH-structure and three seven-gap resonators, reaching 0.8 - 2.2 MeV/u. The installation of REX-ISOLDE is well underway and the first post accelerated radioactive beams are expected to be obtained during late 2000.
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4.
  • Markenroth Bloch, Karin, et al. (författare)
  • 8He-6He: a comparative study of nuclear fragmentation reactions
  • 2001
  • Ingår i: Nuclear Physics, Section A. - Elsevier. - 0375-9474. ; 679:3-4, s. 462-480
  • Tidskriftsartikel (refereegranskat)abstract
    • Dissociation of 227 MeV/u 8He in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (6He+n) as well as diffractive dissociation and inelastic scattering into the (6He+2n) channel. The data are compared with corresponding results from the well-known halo nucleus 6He. In both cases it is found that neutron knock-out is the dominating reaction channel. The relative energy spectrum (6He+n) shows a structure, which is interpreted as being due to the Iπ=3/2− resonance in the 7He ground state with about equal contribution from its Iπ=1/2− spin–orbit partner. The 7He resonance shows a spin alignment similar to that observed in 5He, but with a smaller anisotropy indicating that the structure of the 8He ground state is more complicated than that of 6He. The data in the (6He+2n) channel were used to identify resonances in the excitation energy spectrum of 8He. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2+ and 1−, respectively.
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5.
  • Meister, M., et al. (författare)
  • 8He-6He: a comparative study of electromagnetic fragmentation reactions
  • 2002
  • Ingår i: Nuclear Physics A. - Elsevier. ; 700:1-2, s. 3-16
  • Tidskriftsartikel (refereegranskat)abstract
    • Dissociation of a 227 MeV/u 8He beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus 6He. Coulomb–nuclear interference in the inelastic channel gives evidence for a Iπ=1− resonance in 8He at Ex=4.15 MeV. The deduced B(E1) value of 0.38±0.07 e2 fm2 indicates a uniform distribution of the four neutrons around the greek small letter alpha-particle core.
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6.
  • Meister, M, et al. (författare)
  • Evidence for a new low-lying resonance state in 7He
  • 2002
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 88:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Low-lying resonance states in 7He(6He+n), formed after fragmentation reactions of a 227 MeV/nucleon 8He beam on a carbon target, have been studied. Coincidences between 6He nuclei and neutrons, corresponding to the one-neutron knockout channel in 8He, were selected. The relative energy spectrum in the 6He+n system shows a structure, which is interpreted as the 7He ( Ipi = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the 6He+n system and a width of Gamma = 0.15(8) MeV overlapping with an excited ( Ipi = 1/2(-)) state observed at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV.
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7.
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8.
  • Simon, H., et al. (författare)
  • Two- and three-body correlations: breakup of halo nuclei
  • 2004
  • Ingår i: Nuclear Physics, Section A. - Elsevier. - 0375-9474. ; 734:5, s. 323-326
  • Tidskriftsartikel (refereegranskat)abstract
    • Nuclear knockout reactions at relativistic energies provide a sensitive tool to determine the ground state properties of nuclei close to the drip line. Studies with kinematically complete measurements reveal the initial correlations in the reacting systems and yield spectroscopic information on the continuum states populated in the decay channel. The coincident data of charged fragments and neutrons as well allows to unveil the possible influence of the reaction mechanism to the interpretation of the measurements. Two- and three-body correlations can be observed and allow to determine the internal momentum distributions of halo nuclei as well as the assignment of spins and parities to the populated states in the intermediate systems in the breakup process.
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9.
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10.
  • Cortina-Gil, D., et al. (författare)
  • Experimental evidence for the 8B ground state configuration
  • 2002
  • Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 529:1-2, s. 36-41
  • Tidskriftsartikel (refereegranskat)abstract
    • The 7Be fragments produced in one-proton removal from relativistic 8B nuclei of 936 MeV/nucleon in a carbon target have been detected in coincidence with γ rays emitted by these fragments at the reaction target. It is found that 13 ± 3% of the 7Be fragments are released in the 429 keV excited state, 7Be*, which gives direct experimental information on the ground state configuration of 8B. The longitudinal momentum distributions (p∥) of the 7Be fragments have been measured, both inclusively and in coincidence with de-excitation γ-rays from 7Be*. The widths and cross sections of the respective p∥ distributions are compared with calculations in a three-body cluster model.
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