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Träfflista för sökning "LAR1:cth ;pers:(Nilsson Thomas 1965);pers:(Huyse M.);pers:(Franchoo S.)"

Sökning: LAR1:cth > Nilsson Thomas 1965 > Huyse M. > Franchoo S.

  • Resultat 1-9 av 9
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1.
  • Cederkall, J., et al. (författare)
  • Sub-Barrier Coulomb Excitation of ^110Sn and Its Implications for the ^100Sn Shell Closure
  • 2007
  • Ingår i: Physical Review Letters. ; 98:17
  • Tidskriftsartikel (refereegranskat)abstract
    • The first excited 2(+) state of the unstable isotope Sn-110 has been studied in safe Coulomb excitation at 2.82 MeV/u using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, B(E2 : 0(+) -> 2(+)) 0.220 +/- 0.022e(2) b(2), strengthens the observation of the evolution of the B(E2) values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of Sn-108. It implies that the trend of these reduced transition probabilities in the even-even Sn isotopes is not symmetric with respect to the midshell mass number A = 116 as Sn-100 is approached.
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2.
  • de Walle, J. V., et al. (författare)
  • Coulomb excitation of the N=50 nucleus Zn-80
  • 2008
  • Ingår i: Frontiers in Nuclear Structure, Astrophysics, and Reactions. - 0094-243X. ; 1012, s. 291-295453
  • Konferensbidrag (refereegranskat)abstract
    • Neutron rich Zinc isotopes, including the N=50 nucleus Zn-80, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2(+) states. For the first time, an excited state in Zn-80 was observed and the 2(1)(+) state in Zn-78 was established. The measured B(E2,2(1)(+) -> 0(1)(+)) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus Ni-78.
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3.
  • Kester, O., et al. (författare)
  • Accelerated radioactive beams from REX-ISOLDE
  • 2003
  • Ingår i: Nuclear Instruments & Methods in Physics Research, Section B. - Beam Interactions with Materials and Atoms. - 0168-583X. ; 204, s. 20-30
  • Konferensbidrag (refereegranskat)abstract
    • In 2001 the linear accelerator of the Radioactive beam EXperiment (REX-ISOLDE) delivered for the first time accelerated radioactive ion beams, at a beam energy of 2 MeV/u. REX-ISOLDE uses the method of charge-state breeding, in order to enhance the charge state of the ions before injection into the LINAC. Radioactive singly-charged ions from the on-line mass separator ISOLDE are first accumulated in a Penning trap, then charge bred to an A/q < 4.5 in an electron beam ion source (EBIS) and finally accelerated in a LINAC from 5 keV/u to energies between 0.8 and 2.2 MeV/u. Dedicated measurements with REXTRAP, the transfer line and the EBIS have been carried out in conjunction with the first commissioning of the accelerator. Thus the properties of the different elements could be determined for further optimization of the system. In two test beam times in 2001 stable and radioactive Na isotopes (Na-23-Na-26) have been accelerated and transmitted to a preliminary target station. There Ni-58- and Be-9- and H-2-targets have been used to study exited states via Coulomb excitation and neutron transfer reactions. One MINIBALL triple cluster detector was used together with a double sided silicon strip detector to detect scattered particles in coincidence with gamma-rays. The aim was to study the operation of the detector under realistic conditions with gamma-background from the beta-decay of the radioactive ions and from the cavities. Recently for efficient detection eight tripple Ge-detectors of MINIBALL and a double sided silicon strip detector have been installed. We will present the first results obtained in the commissioning experiments and will give an overview of realistic beam parameters for future experiments to be started in the spring 2002.
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4.
  • Mucher, D., et al. (författare)
  • Shell Structure and Shape Changes in Neutron Rich Krypton Isotopes
  • 2009
  • Ingår i: Capture Gamma-Ray Spectroscopy and Related Topics. - 0094-243X. ; 1090, s. 587-588672
  • Konferensbidrag (refereegranskat)abstract
    • B(E2;2(1)(+) -> 0(1)(+)) values have been measured for the unstable nuclei Kr-88 (N=52) and Kr-92 (N=56) using projectile Coulomb excitation at ISOLDE, CERN. With this experiment the local maximum in E(2(1)(+)) in Kr-92 and the role of the N=56 subshell closure can be studied.
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5.
  • 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 &#947; 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 &#947;-ray yields the B(E2;0(gs)(+)&RARR; 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.
  • 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 &#947; 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 &#947;-ray yields the B(E2;0(gs)(+)&RARR; 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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7.
  • 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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8.
  • 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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9.
  • Walle, J. Van de, et al. (författare)
  • Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 2[sub 1][sup +] State in [sup 80]Zn
  • 2007
  • Ingår i: Physical Review Letters. ; 99:14
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 21+ state in 78Zn could be firmly established and for the first time the 2+-->01+ transition in 80Zn was observed at 1492(1) keV. B(E2,21+-->01+) values were extracted for 74,76,78,80Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.
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