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Träfflista för sökning "WFRF:(Jonson Björn) srt2:(2005-2009);pers:(Krucken R.)"

Sökning: WFRF:(Jonson Björn) > (2005-2009) > Krucken R.

  • Resultat 1-9 av 9
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1.
  • Kanungo, R., et al. (författare)
  • One-Neutron Removal Measurement Reveals O-24 as a New Doubly Magic Nucleus
  • 2009
  • Ingår i: Physical Review Letters. - 0031-9007. ; 102:15
  • Tidskriftsartikel (refereegranskat)abstract
    • The first measurement of the momentum distribution for one-neutron removal from O-24 at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s(1/2) neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that O-24 is a new doubly magic nucleus.
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2.
  • Maierbeck, P., et al. (författare)
  • Probing the single particle structure around Ca-54 with one-neutron knock-out
  • 2008
  • Ingår i: Frontiers in Nuclear Structure, Astrophysics, and Reactions. - 0094-243X. ; 1012, s. 89-93453
  • Konferensbidrag (refereegranskat)abstract
    • The nuclei Ca-47 and Ti-55 were populated in one-neutron knock-out reactions at relativistic energies. Momentum distributions of the residual nuclei as well as gamma-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.
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3.
  • Maierbeck, P., et al. (författare)
  • Structure of 55Ti from relativistic one-neutron knockout
  • 2009
  • Ingår i: Physics Letters B. - 0370-2693. ; 675:1, s. 22-27
  • Tidskriftsartikel (refereegranskat)abstract
    • Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.
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4.
  • Niedermaier, O, et al. (författare)
  • "Safe" Coulomb excitation of Mg-30
  • 2005
  • Ingår i: Physical Review Letters. - 0031-9007. ; 94:17
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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5.
  • Niedermaier, O, et al. (författare)
  • The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE
  • 2005
  • Ingår i: Nuclear Physics A. ; 752, s. 273-278
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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6.
  • Nociforo, C., et al. (författare)
  • Shell Closure N=16 in O-24
  • 2009
  • Ingår i: Nuclear Structure and Dynamics '09. - 0094-243X. ; 1165, s. 90-93461
  • Konferensbidrag (refereegranskat)abstract
    • 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 O-24 is a doubly magic nucleus (Z=8, N=16). Predictions within the shell model calculation for the O-23,O-24 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.
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7.
  • Rodriguez-Tajes, C., et al. (författare)
  • Neutron Knockout at Relativistic Energies across the Psd Shell
  • 2009
  • Ingår i: Acta Physica Polonica B. - 0587-4254. ; 40:3, s. 859-862
  • Konferensbidrag (refereegranskat)abstract
    • One-neutron knockout reactions have been studied in a systematic way for a set of neutron-rich projectiles. The goal of the experiment, performed at GSI, was to explore the evolution of the nuclear structure close to the neutron drip line, in the region between C and Al. The momentum distributions of the surviving fragments and the cross-sections of the knockout process have been measured and used as physical observables. This report focuses on oxygen and nitrogen isotopes around N = 14. In particular, we discuss the Case Of N-12, for which the mentioned observables have been determined for the first time. We will consider O-23, already studied in earlier experiments, as a reference.
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8.
  • Scheit, H., et al. (författare)
  • Coulomb excitation of neutron-rich beams at REX-ISOLDE
  • 2005
  • Ingår i: European Physical Journal A. - 1434-6001. ; 25:Suppl. 1, s. 397-402
  • Konferensbidrag (refereegranskat)abstract
    • After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium gamma spectrometer MINIBALL.
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9.
  • Stefanescu, I, et al. (författare)
  • Coulomb Excitation of 68,70Cu: First Use of Postaccelerated Isomeric Beams
  • 2007
  • Ingår i: Physical Review Letters. ; 98:12, s. 122701-4
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2nu1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N[approximate]40.
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